[Federal Register Volume 76, Number 198 (Thursday, October 13, 2011)]
[Proposed Rules]
[Pages 63720-63762]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-25818]



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Vol. 76

Thursday,

No. 198

October 13, 2011

Part II





Department of the Interior





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Fish and Wildlife Service





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50 CFR Part 17





Endangered and Threatened Wildlife and Plants; 12-Month Finding on a 
Petition To List a Distinct Population Segment of the Red Tree Vole as 
Endangered or Threatened; Proposed Rule

  Federal Register / Vol. 76 , No. 198 / Thursday, October 13, 2011 / 
Proposed Rules  

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R1-ES-2008-0086; 92210-5008-3922-10-B2]


Endangered and Threatened Wildlife and Plants; 12-Month Finding 
on a Petition To List a Distinct Population Segment of the Red Tree 
Vole as Endangered or Threatened

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 12-month petition finding.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a 
12-month finding on a petition to list a distinct population segment of 
the red tree vole (Arborimus longicaudus) as endangered or threatened 
and to designate critical habitat under the Endangered Species Act of 
1973, as amended (Act). The Petition provided three listing options for 
the Service to consider: Listing the dusky tree vole subspecies 
throughout its range; listing the North Oregon Coast population of the 
red tree vole (Arborimus longicaudus) as a distinct population segment 
(DPS); or listing the red tree vole because it is endangered or 
threatened in a significant portion of its range.
    After review of the best available scientific and commercial 
information, we have determined that listing the North Oregon Coast 
population of the red tree vole as a DPS is warranted. However, the 
development of a proposed listing rule is precluded by higher priority 
actions to amend the Lists of Endangered and Threatened Wildlife and 
Plants. Upon publication of this 12-month petition finding, we will add 
this DPS of the red tree vole to our candidate species list. We will 
develop a proposed rule to list this DPS of the red tree vole as our 
priorities allow. We will make any determination on critical habitat 
during development of the proposed listing rule. In any interim period, 
we will address the status of the candidate taxon through our annual 
Candidate Notice of Review (CNOR).

DATES: This finding was made on October 13, 2011.

ADDRESSES: This finding is available on the Internet at http://www.regulations.gov. Supporting documentation we used in preparing this 
finding is available for public inspection, by appointment, during 
normal business hours at the U.S. Fish and Wildlife Service, Oregon 
Fish and Wildlife Office, 2600 S.E. 98th Ave., Suite 100, Portland, OR 
97266; telephone 503-231-6179; facsimile 503-231-6195. Please submit 
any new information, materials, comments, or questions concerning this 
finding to the above street address.

FOR FURTHER INFORMATION CONTACT: Paul Henson, Ph.D., Field Supervisor, 
U.S. Fish and Wildlife Service, Oregon Fish and Wildlife Office (see 
ADDRESSES section). If you use a telecommunications device for the deaf 
(TDD), call the Federal Information Relay Service (FIRS) at 800-877-
8339.

SUPPLEMENTARY INFORMATION:

Background

    Section 4(b)(3)(B) of the Endangered Species Act (Act) (16 U.S.C. 
1531 et seq.) requires that, for any petition to revise the Federal 
Lists of Endangered and Threatened Wildlife and Plants that contains 
substantial scientific and commercial information indicating that 
listing may be warranted, we make a finding within 12 months of the 
date of receipt of the petition on whether the petitioned action is: 
(1) Not warranted; (2) warranted; or (3) warranted, but the immediate 
proposal of a regulation implementing the petitioned action is 
precluded by other pending proposals to determine whether species are 
endangered or threatened, and expeditious progress is being made to add 
or remove qualified species from the Federal Lists of Endangered and 
Threatened Wildlife and Plants. Section 4(b)(3)(C) of the Act requires 
that we treat a petition for which the requested action is found to be 
warranted but precluded as though resubmitted on the date of such 
finding; that is, requiring a subsequent finding to be made within 12 
months. We must publish these 12-month findings in the Federal 
Register.

Previous Federal Actions

    On June 22, 2007, we received a petition dated June 18, 2007, from 
the Center for Biological Diversity and six other organizations and 
individuals (hereafter, ``the petitioners''), requesting that we list 
the dusky tree vole as an endangered or threatened species and 
designate critical habitat. The petitioners requested that if we found 
the dusky tree vole was not a listable entity as a subspecies, we 
either list the North Oregon Coast population of the red tree vole as a 
distinct population segment (DPS), or list the red tree vole because it 
is endangered or threatened in a significant portion of its range, 
including the North Oregon Coast population. On September 26, 2007, we 
sent a letter to Noah Greenwald, Center for Biological Diversity, 
acknowledging our receipt of the petition and providing our 
determination that emergency listing was not warranted for the species 
at that time.
    On October 28, 2008, we published a 90-day finding for the dusky 
tree vole in the Federal Register (73 FR 63919). We found that the 
petition presented substantial information indicating that listing one 
of the following three entities as endangered or threatened may be 
warranted:
    (1) The dusky tree vole subspecies of the red tree vole;
    (2) The North Oregon Coast DPS of the red tree vole; or
    (3) The red tree vole because it is endangered or threatened in a 
significant portion of its range.
    As a result of that finding, we also initiated a status review of 
the species, including an evaluation of the North Oregon Coast 
population of red tree vole and the red tree vole throughout its range. 
This notice constitutes our 12-month finding for the petition to list 
the dusky tree vole as endangered or threatened.

Species Information

    As a putative subspecies, the dusky tree vole is a member of the 
red tree vole taxon. Some of the scientific literature is specific to 
the ``dusky tree vole,'' but much of it describes the red tree vole and 
does not distinguish among subspecies. For that reason, available 
information on the red tree vole is presented below with the assumption 
that it also applies to the dusky tree vole. If the information source 
makes distinctions between the two, they are noted, as appropriate. 
Published literature on the red tree vole also includes work conducted 
on the closely related Sonoma tree vole (Arborimus pomo). Prior to 
1991, these taxa were both considered red tree vole (Johnson and George 
1991, entire). Where pertinent information is lacking or limited for 
the red tree vole, information on the Sonoma tree vole is presented 
because there have been no ecological or life-history differences noted 
for the two species (Smith et al. 2003, p. 187).
    Tree voles are small, mouse-sized rodents that live in conifer 
forests and spend almost all of their time in the tree canopy. Tree 
voles rarely come to the ground, and do so only to move briefly between 
trees. They are one of the few animals to persist on a diet of conifer 
needles, which is their principal food. When eating, tree voles strip 
away the resin ducts within conifer needles and eat the remaining 
portion; resin ducts contain terpenoid chemicals that make

[[Page 63721]]

them unpalatable to most species. Red tree voles live singly (or with 
young, in the case of females) in nests made of vegetation and other 
materials. Swingle (2005, p. 2) summarized the sizes of red tree vole 
nests as ranging from ``very small ephemeral structures about the size 
of a grapefruit, to large old maternal nests that may be nearly as 
large as a bushel basket and completely encircle the trunk of the tree 
(Taylor 1915; Howell 1926; Verts and Carraway 1998).'' Nests of females 
tend to be larger than those of males. Males and females live separate 
lives once leaving the nest, only coming together to breed. Further 
details of the life-history characteristics of tree voles are presented 
below.

Taxonomy and Description

    Tree voles are less than 8.2 inches (in) (209 millimeters (mm)) 
long and weigh up to 1.7 ounces (oz) (49 grams (g)) (Hayes 1996, p. 1; 
Verts and Carraway 1998, p. 301; Forsman 2010, pers. comm.). Pelage 
(fur) color ranges from brownish red to bright brownish-red or orange-
red (Maser et al. 1981, p. 201). The darker coat color has been 
attributed to the dusky tree vole (Bailey 1936, p. 198; Maser et al. 
1981, p. 201). Melanistic (all black) forms of the dusky (Hayes 1996, 
p. 1) and red tree vole (Swingle 2005, p. 46), as well as cream-colored 
red tree voles (Swingle 2005, p. 82), rarely occur.
    Howell (1926, p. 35) described several physical differences between 
voles described as dusky tree voles and red tree voles. These 
differences include coat color, as well as skull and dental 
characteristics. However, Howell (1926, p. 34) based his description of 
the red tree vole on the observations of 40 tree voles, 32 of which 
were from California. At least 28 of the California tree voles were 
collected from Carlotta, Humboldt County, within the range of what is 
now considered the Sonoma tree vole (Howell 1926, p. 41; Blois and 
Arbogast 2006, pp. 953-956). Howell's description of the red tree vole 
was therefore based on a collection that was actually comprised 
primarily of Sonoma tree voles, rendering the comparison to dusky tree 
voles of questionable value.
    The taxonomic history of red and dusky tree voles is complex; a 
comprehensive description can be found in Miller et al. (2010, pp. 64-
65). The red tree vole was first described from a specimen collected in 
Coos County, Oregon (True 1890, pp. 303-304), and originally placed in 
the genus Phenacomys. The dusky tree vole was first described from a 
dead specimen found in Tillamook County and originally classified as a 
distinct species, P. silvicolus (Howell 1921, entire), later renamed P. 
silvicola (Miller 1924, p. 400). Taylor (1915, p. 156) established the 
subgenus Arborimus for tree voles, which Johnson (1968, p. 27; 1973, p. 
243) later proposed elevating to full generic rank, although this genus 
has not been universally adopted (e.g., Verts and Carraway 1998, pp. 
309-311). For the purpose of this finding, we use the generic 
classification, Arborimus, adopted by the petitioners.
    Johnson (1968, p. 27) concluded that analysis of blood proteins and 
hemoglobin from dusky and red tree voles ``* * * suggested combining 
the named forms of Arborimus into a single species * * *''. Hall (1981, 
p. 788) cited Johnson (1968, p. 27) as suggesting a ``subspecific 
relationship of the two taxa,'' and others have cited Johnson as well 
in supporting the classification of the dusky tree vole as a subspecies 
(e.g., Maser and Storm 1970, p. 64; Johnson and George 1991, p. 1). 
However, based on a lack of detectable genetic differences and a lack 
of consistently verifiable morphological differences between dusky and 
red tree voles, Bellinger et al. (2005, p. 207) suggested subspecific 
status of the dusky tree vole may not be warranted.
    Miller et al. (2006a, entire) analyzed mitochondrial DNA sequences 
from red tree voles throughout their range in Oregon. This study was 
not designed to address red tree vole taxonomy, but rather, how 
historical processes may have affected the genetic diversity and 
structure of the red tree vole across much of its range. The authors 
found significant genetic discontinuities based on unique haplotypes 
that result in three genetically distinct groupings of red tree voles. 
A primary discontinuity divided the red tree vole's range into a 
northern and a southern region in terms of genetic makeup as determined 
from mitochondrial DNA. Some overlap of these two genetic groups 
occurred, but in general, red tree voles north of Douglas and 
southeastern Lane Counties were genetically different from tree voles 
to the south (Miller et al. 2006a, Fig.1, pp. 146, 151-152). There are 
no known geographic or geological features that coincide with this 
genetic discontinuity that might explain this genetic break. The 
northern genetic group was further subdivided by a secondary 
discontinuity that coincided with the Willamette Valley, a non-forested 
barrier currently separating individuals in the northern Oregon Coast 
Range to the west from the Cascade Range to the east (Miller et al. 
2006a, Fig.1, pp. 146, 151-152).
    Although Miller et al. (2006a, entire) found genetic 
discontinuities in the red tree vole in Oregon, the authors did not 
comment on the taxonomic status of the species. Subsequent 
conversations with the geneticists who authored this paper indicated 
that the genetic differences described in Miller et al. (2006a, entire) 
were substantial enough to potentially warrant taxonomically 
classifying the three genetically distinct groups as separate 
subspecies if there were corresponding differences in other traits, 
such as behavior or morphology, to provide additional support (Miller 
and Haig 2009, pers. comm.). Recent review of external morphological 
characters by Miller et al. (2010, entire) did not distinguish dusky 
tree voles from red tree voles, but the authors noted that additional 
analysis of other physical characteristics (e.g., fur color) would be 
required to better determine the dusky tree vole's taxonomic status. 
The Integrated Taxonomic Information System (ITIS), a database 
maintained by a partnership of U.S., Canadian, and Mexican agencies, 
other organizations, and taxonomic specialists to provide 
scientifically credible taxonomic information, does not recognize the 
dusky tree vole as a subspecies of the red tree vole (information 
retrieved 15 March 2011, from the ITIS database). Wilson and Reeder 
(2005, entire) is the industry standard for mammalian taxonomy. 
Subspecies were not recognized until the most recent edition, published 
in 2005. Although Wilson and Reeder (2005, pp. 962-963) recognize the 
dusky tree vole as a subspecies, the more recent research on tree vole 
genetics and analyses attempting to clarify the taxonomic status of the 
dusky tree vole have only become available subsequent to that review, 
and therefore were not considered at the time that volume was 
published.

Range and Distribution

    Tree voles are endemic to the humid, coniferous forests of western 
Oregon and northwestern California (Maser 1966, p. 7). The red tree 
vole occurs in western Oregon from below the crest of the Cascade Range 
to the Pacific coast (Hayes 1996, p. 2; Verts and Carraway 1998, pp. 
309-310), with a geographic range covering approximately 16.3 million 
acres (ac) (6.6 million hectares (ha)) across multiple ownerships (USDA 
and USDI 2007, p. 287) (Figure 1).
BILLING CODE 4310-55-P

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[GRAPHIC] [TIFF OMITTED] TP13OC11.000

BILLING CODE 4310-55-C
    The southern boundary of the range of the red tree vole borders the 
range of the Sonoma tree vole, which Johnson and George (1991, p. 12) 
classified as a separate species from the red tree vole. Johnson and 
George (1991, pp. 11-12) suggested the break between the ranges of 
these two species was the Klamath Mountains along the Oregon-California 
border. Murray (1995, p. 26) considered the boundary between the two 
species to be the Klamath River in northwestern California. A recent 
mitochondrial DNA analysis supports the classification of tree voles in 
northwestern California (Del Norte County) as Arborimus longicaudus 
(Blois and Arbogast 2006, pp. 956, 958).
    The red tree vole has not been found north of the Columbia River 
(Verts and Carraway 1998, p. 309), but the actual northern limit of its 
historical distribution in northwestern Oregon is unclear. Within the 
Oregon Coast Range, the northernmost tree vole collection site was in 
the vicinity of Saddle Mountain in central Clatsop County (Verts and 
Carraway 1998, pp. 310, 546; Forsman and Swingle 2009, pers. comm.). 
Although no tree voles have been detected in recent search efforts in 
northern Clatsop and Columbia

[[Page 63723]]

Counties (Forsman and Swingle 2009, unpublished data), the area 
historically had extensive forests with large Douglas-fir (Pseudotsuga 
menziesii) and western hemlock (Tsuga heterophylla) trees conducive to 
tree vole habitat (Robbins 1997, pp. 205-206). Therefore, we believe it 
is reasonable to assume that tree voles were present in those areas 
prior to the late 1800s and early 1900s when virtually all old forests 
in the region were clear-cut or burned. The Columbia River was 
considered Oregon's most productive logging center in the late 1800s 
(Robbins 1997, p. 220), and it is likely that virtually all of the 
suitable tree vole habitat in Clatsop, Columbia, and Washington 
Counties was removed before tree vole occurrence could be recorded. 
Whether tree voles may persist undetected in Columbia County and 
northern Clatsop County is not known at this time; although not 
detected in the most recent search efforts, tree voles may be 
overlooked if they are sparsely distributed or few in number.
    Farther east, the red tree vole occurs in the Columbia River Gorge 
from Wahkenna Creek to Seneca Fouts State Park, 4 miles (mi) (6 
kilometers (km)) west of Hood River (Forsman et al. 2009b, p. 230). The 
red tree vole range had been described as west of the crest of the 
Cascade Range in Oregon (Corn and Bury 1986, p. 405). However, recent 
surveys have also found them just east of the Cascade Range crest, in 
the headwaters of the Lake Branch of Hood River, 19 mi (30 km) 
southwest of the town of Hood River (Forsman et al. 2009b, p. 227).
    Surveys conducted for red tree voles by the Forest Service and the 
Bureau of Land Management as part of the Survey and Manage program 
under the Northwest Forest Plan (NWFP) have provided additional 
information on the distribution of the red tree vole (USDA and USDI 
2007, p. 289). These surveys indicate red tree voles are uncommon and 
sparsely distributed in much of the northern Coast Range and northern 
Cascade Range of Oregon. Forsman et al. (2004, p. 300) reached the same 
conclusion based on remains of red tree voles in pellets of northern 
spotted owls (Strix occidentalis caurina), although data were sparse 
from the northern Oregon Coast Range compared to the rest of the red 
tree vole's range. Based on these surveys and data from owl pellets, 
the eastern limit of red tree vole distribution in southwestern Oregon 
appears to include forested areas in Josephine County and a narrow band 
along the western and northern edges of Jackson County (Forsman et al. 
2004, pp. 297-298; USDA and USDI 2007, p. 289).
    Red tree voles are generally restricted to lower elevation 
coniferous forests, although there are a few records of this species 
above 4,265 feet (ft) (1,300 meters (m)) (Manning and Maguire 1999, 
entire; Forsman et al. 2004, p. 300). Hamilton (1962, p. 503) suggested 
red tree voles may be limited to lower elevations because their nests 
do not provide adequate insulation during winter. Because tree voles 
are active throughout the year, it is also possible they are absent 
from high-elevation areas because they find it difficult to forage on 
limbs covered with snow and ice during winter (Forsman et al. 2004, p. 
300).
    The range of the putative dusky tree vole is less clear than that 
of the red tree vole. Johnson and George (1991, p. 12) described its 
range as restricted to the western slope of the Coast Range in 
Tillamook and Lincoln Counties. However, Maser (1966, p. 16) summarized 
collection and nest records for the dusky tree vole from locations east 
of the crest of the Coast Range down to the western edge of the 
Willamette Valley in Washington, Yamhill, Polk, Benton, and Lane 
Counties. Maser (2009, pers. comm.) believed the southern limit of the 
dusky tree vole to be in the vicinity of the Smith or Umpqua Rivers 
(western Douglas County) based on a shift in vole behavior and habitat 
type. Brown (1964, p. 648) mentioned four dusky tree vole museum 
specimens collected near Molalla in Clackamas County east of the 
Willamette Valley. Howell (1926, p. 34) referred to Stanley Jewett, a 
fellow naturalist, finding ``unmistakable evidence'' of red tree voles 
in old nests near Bonneville, in far eastern Multnomah County at the 
foot of the Cascade Range, and then goes on to say, ``Though this sign 
may possibly have been of longicaudus, it is considered more likely to 
have been of silvicola.'' However, he did not elaborate on why he 
concluded that it was indicative of the dusky tree vole. Maser (1966, 
p. 8) observed that tree voles historically collected north of Eugene 
and west of the Willamette Valley were typically classified as dusky 
tree voles, while those collected north of Eugene and east of the 
Willamette Valley were almost all identified as red tree voles.

Home Range and Dispersal

    The only published data on home range sizes and dispersal come from 
red tree voles radio-collared in the southern Coast Range and southern 
Cascades of Douglas County in southwestern Oregon (Swingle 2005, pp. 
51-63, 84-89; Swingle and Forsman 2009, entire). Of 45 radio-collared 
red tree voles, 18 had home ranges consisting of their nest tree and a 
few adjacent trees, whereas the remainder occupied up to 6 different 
nests spaced up to 532 ft (162 m) apart in different trees (Swingle and 
Forsman 2009, p. 277). Mean and median home ranges were 0.43 ac (0.17 
ha) and 0.19 ac (0.08 ha), respectively (Swingle and Forsman 2009, p. 
278). Home range sizes did not differ among gender, age, or among voles 
occurring in young (22-55 years old) versus old (110-260 years old) 
forests (Swingle and Forsman 2009, pp. 277-279). An unpublished study 
conducted by Brian Biswell and Chuck Meslow found mean male home ranges 
of 0.86 ac (0.35 ha) and mean female home ranges of 0.37 ac (0.15 ha) 
(Biswell and Meslow, unpublished data referenced in USDA and USDI 
2000b, p. 8). Dispersal distances of nine subadults ranged from 10 to 
246 ft (3 to 75 m) (Swingle 2005, p. 63). The longest known straight-
line dispersal distance was for a subadult male who traveled 1,115 ft 
(340 m) over the course of 40 days (Biswell and Meslow, unpublished 
data referenced in USDA and USDI 2000b, p. 8).

Habitat

    Red tree voles are found exclusively in conifer forests or in mixed 
forests of conifers and hardwoods (Hayes 1996, p. 3). Throughout most 
of their range, they are principally associated with Douglas-fir for 
foraging and nesting (Jewett 1920, p. 165; Bailey 1936, p. 195). 
However, their nests have also been documented in Sitka spruce (Picea 
sitchensis) (Jewett 1920, p. 165), grand fir (Abies grandis), western 
hemlock, Pacific yew (Taxus brevifolia), and non-conifers such as 
bigleaf maple (Acer macrophyllum) and golden chinquapin (Castanopsis 
chrysophylla) (Swingle 2005, p. 31). Hardwoods are generally not 
recognized as an important habitat component (USDA and USDI 2002, p. 
1). Tree vole nests are located in the forest canopy and are 
constructed from twigs and resin ducts discarded from feeding, as well 
as fecal pellets, lichens, dead twigs, and conifer needles (Howell 
1926, p. 46; Clifton 1960, pp. 53-60; Maser 1966, pp. 94-96; Gillesberg 
and Carey 1991, p. 785; Forsman et al. 2009a, p. 266). On the occasions 
when tree voles nest in non-conifers or snags, they are virtually 
always in trees that have limbs interconnected with adjacent live 
conifers where the voles can obtain food (Maser 1966, p. 78; Swingle 
2005, p. 31). Within the northern Oregon Coast Range, primarily in the 
Sitka spruce plant series (see Distinct Vertebrate Population Segment 
Analysis for plant

[[Page 63724]]

series description), tree vole diet and nest tree species selection 
favors western hemlock and Sitka spruce (Walker 1930, pp. 233-234; 
Forsman et al. 2008, Table 2; Forsman and Swingle 2009, pers. comm.; 
Maser 2009, pers. comm.), although some vole nests have been found in 
Douglas-fir in this plant series (Howell 1921, p. 99; Jewett 1930, pp. 
81-83; Forsman and Swingle 2009, pers. comm.).
    Based on their study of small mammal habitat associations in the 
Oregon Coast Range, Martin and McComb (2002, p. 262) considered red 
tree voles to be habitat specialists. In that study of forests of 
different patch types, red tree voles selected ``conifer large 
sawtimber patch types'' and landscapes that minimize fragmentation of 
mature conifer forest (Martin and McComb 2002, pp. 259, 261, 262). The 
vegetation classification scheme used by Martin and McComb (2002, p. 
257) defines the conifer large sawtimber patch type as forest patches 
with greater than 70 percent conifer composition, more than 20 percent 
canopy cover, and mean diameter at breast height (dbh) of greater than 
21 in (53.3 cm) (it should be noted that studies where researchers 
actually measured the canopy cover of stands used by red tree voles 
indicate the minimum canopy cover requirements of red tree voles are 
much higher, on the order of 53 to 66 percent (e.g., Swingle 2005, p. 
39)). Red tree voles were most abundant in contiguous mature conifer 
forest (unfragmented landscapes), and were negatively affected by 
increasing patch densities at the landscape scale (Martin and McComb 
2002, p. 262).
    Although red and Sonoma tree voles occur and nest in young forests 
(Jewett 1920, p. 165; Brown 1964, p. 647; Maser 1966, p. 40; Corn and 
Bury 1986, p. 404; Thompson and Diller 2002, entire; Swingle and 
Forsman 2009, p. 277), most comparisons of relative abundance from 
pitfall trapping and nest presence data show increased occurrence in 
older forests throughout the range of these species (Corn and Bury 
1986, p. 404; Corn and Bury 1991, pp. 251-252; Ruggiero et al. 1991, p. 
460; Meiselman and Doyle 1996, p. 38; Gomez and Anthony 1998, p. 296; 
Martin and McComb 2002, p. 261; Jones 2003, p. 29; Dunk and Hawley 
2009, entire). The occurrence of active nests in remnant older trees in 
younger stands indicates the importance of legacy structural 
characteristics (USDA and USDI 2002, p. 1). Although the bulk of the 
evidence points to forests with late-successional characteristics as 
important to the red tree vole, we lack specific data on the minimum 
size of trees or stands required to sustain populations of the red tree 
vole over the long term.
    There is no single description of red tree vole habitat and a wide 
variety of terms have been used to describe the older forest stands the 
tree voles tend to select (e.g., late-successional, old-growth, large 
conifer, mature, structurally complex). Where these terms appear in 
cited literature, or where specific ages are referred to, we refer to 
them in this analysis. Otherwise, we use the term ``older forest'' when 
collectively referring to these stand conditions. In using the term 
``older forest,'' we are not implying a specific stand age that 
represents tree vole habitat. Rather, we use the term to represent the 
mixture of old and large trees, multiple canopy layers, snags and other 
decay elements, understory development and biologically complex 
structure and composition often found in forests selected by tree 
voles.
    The most extensive and intensive analysis of red tree vole habitat 
associations on Federal lands throughout the vole's range found a 
strong association between tree vole nest presence and late-
successional and old-growth forest conditions (forests over 80 years 
old), with optimal red tree vole habitat being especially rare (Dunk 
and Hawley 2009, p. 632). Throughout their range on Federal land, the 
probability of red tree vole nest presence (Po) in the highest quality 
habitat (forest exhibiting late-successional structural 
characteristics) was 7 times more than expected based on the 
proportional availability of that habitat, whereas in lowest quality, 
early-seral forest conditions, Po was 7.6 times less than expected 
based on availability (Dunk and Hawley 2009, p. 632). In other words, 
red tree voles demonstrated strong selection for nesting in stands with 
older forest characteristics, even though that forest type was 
relatively rare across the landscape. Conversely, tree voles avoided 
nesting in younger stand types that were much more common across the 
landscape.
    Trees containing tree vole nests are significantly larger in 
diameter and height than those without nests (Gillesberg and Carey 
1991, p. 785; Meiselman and Doyle 1996, p. 36 for the Sonoma tree 
vole). Other forest conditions associated with red tree vole habitat 
include the number of large trees and variety of tree size distribution 
(Dunk and Hawley 2009, p. 632). Carey (1991, p. 8) suggested that tree 
voles seem especially well-suited to the stable conditions of old-
growth Douglas-fir forests (multi-layered stands over 200 years old, 
with decay elements). Old-growth trees may be optimum tree vole habitat 
because primary production is high and needles are concentrated, 
providing maximum food availability (Carey 1991, p. 8). In addition, 
old-growth canopy buffers weather changes and has high water-holding 
capacity, providing fresh foliage and a water source (Gillesberg and 
Carey 1991, pp. 786-787), as well as numerous cavities and large limbs 
that provide stable nest substrates.
    As noted above, tree voles can be found in younger forests, 
sometimes at fairly high densities (Howell 1926, pp. 41-45: Maser 1966, 
pp. 216-217; Thompson and Diller 2002, p. 95). It is not understood how 
younger forests influence the abundance, persistence, or dispersal of 
red tree voles. Carey (1991, p. 34) suggested younger forests were 
population sinks for red tree voles. Based on surveys in young forests 
(22-55 years old) and observations of radio-collared tree voles, 
Swingle (2005, pp. 78, 94) and Swingle and Forsman (2009, pp. 283-284) 
concluded that some young forests may be important habitat for tree 
voles, particularly in landscapes where old forests have largely been 
eliminated or currently exist in isolated patches. However, Swingle 
(2005, pp. 78, 94) cautioned against using the occasional presence of 
tree voles in young forests to refute the importance of old forest 
habitats to tree voles. Young forest stands may serve as interim 
habitat for tree voles and may provide connectivity between remnant 
patches of older forest, but whether younger forests are capable of 
supporting viable populations of tree voles over the long term is 
uncertain. The limited evidence available suggests that tree vole 
occupation of younger forest stands may be relatively short-lived 
(Diller 2010, pers. comm.) or intermittent (Hopkins 2010, pers. comm.).
    After weighing all of the best available information, we conclude 
that although red tree voles may use younger forest types to some 
degree, the preponderance of evidence suggests red tree voles 
demonstrate strong selection for forests with older forest conditions, 
as well as contiguous forest conditions. Whether tree voles can 
potentially persist in younger forests over the long term is unknown 
(USDA and USDI 2007, p. 291). However, although the data are limited, 
the available evidence suggests that red tree voles likely do not 
maintain long-term or consistent populations in younger stands (Diller 
2010, pers. comm.; Hopkins 2010, pers. comm.). There is a relatively 
large body of evidence, on the other hand, that red tree voles exhibit 
strong selection for areas of contiguous habitat exhibiting

[[Page 63725]]

conditions characteristics of older, mature forests (Corn and Bury 
1986, p. 404; Corn and Bury 1991, pp. 251-252; Ruggiero et al. 1991, p. 
460; Meiselman and Doyle 1996, p. 38; Gomez and Anthony 1998, p. 296; 
Martin and McComb 2002, p. 261; Jones 2003, p. 29; Dunk and Hawley 
2009, entire). We therefore further conclude that unfragmented forests 
with late-successional characteristics are thus most likely to provide 
for the long-term persistence of the species, and in this finding we 
consider these older forest types as representative of high-quality 
habitat for the red tree vole.
    Tree voles may tolerate some forest fragmentation, but the point at 
which forest gaps become large enough to impede their movements or 
successful dispersal is not known. Howell (1926, p. 40) suggested that 
``considerable'' expanses of land without suitable trees are a barrier 
to tree vole movements. However, as noted earlier, known dispersal 
distances for red tree voles are quite short, ranging from 10 to 246 ft 
(3 to 75 m) (Swingle 2005, p. 63), with 1,115 ft (340 m) being the 
longest known dispersal distance (Biswell and Meslow, unpublished data 
referenced in USDA and USDI 2000b, p. 8). This suggests that relatively 
small distances, roughly less than 1,200 ft (366 m) between forest 
patches, may serve as effective barriers to dispersal or recolonization 
for red tree voles. Radio-collared tree voles crossed logging roads, 
first-order streams, and canopy gaps up to 82 ft (25 m) wide (Biswell 
and Meslow, unpublished data referenced in USDA and USDI 2000b, p. 8; 
Swingle and Forsman 2009, p. 283). Some of these crossings occurred on 
multiple occasions by a single vole. This suggests that ``small forest 
gaps'' (Swingle 2005, p. 79) may not greatly impair tree vole movement, 
but increasing gap size may be expected to limit tree vole movement. In 
addition, Swingle (2005, p. 79) suggested that the necessity of 
descending to the ground to cross openings may reduce survival. There 
are three records of red tree voles captured in clearcuts (Borrecco 
1973, pp. 34, 36; Corn and Bury 1986, pp. 404-405; Verts and Carraway 
1998, p. 310), in one case over 656 ft (200 m) from the forest edge. In 
two of these instances, the authors suggested the individuals were most 
likely in the act of dispersing.
    In summary, based on our evaluation of the best scientific and 
commercial data available, as detailed above, for the purposes of this 
finding we consider older forests with late-successional 
characteristics to represent high-quality habitat for red tree voles, 
and younger forests in early-seral condition to represent low-quality, 
transitional habitat for red tree voles. In addition, we consider it 
likely that younger forests only play a role as interim, low-quality 
habitat for red tree voles if they occur in association with older 
forest patches or remnants.

Reproduction

    Red tree vole litter sizes are among the smallest compared to other 
rodents of the same subfamily, averaging 2.9 young per litter (range 1 
to 4) (Maser et al. 1981, p. 205; Verts and Carraway 1998, p. 310). 
Clifton (1960, pp. 119-120) reported that captive tree voles became 
sexually mature at 2.5 to 3.0 months of age. Females breed throughout 
the year, with most reproduction occurring between February and 
September (Swingle 2005, p. 71). Red tree voles are capable of breeding 
and becoming pregnant immediately after a litter is born (Clifton 1960, 
p. 130; Hamilton 1962, pp. 492-495; Brown 1964, pp. 647-648), resulting 
in the potential for females to have two litters of differently aged 
young in their nests (Swingle 2005, p. 71; Forsman et al. 2009a, p. 
270). Captive tree voles may have litters just over a month apart 
(Clifton 1960, p. 130). Forsman et al. (2009a, p. 270) observed two 
female voles in the wild that produced litters at 30 to 35 day 
intervals. Young tree voles develop more slowly than similar-sized 
rodents of the same subfamily (Howell 1926, pp. 49-50; Maser et al. 
1981, p. 205), first exiting the nest at 30 to 35 days old, and not 
dispersing until they are 47 to 60 days old (Swingle 2005, p. 63; 
Forsman et al. 2009a, pp. 268-269).

Diet

    Tree voles are unique in that they feed exclusively on conifer 
needles and the tender bark of twigs that they harvest from conifers. 
In most of their range, they feed primarily on Douglas-fir (Howell 
1926, p. 52; Benson and Borell 1931, p. 230; Maser et al. 1981, p. 
205). In portions of the northern coastal counties of Oregon (Lincoln, 
Tillamook, and Clatsop), tree voles also consume needles from western 
hemlock and Sitka spruce, and in some parts of their range they feed on 
grand fir, bishop pine (Pinus muricata), and introduced Monterrey pine 
(P. radiata) (Jewett 1920, p. 166; Howell 1926, pp. 52-53; Walker 1930, 
p. 234; Wooster and Town 2002, pp. 182-183; Forsman and Swingle 2009, 
pers. comm.; Swingle 2010, pers. comm.). Conifer needles contain 
filamentous resin ducts that are filled with terpenoids, chemicals that 
serve as defensive mechanisms for trees by making the leaves 
unpalatable. Tree voles have adapted to their diet of conifer needles 
by stripping away these resin ducts and eating the more palatable 
portion of the needle (Benson and Borell 1931, pp. 228-230; Perry 1994, 
pp. 453-454; Maser 1998, pp. 220-221; Kelsey et al. 2009, entire). 
Resin ducts typically run the length of the needle, but may be located 
in different portions of the needle, depending on the tree species; 
this forces the tree vole to behave differently depending on the tree 
species on which they forage. As an example, the resin ducts in 
Douglas-fir needles are located along the outer edges of the needle, so 
tree voles remove the outside edge and consume the remaining middle 
portion of the needle. Conversely, the resin ducts of western hemlock 
are located away from the outside edges along the midline of the 
needle. Thus, voles foraging on hemlock needles will consume the outer 
edge of the needle and discard the center (Clifton 1960, pp. 35-45; 
Forsman and Swingle 2009, pers. comm.; Kelsey et al. 2009, entire; 
Maser 2009, pers. comm.).
    Within the Sitka spruce plant series of the northern Oregon Coast 
Range of Oregon, tree voles appear to prefer, and perhaps require, a 
diet of western hemlock and Sitka spruce needles (Walker 1930, p. 234; 
Forsman and Swingle 2009, pers. comm.; Maser 2009, pers. comm.;). Voles 
in the Sitka spruce plant series rarely forage on Douglas-fir, even 
where it is available; foraging on Douglas-fir only becomes more 
evident where the Sitka spruce plant series transitions into the 
adjacent western hemlock series (Forsman and Swingle 2009, pers. comm.; 
Forsman and Swingle 2009, unpublished data). Maser (2009, pers. comm.) 
observed that tree voles adapted to a diet of western hemlock starved 
to death in captivity because they would not eat the Douglas-fir 
needles they were offered. Because the resin ducts of western hemlock, 
Sitka spruce, and Douglas-fir needles are in different locations on the 
needle, their removal requires a different behavior depending on which 
species is being eaten (Clifton 1960, pp. 35-49; Kelsey et al. 2009, 
entire). Maser (2009, pers. comm.) suspected that voles raised in 
stands of western hemlock never learned the required behavior for 
eating Douglas-fir, although Walker (1930, p. 234) observed a captive 
vole raised on hemlock needles that preferred hemlock but would eat fir 
or spruce in the absence of hemlock. Conversely, voles taken from 
Douglas-fir stands have been observed to eat both Douglas-fir and 
western hemlock in captivity (Clifton

[[Page 63726]]

1960, p. 44; Maser 2009, pers. comm.), although voles appear to be 
reluctant to switch between tree species (Walker 1930, p. 234; Forsman 
2010, pers. comm.).
    Tree voles appear to obtain water from their food and by licking 
water off of tree foliage (Clifton 1960, p. 49; Maser 1966, p. 148; 
Maser et al. 1981, p. 205; Carey 1996, p. 75). In keeping captive 
Sonoma tree voles, Hamilton (1962, p. 503) noted that it was important 
to keep leaves upon which they fed moist, otherwise the voles would 
lose weight and die. The need for free water in the form of rain or dew 
on foliage may explain why the distribution of tree voles is limited to 
relatively humid forests in western Oregon and California (Howell 1926, 
p. 40; Hamilton 1962, p. 503). However, there are no quantitative data 
on water consumption by tree voles, and some forests in which they 
occur (e.g., portions of southwestern Oregon) have little rain or dew 
during the summer months. How they are able to persist under such 
conditions is unclear.

Mortality

    In the only quantitative study conducted to date, Swingle et al. 
(2010, p. 258) found that weasels (Mustela spp.) were the primary 
predators of red tree voles. However, many other animals feed on tree 
voles, including ringtails (Bassariscus astutus) (Alexander et al. 
1994, p. 97), fisher (Martes pennanti) (Golightly et al. 2006, p. 17), 
northern spotted owls (Forsman et al., 1984, p. 40), barred owls (Strix 
varia) (Wiens 2010, pers. comm.), and a variety of other nocturnal and 
diurnal raptors (Miller 1933, entire; Maser 1965a, entire; Maser 1965b, 
entire; Forsman and Maser 1970, entire; Reynolds 1970, entire; Graham 
and Mires 2005, entire). Other documented predators include the 
Steller's jay (Cyanocitta stelleri) (Howell 1926, p. 60), a gopher 
snake (Pituophis catenifer) (Swingle et al. 2010, p. 258), domestic 
dogs (Canis familiaris) (Swingle et al. 2010, p. 258), and house cats 
(Felis catus) (Swingle 2005, pp. 90-91). In addition, Maser (1966, p. 
164) found tree vole nests that had been torn apart and inferred the 
destruction was likely caused by northern flying squirrels (Glaucomys 
sabrinus), raccoons (Procyon lotor), western gray squirrels (Sciurus 
griseus), or Douglas' squirrels (Tamiasciurus douglasii), apparently in 
search of young voles. Forsman (2010, pers. comm.) recorded video 
footage of northern flying squirrels, western gray squirrels, and 
Douglas' squirrels chasing tree voles or tearing into tree vole nests 
in what appeared to be attempts to capture voles.
    Swingle et al. (2010, p. 259) estimated annual survival of radio-
collared tree voles to be 15 percent. Little is known about the 
vulnerability of red tree voles to predators in different habitats. 
Swingle (2005, pp. 64, 90) found that of 25 documented cases of 
predation on radio-collared voles, most occurred in young (22-55 years 
old) forests (Forsman and Swingle 2009, pers. comm.). Predation by 
weasels, which accounted for 60 percent of the predation events, 
occurred only in the 22-55-year-old forests, and 80 percent of the 
weasel predation was on female voles. Most of the radio-collared sample 
consisted of females and were in young forest, so forest age and vole 
gender explained little of the variation in the data (Forsman 2010, 
pers. comm.; Swingle 2010, pers. comm.). Although there was no 
statistical difference in predation rates among forest ages and vole 
gender, Swingle et al. (2010, p. 260) suspected weasel predation on 
tree voles may be inversely proportional to nest height. Tree vole 
nests tend to be found in the lower portion of the tree crown 
(Gillesburg and Carey 1991, pp. 785-786; Swingle 2005, pp. 29-30), and 
tree vole nests tend to be higher above the ground in older stands or 
larger trees than in younger stands or smaller trees (Zentner 1966, pp. 
18-20; Vrieze 1980, pp. 18, 32-33; Meiselman and Doyle 1996, p. 38; 
Swingle 2005, pp. 29-30). Thus, tree voles could be more prone to 
predation in shorter trees that comprise younger stands and limit the 
height of nests above the ground. Swingle et al. (2010, p. 261) also 
suggested that female tree voles may be more susceptible to predation 
than males because they occupy larger, more conspicuous nests and spend 
more time outside the nest collecting food for their young.
    Other mortality sources include disease, old age, storms, forest 
fires, and logging (Maser et al. 1981, p. 206). Carey (1991, p. 8) 
suggested that forest fires and logging are far more important 
mortality factors than predation in limiting vole abundance.

Defining a Species Under the Act

    Section 3(16) of the Act defines ``species'' to include any species 
or ``subspecies of fish or wildlife or plants, and any distinct 
population segment of any species of vertebrate fish or wildlife which 
interbreeds when mature'' (16 U.S.C. 1532(16)). Our implementing 
regulations at 50 CFR 424.11 provide further guidance for determining 
whether a particular taxon or population is a species for the purposes 
of the Act: ``[T]he Secretary shall rely on standard taxonomic 
distinctions and the biological expertise of the Department and the 
scientific community concerning the relevant taxonomic group'' (50 CFR 
424.11(a)). As previously noted, we were petitioned to list the dusky 
tree vole as a subspecies of the red tree vole. The petitioners 
requested that if we found that the dusky tree vole was not a listable 
entity as a subspecies, then we subsequently consider whether it should 
be listed as the North Oregon Coast DPS of the red tree vole. 
Alternatively, the petitioners requested that the dusky tree vole be 
protected by listing the red tree vole because it is endangered or 
threatened in a significant portion of its range. The analysis to 
determine whether this is a viable subspecies or DPS according to 
section 3(16) of the Act follows.

Subspecies Analysis

    There is no universally accepted definition of what constitutes a 
subspecies, and the use of the term subspecies may vary among taxonomic 
groups (Haig et al. 2006, entire). To be operationally useful, 
subspecies must be discernible from one another (i.e., diagnosable), 
not merely exhibit mean differences (Patten and Unitt 2002, pp. 28, 
34). This element of ``diagnosability,'' or the ability to consistently 
distinguish between populations, is a common thread that runs through 
all subspecies concepts. It is important to use multiple sources of 
information when evaluating a taxon's status. The greater the 
concurrence among multiple morphological, molecular, ecological, 
behavioral, and physiological characteristics, the higher the level of 
confidence in the taxonomic classification (Haig et al. 2006, p. 1591). 
To assess subspecies classification for the dusky tree vole, we 
evaluated all the available data to determine whether the evidence 
points to a consistent separation of the putative dusky tree voles from 
the remaining population of red tree voles. If the assessment of these 
multiple characteristics provides a clear and consistent separation of 
the putative dusky tree vole subspecies from the remaining red tree 
vole population, such that any individual from the range of the dusky 
tree vole would likely be correctly assigned to that subspecies on the 
basis of the suite of characteristics analyzed, that evidence would be 
considered indicative of a likely valid subspecies.

Geography

    As described under Range and Distribution, there is no clear 
demarcation for the range of the putative dusky tree vole. All

[[Page 63727]]

descriptions include the western slope of the northern Oregon Coast 
Range, typically Tillamook and Lincoln Counties. Other descriptions 
expand this range to include the east slope of the Oregon Coast Range 
(Maser 1966, p. 16), and south to include the coastal portion of 
Douglas County (Maser 2009, pers. comm.). Still others suggest tree 
voles found in the foothills of the Cascade Range (Brown 1964, p. 648) 
and in the Columbia River Gorge (Howell 1926, p. 34) were dusky tree 
voles. Contemporary descriptions of the dusky tree vole range usually 
reference Johnson and George (1991, p. 12), who, despite not finding 
any strong morphometric or karyologic (chromosomal) differences between 
the subspecies, state the two taxa, ``* * * now can be properly 
delineated geographically.'' Johnson and George (1991, p. 12) go on to 
describe the dusky tree vole range as the Pacific slope of the Oregon 
Coast Range in Tillamook and Lincoln Counties without substantiating 
the basis for their geographic delineation. There is thus no clear and 
consistent description of what may constitute the range of the ``dusky 
tree vole.''

Blood Proteins

    Johnson (1968, p. 27) analyzed blood proteins of dusky tree voles, 
red tree voles, and heather voles (Phenacomys intermedius) to determine 
whether Arborimus should remain as a subgenus under Phenacomys or be 
elevated to a full genus. Multiple authors cite this work to support 
the classification of the dusky tree vole as a subspecies of the red 
tree vole (e.g., Maser and Storm 1970, p. 64; Hall 1981, p. 788; 
Johnson and George 1991, p. 1). However, we fail to reach this 
conclusion based on Johnson's (1968, p. 27) work. Johnson (1968, p. 27) 
describes his results as follows:

    The tree mice of the species Arborimus longicaudus (including A. 
silvicola) have in the past been included with the heather vole, 
Phenacomys intermedius. Two specimens of P. intermedius (of two 
subspecies) and 16 specimens of A. longicaudus (of two subspecies) 
were examined. In these two species the serum proteins and 
hemoglobins have suggested combining the named forms of Arborimus 
into a single species, and separating the genera Arborimus and 
Phenacomys.

    Although Johnson (1968, p. 27) concluded that the named forms 
longicaudus and silvicola should be combined, he did not make any 
further determination on whether or not silvicola should be retained as 
a subspecies. We therefore question whether Johnson (1968, p. 27) 
definitively designates silvicola as a subspecies. While Hall (1981, p. 
788) cited Johnson (1968, p. 27) as suggesting a ``subspecific 
relationship of the two taxa,'' he also notes that this designation is 
a ``provisional arrangement'' because of the existing uncertainty about 
the relationship of the two taxa.

Genetics

    In this section and the Summary section below we describe and 
analyze the research on tree vole genetics as it relates to answering 
the question of whether or not the dusky tree vole is a taxonomically 
valid subspecies of the red tree vole. This should not be confused with 
our analysis later in this document (see Distinct Vertebrate Population 
Segment Analysis) wherein we evaluate the genetics research as it 
relates to its contribution towards determining the discreteness and 
significance of a potential DPS of the red tree vole.
    Bellinger et al. (2005, p. 207) failed to find detectable genetic 
differences between dusky and red tree voles, suggesting that 
subspecific status may not be warranted. Miller et al. (2006a, p. 145) 
found three distinct genetic entities in their analysis of 
mitochondrial DNA of red tree voles throughout Oregon. For this 
analysis, we are interested in the genetic entity that Miller et al. 
(2006a, p. 151) labeled the ``Northern Coast range'' sequence. While 
Miller et al. (2006a, entire) do not describe specific boundaries for 
this entity, the sampling locations in this entity are distributed 
across the northern Oregon Coast Range, extending south to latitudes 
roughly equivalent with the cities of Eugene and Florence (see Figure 1 
for city locations). This genetic entity encapsulates most of the range 
descriptions of the putative dusky tree vole. Although the objective of 
Miller et al. (2006a, entire) was not to address the taxonomy of the 
dusky tree vole, in subsequent conversations with the authors, they 
concluded that the genetic differences between these groups were 
sufficient to potentially support subspecies recognition if there were 
congruent differentiations in other characteristics (Miller and Haig 
2009, pers. comm.).

Morphology

    The dusky tree vole has been described as darker than the red tree 
vole (Bailey 1936, p. 198; Maser et al. 1981, p. 201; Hall 1981, p. 
788; Johnson and George 1991, p. 12), but there has been no analysis to 
indicate an identifiable change in coat color either between the two 
entities or that corresponds with the boundaries of the haplotype 
groups found in Miller et al. (2006a, entire) (see Genetics, above). 
Maser (2007, pers. comm.; 2009, pers. comm.) postulated that the darker 
coat color in voles from the northern Oregon Coast Range was due to the 
denser, darker forests in which a darker coat provided a more cryptic 
coloration than a lighter coat color. Assuming this hypothesis is 
correct, because there is a gradual transition of tree species and 
forest composition as one progresses south in the Coast Range, it is 
reasonable to hypothesize that a corresponding change in coat color may 
also be gradual rather than abrupt and thus not easily discernable from 
the red tree vole. This needs to be evaluated using a consistent and 
repeatable method for comparing pelage color. Such an analysis is 
currently being conducted but is not available for this review (Forsman 
2010, pers. comm.).
    In measuring multiple morphometric features, Johnson and George 
(1991, p. 5) found statistical differences distinguishing Oregon tree 
voles from California samples, but were not able to easily detect 
discernable differences between samples within Oregon or California. 
Miller et al. (2010, p. 69) found statistically significant differences 
in some external morphological features between putative dusky tree 
voles and red tree voles. Although these differences were statistically 
significant in distinguishing between groups of tree voles, they were 
of little diagnostic utility because they were so subtle they could not 
be used to reliably classify an individual tree vole as a dusky tree 
vole or a red tree vole (Miller et al. 2010, p. 67). A possible 
explanation for the statistical difference, yet lack of diagnostic 
utility, is that the morphological features measured also exhibited a 
positive correlation with latitude; tree voles from the northern part 
of the range were larger than tree voles from the southern part of the 
range. This is a clinal pattern consistent with Bergmann's Rule, an 
ecological principle stating that larger forms of species tend to be 
associated with cooler climate and higher latitude (Miller et al. 2010, 
p. 69).

Behavior

    Tree voles within the narrow band of Sitka spruce found along the 
coastal portion of the northern Oregon Coast Range north of Newport 
exhibit a different diet than voles in the rest of the range, foraging 
on Sitka spruce or western hemlock rather than on Douglas-fir (Walker 
1930, p. 234; Forsman and Swingle 2009, pers. comm.) (see above under 
Diet). This diet requires a different treatment of needles

[[Page 63728]]

than in other areas because resin ducts in spruce and hemlock are 
located in different parts of the needle than in Douglas-fir (Kelsey et 
al. 2009, pp. 12-13). While this behavioral difference exists primarily 
in the Sitka spruce plant series of the northern Oregon Coast Range, it 
comprises only a small portion of the area within the northern Coast 
Range genetic sequence found by Miller et al. (2006a, pp. 150-151; see 
Genetics, above) and does not correspond to the general boundaries of 
that genetic entity, nor does it correspond to any of the various 
boundaries of the putative dusky tree vole's range.

Summary

    Bellinger et al. (2005, p. 207) concluded that the absence of 
detectable genetic differences between red tree voles and putative 
dusky tree voles, combined with the lack of consistently verifiable 
morphological differences, suggested that the subspecific status of the 
dusky tree vole might not be warranted. Miller et al. (2006a, entire) 
found evidence of marked genetic differences in the red tree vole that 
could indicate the existence of a possible subspecies, although they 
did not explicitly address the implications of their work on red tree 
vole taxonomy. Subsequent conversations with the authors, however, 
indicated that observed genetic differences were sufficient to 
potentially support recognition of the dusky tree vole as a subspecies 
if there were additional differentiations in identifiable 
characteristics and if the boundaries of those differentiations were 
congruent with the ``Northern Coast range'' genetic grouping identified 
in Miller et al. (2006a, p. 151). However, our review of the best and 
most current data on the genetics, behavior, morphology, and range of 
the putative dusky tree vole reveals no other characteristics of 
diagnostic utility that correspond with the ``Northern Coast range'' 
haplotype grouping identified by Miller et al. (2006a, p. 151). There 
is not a consistent and well-substantiated range description of the 
dusky tree vole. Although some morphological differences may occur 
between the red tree vole and the putative dusky tree vole, these 
differences have little diagnostic utility and may only represent a 
clinal variation, as would be expected between northern and southern 
populations of the red tree vole based on Bergmann's Rule (an 
ecogeographic principle that states that animals at more northerly 
latitudes tend to be larger than individuals of the same species at 
more southerly latitudes) (Miller et al. 2010, entire). The prevailing 
behavior of foraging on western hemlock and Sitka spruce within the 
Sitka spruce plant series does not correspond to the geographic range 
of the ``Northern Coast range'' genetic entity described by Miller et 
al. (2006a, p. 151), but comprises only a small portion of the range of 
that haplotype group. Presumptive differences in coloration, which 
served as one of the primary bases for the original subspecies 
distinction of the dusky tree vole, have never been quantified. Such a 
conventional approach to subspecies designation, used historically and 
frequently based on apparent geographic or clinal variation, is often 
not supported when tested by more rigorous analyses of multiple 
characters (e.g., Thorpe 1987, pp. 7, 9).
    Given the lack of diagnostic characteristics that correspond with 
the ``Northern Coast range'' haplotype group described by Miller et al. 
(2006a, p. 151) and the findings of Bellinger et al. (2005 entire) and 
Miller et al. (2010 entire) that there are no detectable genetic or 
morphological differences yet found between dusky tree voles and red 
tree voles, we do not believe there is sufficient evidence to indicate 
that the dusky tree vole is a distinct subspecies. Although the dusky 
tree vole was recognized as a subspecies in Wilson and Reeder's Mammal 
Species of the World (2005, pp. 962-963), we note that this reference 
did not recognize, or was published prior to, the availability of the 
work of Bellinger et al. (2005, entire) and Miller et al. (2006a, 
entire; 2010 entire). Subsequent to the publication of some of these 
latter works, the Oregon Natural Heritage Information Center ceased 
recognition of the dusky tree vole as a subspecies (ORNHIC 2007, p. 
17), as did the U.S. Forest Service and Bureau of Land Management's 
Survey and Manage program (USDA and USDI 2007, p. 289). Finally, the 
dusky tree vole is not recognized as a valid subspecies of the red tree 
vole in the Integrated Taxonomic Information System (ITIS 2011). 
Therefore, based on the best available scientific and commercial data, 
as described above, we have concluded that the dusky tree vole is not a 
valid subspecies, and therefore is not eligible for listing as such 
under the Act. We must next evaluate whether the North Oregon Coast 
population of the red tree vole is a DPS to determine whether it would 
constitute a listable entity under the Act.

Distinct Vertebrate Population Segment Analysis

    The Service and the National Marine Fisheries Service (now the 
National Oceanic and Atmospheric Administration--Fisheries), published 
the Policy Regarding the Recognition of Distinct Vertebrate Population 
Segments Under the Endangered Species Act (DPS Policy) in the Federal 
Register on February 7, 1996 (61 FR 4722) to guide the implementation 
of the DPS provisions of the Act. Under the DPS Policy, three elements 
are considered in the decision regarding the establishment and 
classification of a population of a vertebrate species as a possible 
DPS. These are applied similarly for additions to and removals from the 
Lists of Endangered and Threatened Wildlife and Plants. These elements 
are:
    (1) The discreteness of a population in relation to the remainder 
of the species to which it belongs;
    (2) The significance of the population segment to the species to 
which it belongs; and
    (3) The population segment's conservation status in relation to the 
Act's standards for listing, delisting, or reclassification (i.e., is 
the population segment endangered or threatened?).
    In the petition, we were asked to consider listing a DPS for the 
red tree vole in the North Oregon Coast portion of its range if we did 
not conclude that the dusky tree vole was a valid subspecies of the red 
tree vole. In accordance with our DPS Policy, this section details our 
analysis of the first two elements, described above, to assess whether 
the vertebrate population segment under consideration for listing may 
qualify as a DPS.
    Specific to red tree vole genetics, as we noted above (see 
Subspecies Analysis), in this section we have reviewed the research on 
red tree vole genetics and evaluated whether or not the genetics 
evidence supports identifying a population segment that meets the 
discreteness and significance standards described above. Although 
genetic research indicates that the putative dusky tree vole may not be 
a valid subspecies (e.g. Bellinger et al. 2005, entire; Miller et al. 
2010, entire), whether or not a population segment is discrete and 
significant is a different question and these works do not exclude the 
possibility that there is a discrete and significant population segment 
for the red tree vole.

Discreteness

    The DPS Policy's standard for discreteness requires an entity to be 
adequately defined and described in some way that distinguishes it from 
other representatives of its species. A population segment of a 
vertebrate species may be considered discrete if it

[[Page 63729]]

satisfies either of the following two conditions:
    (1) It is markedly separated from other populations of the same 
taxon as a consequence of physical, physiological, ecological, or 
behavioral factors (quantitative measures of genetic or morphological 
discontinuity may provide evidence of this separation); or
    (2) It is delimited by international governmental boundaries within 
which significant differences in control of exploitation, management of 
habitat, conservation status, or regulatory mechanisms exist.
    The North Oregon Coast portion of the red tree vole range is 
markedly separated from the rest of the species' range based on the 
genetic discontinuities described by Miller et al. (2006a, pp. 150-
151). Miller et al. (2006a, entire) examined phylogeographical patterns 
by analyzing mitochondrial control region sequences of 169 red tree 
voles sampled from 18 areas across the range of the species in Oregon. 
In addition, they analyzed Cytochrome b sequences from a subset of 
these samples. Through phylogenetic network and spatial genetic 
analyses, the researchers found a primary genetic discontinuity 
separating red tree voles from the northern (areas A through F (Miller 
et al. 2006a, Figure 1, pp. 146, 151-152)) and southern (areas G 
through R (Miller et al. 2006a, Figure 1, pp. 146, 151-152)) sampling 
areas; a secondary discontinuity separated the northern sampling areas 
into eastern (areas B, E, and G (Miller et al. 2006a, Figure 1, pp. 
146, 151-152)) and western (areas A, C, D, and F (Miller et al. 2006a, 
Figure 1, pp. 146, 151-152)) subdivisions separated by the Willamette 
Valley (Miller et al. 2006a, pp. 150-153). Miller et al. (2006a, p. 
151) labeled the eastern subdivision as the ``Northern Cascade range'' 
sequence, and the western subdivision the ``Northern Coast range'' 
sequence, reflecting the associated mountain ranges. As described in 
the Taxonomy and Description section, above, genetic researchers 
considered the degree of genetic difference between the 3 groupings of 
red tree voles to be highly significant (Miller and Haig 2009, pers. 
comm.). We thus consider the population of red tree voles represented 
by the ``Northern Coast range'' haplotypes to be markedly separated 
from other populations of the taxon as evidenced by quantitative 
measures of genetic discontinuity.
    Red tree voles within the ``Northern Coast range'' haplotype 
(genetic) group identified by Miller et al. (2006a, pp. 150-151) came 
from several specific sampling locations, but the researchers did not 
attempt to delineate precise boundaries between the three genetic 
groupings of red tree voles in Oregon. We have therefore defined the 
boundary of the northern Coast Range population of red tree voles based 
on a combination of convergent genetic, physical, and ecological 
characteristics. To assist in this delineation, we relied in part on 
the physiographic provinces used in the Northwest Forest Plan because 
they incorporate physical, biological, and environmental factors that 
shape large landscapes (FEMAT 1993, p. IV-5). In addition, much of the 
forest-related research relevant to our analysis has been based on 
these province delineations. We interpret the area occupied by the 
``Northern Coast range'' genetic group of red tree voles to include 
that portion of the Oregon Coast Range Physiographic Province (FEMAT 
1993, pp. II-27, IV-7) from the Columbia River south to the Siuslaw 
River. In addition, the Willamette Valley to the east of the northern 
Oregon Coast Range provides a geographic barrier for genetic exchange 
between red tree voles found in the northern Oregon Coast Range and 
those found in the northern Cascade Range; the western edge of the 
Willamette Valley thus forms a natural eastern boundary for the red 
tree vole population in the northern Oregon Coast Range.
    As for the southern limit of the ``Northern Coast range'' 
haplotypes, there is no identifiable geographic boundary that may act 
as a genetic barrier. We chose the Siuslaw River as an identifiable 
feature that approximates a divide between Miller et al.'s (2006a, pp. 
150-151) southern and northern haplotypes in the Oregon Coast Range. 
This is an area where vegetation transitions from more mesic vegetation 
species in the north to drier vegetation in the south (Franklin and 
Dyrness 1973, p. 72; McCain 2009, pers. comm.). In addition, the 
Siuslaw River creates an approximate break between ecosystems that 
experience longer fire return intervals to the north and shorter return 
intervals to the south (Hardt 2009, pers. comm.). This area transitions 
into the southern end of the western hemlock vegetation zone, which has 
a patchier fire severity distribution as compared to the northern 
Oregon Coast Range, which is characterized by high fire severities 
(Agee 1993, pp. 211-213). This delineation of the boundary of the 
northern Oregon Coast Range population of the red tree vole, described 
above, is shown in Figure 2.
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    There is some overlap of haplotypes in the lineage of sequences 
unique to the northern Oregon Coast Range and the southern portion of 
the tree vole range (Miller et al. 2006a, pp. 153-154). This overlap, 
combined with the absence of an obvious geographical barrier to genetic 
interchange, leads to a hypothesis that the observed genetic 
discontinuity in this area represents a zone of secondary contact 
between lineages that were divided during the most recent glaciation 
approximately 12,000 years ago (Miller et al. 2006a, p. 154). Although 
the Cordilleran ice sheet of the Wisconsin glaciation did not overlay 
present-day Oregon, associated climate change during the glaciation 
fragmented the forest landscape (Bonnicksen 2000, pp. 8-10, 15-16, 24-
25). Subalpine forests occupied much of northwestern Oregon, with 
western hemlock and Sitka spruce remaining only in isolated, protected 
areas (Bonnicksen 2000, p. 25). These potential bottlenecks in northern 
populations may have separated red tree voles into separate lineages 
that continue to exist today (Miller et al. 2006a, p. 154). A similar 
genetic discontinuity is found in the southern torrent salamander 
(Rhyacotriton

[[Page 63731]]

variegatus) in this vicinity (Miller et al. 2006b, p. 565). In 
addition, multiple plant species exhibit genetic discontinuities in the 
vicinity of the central Oregon Coast (Soltis et al. 1997, pp. 353-359).
    We conclude that the North Oregon Coast population of the red tree 
vole is markedly separated from the remainder of the red tree vole 
population and meets the discreteness criterion for the DPS Policy 
based on quantitative measures of genetic discontinuity. Genetic 
distribution in the red tree vole is not random, with a markedly 
distinct group of haplotypes located in the northern Oregon coast. The 
Willamette Valley likely serves as a genetic barrier between the North 
Oregon Coast tree vole population and tree voles in the northern 
Cascades. While there is no currently identifiable geographic barrier 
to the south, glacial activity at the end of the Pleistocene Epoch may 
have been responsible for creating multiple lineages of red tree voles, 
as well as other species, that are still identifiable today. The 
Siuslaw River is an identifiable feature that appears to be 
approximately coincident with the southernmost boundary of the 
``Northern Coast range'' genetic group of the red tree vole (Miller et 
al. 2006a, p. 151).

Significance

    If we have determined that a vertebrate population segment is 
discrete under our DPS Policy, we then consider its biological and 
ecological significance to the taxon to which it belongs in light of 
Congressional guidance (see Senate Report 151, 96th Congress, 1st 
Session) that the authority to list a DPS be used ``sparingly'' while 
encouraging the conservation of genetic diversity. To evaluate whether 
a discrete vertebrate population may be significant to the taxon to 
which it belongs, we consider the best available scientific evidence. 
As precise circumstances are likely to vary considerably from case to 
case, the DPS Policy does not describe all the classes of information 
that might be used in determining the biological and ecological 
significance of a discrete population. However, the DPS Policy 
describes four possible classes of information that provide evidence of 
a population segment's biological and ecological significance to the 
taxon to which it belongs. This evaluation may include, but is not 
limited to:
    (1) Persistence of the discrete population segment in an ecological 
setting that is unusual or unique for the taxon;
    (2) Evidence that loss of the discrete population segment would 
result in a significant gap in the range of the taxon;
    (3) Evidence that the discrete population segment represents the 
only surviving natural occurrence of a taxon that may be more abundant 
elsewhere as an introduced population outside its historical range; or
    (4) Evidence that the discrete population segment differs markedly 
from other populations of the species in its genetic characteristics.
    Persistence of the DPS in an ecological setting that is unique or 
unusual for the taxon. The Sitka spruce plant series in the northern 
Oregon coast appears to be a unique ecological setting for a portion of 
the population of the red tree vole that was determined to be discrete. 
The Sitka spruce series occurs in the strongly maritime climate near 
the ocean, following the coastal fog up river valleys. Sitka spruce 
ranges from southcentral Alaska to northern California, with the most 
extensive portion of its range occurring in southeastern Alaska and 
northern British Columbia, Canada (Burns and Honkala 1990, Sitka spruce 
chapter). Although present at some level along most of the Oregon 
coastline, it is more limited in this southern portion of its range, 
but extends much farther inland toward the northern part of the Oregon 
Coast Range than in the southern portion, where ridge systems along the 
coastline intercept the fog layer (Franklin and Dyrness 1973, pp. 58-
70; McCain and Diaz 2002, p. 59). With the exception of scattered small 
patches on the southern and central Oregon coast, the majority of the 
Sitka spruce plant series in Oregon lies in the area encompassed by the 
North Oregon Coast population of red tree voles (McCain and Diaz 2002, 
p. 61). It is in the Sitka spruce plant series that the alternative 
tree vole diet of western hemlock and Sitka spruce needles predominates 
(see Diet section). Douglas-fir appears to have been historically 
uncommon in the Sitka spruce series (Agee 1993, p. 194). Little 
variation in annual temperature, minor summer plant moisture stress, 
and very high precipitation make the Sitka spruce series extremely 
productive, producing large trees relatively quickly, and containing 
plant associations that tend to develop and maintain older forest 
characteristics important to a variety of wildlife species.
    The Sitka spruce plant series is the only portion of the red tree 
vole range where the consumption of western hemlock and Sitka spruce is 
the dominant foraging behavior. Within the extent of the ``Northern 
Coast range'' genetic grouping identified by Miller et al. (2006a, p. 
151), this behavior is exhibited by tree voles in the western portions 
of Lincoln, Tillamook, and Clatsop Counties. While there is evidence of 
individual red tree voles elsewhere in the range foraging on species 
other than Douglas-fir, these are rare occurrences and nowhere else in 
the range of the red tree vole does a non-Douglas-fir diet dominate. 
This alternative diet appears well ingrained, as evidenced by wild 
voles adapted to a diet of western hemlock refusing to eat Douglas-fir 
in captivity and ultimately starving to death (Maser 2009, pers. 
comm.). This ecological setting has resulted in a foraging behavior 
that appears relatively inflexible and unique to the red tree voles in 
this area, as red tree voles in forests dominated by Douglas-fir 
apparently exhibit greater behavioral plasticity and have been observed 
to eat western hemlock and Sitka spruce in captivity (Clifton 1960, p. 
44; Maser 2009, pers. comm.).
    The ecological setting and unique foraging behavior of red tree 
voles in the northern Oregon Coast Range create different selective 
pressures for the animals in this portion of their range relative to 
red tree voles in the remainder of the taxon's range. Such selective 
pressures are the foundation of speciation, and such distinct traits 
may be crucial to species adaptation in the face of changing 
environments (Lesica and Allendorf 1995, p. 756). We find the discrete 
population of tree voles in the northern Oregon Coast Range contains a 
unique ecological setting in the form of the Sitka spruce plant series 
because the plant series is extremely limited within the red tree vole 
range, and because of the relatively unique and inflexible foraging 
behavior tied to this plant series that may be indicative of ongoing 
speciation. However, the geographic range in which this ecological 
setting and associated unusual foraging behavior is expressed does not 
correspond to the range of the tree voles identified under the 
discreteness criterion, above, as it occurs in only a subset of the 
range of tree voles with the ``Northern Coast range'' genetic grouping 
(Miller et al. 2006a, p. 151). Therefore, although we recognize this 
ecological setting and the associated unique foraging behavior of tree 
voles to be potentially important from an evolutionary perspective, we 
find that the discrete population of tree voles in the northern Coast 
Range as a whole do not meet this significance criterion under the DPS 
policy.
    Evidence that loss of the DPS would result in a significant gap in 
the range of the taxon. The loss of the North

[[Page 63732]]

Oregon Coast portion of the red tree vole range would result in a 
roughly 24 percent reduction in the range of the red tree vole. This 
loss is significant for multiple reasons, in addition to the fact that 
it represents nearly one-quarter of the total range of the species. For 
one, it would occur in the part of the range where the alternative 
foraging behavior of feeding on spruce and hemlock is the dominant 
behavior observed. Although this behavior is expressed in only a subset 
of this portion of the range, it is unique to this portion of the range 
and is of potential evolutionary significance, therefore its loss would 
be significant to the taxon as a whole. Secondly, while loss of the 
North Oregon Coast population would not create discontinuity in the 
remaining range, species at the edge of their range may be important in 
maintaining opportunities for speciation and future biodiversity 
(Fraser 1999, p. 50), allowing adaptation to future environmental 
changes (Lesica and Allendorf 1995, p. 756). Furthermore, peripheral 
populations may represent refugia for species as their range is 
reduced, as described by Lomolino and Channell (1995, p. 339), who 
found range collapses in mammal species to be directed towards the 
periphery. Genetically divergent peripheral populations, such as the 
North Oregon Coast population of the red tree vole, are often of 
disproportionate importance to the species in terms of maintaining 
genetic diversity and therefore the capacity for evolutionary 
adaptation (Lesica and Allendorf 1995, p. 756). Finally, in the face of 
predictions that climate change will result in species' ranges shifting 
northward and to higher elevations (Parmesan 2006, pp. 648-649; IPCC 
2007, p. 8; Marris 2007, entire) (see Factor E. Other Natural or 
Manmade Factors Affecting the Species' Continued Existence), the 
northern Oregon Coast Range may become a valuable refugium from climate 
change effects for the species, as it includes the northernmost portion 
of the red tree vole's range as well as higher elevations near the 
Oregon Coast Range summit. Based on the above considerations, we 
therefore conclude that loss of the North Oregon Coast population of 
the red tree vole would result in a significant gap in the range of the 
taxon.
    Evidence that the DPS represents the only surviving natural 
occurrence of a taxon that may be more abundant elsewhere as an 
introduced population outside its historical range. As part of a 
determination of significance, our DPS Policy suggests that we consider 
whether there is evidence that the population represents the only 
surviving natural occurrence of a taxon that may be more abundant 
elsewhere as an introduced population outside its historical range. The 
North Oregon Coast population of the red tree vole is not the only 
surviving natural occurrence of the species and has not been introduced 
outside of its historical range. Consequently, this factor is not 
relevant to our determination regarding significance.
    Evidence that the DPS differs markedly from other populations of 
the species in its genetic characteristics. Red tree voles exhibit 
marked genetic structure. As described under Discreteness, above, 
Miller et al. (2006a, entire) characterized patterns of genetic 
divergence across the range of the red tree vole in western Oregon 
based on analyses of mitochondrial DNA from 18 sampling areas. The 
results of their spatial analysis of molecular variance revealed three 
distinctive genetic groupings of red tree voles in Oregon: A 
``southern'' haplotype group, and a ``northern'' haplotype group that 
was further subdivided into 2 groups, the ``Northern Cascade range'' 
and ``Northern Coast range'' groups (Miller et al. 2006a, Figure 3, p. 
151). The sampling areas that correspond to the ``Northern Coast 
range'' subdivision of the ``northern'' group (Areas A, C, D, and F) 
correspond to the entity we have described here as the North Oregon 
Coast population of the red tree vole. In the 4 sampling areas for the 
``Northern Coast range'' genetic sequence (Miller et al. 2006a, p. 
151), 20 out of the 21 D-loop haplotypes identified were unique to 
those locations, and in 3 of 4 sampling areas, 100 percent of the 
individuals sampled had a location-specific haplotype (60 percent of 
the individuals had a location-specific haplotype in the fourth 
sampling area; a single haplotype from Area C was also detected in Area 
N) (Miller et al. 2006a, Table 1, p. 148; Appendix, pp. 158-159). 
Although the researchers could not identify a strict discontinuity or 
barrier between the northern and southern groupings, which exhibited 
the greatest genetic distances, they suggest that the Willamette Valley 
serves as an important phylogeographical barrier that is likely 
responsible for the secondary genetic discontinuity identified between 
red tree voles in the western (``Northern Coast range'' sequence) and 
eastern (``Northern Cascade range'' sequence) portions of the northern 
haplotypes group (Miller et al. 2006a, pp. 151, 155).
    Loss of the North Oregon Coast population of the red tree vole 
would eliminate a unique set of genetic haplotypes from the red tree 
vole population. Retaining genetic variation provides a wider 
capability for species to adapt to changing environmental conditions 
(Frankham et al. 2002, p. 46). Peripheral populations that are known to 
be genetically divergent from other conspecific populations, such as 
the North Oregon Coast population of the red tree vole, may have great 
conservation value in providing a species with the capacity to adapt 
and evolve in response to accelerated environmental changes (Lesica and 
Allendorf 1995, p. 757). Changing environmental conditions are almost a 
certainty for the red tree vole, given the prevailing recognition that 
warming of the climate system is unequivocal (IPCC 2007, p. 30). The 
importance of maximizing the genetic capacity to adapt and respond to 
the environmental changes anticipated is therefore magnified. 
Furthermore, preservation of red tree voles and their unique genetic 
composition at the northern extent of their range may be particularly 
important in the face of climate change, as most northern-hemisphere 
temperate species are shifting their ranges northward in response to 
that phenomenon, and species that cannot shift northward have suffered 
range contractions from loss of the southernmost populations (Parmesan 
2006, pp. 647-648, 753; IPCC 2007, p. 8). Given that the Columbia River 
presents an apparent absolute barrier to northward expansion of the 
species, the northern Coast Range population of the red tree vole may 
provide an important refugium for the persistence of the species if 
more southerly populations are extirpated in the face of climate 
change. Losing an entire unique genetic component of the red tree vole, 
with its inherent adaptive capabilities, is significant and could 
compromise the long-term viability of the species as a whole. We 
therefore conclude the marked difference in genetic characteristics of 
the North Oregon Coast population relative to other populations of the 
red tree vole meets the significance criterion of the DPS Policy.

DPS Conclusion

    We have evaluated the North Oregon Coast population of the red tree 
vole to determine whether it meets the definition of a DPS, addressing 
discreteness and significance as required by our policy. We have 
considered the genetic differences of the North Oregon Coast population 
relative to the remainder of the taxon, the ecological setting of the 
northern Oregon Coast Range, and the proportion

[[Page 63733]]

of the range of the red tree vole that the North Oregon Coast 
population comprises. We conclude that the North Oregon Coast 
population of the red tree voles is a valid distinct population segment 
under the 1996 DPS Policy (Figure 2). The North Oregon Coast population 
meets the discreteness criterion of the DPS Policy because it is 
markedly separated from the remainder of the taxon based on genetic 
differences. Genetic distribution in the red tree vole is not random, 
but exhibits a markedly distinct group of haplotypes located in the 
northern Oregon Coast Range (Miller et al. 2006a, entire). We also 
conclude that the North Oregon Coast population of red tree voles is 
significant on multiple accounts. The loss of this population would 
virtually eliminate a unique genetic component of the red tree vole, 
substantially reducing genetic diversity and consequently limiting the 
species' ability to evolve and adapt to changing environments. Loss of 
this population, which comprises 24 percent of the range of the red 
tree vole, would result in a significant gap in the range, primarily 
because of the value of peripheral populations in maintaining diversity 
and evolutionary adaptation, and because this area may provide a 
valuable refugium in the event of predicted climate change. The loss of 
red tree voles in the northern Oregon Coast Range would also result in 
the loss of a unique alternative foraging behavior exhibited by tree 
voles in the Sitka spruce plant series. Although this behavior occurs 
in a subset of the area encompassed by the North Oregon Coast 
population (Forsman and Swingle 2009, unpublished data), it is of 
potential evolutionary significance to the species; therefore the loss 
of that portion of the species' range that includes this subpopulation 
would be of significance to the taxon as a whole.
    Because this population segment meets both the discreteness and 
significance elements of our DPS Policy, the North Oregon Coast 
population segment of the red tree vole qualifies as a DPS in 
accordance with our DPS Policy, and as such, is a listable entity under 
the Act (hereafter ``North Oregon Coast DPS'' of the red tree vole). 
Because we have determined the DPS to be a listable entity, we do not 
need to analyze the alternative presented by the petitioners, which was 
protecting what they labeled the dusky tree vole via listing the red 
tree vole because it is endangered or threatened in a significant 
portion of its range. Below we provide an analysis of threats to the 
North Oregon Coast DPS of the red tree vole, based on the five listing 
factors established by the Act.

Summary of Information Pertaining to the Five Factors

    Section 4 of the Act (16 U.S.C. 1533), and implementing regulations 
(50 CFR part 424) set forth procedures for adding species to, removing 
species from, or reclassifying species on the Federal Lists of 
Endangered and Threatened Wildlife and Plants. Under section 4(a)(1) of 
the Act, a species may be determined to be endangered or threatened 
based on any of the following five factors:
    (1) The present or threatened destruction, modification, or 
curtailment of its habitat or range;
    (2) Overutilization for commercial, recreational, scientific, or 
educational purposes;
    (3) Disease or predation;
    (4) The inadequacy of existing regulatory mechanisms; and
    (5) Other natural or manmade factors affecting its continued 
existence.
    In making this finding, information pertaining to the North Oregon 
Coast DPS of the red tree vole in relation to the five factors provided 
in section 4(a)(1) of the Act is discussed below. In considering what 
factors might constitute threats to a species, we must look beyond the 
exposure of the species to a particular factor to evaluate whether the 
species may respond to that factor in a way that causes actual impacts 
to the species. If there is exposure to a factor and the species 
responds negatively, the factor may be a threat and, during the status 
review, we attempt to determine how significant a threat it is. The 
identification of factors that could impact a species negatively may 
not be sufficient to compel a finding that the species warrants 
listing. The information must include evidence sufficient to suggest 
that these factors, singly or in combination, are operative threats 
that act on the species to the point that the species may meet the 
definition of endangered or threatened under the Act.

Factor A. The Present or Threatened Destruction, Modification, or 
Curtailment of Its Habitat or Range

Past and Current Range and Abundance
    Because of its arboreal existence and difficulty to observe and 
capture, little is known about the past and current population sizes of 
red tree voles. It is difficult to accurately estimate the size of a 
local tree vole population, let alone the population of the entire 
species (Howell 1926, p. 56; Blois and Arbogast 2006, p. 958). 
Estimates indicate that observers using ground-based survey methods may 
only see approximately half of the nests, with a bias towards observing 
more nests in younger forests than in older forests due to the greater 
visibility (Howell 1926, p. 45; Swingle 2005, pp. 78, 80-81; Swingle 
and Forsman 2009, p. 284). While nests can be counted and assessments 
have been made of the activity status of the nests, translating nest 
counts to numbers of voles does not yield good population estimates 
because some nests will be missed, some individuals occupy multiple 
nests, and determining whether nests are actively occupied is not 
possible without climbing to the nests and dissecting or probing them 
for voles (Swingle and Forsman 2009, p. 284). Using the presence or 
absence of green resin ducts and cuttings to determine the activity 
status of nests, which formerly had been a common method used in tree 
vole surveys, is now known to be unreliable for assessing actual nest 
occupancy by voles because the resin ducts can retain a fresh 
appearance for long periods of time if stored in the nest or out of 
sunlight, resulting in potential overestimates of active nest occupancy 
(USDA and USDI 2007, p. 290).
    Although historical observations of tree voles are useful for 
assessing the range of the species, they may also be biased because 
collectors did not sample randomly. Thus, historical locations of tree 
voles tend to occur in clusters where a few collectors spent a lot of 
time searching for them. Until extensive surveys were conducted by the 
Forest Service and BLM as part of the Survey and Manage program adopted 
in 1994 under the NWFP, much of the range of the red tree vole had 
never been searched. The lack of historical documentation of tree vole 
presence thus cannot be interpreted as meaning that tree voles had 
limited populations or were historically absent from an area, 
especially if that area formerly provided suitable forest habitat for 
tree voles and was contiguous with known occupied areas. Surveys by 
naturalists in the late 1800s and early 1900s were more of an inventory 
to find new species and to determine species presence as opposed to 
determining abundance of a particular species (Jobanek 1988, p. 370). 
Only portions of Oregon were surveyed, and coverage was cursory and 
localized. Given the arboreal existence of the red tree vole and 
difficulty of finding and observing them, few specimens were collected 
or observed until more was understood about their life history (Bailey 
1936, p. 195; Jobanek 1988, pp. 380-381). Many

[[Page 63734]]

nests were simply inaccessible to early naturalists. Nests were often 
high up in big trees, many of which were too large to climb without the 
benefit of modern climbing equipment, or the trees lacked enough 
branches on the lower bole to readily free-climb (e.g. Jobanek 1988, p. 
391). Howell (1921, p. 99) noted that there was little hope for finding 
tree voles in virgin timber because of the large trees and the abundant 
moss that might conceal ``a score of hidden nests.'' Vernon Bailey, 
Chief Naturalist of the U.S. Bureau of Biological Survey, considered 
the red tree vole to be abundant in the wild yet rare in museum 
collections because of the difficulty in collecting them (Jobanek 1988, 
p. 382). Murray Johnson, the most prolific early collector of tree 
voles, spent most of his time searching in young forests because he 
could not climb big trees (Forsman 2010, pers. comm.).
    Red tree voles are found on both the eastern and western slopes of 
the Oregon Coast Range. Although there are no records of red tree voles 
in Clatsop County north of Saddle Mountain or in Columbia County, there 
is no reason to believe that tree voles did not once occur there given 
the presence of historical habitat (see Range and Distribution). There 
is a gap in the distribution of tree vole specimens and nests south of 
Saddle Mountain State Park in south-central Clatsop County, through the 
eastern two-thirds of Tillamook County south to the town of Tillamook 
(Forsman et al. 2009b, p. 229). There are no historical records of 
voles collected in this area, but there is also no evidence that early 
naturalists searched this area for tree voles. This gap in the range 
corresponds roughly with the area of the Tillamook burn, a stand-
replacing fire that burned over 300,000 acres (121,400 ha) in 1933 
(Pyne 1982, pp. 330-331). This area reburned in three successive fires 
over the next 18 years, for a combined total burn area of 350,000 acres 
(141,650 ha) (Pyne 1982, pp. 330-331). It is reasonable to conclude 
that voles were present in this area prior to the fire, considering 
that much of the burned area contained older forest similar to forests 
occupied by tree voles in areas adjacent to the burn.
    Extensive surveys done throughout the range of the red tree vole as 
part of the NWFP Survey and Manage program have resulted in information 
that has helped to refine the distribution of the red tree vole (USDA 
and USDI 2000a, p. 376; USDA and USDI 2007, pp. 289-290). Information 
gleaned from these more recent surveys indicate that tree voles 
continue to be widely distributed throughout much of their range in 
Oregon with the exception of the northern Oregon Coast Range, 
particularly the area within the DPS north of Highway 20. This portion 
of the Coast Range north of Highway 20 accounts for nearly three-
quarters of the DPS. Within the DPS, 36 percent of the Federal land, 92 
percent of the State and County ownership, and 77 percent of the 
private ownership lies north of Highway 20 (Figure 2). In other words, 
this portion of the DPS is primarily in State, County, and private 
ownership, with relatively little Federal land. In the northern Oregon 
Coast Range north of Highway 20, tree voles are now considered uncommon 
and sparsely distributed compared to the rest of the range, based on 
observations of vole nests classified as recently occupied (USDA and 
USDI 2007, pp. 289, 294). Furthermore, the few nests that are recorded 
in this portion of the DPS likely result in overestimation of tree vole 
occupancy given errors in nest activity classification (USDA and USDI 
2007, p. 290) and the difficulty in translating nest counts to vole 
numbers discussed earlier in this section.
    Descriptions of historical search efforts for red and Sonoma tree 
voles indicate that once the species' behavior and life history were 
understood, searchers were more successful in finding tree voles, often 
with little difficulty. Observers typically noted the patchy 
distribution of voles, and once they found voles, they tended to 
readily find multiple nests and voles in the same area (Taylor 1915, 
pp. 140-141; Howell 1926, pp. 42-43; Clifton 1960, pp. 24-30; Maser 
1966, pp. 170, 216-217; Maser 2009, pers. comm.; Forsman and Swingle 
2010, p. 104). For example, Clifton (1960, pp. 24-30) averaged one day 
searching for every red tree vole ``colony'' found near Newberg, 
Oregon, and Howell described more than 50 Sonoma tree voles being 
collected over 2 days near Carlotta, California in 1913 (Howell 1926, 
p. 43).
    In contrast, between 2002 and 2006, Forsman and Swingle (2006, 
unpublished data) spent 1,143 person-hours searching potential vole 
habitat in or near areas where voles historically occurred in or 
immediately adjacent to the DPS and captured or observed only 27 voles, 
equating to 42 hours of search effort per vole found. Although a 
rigorous quantitative comparison cannot be made between recent and 
historical observation data, the above anecdotal information indicates 
that tree vole numbers are greatly reduced in the DPS--red tree voles 
are now scarce in the same areas where they were once found with 
relative ease. Similarly, decreases in Sonoma tree vole numbers have 
been observed, although not quantified, over the past decade (Diller 
2010, pers. comm.). The weight of evidence suggesting that tree voles 
are less abundant now increases upon considering that most historical 
observations were by naturalists who primarily collected voles from 
younger forests where nests were more easily observable and accessible 
by free-climbing (e.g. Howell 1926, p. 42; Clifton 1960, p. 34; Maser 
2009, pers. comm.; Forsman 2010, pers. comm.). These early naturalists 
were limited in the size and form (e.g., presence or absence of low-
lying limbs that allowed for free-climbing) of trees they could climb, 
unlike current researchers, yet found many voles with relatively little 
effort. In contrast, researchers in recent years searching these same 
areas have captured comparatively few voles per unit effort, using 
state-of-the-art climbing gear to access every potential nest observed, 
regardless of tree form or size (Forsman 2009, pers. comm.; Forsman and 
Swingle 2006, unpublished data; 2009, pers. comm.). Although rigorous 
population estimates cannot be determined from these data, the evidence 
suggests that red tree voles are now much less abundant within the DPS 
than they were historically.
    Habitat loss appears to at least partly explain the apparent 
reduction in tree vole numbers, both rangewide and within the DPS. As 
an example, many researchers have noted a continual decrease in both 
habitat and numbers of Sonoma tree voles near Carlotta, California, 
from 1913 through 1977 (Howell 1926, p. 43; Benson and Borell 1931, p. 
226; Zentner 1966, p. 45). Specific to the North Oregon Coast DPS, 
Forsman and Swingle (2009, pers. comm.) noted the reduction or loss of 
habitat in areas where tree voles historically occurred; habitat loss 
seemed especially prominent in coastal areas and along the Willamette 
Valley margin, where Forsman and Swingle (2009, unpublished data; 2009, 
pers. comm.) observed that some historical collecting sites had since 
been logged and found fewer voles than were historically collected from 
these areas. The apparently significant decline in tree vole abundance 
within the North Oregon Coast DPS of the red tree vole appears to 
correspond with the extensive historical loss of the older forest type 
that provides the highest quality habitat for the red tree vole, as 
well as the ongoing harvest of timber on short rotation schedules that 
maintains the remaining forest in lower quality early seral conditions 
in perpetuity. In

[[Page 63735]]

addition, continuing timber harvest in younger forest areas adjacent to 
remaining patches of older forest diminishes the habitat quality of 
these stands by maintaining them in an isolated and fragmented 
condition that may not allow for persistent populations of red tree 
voles.
    Landscapes in the Oregon Coast Range have become increasingly 
fragmented and dominated by younger patches of forest, as old and 
mature forests have been converted to younger stands through 
anthropogenic alteration (Wimberly et al. 2000, p. 175; Martin and 
McComb 2002, p. 255; Wimberly 2002, p. 1322; Wimberly et al. 2004, p. 
152; Wimberly and Ohmann 2004, pp. 631, 635, 642). The historical loss 
of large contiguous stands of older forest has manifested in the 
current primary threats to the North Oregon Coast DPS of the red tree 
vole of insufficient habitat, habitat fragmentation, and isolation of 
small populations; these threats are addressed under Factor E, below. 
Here we address the effects of varying levels of ongoing habitat loss 
and modification in the North Oregon Coast DPS of the red tree vole. We 
first provide some background on the historical environmental 
conditions in the DPS, as this provides important context for 
understanding the effects of ongoing timber harvest on the habitat of 
the red tree vole.
Modification of Oregon Coast Range Vegetation
    Within the Oregon Coast Range Province, the amount of forests that 
have the type of structure and composition favored by red tree voles 
has experienced significant loss over the past century, primarily due 
to timber harvest. While the total area of closed canopy forest 
remained fairly stable from 1936 to 1996, major shifts have occurred in 
the distribution, age, and structure of these forested cover classes. 
Most germane to red tree voles, there has been a change from a 
landscape dominated by large conifers with quadratic mean tree 
diameters greater than or equal to 20 in (51 cm) to a landscape 
dominated by smaller conifers. Specifically, the percent cover of large 
conifers in the Coast Range Province declined from 42 percent in 1936 
to 17 percent in 1996 (Wimberly and Ohmann 2004, p. 631). On Federal 
lands, timber harvest has declined substantially since the inception of 
the NWFP in 1994 (Spies et al. 2007a, p. 7). Moeur et al. (2005, pp. 
95-100) even showed a 19 percent increase in older forests (minimum 
quadratic mean diameter 20 in (51 cm) and canopy cover greater than 10 
percent, regardless of structural complexity) on Federal lands in the 
NWFP during the first 10 years of its implementation. However, more 
recently, better data and analysis methods have indicated that in fact 
there has been a slight net decline in older forest on Federal lands 
between 1994 and 2007. Specifically on Federal lands in the Oregon 
Coast Range, older forest has declined from 44.2 percent to 42.9 
percent (Moeur et al. 2010a, Figure 1).
    There is some indication that managed second-growth forests are not 
developing characteristics identical to natural late-successional 
forests, and that second-growth forests and clearcuts exhibit reduced 
diversity of native mammals typically associated with old-growth forest 
conditions (Lomolino and Perault 2000, pp. 1526, 1529). The historical 
losses of late-successional forest and ongoing management of most 
forests on State, County, and private lands for harvest on a short-
rotation schedule have resulted in the destruction of the older forest 
habitats favored by red tree voles; these older forest habitats now 
persist largely in small, isolated fragments across the DPS. Because of 
the historical loss of older forest stands, the remaining habitat now 
contains forests in earlier seral stages, which provide lower-quality 
habitat for red tree voles. The ongoing management of much of the 
forest within the DPS for timber harvest on relatively short rotation 
schedules, particularly on State, County, and private lands, 
contributes to the ongoing modification of tree vole habitat by 
maintaining forests in low quality condition; most of the younger 
forest types within the DPS are avoided by tree voles for nesting. 
Although younger forests may provide important interim or dispersal 
habitats for red tree voles, it is unlikely that forests lacking the 
complexity and structural characteristics typical of older forests can 
support viable populations of red tree voles over the long term. These 
concepts are explored further in the section, Continuing Modification 
and Current Condition of Red Tree Vole Habitat, below.
Habitat Loss From Timber Harvest
    In their analysis of forest trends, Wimberly and Ohmann (2004, p. 
643) found that land ownership had the greatest influence on changes in 
forest structure between 1936 and 1996, with State and Federal 
ownership retaining more large-conifer structure than private lands. 
Loss of large-conifer stands to development was not considered a 
primary cause of forest type change. Instead, loss to disturbance, 
primarily timber harvest, was the biggest cause, with fires accounting 
for a small portion of the loss (Wimberly and Ohmann 2004, pp. 643-
644). Between 1972 and 1995, timber clearcut harvest rates in all stand 
types were nearly three times higher on private land (1.7 percent of 
private land per year) than public land (0.6 percent of public land per 
year), with the Coast Range dominated by private industrial ownership 
and having the greatest amount of timber harvest as compared to the 
adjacent Klamath Mountain and Western Cascades Provinces (Cohen et al. 
2002, pp. 122, 124, 128). Within the Coast Range, there has been a 
substantial shift in timber harvest from Federal to State and private 
lands since the 1980s, with an 80 to 90 percent reduction in timber 
harvest rates on Federal lands (Azuma et al. 2004, p. 1; Spies et al. 
2007b, p. 50).
    More than 75 percent of the future tree harvest is expected to come 
from private timberlands (Johnson et al. 2007, entire; Spies et al. 
2007b, p. 50) and modeling of future timber harvests over the next 50 
years indicates that current harvest levels on private lands in western 
Oregon can be maintained at that rate (Adams and Latta 2007, p. 13). 
Loss and modification of tree vole habitat within the northern Oregon 
Coast Range is thus expected to continue, albeit at a lower rate on 
State and Federal lands compared to private lands (see discussion under 
Factor D, below). However, even on Federal lands, which provide the 
majority of remaining suitable habitat for red tree voles within the 
DPS, some timber harvest is expected to continue in those land 
allocations where allowed under their management plans. Although some 
forms of harvest may not exert a significant negative impact on red 
tree voles if managed appropriately (for example, thinning in Late-
Successional Reserves (LSRs) or Late-Successional Management Areas 
(LSMAs) with the goal of enhancing late-successional characteristics 
over the long term), lands in the Timber Management Area (TMA) and 
Matrix allocation are intended for multiple uses, including timber 
harvest. As an example, since the inception of the NWFP, 55 percent of 
the timber harvest on BLM lands within the DPS came from the Matrix 
allocation, 20 percent from Adaptive Management Areas (AMAs), and 25 
percent came from LSRs both within and outside the AMA (BLM 2010, 
unpublished data). These numbers do not include harvest within Riparian 
Reserves, which overlay all land allocations. Within the DPS, 
approximately 156,844 ac (63,475 ha)

[[Page 63736]]

are in the Matrix and TMA allocations, combined.
Continuing Modification and Current Condition of Red Tree Vole Habitat
    The loss of much of the older forest within the DPS has reduced 
high-quality habitat for tree voles to relatively small, isolated 
patches; these conditions pose a significant threat to red tree voles, 
which are especially vulnerable to the effects of isolation and 
fragmentation due to their life-history characteristics (see Factor E, 
below). Tree voles are naturally associated with unfragmented 
landscapes, and are considered habitat specialists that select areas of 
contiguous mature forest; they are not adapted to fragmented landscapes 
and early seral habitat patches (Martin and McComb 2002, p. 262). At 
present and for the foreseeable future, however, much of the remaining 
forest on State and private lands in the North Coast Range DPS is 
managed for timber production, as are lands within the Matrix and TMA 
allocations of the Federal lands (see Factor D below). Managing for 
timber production either removes existing habitat or prevents younger 
stands from developing into suitable habitat due to short harvest 
rotations. Remaining older forest habitat tends to be in small, 
isolated patches (see Factor E below); we consider such forest 
conditions to provide poor habitat for the red tree vole and unlikely 
to sustain the species over the long term. Although some State land and 
much of the Federal ownership is managed for development or maintenance 
of late-successional habitat or old-forest structure conditions, active 
management such as thinning activities are allowed and encouraged to 
develop the desired stand conditions. However, thinning stands occupied 
by tree voles can reduce vole numbers or eliminate them (see below).
    The most comprehensive analysis of current red tree vole habitat 
conditions specific to the North Coast Range DPS is a report by Dunk 
(2009, entire). Dunk (2009, p. 1) applied a red tree vole habitat 
suitability model (Dunk and Hawley 2009, entire) to 388 Forest 
Inventory Analysis (FIA) plots systematically distributed on all 
ownerships throughout the DPS (the FIA is a program administered by the 
USDA Forest Service, and is a national scientific inventory system 
based on permanent plots designed to monitor the status, conditions, 
and trends of U.S. forests). FIA plots are resampled every 10 years to 
monitor changes in forest vegetation. The red tree vole habitat 
suitability model estimates the probability of red tree vole nest 
presence (Po) from 0 to 1; the larger values of Po (e.g., 0.9 or 0.8) 
represent a greater probability of nest presence and correlate to 
presumed higher quality habitat. Based on their model results, Dunk and 
Hawley (2009, p. 630) considered a Po of greater than or equal to 0.25 
as likely having presence of a tree vole nest in an FIA plot; a Po of 
less than 0.25 was considered as not likely to have a tree vole nest. 
The Po cutoff point of 0.25 represents the value that achieved the 
highest correct classification of occupied and non-occupied sites while 
attempting to reduce the error of misclassifying plots that actually 
had nests as plots without nests; plots with Po greater than 0.25 are 
assumed to represent suitable tree vole habitat. Based on this 
assumption that a Po value of 0.25 represents suitable tree vole 
habitat, Dunk (2009, pp. 4, 7) found that 30 percent of the plots on 
Federal lands within the DPS had suitable habitat, but only 4 and 5 
percent of the plots on private and State lands within the DPS, 
respectively, had suitable habitat. Across all landownerships in the 
DPS collectively, 11 percent of the plots had potentially suitable 
habitat for red tree voles. Thus within the DPS, there is relatively 
little suitable habitat remaining for the red tree vole, and this 
suitable habitat is largely restricted to Federal lands. State and 
private lands, which comprise the majority of the DPS (78 percent of 
the land area), provide little suitable habitat for tree voles.
    Dunk and Hawley (2009, p. 631) also compared red tree vole usage of 
forest types with their proportional availability on the landscape; 
this is an important measure of habitat selection by the species. If 
red tree voles do not select for any particular forest type condition, 
we would expect usage of different forest types to be proportional to 
their availability. If a forest type is used less than expected based 
on its availability, that is assumed to represent selection against 
that forest type; in other words, the species avoids using that forest 
type, even though it is available. If a forest type is used more than 
expected based on availability, that is assumed to represent selection 
for that forest type; the species is seeking out that forest type, 
despite the fact that it is less readily available. The forest type 
that tree voles select is assumed to be suitable habitat.
    Combining the strength of selection analysis done by Dunk and 
Hawley (2009, p. 631) with the current habitat condition in the DPS 
based on FIA data, almost 90 percent of the DPS is in a forest type 
condition that red tree voles tend to avoid, while only 0.3 percent of 
the DPS is in a forest type that red tree voles tend to strongly select 
for (Figure 3). This is based on evaluation of the FIA plots, comparing 
those with the lowest probability of selection by tree voles for 
nesting (lowest 20 percent of probability classes; nearly 87.3 percent 
of FIA plots across all landownerships within the DPS were in this 
condition) with those with the greatest strength of selection (highest 
20 percent of probability classes; 0.3 percent of FIA plots across all 
landownerships were in this condition). Assuming that tree voles 
exhibit the strongest selection for the highest quality habitats, this 
translates into roughly 11,605 ac (4,700 ha) of high-quality habitat 
remaining for red tree voles distributed across a DPS roughly 3.8 
million ac (1.6 million ha) in size. Furthermore, although some nests 
may have been missed during tree vole surveys, the nest estimates used 
by Dunk and Hawley (2009, entire), and subsequently applied by Dunk 
(2009, entire), likely overestimate probable tree vole occupancy for 
two reasons. First, occupied sites were based on locations of tree vole 
nests, and as explained earlier, the presence of nests, even those 
classified as ``active,'' do not necessarily equate to tree vole 
occupancy. Second, the analyses were based on plot-level data at the 
scale of less than 2.5 ac (1 ha). The distribution of tree vole habitat 
and effects of habitat fragmentation, connectivity, and possible 
metapopulation dynamics may also influence the presence of tree voles 
on a site such that a 2.5 ac (1 ha) plot of highly suitable habitat 
isolated from other suitable habitat is less likely to contain or 
sustain tree voles than connected stands (Dunk 2009, p. 9). Thus, its 
actual likelihood of occupancy may be lower than predicted by the model 
due to its landscape context. The sample patch size used by Dunk (2009, 
entire) is less than the 5-10 acres (2-4 ha) in which Hopkins (2010, 
pers. comm.) found nests of tree voles and substantially less than the 
minimum forest stand size of 75 ac (30 ha) in which individual tree 
voles have been found (Huff et al. 1992, p. 7). Whether either of these 
minimum patch sizes can sustain a population of red tree voles over the 
long term is unknown and is influenced by such things as habitat 
quality within and surrounding the stand, position of the stand within 
the landscape, and the ability of individuals to move among stands 
(Huff et al. 1992, p. 7; Martin and McComb 2003, pp. 571-579). Given 
the conservative assumptions of the model, the amount of remaining 
likely suitable habitat within the DPS reported by Dunk (2009, entire) 
may represent a best-case

[[Page 63737]]

scenario, and the amount of remaining habitat suitable for red tree 
voles is likely less than estimated here.
BILLING CODE 4310-55-P
[GRAPHIC] [TIFF OMITTED] TP13OC11.002

BILLING CODE 4310-55-C
    Spies et al. (2007b, entire) modeled red tree vole habitat in the 
Coast Range Physiographic Province of Oregon (physiographic provinces 
are geographic divisions of areas of distinctive topography and 
geomorphic structure).

[[Page 63738]]

Their results indicated that tree vole habitat currently makes up 
almost 50 percent of the province, with just under half of that habitat 
occurring on private lands (Spies et al. 2007a, p. 10, Figure 2). While 
this assessment of the current condition of tree vole habitat in 
coastal Oregon differs from Dunk (2009, entire), we believe Dunk to be 
a more accurate description of red tree vole habitat in the DPS and 
rely more heavily on that work for the following reasons. Dunk's 
analysis is specific to the DPS, whereas the Coast Range Physiographic 
Province, which includes the DPS, covers an additional 1.8 million 
acres (728,000 ha) extending to the south of the DPS. Second, Spies et 
al. (2007b, p. 51, Appendix D) assessed tree vole habitat by developing 
habitat capability index models that reflect habitat characteristics 
important for survival and reproduction based on literature and expert 
opinion. The variables they used were restricted to existing geographic 
information system layers that could be projected into the future using 
forest dynamics models. They were not able to empirically verify their 
red tree vole habitat capability index model with independent data, 
although it was reviewed by two published experts. Dunk's analysis 
(2009, entire) relied on the red tree vole habitat model described in 
Dunk and Hawley (2009, entire), which was empirically developed based 
on presence or absence of red tree vole nests in FIA plots on Federal 
lands throughout most of the tree vole range. Dunk (2009, entire) then 
applied that model to FIA plots across all ownerships within the DPS to 
describe current tree vole habitat distribution based on existing field 
data.
    As noted earlier, although red tree voles are widely considered 
habitat specialists strongly associated with older forests, they may 
also be found in younger stands (Maser 1966, pp. 216-217; Thompson and 
Diller 2002, p. 95; Swingle and Forsman 2009, pp. 278, 284), which are 
much more abundant in the DPS. Although some have suggested that these 
young forests may be population sinks (Carey 1991, p. 34), the role of 
younger stands in tree vole population dynamics is unclear. Tree voles 
in young stands may represent attempts of emigrants to establish 
territories, or may be residual populations that tolerate habitat 
disturbance (USDA and USDI 2000a, p. 378). It is possible that some 
young stands are on unique microsites where tree voles are able to 
reinvade and persist in the developing stands (Forsman 2010, pers. 
comm.). Younger stands may also be important for allowing dispersal and 
short-term persistence in landscapes where older forests are either 
isolated in remnant patches or have been largely eliminated (Swingle 
2005, p. 94). The presence of individuals within a particular habitat 
condition does not necessarily mean the habitat is optimal, and 
individuals may be driven into marginal habitat if it is all that is 
available (Gaston et al. 2002, p. 374). Swingle and Forsman (2009, 
entire) found radio-collared tree voles in young stands throughout the 
year, but occupancy of younger stands appears to be short-term or 
intermittent (USDA and USDI 2000a, p. 378; Diller 2010, pers. comm.; 
Hopkins 2010, pers. comm.).
    There are few data on survival of tree voles in younger stands. The 
only study conducted to date suggested no difference in annual survival 
of tree voles in young (22-55 years) and old (110-260 years) stands, 
but the authors cautioned that their sample sizes were small and had 
low power to detect effects (Swingle 2005, p. 64; Forsman and Swingle 
2009, pers. comm.). Thinning younger stands occupied by tree voles can 
reduce or eliminate voles from these stands (Biswell 2010, pers. comm.; 
Swingle 2010, pers. comm.), and Carey (1991, p. 8) suggests activities 
that result in rapidly developing (changing, unstable) younger forests 
are a limiting factor for red tree voles. Conversely, when vole nests 
classified as occupied (based on indication of activity such as 
presence of fresh green resin ducts) were protected with a 10-acre 
buffer zone during thinning treatments, Hopkins (2010, pers. comm.) 
continued to find signs of occupancy at these nests post-treatment, 
although signs of occupancy were intermittent through time. However, 
Hopkins' (2010, pers. comm.) results are subject to the limitations of 
using the presence or absence of green resin ducts to determine the 
activity status of nests (see the beginning of Factor A, above). Red 
tree voles may ultimately come back to a treated stand, but how long it 
will be after the treatment before the stand is reoccupied is unknown. 
If and when tree voles return likely depends on a multitude of factors 
including magnitude, intensity and frequency of the treatment within 
the stand, type and amount of structure left after treatment (e.g., 
large trees), and whether or not there is a refugium or source 
population nearby that is available to supply voles for recruitment 
when the treated stand becomes suitable again (Biswell 2010, pers. 
comm.; Forsman 2010, pers. comm.; Hopkins 2010, pers. comm.; Swingle 
2010, pers. comm.). Thus, while the value of younger stands as suitable 
habitat to voles is unclear, they may provide some value in otherwise 
denuded landscapes, and thinning treatments in these stands have the 
potential to further reduce vole numbers, especially if thinning design 
does not account for structural features and the connectivity of those 
features that are important to red tree voles (Swingle and Forsman 
2009, p. 284). Swingle (2005, pp. 78, 94), however, cautions against 
using the occasional presence of tree voles in young forests to refute 
the importance of old forest habitats to tree voles.
    In summary, whether red tree voles in younger forests can persist 
over long periods or are ephemeral populations that contribute little 
to overall long-term population viability remains unknown at this time 
(USDA and USDI 2007, p. 291). However, the recent work of Dunk (2009, 
entire) and Dunk and Hawley (2009, entire) indicate that red tree voles 
display strong selection for forests with late-successional structural 
characteristics.
    Although the role of younger forest is uncertain, based on our 
evaluation of the best available scientific data, as described above, 
we conclude that older forests are necessary habitat for red tree voles 
and that younger stands will rarely substitute as habitat in the 
complete or near absence of older stands. While some State land and 
much of the Federal ownership is managed for development or maintenance 
of late-successional habitat or old-forest structure conditions, full 
development of this habitat has yet to occur (see below). In addition, 
thinning activities designed to achieve these objectives can reduce or 
eliminate tree voles from these stands. The ongoing management of 
forests in most of the North Oregon Coast DPS for the purposes of 
timber production thus contributes to the threat of habitat 
modification for the red tree vole, as forest habitats are prevented 
from attaining the high-quality older forest characteristics naturally 
selected by red tree voles and are maintained in a low-quality 
condition for red tree voles in the DPS. Our evaluation of the 
remaining older forest patches within the DPS indicate they are likely 
insufficient to sustain red tree voles over the long term due to their 
relatively small size and isolated nature (see Factor E, below).
Projected Trends in Red Tree Vole Habitat
    Implementing current land management policies in the Coast Range 
Province is projected to provide an increase (approximately 20 percent) 
in

[[Page 63739]]

red tree vole habitat over the next 100 years, primarily on Federal and 
State lands (Spies et al. 2007b, p. 53). Vegetation simulations 
indicate that private industrial timber lands will generally be 
dominated by open and small- and medium-sized conifer forests. Old 
forest structure and habitat will strongly increase on Federal and 
State lands, and large, continuous blocks of forest will increase 
primarily on Forest Service and State lands (Johnson et al. 2007, pp. 
41-42). The estimate of older forests on State lands, however, may be a 
substantial overestimate because the analysis was not able to fully 
incorporate the complexity of the State forest management plan (Johnson 
et al. 2007, p. 43; Spies et al. 2007a, p. 11). In addition, the Oregon 
Department of Forestry (ODF) has since reduced the targeted level of 
old forest to be developed in northwestern Oregon forests (ODF 2001, p. 
4-48; 2010c, p. 4-48). Yet even with the projected increase, the 
amounts of old forest will not approach historical levels estimated to 
have occurred over the last 1,000 years in the Coast Range Province 
(Spies et al. 2007a, pp. 10-11), and these blocks of restored older 
forest will continue to be separated by forests in earlier seral stages 
on private lands. Although restoration of Oregon Coast Range forests to 
historical levels of older forest conditions is not requisite for the 
conservation of red tree voles, we have no evidence to suggest the 
present dearth of suitable habitat for the red tree vole will be 
alleviated by the modest projected increases in older forest conditions 
on Federal and State lands within the DPS. Even though the amount of 
suitable habitat on public lands may eventually increase, these patches 
of suitable habitat will remain fragmented due to landownership 
patterns and associated differences in management within the DPS. 
Furthermore, the time required for stand development to achieve these 
improved conditions, 100 years, is substantial; whether these gradual 
changes will occur in time to benefit the red tree vole in the North 
Oregon Coast DPS is unknown. However, we anticipate that any patches of 
suitable habitat that may be found on public lands within the DPS 100 
years from now will continue to be fragmented and isolated, due to the 
management practices on intervening private lands that inhibit 
connectivity. Thus, although projected future conditions represent a 
potential improvement in suitable habitat for the red tree vole, the 
time lag in achieving these conditions and the fragmented nature of 
public lands in the northern Oregon Coast Range suggests that a 
potential gain of 20 percent more suitable habitat 100 years from now 
is likely not sufficient to offset the loss, modification, and 
fragmentation of habitat and isolation of populations that collectively 
pose an immediate threat to the red tree vole in the DPS.
    Loss of forest land to development is projected to occur in 10 
percent of the Coast Range Province, and would most likely occur on 
non-industrial private lands, near large metropolitan areas, and along 
the Willamette Valley margin (Johnson et al. 2007, p. 41; Spies et al. 
2007a, p. 11). Although timber production in the Coast Range has 
shifted by ownership class, declining on Federal lands and increasing 
on private lands, overall production is projected to stay at recent 
harvest levels. Actual production may result in levels higher than 
projected because harvest levels estimated for private industrial 
timberland were conservative (Johnson et al. 2007, pp. 42-43) and 
timber production on State lands may be underestimated by 20 to 50 
percent (Johnson et al. 2007, p. 43). Johnson et al. (2007, pp. 45-46) 
described several key uncertainties that were not accounted for in 
their projections of future trends in the Coast Range that could 
potentially affect their results. These uncertainties include: effects 
of climate change; recently adopted initiatives that may result in an 
increased loss of forest land to cities, towns, and small developments; 
a possible decrease in global competitiveness of the Coast Range forest 
industry; sales of industrial forests to Timber Management Investment 
Organizations that may result in a shift of land use to other types of 
development; the effects of Swiss needle cast on the future of 
plantation forestry; and effects of wildfire. Most of these scenarios 
would result in a loss of existing or potential tree vole habitat, 
contributing further to the present loss, modification, fragmentation, 
and isolation of habitat for the red tree vole within the DPS, although 
the magnitude of that loss is uncertain. In conclusion, while modest 
increases in tree vole habitat are expected to occur in the Oregon 
Coast Range over the next century, they are limited primarily to 
Federal lands and, to some lesser degree, State lands, although the 
amount of older forests on State lands may be an overestimate. As 
described above, the time lag in achieving this potential increase in 
suitable habitat and the fragmented nature of public lands, especially 
those Federal lands with the highest quality habitats, suggests that 
any future gains are likely not sufficient to offset the present threat 
of habitat loss, modification, or fragmentation, and its ongoing 
contribution to the isolation of red tree voles in the DPS.

Summary of Factor A

    The North Oregon Coast DPS of the red tree vole is threatened by 
the effects of both past and current habitat loss, including ongoing 
habitat modification that results in the maintenance of poor quality 
forest habitats and insufficient older forest habitats, addressed here, 
and habitat fragmentation and isolation of small populations, addressed 
under Factor E. Most of the DPS, nearly 80 percent, is in State, 
County, and private ownership, and most of the forested areas are 
managed for timber production. Ongoing timber harvest on a short 
rotation schedule over most of this area maintains these forest 
habitats in a low-quality condition, preventing these younger stands 
from developing the older forest conditions most suitable for red tree 
voles. Although the role of younger forest stands is not entirely 
clear, we conclude the preponderance of the best available information 
suggests that red tree voles are habitat specialists strongly 
associated with unfragmented forests that exhibit late-successional 
characteristics; while younger forests may play an important role as 
interim or dispersal habitat, older forests are required to maintain 
viable populations of red tree voles over the long term. The ongoing 
management of forests in the North Oregon Coast DPS for the purposes of 
timber harvest thus contributes to the threat of habitat modification 
for the red tree vole, as forest habitats are prevented from attaining 
the high-quality older forest characteristics naturally selected by red 
tree voles and are maintained in a low-quality condition for red tree 
voles in the DPS.
    Factors that hinder the development and maturation of younger 
forest stages into late-successional forest conditions contribute to 
the ongoing modification of suitable habitat and maintain the present 
condition of insufficient remaining older forest habitat for the red 
tree vole in the DPS. The persistence and development of high-quality 
tree vole habitat over the next century under existing management 
policies is likely to occur primarily on Federal lands, and to a lesser 
degree on State lands. However, as Federal lands make up less than a 
quarter of the area of the DPS, even with eventually improved 
conditions, suitable red tree vole habitat will remain restricted in 
size and in a

[[Page 63740]]

fragmented, isolated condition for the foreseeable future. In the 
interim, thinning activities designed to accelerate the development of 
late-successional forest structure conducive to tree vole habitat may 
reduce or eliminate local populations for an undetermined amount of 
time.
    Declines in the amount of older forest within the Coast Range 
Province are unprecedented in recent history (Wimberly et al. 2000, pp. 
176-178). This decline has translated into substantial habitat loss for 
red tree voles, with only 11 percent (approximately 425,000 ac (173,000 
ha)) of the nearly 4 million acres (1.6 million ha) within the DPS 
boundary assumed to be potentially suitable habitat (Dunk 2009, p. 5). 
Most of this suitable habitat is restricted to Federal lands that lie 
in two discontinuous clusters within the DPS. State and private lands, 
which collectively comprise nearly 80 percent of the DPS area, provide 
very little suitable habitat; roughly 4 to 5 percent of the State and 
private lands are considered potentially suitable habitat for red tree 
voles (Dunk 2009, pp. 6-7).
    Nearly 90 percent of the DPS is currently in a habitat condition 
avoided by red tree voles, and only 0.3 percent of the DPS is in a 
condition for which red tree voles show strong selection for nesting 
(Dunk 2009, p. 7). Given that nest presence does not correspond exactly 
with vole presence, and that the FIA sampling design may include 
habitat that is unavailable to tree voles, this is likely an 
overestimate of potential red tree vole habitat. Although Federal lands 
offer some protection and management of red tree vole habitat, 
indications are that there may not be enough habitat in suitable 
condition to support red tree voles north of U.S. Highway 20. In this 
area of the DPS Federal land is limited, connectivity between blocks of 
Federal land is restricted, and there are few known vole sites 
currently available to potentially recolonize habitat as it matures 
into suitable condition. Surrounding private timber lands are not 
expected to provide long-term tree vole habitat over the next century, 
and projections of suitable tree vole habitat on State land may be 
overestimates.

Conclusion for Factor A

    Recent surveys at locations within the DPS where voles were readily 
captured 30 to 40 years ago have resulted in significantly fewer voles 
captured per unit of survey effort compared to historical collections. 
This suggests that tree vole numbers have declined in many areas where 
voles were once readily obtained by early collectors such as Alex 
Walker, Murray Johnson, Doug Bake, Chris Maser, and Percy Clifton 
(Forsman 2009, pers. comm.). Although standardized quantitative data 
are not available to rigorously assess population trends of red tree 
voles, we believe it is reasonable to conclude that, based on 
information from retrospective surveys of historical vole collection 
sites, red tree voles have declined in the DPS and no longer occur, or 
are now scarce, in areas where they were once relatively abundant. Loss 
of habitat in the DPS, primarily due to timber harvest, has been 
substantial and has probably been a significant contributor to the 
apparent decline in tree vole numbers. Current management practices for 
timber production, particularly on the State, and privately-owned lands 
that comprise the vast majority of the DPS, keep the majority of the 
remaining forest habitat from maturing and developing the late-
successional characteristics that comprise highly suitable habitat for 
red tree voles. Current management for timber harvest thereby 
contributes to the ongoing modification of tree vole habitat, as well 
as the fragmented and isolated condition of the remaining limited older 
forest habitat for the species. Indications are that the remaining 
older forest patches are likely too small and isolated to maintain red 
tree voles over the long term (see Factor E, below). The biology and 
life history of red tree voles render the species especially vulnerable 
to habitat fragmentation, isolation, and chance environmental 
disturbances such as large-scale fires that could reasonably be 
expected to occur within the DPS within the foreseeable future (Martin 
and McComb 2003, p. 583; also addressed in Factor E). Based on our 
evaluation of present and likely future habitat conditions, we conclude 
that the ongoing effects of the destruction, modification, and 
curtailment of its habitat, in conjunction with other factors described 
in this finding, pose a significant threat to the persistence of the 
North Oregon Coast DPS of the red tree vole.
    We have evaluated the best available scientific and commercial data 
on the present or threatened destruction, modification, or curtailment 
of the habitat or range of the North Oregon Coast DPS of the red tree 
vole, and determined that this factor poses a significant threat to the 
continued existence of the North Oregon Coast DPS of the red tree vole, 
when we consider this factor in concert with the other factors 
impacting the DPS.

Factor B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    We are not aware of any information that indicates that 
overutilization for commercial, recreational, scientific, or 
educational purposes threatens the continued existence of the North 
Oregon Coast DPS of the red tree vole and have determined that this 
factor does not pose a significant threat to the viability of the North 
Oregon Coast DPS of the red tree vole.

Factor C. Disease or Predation

    We are not aware of any information that indicates that disease 
threatens the North Oregon Coast DPS of the red tree vole, now or in 
the foreseeable future. With respect to predation, the red tree vole is 
prey for a variety of mammals and birds (see above under Mortality), 
although voles persist in many areas despite the large numbers of 
predators (Forsman et al. 2004, p. 300). However, barred owls have 
recently expanded into the Pacific Northwest and are a relatively new 
predator of red tree voles. Although a recent pellet study indicates 
that barred owls occasionally prey on tree voles (Wiens 2010, pers. 
comm.), the long-term effects of this new predator are uncertain. 
Barred owls have a more diverse diet than northern spotted owls, an 
established tree vole predator (Courtney et al. 2004, p. 7-40). While 
the varied diet of the barred owl may potentially limit their pressure 
as predators on tree voles, the fact that they outnumber spotted owls 
in the southern portion of the DPS by a 4:1 ratio (Wiens 2010, pers. 
comm.) may increase that pressure. Whether predation on red tree voles 
may significantly increase as a result of growing numbers of barred 
owls is unknown. Therefore, we cannot draw any conclusions as to the 
impact of barred owl predation on red tree voles in the DPS at this 
time.

Conclusion for Factor C

    While predators undoubtedly have some effect on annual fluctuations 
in tree vole numbers, there is no evidence to suggest that changes in 
predation rates have caused or will cause long-term declines in tree 
vole numbers. Tree voles are exposed to a variety of predators and as a 
prey species they have adapted traits that reduce their exposure and 
vulnerability to predation; examples include cryptic coloration and 
leaping from trees when pursued (Maser et al. 1981, p. 204), or 
minimizing the duration of individual foraging bouts outside of the 
nest (Forsman et al. 2009a, p. 269). While habitat alterations

[[Page 63741]]

may affect the exposure and vulnerability of tree voles to predators 
(see above under Mortality), predators themselves do not appear to be a 
principal threat affecting long-term trends in red tree vole numbers. 
We therefore conclude that the continued existence of the red tree vole 
in the North Oregon Coast DPS is not threatened by disease or 
predation, nor is likely to become so.
    We have evaluated the best available scientific and commercial data 
on the effects of disease or predation on the North Oregon Coast DPS of 
the red tree vole, and determined that this factor does not pose a 
significant threat to the viability of the North Oregon Coast DPS of 
the red tree vole.

Factor D. Inadequacy of Existing Regulatory Mechanisms

    Timber harvest has been identified as the primary cause of 
vegetation change and loss of red tree vole habitat in the Oregon Coast 
Range Province (Wimberly and Ohmann 2004, pp. 643-644) (see Factor A 
discussion, above). Although most of the losses of late-successional 
forest conditions occurred historically, these losses, combined with 
current management of younger forests on both private and public lands, 
contribute to the ongoing modification, curtailment, fragmentation, and 
isolation of habitat for the red tree vole in the DPS. The inadequacy 
of existing regulatory mechanisms in regard to timber harvest 
contributes to these threats. Regulations for timber harvest differ 
among land ownerships and are explained in separate sections below.
Regulatory Mechanisms on Private Land
    Private lands make up 62 percent of the DPS, and over 75 percent of 
timber harvest in the Coast Range Province is expected to come from 
private forest lands (Johnson et al. 2007, entire; Spies et al. 2007b, 
p. 50). The Oregon Forest Practice Administrative Rules and Forest 
Practices Act (OAR) (Oregon Department of Forestry 2010a, entire) apply 
on all private and State-owned lands in Oregon, regulating activities 
that are part of the commercial growing and harvesting of trees, 
including timber harvesting, road construction and maintenance, slash 
treatment, reforestation, and pesticide and fertilizer use. The OAR 
provide additional guidelines intended for protection of soils, water, 
fish and wildlife habitat, and specific wildlife species while engaging 
in tree growing and harvesting activities. The red tree vole is not one 
of the specific species provided for in the OAR, and we are not aware 
of any proactive management for tree voles on private timberlands in 
Oregon.
    Per the Oregon Revised Statute, an average of two snags or green 
trees per ac (0.8 per ha) greater than 30 ft (9 m) tall and 11 in (28 
cm) diameter are required to be left in harvest units greater than 25 
ac (10 ha) (ORS 527.676); up to half of these trees may be hardwoods. 
Retention buffers are required around northern spotted owl nest sites 
(70 ac (28 ha) of suitable habitat) (OAR 629-665-0210), bald eagle nest 
sites (330-ft (100-m) buffer) (OAR 629-665-0220,), bald eagle roost 
sites (300-ft (100-m) buffer) (OAR 629-665-0230), and great blue heron 
nest sites (300-ft (91-m) buffer) (OAR 629-665-0120). In addition, 
foraging trees used by bald eagles (OAR 629-665-0240) and osprey nest 
trees and associated key nest site trees (OAR 629-665-0110) are also 
protected from timber harvest. In all cases, protections of these sites 
are lifted when the site is no longer considered active (OAR 629-665-
0010).
    Within the Coast Range, small perennial streams that are neither 
fish bearing nor a domestic water source have no tree retention 
requirements. With respect to all other perennial streams, no harvest 
is allowed within 20 ft (6 m). In addition, riparian management areas 
are established around all fish-bearing streams and large or medium 
non-fish-bearing streams; their distances range from 20 to 100 ft (6 to 
30 m) beyond the stream, depending on the stream size and fish-bearing 
status. Within these riparian management areas, from 40 to 300 square 
ft (4 to 28 square m) of basal area must be retained for every 1,000 ft 
(305 m) of stream; basal area retention levels depend on stream size, 
fish presence, and type of harvest (OAR 629-640-0100 through 629-640-
0400). Trees within the no-harvest 20-ft (6-m) buffer count towards 
these retention requirements. To meet the basal area requirement within 
the riparian management areas of large and medium streams, a minimum 
number of live conifers must be retained to meet shade requirements. 
Depending on stream size and fish-bearing status, live conifer 
retention requirements range from 10 to 40 per 1,000 ft (305 m) of 
stream, with a minimum size of either 8 or 11 in (20 or 28 cm) dbh. If 
the basal area requirements are still not met with the minimum conifer 
retention, the remainder can be met with trees greater than 6 in (15 
cm); a portion of this retention can be met with snags and hardwoods 
(excluding red alder (Alnus rubra)). For all streams where the pre-
harvest basal area of the riparian area is less than the targeted 
retention level, timber harvest may still occur (section 6 of OAR 629-
640-0100 and section 7 of OAR 629-640-0200). In addition, basal area 
credits may be granted, upon approval, for other stream enhancements, 
such as placing downed logs in streams to enhance large woody debris 
conditions (OAR 629-640-0110). Thus, while basal area credits may 
produce in-stream enhancements, they simultaneously reduce potential 
arboreal habitat for red tree voles.
    Given the extensive network of streams within the Coast Range, 
riparian management areas appear to have potential in providing 
connectivity habitat for red tree voles between large patches of 
remnant older forest stands. However, given the minimum tree retention 
sizes and numbers prescribed under the OAR, we believe them to be 
insufficient to provide adequate habitat to sustain populations of red 
tree voles, and likely not sufficient to provide connectivity between 
large patches of remnant older forest stands. As an example, the 
streamside rules applying the most protection apply around fish-bearing 
streams (sections 5-7 of OAR 629-640-100). Although these sections 
require retention of 40 live conifer trees per 1,000 ft (305 m) along 
large streams, and 30 live conifer trees along medium streams, these 
trees need only be 11 in (28 cm) dbh for larger streams and 8 in (20 
cm) dbh for medium streams to count toward these requirements. Although 
these regulatory requirements are stated as minimums, they potentially 
allow for conditions such that the remaining trees will likely be far 
smaller than those generally utilized by red tree voles, and the 
remaining trees may be relatively widely dispersed along the riparian 
corridor, thereby impeding arboreal movement. Furthermore, the purpose 
of tree retention in riparian management areas is to retain stream 
shade, and retaining a minimum number of live conifers is designed to 
distribute that shade along the stream reach by retaining more, smaller 
trees to meet the basal area requirements rather than concentrate the 
targeted basal area into a few large trees. Consequently, there is 
little incentive to retain any larger trees within the riparian 
management areas.
    Although in general biological corridors are believed to be 
beneficial for the conservation of fragmented populations by allowing 
for genetic interchange and potential recolonization (e.g., Bennett 
1990, entire; Fahrig and Merriam 1994, p. 51; Rosenberg et al. 1997, p. 
677), possible disadvantages may include potential increases in 
predation, parasitism, and invasion of interior habitats by introduced 
species

[[Page 63742]]

(e.g., Wilcove et al. 1986, pp. 249-250; Simberloff and Cox 1987, pp. 
66-67; Yahner 1988, p. 337; Simberloff et al. 1992, p. 498). Long, 
narrow strips of habitat suffer from a high ratio of edge to interior, 
resulting in ``edge effects'' such as altered microclimates and 
potentially increased vulnerability to generalist predators (Yahner 
1988, p. 337; Saunders et al. 1991, pp. 20-22; Chen et al. 1993, p. 
220). In old-growth Douglas-fir forests, altered environmental 
conditions may extend up to 137 m (450 ft) from the forest edge, to the 
extent that patches less than 10 ha (25 ac) in size provide essentially 
no forest interior habitat (Chen et al. 1992, p. 395).
    The successful use of corridors to maintain regional populations is 
highly species-specific (Rosenberg et al. 1997, p. 683; Debinski and 
Holt 2000, p. 351), and depends on the spatial configuration of the 
remaining habitat, the quality of the corridor habitat, and the habitat 
specificity and dispersal ability of the species in question (Henein 
and Merriam 1990, p. 157; Fahrig and Merriam 1994, p. 53; With and 
Crist 1995, entire; Rosenberg et al. 1997, entire). In general, habitat 
specialists with limited dispersal capabilities, such as the red tree 
vole, have a lower ``critical threshold'' for responding to fragmented 
habitats; such species may experience the environment as functionally 
disconnected even when their preferred habitat still comprises nearly 
half of the landscape (With and Crist 1995, p. 2452; Pardini et al. 
2010, p. 6). Reduced survival probability for animals moving through 
linear corridors of habitat may potentially be offset by large numbers 
of dispersers, but for animals with relatively low reproductive rates 
and low mobility, such as the red tree vole, survival probability may 
be compromised under such conditions (Martin and McComb 2003, p. 578). 
Poor-quality habitat conditions for red tree voles in riparian 
management areas, such as from reduced canopy cover, may reduce their 
probability of survival in moving through such a patch (Martin and 
McComb 2003, p. 577). For example, there is some evidence that small 
mammals may experience increased risk and local extinction events of 
predation in narrow corridors or isolated fragments of habitat (e.g., 
Henderson et al. 1985, p. 103; Mahan and Yahner 1999, pp. 1995-1996). 
Although riparian buffers are frequently suggested as potential 
corridors for dispersal, Soul[eacute] and Simberloff (1986, pp. 33-34) 
specifically suggest that forest interior species such as the red tree 
vole would likely avoid using such areas for movement between remaining 
patches of conifer forest. Observations that red tree voles are now 
apparently absent from forest stands where they historically occurred 
indicate riparian management areas are likely not functioning as 
successful corridors for dispersal and recolonization by red tree voles 
in the DPS.
    Although the OAR do not specifically provide protection for red 
tree voles, some protections may be afforded to individuals that are 
incidentally found within buffers retained for sensitive wildlife 
sites. However, such scattered remnants of possible habitat are 
unlikely to protect viable populations due to their small size and 
fragmented and isolated nature. In addition, these protected areas can 
be logged if the site is no longer occupied by the target species. The 
short timber harvest rotations (e.g., in calculating its riparian rule 
standards, OAR assume 50-year rotations for even-aged stands, and 25-
year entry intervals for uneven-aged management) in the surrounding 
landscape further limits the potential for a well-connected tree vole 
population. Although tree voles have been found in these younger 
stands, frequent thinnings, larger harvest units, and the tendency for 
these large harvest units to aggregate into larger blocks of younger 
stands that are unlikely to develop into red tree vole habitat (Cohen 
et al. 2002, p. 131) decrease the likelihood that tree voles will 
persist on industrial private timber lands even with protections 
afforded to other species per the OAR. Therefore, based on the above 
assessment, we conclude that existing regulatory mechanisms on private 
land are inadequate to ameliorate the threat of habitat loss and 
fragmentation and provide for the conservation of the North Oregon 
Coast DPS of the red tree vole.

Summary of Regulatory Mechanisms on Private Land

    Private lands comprise more than 60 percent of the DPS, and most of 
the projected future timber harvest in the Oregon Coast Range is 
anticipated to come from these lands. The Oregon Forest Practices 
Administrative Rules and Forest Practices Act (OAR) provide the current 
regulatory mechanism for timber harvest on private lands within the 
DPS. The stated goal of the OAR is to provide for commercial growing 
and harvesting of trees. The OAR additionally provide guidelines 
intended to protect soils, water, and fish and wildlife habitat, 
including protection of specific wildlife species, during the course of 
these activities. The red tree vole is not one of the specific species 
protected by the OAR, and due to its relatively specialized habitat 
requirements and limited dispersal capability, provisions intended to 
conserve habitat for other wildlife species are likely inadequate to 
provide for the conservation of the red tree vole. Despite the 
incidental benefits provided by protective measures for aquatic 
resources and other wildlife, management under this regulatory 
mechanism results in much of the habitat for the red tree vole being 
continually modified such that insufficient high-quality habitat (well-
connected stands with older forest characteristics) is maintained, and 
remnant older forest patches remain fragmented and isolated due to 
intensive management in the surrounding landscape. We therefore 
conclude that existing regulatory mechanisms on private land are 
inadequate to provide for the conservation of the North Oregon Coast 
DPS of the red tree vole, as they contribute to threats of habitat 
destruction, modification, or curtailment under Factor A, as well as 
the threats of habitat fragmentation and isolation of small populations 
under Factor E.
Regulatory Mechanisms on State Land
    State lands make up 16 percent of the DPS, totaling just over 
600,000 ac (242,800 ha). Although there are some scattered State parks 
located primarily along the coastal headlands, virtually all of the 
State ownership in the DPS is land managed by the Oregon Department of 
Forestry (ODF) in the Tillamook and Clatsop State Forests, as well as 
other scattered parcels of State forest land in the southern half of 
the DPS. State forest lands are to be actively managed, assuring a 
sustainable timber supply and revenue to the State, counties, and local 
taxing districts (ODF 2010c, pp. 3-2, 3-4 to 3-5). Annual timber 
harvests projected over the next decade for each of the three State 
Forest districts within the DPS sum to 181 million board feet (422,000 
cubic m) (ODF 2009, p. 59; 2011a, p. 69; 2011b, p. 65). Harvest 
intensities (annual harvest per acre of landbase) differ by district; 
harvest intensity for the Tillamook District, which comprises half of 
the State Forest ownership within the DPS, is projected at 188 board 
feet per acre (0.526 and 0.530 cubic m per ha) per year. The Astoria 
and Forest Grove Districts project substantially higher harvest 
intensities of 526 and 530 board feet per acre per year, respectively. 
Acreages used to calculate harvest intensity may include

[[Page 63743]]

acres that are not capable of producing forest and may be a slight 
underestimate.
    The overarching statutory goal for management of State forest lands 
is to provide, ``healthy, productive, and sustainable forest ecosystems 
that over time and across the landscape provide a full range of social, 
economic, and environmental benefits to the people of Oregon'' (ODF 
2010c, p. 3-12). Common School Forest Lands comprise 3 percent of the 
northwestern Oregon State Forests, and they are to be managed to 
maximize income to the Common School Fund (ODF 2010c, p. 3-2). To the 
extent that it is compatible with these statute-based goals, wildlife 
resources are to be managed in a regional context, providing habitats 
that contribute to maintaining or enhancing native wildlife populations 
at self-sustaining levels (ODF 2010c, pp. 3-12, 3-14).
    The Northwestern Oregon State Forest Management Plan provides 
management direction for the State Forests within the DPS (ODF 2010c, 
p. 1-3). There is no specific direction in the ODF northwestern forest 
management plan recommending or requiring surveys or protecting tree 
vole sites if they are found on State lands. ODF personnel are 
recording tree vole nest locations as ancillary information collected 
during climbing inspections of marbled murrelet (Brachyramphus 
marmoratus) nests (Gostin 2009, pers. comm.), but are not implementing 
management or conservation measures to known sites beyond recording the 
nests.
    Red tree voles are, however, one of several species of concern 
identified by ODF for which anchor habitats have been established (ODF 
2010c, pp. 4-82 to 4-83, E-42). Anchor habitats are, ``intended to 
provide locales where populations will receive a higher level of 
protection in the short-term until additional suitable habitat is 
created across the landscape'' (ODF 2010c, p. 4-82). They are not 
intended to be permanent reserves. Terrestrial anchor habitats are 
intended to benefit species associated with older forest and interior 
habitat conditions, and management within them will promote the 
development of complex forest structure (ODF 2010c, pp. 4-82 to 4-83). 
Within the State Forests in the DPS, there are 11 terrestrial anchor 
habitat areas totaling 40,706 ac (16,474 ha) with a mean size of 3,701 
ac (1,498 ha) (ODF 2011, unpublished data).
    Although the OAR apply on all State lands, the ODF may develop 
additional site-specific management regulations that are potentially 
more stringent than those set forth in the OAR. With respect to 
management around marbled murrelet and northern spotted owl sites, ODF 
exceeds the protections called for by the OAR. Spotted owl sites are 
protected by a 250-acre (101-ha) core area around the nest, maintenance 
of 500 acres of suitable habitat within 0.7 mi (1.1 km) of the nest, 
and 40 percent of habitat within 1.5 mi (2.4 km) of the nest (ODF 2008, 
2010b). Currently there are three owl sites on ODF State Forests within 
the DPS, and another six in adjacent lands wherein buffers from these 
sites overlap onto ODF ownership (ODF 2011, unpublished data). Marbled 
murrelet management areas (MMMA) are established around marbled 
murrelet occupied sites (ODF 2010d) with the purpose of retaining 
habitat function. There are 42 MMMAs within the DPS totaling 6,281 
acres (2,542 ha), averaging 150 acres (61 ha), and ranging in size from 
13 to 623 acres (5 to 252 ha) (ODF 2011, unpublished data). Sixteen 
percent of the MMMA acres occur within terrestrial anchor areas. ODF 
also applies the OAR protection buffers for bald eagle nests and 
roosts, and great blue heron nests (see Regulatory Mechanisms on 
Private Land above).
    ODF regulations for fish-bearing streams provide a 170-ft (52 m) 
buffer on each side, with no harvest within 25 ft (7.6 m), management 
for mature forest (basal area of 220 square ft (20 square m) of trees 
greater than 11 in (28 cm) dbh) between 25 and 100 ft (7.6 and 30 m) of 
the stream, and retention of 10 to 45 conifers and snags per acre (4 to 
18 per ha) between 100 and 170 ft (30 and 52 m) of the stream (ODF 
2010c, p. J-7). Large and medium streams that are not fish-bearing have 
management standards similar to fish-bearing streams except that 
conifer and snag retention levels between 100 and 170 ft (30 to 52 m) 
from the stream are reduced to 10 per ac (4 per ha) (ODF 2010c, p. J-
8). Management standards for small, perennial, non-fish-bearing 
streams, as well as intermittent streams considered ``high energy 
reaches'' (ODF 2010c, pp. J-9--J-10), apply to at least 75 percent of 
the stream reach and include no harvest within 25 ft (7.6 m), retain 15 
to 25 conifer trees and snags per acre (6 to 10 per ha) between 25 to 
100 ft (7.6 to 30 m) of the stream, and retain 0 to 10 conifer trees 
and snags per acre (0 to 4 per ha) between 100 to 170 ft (30 to 52 m). 
Additional management standards also apply within 100 ft (30 m) of 
intermittent streams (ODF 2010c, p. J-10). Within harvest units, all 
snags are to be retained, and green tree retention must average 5 per 
ac (2 per ha) (ODF 2010c, pp. 4-53 to 4-54). Although riparian 
retention levels on ODF lands are larger than what is required on 
private lands, they still allow for a reduction in existing habitat 
suitability for red tree voles, with minimum retention levels not 
meeting tree vole habitat requirements due to reduced stand densities 
and lack of crown continuity.
    State forests are managed for specific amounts of forest structural 
stages. The objective is to develop 15 to 25 percent of the landscape 
into older forest structure (32 in (81 cm) minimum diameter trees, 
multiple canopy layers, diverse structural features, and diverse 
understory) and 15 to 25 percent into layered structure (two canopy 
layers, diverse multi-species shrub layering, and greater than 18 in 
(46 cm) diameter trees mixed with younger trees) over the long term 
(ODF 2010c, p. 4-48). Attainment of these objectives would benefit the 
red tree vole; however, this is not the current condition of State 
forests within the DPS, and these desired future conditions are not 
projected to be reached for at least 70 years (ODF 2010c, p I-13). At 
present, only about 1 percent of the State forests in northwestern 
Oregon is currently in older forest structure and 12 percent is in a 
layered structure condition (ODF 2003a, pp. 4, 12; ODF 2003b, pp. 4, 
16; ODF 2009, pp. 4, 21; ODF 2011a, pp. 6, 20, 23; ODF 2011b, pp. 6, 
25). While 13 percent of the State forests is in a complex structure 
category (old forest and layered forest structure, combined), only a 
small subset of this likely provides tree vole habitat given that only 
5 percent of the State land is considered actual red tree vole habitat 
(Dunk 2009, pp. 5, 7).
    Given the description provided (ODF 2010c, p. 4-48), we estimate 
the older forest structure condition as defined by the ODF would 
generally provide red tree vole habitat. However, only some portion of 
the layered structure condition appears to be suitable tree vole 
habitat, and that is likely to be stands with more complexity that are 
closer in condition to that found in stands classed as old forest 
structure. Thus, stands that currently meet tree vole habitat 
requirements on State lands are limited to 5 percent of the ownership 
and, given such a low proportion, most likely isolated. Furthermore, 
the direction is to actively manage these landscapes to meet the 
targeted forest structure stages via thinning activities that promote 
desired structural features. The use of thinning activities to create 
stands that may be suitable habitat for red tree voles has not been 
tested; to the extent we can develop the appropriate structure and 
conditions in the long term, such

[[Page 63744]]

treatments in the surrounding landscape over the short term likely 
further limits the potential for a well-connected tree vole population 
in the interim. Meanwhile, tree voles would have to persist in these 
small patches of suitable habitat for decades before more suitable 
habitat developed.
    The effects of thinning treatments on red tree voles is not well 
understood. Younger stands may be important for allowing dispersal and 
short-term persistence of tree voles in landscapes where older forests 
are either isolated in remnant patches or have been largely eliminated 
(Swingle 2005, p. 94). Thinning these younger stands, while designed to 
develop late-successional habitat characteristics in the long term, has 
the potential to degrade or remove tree vole habitat in the short term, 
especially if thinning design does not account for structural features 
and the connectivity of those features that are important to red tree 
voles (Swingle and Forsman 2009, p. 284). As reported in USDA and USDI 
(2002, p. 13), although old, inactive red tree vole nests have been 
found in thinned stands and shelterwood treatments, no occupied nests 
have been found, suggesting that red tree voles are susceptible to 
stand level disturbances that alter the canopy layer and may cause 
sites to become unsuitable. Biswell (2010, pers. comm.) and Swingle 
(2010, pers. comm.) have also observed reduction in numbers or 
elimination of red tree voles from stands that have been thinned. 
Hopkins (2010, pers. comm.) found that buffering nests with a 10-ac (4-
ha) buffer would result in the presence of nests post-thinning, but he 
did not attempt to verify vole occupancy through visual observations of 
voles.
    Although State Forest lands are managing part of their landbase to 
retain and develop some older forest habitat, the lack of survey and 
protection mechanisms to protect existing tree vole sites, combined 
with the limited availability of current suitable habitat and intensity 
of harvest and thinning activities between protected areas, leads us to 
conclude that existing regulatory mechanisms on State lands are 
inadequate to ameliorate the threat of habitat loss and fragmentation 
and provide for the conservation of the North Oregon Coast DPS of the 
red tree vole.

Summary of Regulatory Mechanisms on State Land

    As discussed above under ``Regulatory Mechanisms on Private Land,'' 
there may be some ancillary benefits to red tree voles from actions 
taken to protect other wildlife species. In addition to OAR 
requirements to provide buffers to protect certain wildlife species, 
ODF provides additional buffers for spotted owls and marbled murrelets, 
as well as additional retention blocks in the form of terrestrial 
anchor habitats scattered throughout its ownership. While these areas 
provide for some habitat retention, some are likely too small and most 
too isolated to provide for a species with limited dispersal ability, 
such as the red tree vole. Furthermore, without pre-project surveys for 
voles, the species will need to serendipitously be in these retention 
blocks to be afforded any protections. Occupied vole sites outside 
these areas would be lost with any timber harvest activity. This 
precludes the opportunity to potentially reduce isolation and provide 
for additional retention blocks elsewhere on the landscape where tree 
voles may actually be present, thereby improving their dispersal 
potential.
    Because of the small amounts (13 percent) of complex forest habitat 
(1 percent older forest and 12 percent layered forest structure) 
currently available on State lands throughout the DPS, there is limited 
ability to maintain persistent populations of red tree voles on this 
ownership. Also, not all areas of these combined structure categories 
may provide tree vole habitat, considering that empirical evidence 
indicates only 5 percent of the State ownership within the DPS is 
currently considered tree vole habitat (Dunk 2009, pp. 5, 7). State 
Forest Management Plans call for developing more of these older 
habitats, but these conditions are not expected to be reached for at 
least 70 years. Moreover, the use of thinning activities to create 
stands that may be suitable habitat for red tree voles has not been 
tested; to the extent we can develop the appropriate structure and 
conditions, it is reasonable to conclude that much of the 15 to 25 
percent of the landscape targeted as older forest structural condition 
may eventually be suitable tree vole habitat. However, as described 
above, based on the currently observed proportion of suitable red tree 
vole habitat relative to layered forest conditions, it is likely only 
some undetermined portion of the 15 to 25 percent of the landscape 
targeted as layered forest condition may provide suitable habitat. 
Finally, thinning activities designed to meet these long-term structure 
targets may place additional limitations on the ability of tree vole 
populations to be well connected over those next 70 years.
    Although the State does manage their forests with an eventual 
increase in older forest conditions as a goal, most of the State lands 
within the DPS are managed for some level of continuing timber harvest. 
The loss and modification of red tree vole habitat on State lands, 
compounded by isolation of existing habitat as a result of timber 
harvest, continues under existing regulatory mechanisms. In addition, 
there are no mechanisms in place to protect existing occupied tree vole 
sites outside of retention areas. We therefore conclude that existing 
regulatory mechanisms on State land are inadequate to provide for the 
conservation of the North Oregon Coast DPS of the red tree vole, as 
they contribute to threats of habitat destruction, modification, or 
curtailment under Factor A, as well as the threats of habitat 
fragmentation and isolation of small populations under Factor E.
Regulatory Mechanisms on Federal Land
    Federal lands comprise 22 percent of the DPS (851,000 ac (344,400 
ha)) and are concentrated in two separate areas. The southernmost 
portion lies between U.S. Highway 20 and the Siuslaw River, and makes 
up roughly two-thirds of the Federal lands within the DPS (Figure 2). 
The remaining Federal ownership, although more fragmented and dispersed 
than the southern portion in terms of ownership pattern, is generally 
located between Lincoln City and Tillamook, with a few scattered 
parcels of BLM land in Columbia and Washington Counties. The Siuslaw 
National Forest comprises 41 percent of the Federal land in the DPS, 
and the Salem and Eugene BLM Districts make up the remainder. Federal 
lands have been managed under the Northwest Forest Plan (NWFP) (USDA 
and USDI 1994, entire), although there is past and ongoing litigation 
that has, and will continue to, affect management planning for BLM 
within the DPS (see below). Implementation of the NWFP resulted in an 
80 to 90 percent reduction of timber harvests from Federal lands in the 
Coast Range compared to levels in the 1980s (Spies et al. 2007b, p. 
50). Approximate timber harvests projected for the next 2 years on the 
Federal ownership in the North Oregon Coast DPS sum to 99 million board 
feet (231,000 cubic m) on average per year (Herrin 2011, pers. comm.; 
Nowack 2011, pers. comm.; Wilson 2011, pers. comm.). This may include 
harvest in some areas within an administrative unit that is not 
encompassed by the DPS, primarily that portion of the Siuslaw National 
Forest that lies south of the Siuslaw River (approximately 15 percent 
of the forest acreage). Currently, all the harvest on

[[Page 63745]]

Federal land in the North Oregon Coast DPS occurs as thinning. Harvest 
intensity (annual harvest per acre of landbase) differs by 
administrative unit and ranges from 66 board feet per acre (0.066 cubic 
m per ha) per year on the Siuslaw National Forest to 154 board feet per 
acre (0.154 cubic m per ha) per year on that portion of the Eugene BLM 
District within the DPS. Acreages used to calculate harvest intensity 
may include acres that are not capable of producing forest, and may be 
slightly underestimated.
    Within the DPS, BLM has operated under two different management 
plans over the past several years. On December 30, 2008, BLM published 
Records of Decision (ROD) for the Western Oregon Plan Revisions (WOPR), 
which revised the Resource Management Plans for the BLM units in 
western Oregon, including those units within the DPS. The WOPR meant 
that BLM would no longer be managing their land under the standards and 
guidelines of BLM's 1995 Resource Management Plans, which had adopted 
the Northwest Forest Plan. On July 16, 2009, the Acting Assistant 
Secretary for Lands and Minerals administratively withdrew the WOPR 
RODs. The administrative withdrawal of WOPR was challenged in court 
(Douglas Timber Operators, Inc. v. Salazar, 09-1704 JDB (D.D.C.). On 
March 31, 2011, the United States District Court for the District of 
Columbia vacated and remanded the administrative withdrawal of the WOPR 
RODs, effectively reinstating the WOPR RODs as the operative Resource 
Management Plan for BLM lands within the DPS. However, there remains 
ongoing litigation, the result of which could affect the implementation 
of WOPR (e.g. Pacific Rivers Council v. Shepard, Case No. 3:2011-cv-
00442 (D. Or.); AFRC v. Salazar-DOI/Locke, Case No. 1:11-cv-01174 
(D.D.C.)). Our analysis of existing regulatory mechanisms on Federal 
lands reflects the current management plans that are officially in 
place. That is, the NWFP for Forest Service lands, and the WOPR for BLM 
lands.
    Of the Federal lands in the DPS, 34 percent are managed as LSRs, 
and 14 percent are managed as an Adaptive Management Area (AMA), which 
includes additional LSR management in portions of the AMA (see below). 
Another 18 percent are managed as Late-Successional Management Area 
(LSMA). The primary management objectives in LSRs, an NWFP allocation, 
are to protect and enhance late-successional forest conditions (USDA 
and USDI 1994, p. C-11). The LSMAs, established under WOPR, have a 
similar objective as LSRs, with a focus on maintaining and developing 
habitat for northern spotted owls and marbled murrelets (USDI 2008, p. 
2-28). The combined area of LSR and LSMA equals 52 percent of the 
Federal ownership managed for the purpose of developing and maintaining 
late-successional conditions, although not all of the acres in these 
allocations currently meet that condition. Although forest structure 
can vary widely with vegetation type, disturbance regime, and 
developmental stage, in Douglas-fir stands of western Oregon, 80 years 
of age is the point at which stands can begin to develop the structural 
complexity that is of value to late-successional species (e.g., canopy 
differentiation and multiple canopy layers; understory development; 
large limbs; large snags and logs; tree decay and deformities in the 
form of hollow trees, broken tops, large cavities; and epicormic 
branching) (USDA and USDI 1994, pp. B-2 through B-7). Thinning and 
other silvicultural treatments are allowed in LSRs and LSMAs if needed 
to create and maintain late-successional forest conditions. Within 
LSRs, thinning is allowed in stands up to 80 years old, except for the 
Northern Coast AMA, where it is allowed in stands up to 110 years (USDA 
and USDI 1994, p. C-12). There is no age limit for thinning in LSMAs 
(USDI 2008, p. 2-28). Salvage after stand-replacement disturbances is 
allowed in LSRs and LSMAs, although there are different standards and 
guidelines in place for these allocations (USDA and USDI 1994, pp. C-13 
through C-16; USDI 2008, pp. Summary-9, 2-28 to 2-32).
    The emphasis of the Northern Coast Range AMA, an NWFP allocation, 
is to restore and maintain late-successional forest habitat consistent 
with marbled murrelet guidelines (USDA and USDI 1994, p. D-15) through 
developing and testing new approaches that integrate ecological, 
economic, and other social objectives. Although 14 percent of the 
Federal land in the DPS is allocated as AMA, 10 percent of Federal land 
is managed as LSR within the AMA, meaning that LSR standards and 
guidelines are to be followed unless reconsidered as part of the AMA 
plan. The current AMA plan has retained the original NWFP standards and 
guidelines for LSRs, so in effect 62 percent of the Federal ownership 
is currently managed as LSR (52 percent LSR and LSMA, combined, and 10 
percent AMA managed as LSR). The one difference in LSR management 
within the AMA as compared to the rest of the NWFP area is that 
thinning is allowed in stands up to 110 years of age in the AMA, as 
described above. Additional areas of older and more structurally 
complex forest is retained under the WOPR in the Deferred Timber 
Management Area allocation, but only through the year 2023; this land 
allocation makes up less than 0.5 percent of the Federal ownership 
within the DPS.
    Of the 34 percent of Federal lands not designated as LSR or AMA in 
the DPS, 18 percent is classified as either Matrix (6 percent) or 
Timber Management Area (TMA) (12 percent), NWFP and WOPR land 
allocations, respectively. These allocations are where commercial 
timber harvest is expected to occur (e.g., regeneration harvest such as 
clearcuts).
    Allocations to protect streams and other water bodies include 
Riparian Management Areas (RMA) under the WOPR, and Riparian Reserves 
(RR) under the NWFP. Under the WOPR, the width of RMAs are reduced for 
most water bodies by up to half the distances compared to Riparian 
Reserves under the NWFP (USDA and USDI 1994b, pp. C-30 through C-31; 
USDI 2008, p. 2-33). Silvicultural activities, such as thinning, are 
allowed in these allocations to meet specific aquatic and riparian 
objectives (USDA and USDI 1994, pp. C-30 through C-31; USDI 2008, 2-32 
through 2-34). Riparian Management Areas have been mapped under WOPR 
and comprise 4 percent of the Federal ownership within the DPS. Under 
the NWFP, stream densities in the Coast Range result in much of the 
Matrix allocation being overlain by Riparian Reserves that can be 
anywhere from 150 to 500 ft (76 to 152 m) wide on each side of the 
stream, depending on the waterbody and site condition (USDA and USDI 
1994b, pp. C-30 through C-31; Davis 2009, pers. comm.). Overlaying 
Riparian Reserves and protections for other species called for in the 
NWFP can substantially reduce the area of Matrix available for timber 
harvest. For example, between riparian reserves and other protections 
required by the NWFP, only 3 percent of the Siuslaw National Forest is 
available for timber harvest other than thinning treatments designed to 
meet ecological objectives (Davis 2009, pers. comm.).
    The remaining 10 percent of lands in the DPS under Federal 
ownership are in Congressional Reserves, Administratively Withdrawn 
Areas, and other areas under special management and not available for 
timber harvest. These areas may or may not be conducive to developing 
and maintaining older forest conditions, depending on their underlying 
management emphasis.
    In 2007, the BLM and the Forest Service signed Records of Decision

[[Page 63746]]

(USDA 2007, entire; USDI 2007, entire) that eliminated the Survey and 
Manage mitigation measures from the BLM Resource Management Plans and 
the Forest Service Land and Resource Management Plans. These decisions 
were challenged in court (Conservation Northwest v. Rey, Case No. C-08-
1067-JCC (W.D. Wash.)). On December 17, 2009, the court issued a 
decision finding multiple National Environmental Policy Act (NEPA) 
inadequacies in the 2007 Final Supplemental Environmental Impact 
Statement. The parties to this litigation reached a settlement 
agreement that was approved by the court on July 6, 2011. The 
settlement agreement reinstates the 2001 Survey and Manage ROD (USDA 
and USDI 2001, entire), as modified by the settlement agreement, for 
those Forest Service and BLM units within the area covered by the NWFP. 
The 2011 Settlement Agreement makes four modifications to the 2001 ROD. 
It (1) acknowledges existing exemptions (Pechman exemptions) from 
Survey and Manage Standards and Guidelines as a result of an earlier 
court-approved stipulation from different litigation (Northwest 
Ecosystem Alliance v. Rey, Case No. 04-844-MJP (W.D. Wash.)); (2) 
updates the 2001 Survey and Manage species list; (3) establishes a 
transition period for application of the species list; and, (4) 
establishes new exemption categories (2011 Exemptions), to which known 
site management may apply. Under the 2011 settlement agreement, the 
Pechman exemptions continue to apply to projects classified into four 
categories and include thinning in stands younger than 80 years old, 
replacing or removing culverts, improving riparian and stream habitat, 
and using prescribed fire to treat hazardous fuels.
    The 2011 settlement agreement establishes seven categories of new 
exemptions.
    The following categories of activities are exempt from pre-
disturbance surveys for species on the Survey and Manage list, but 
known site management may apply: (1) Recreation; (2) fish and wildlife 
habitat restoration; (3) treatment of weeds and sudden oak death; (4) 
certain hazardous fuel treatments in Wildland Urban Interface; (5) 
bridges; (6) non-commercial fuel treatments; and (7) restoration 
projects involving commercial logging. The 2011 settlement agreement 
contains specific directions applying known site management for 
projects applying the 2011 exemptions, which vary depending upon the 
2011 exemption applied, and a species' Survey and Manage category.
    Although the Survey and Manage standards and guidelines are an 
artifact of the NWFP--and BLM is currently operating under the WOPR and 
not the NWFP--as signatories to the Survey and Manage settlement 
agreement, they are applying the Survey and Manage program, as 
described above, on their ownership within the DPS. The red tree vole 
falls under the Survey and Manage standards and guidelines; thus, prior 
to certain habitat-disturbing activities, surveys and subsequent 
management of high-priority sites are required for red tree voles. All 
sites on Federal land within the DPS are considered high-priority sites 
with the exception of 198,000 ac (80,130 ha) of the southernmost 
portion of the DPS (primarily located within the Siuslaw River 
drainage). Some tree vole sites on Federal land in this portion of the 
DPS would not be considered high-priority sites, depending on the 
amount of reserve land allocation in the watershed, habitat quality, 
number of active vole nests detected in survey areas, and the total 
survey effort (USDA and USDI 2003).
    Although federally managed lands are expected to provide for large, 
well-distributed populations of red tree voles throughout most of their 
range, the northern Oregon Coast Range north of Highway 20 within the 
DPS is an exception. For this area, despite of the majority of the 
Federal land being managed as LSRs or LSMAs, the Final Environmental 
Impact Statement analyzing the effects of discontinuing the NWFP Survey 
and Manage program concluded that regardless of the tree vole's status 
as a Survey and Manage species, the combination of small amounts of 
Federal land, limited connectivity between these lands, and few known 
vole sites would result in habitat insufficient to support stable 
populations of red tree voles north of Highway 20 (USDA and USDI 2007, 
pp. 291-292). Federal lands provide more habitat for red tree voles 
than other ownerships in the DPS and have land allocations, such as 
LSRs, that require management to maintain and restore late-successional 
conditions that are more suitable as red tree vole habitat. However, 
the limited amount of Federal lands in the DPS restricts red tree vole 
distribution and magnifies the effect of habitat loss occurring from 
stochastic events, further limiting the red tree vole's ability to 
persist in an area or recolonize new sites (see Factors A and E).
    Thinning treatments are allowed in LSRs and LSMAs, but their effect 
on red tree voles is not well understood. Younger stands may be 
important for allowing dispersal and short-term persistence of tree 
voles in landscapes where older forests are either isolated in remnant 
patches or have been largely eliminated (Swingle 2005, p. 94). Thinning 
these younger stands, while designed to develop late-successional 
habitat characteristics in the long term, has the potential to degrade 
or remove tree vole habitat characteristics in the short term, 
especially if thinning design does not account for structural features 
and the connectivity of those features that are important to red tree 
voles (Swingle and Forsman 2009, p. 284). As reported in USDA and USDI 
(2002, p. 13), although old, inactive red tree vole nests have been 
found in thinned stands and shelterwood treatments, no occupied nests 
have been found, suggesting that red tree voles are susceptible to 
stand-level disturbances that alter the canopy layer and may cause 
sites to become unsuitable. Biswell (2010, pers. comm.) and Swingle 
(2010, pers. comm.) have also observed reduction in numbers or 
elimination of red tree voles from stands that have been thinned. 
Hopkins (2010, pers. comm.) found that buffering nests with a 10-ac (4-
ha) buffer would result in the presence of nests post-thinning, but he 
did not attempt to verify vole occupancy through visual observations of 
voles.
    Red tree voles are afforded more protection on Federal lands than 
on State Forest and private lands within the DPS, primarily as a result 
of the Survey and Manage protections. Before commencing timber harvest 
activities (except for thinning activities in stands under 80 years 
old), projects must be surveyed for tree voles and high priority sites 
protected. Thirty percent of the Federal ownership is currently 
considered tree vole habitat; 62 percent of the Federal ownership is in 
a land allocation wherein management objectives call for retaining and 
developing late-successional and old forest structural conditions. 
Another 10 percent are in allocations that preclude timber harvest, 
although not all of these allocations may develop habitat suitable for 
tree voles. However, most of the Federal landbase should develop into 
conditions suitable as red tree vole habitat at some point in the 
future given the current Federal land management. In addition, conifer-
dominated forests in Riparian Reserves and Riparian Management Areas 
may provide additional future habitat. Thinning activities designed to 
develop older forest conditions in the long term may limit the 
dispersal capability and connectivity of local tree vole

[[Page 63747]]

populations in the short term. Except for the limited amount and 
isolated nature of Federal lands north of Highway 20, federally managed 
lands are expected to provide for large, well-distributed populations 
of red tree voles throughout the rest of their range within the DPS. 
Based on the above assessment, we conclude that existing regulatory 
mechanisms on Federal land are adequate to provide for the conservation 
of the North Oregon Coast DPS of the red tree vole.

Summary of Regulatory Mechanisms on Federal Land

    Although they comprise less than one-quarter of the land area 
within the DPS, Federal lands provide the majority of remaining high-
quality, older forest habitat for red tree voles within the DPS. The 
implementation of the Northwest Forest Plan in 1994 led to a dramatic 
decrease in timber harvest on Federal lands. Management direction for 
the Forest Service (under the NWFP) and BLM (under the WOPR) calls for 
maintaining or restoring late-successional forest conditions on a 
majority of these lands within the DPS. Although some level of timber 
harvest continues on these Federal lands, particularly in the Matrix 
and Timber Management Area allocations, it affects less than a quarter 
of the DPS. Some degree of thinning also occurs within LSRs and LSMAs 
within the DPS, but if managed according to the standards and 
guidelines of the respective management plans, and if such thinning 
does not exceed the current rates, the effects of such treatments on 
red tree voles are believed to be relatively minor. The recent 
reinstatement of Survey and Manage standards and guidelines contributes 
to the conservation of the red tree vole and its habitat within the 
DPS. We therefore consider existing regulatory mechanisms adequate to 
provide for the conservation of the red tree vole on Federal lands 
where they occur within the DPS. However, the insufficient quantity of 
Federal lands and their distribution within the DPS contribute to the 
threat of habitat fragmentation, isolation, and potential extirpation 
of local populations due to stochastic events, as detailed in Factor E, 
below.

Conclusion for Factor D

    Existing regulatory mechanisms are inadequate to provide for the 
protection and management of red tree voles on the 78 percent of the 
DPS made up of non-Federal (private and State) lands. The State of 
Oregon has regulatory mechanisms in place on private and State lands 
designed to provide for commercial timber harvest on relatively short 
rotation schedules, while simultaneously conserving habitat and 
protecting specific wildlife species during the course of activities 
associated with timber growth and harvest. The red tree vole is not one 
of those specific species targeted for protection under the OAR, and, 
due to its relatively specialized habitat requirements and limited 
dispersal abilities, many of the guidelines intended to conserve other 
wildlife species are not sufficient to provide adequate habitat for the 
red tree vole. Although some individual red tree voles may enjoy 
incidental benefits if they are located within tree retention or buffer 
areas, these small buffer areas are not expected to provide for long-
term persistence of red tree vole populations given their isolated 
nature and the allowance for removal of some buffers if the target 
species are no longer present. In addition, short rotations and 
intensive management of the surrounding stands will not likely develop 
or retain the structural features advantageous to red tree voles, thus 
contributing to the threat of habitat modification and maintaining the 
isolation of any tree voles that may be present in these areas. Timber 
harvest rates are expected to continue at current levels on private 
lands. Protection measures in addition to the OAR regulations are 
provided on State Forest lands, allowing for more retained and 
protected areas on the landscape. State Forests are also being managed 
to increase the amount of structurally complex forests. However, loss 
and modification of red tree vole habitat on private and State lands as 
a result of timber harvest continues under existing regulatory 
mechanisms. Furthermore, there are no mechanisms in place to locate and 
protect existing occupied tree vole sites outside of retention areas.
    Although Federal lands offer some habitat protection and 
management, there may not be enough habitat in a condition to provide 
for the red tree vole north of U.S. Highway 20 where Federal land is 
limited. There is restricted connectivity among blocks of Federal land 
in this area, and few known vole sites currently available to 
recolonize habitat. Given survey and protection measures in place for 
tree voles, the low level of timber harvest compared to other 
ownerships, and the projected management of over 62 percent of their 
landbase to maintain or develop late-successional conditions, current 
regulatory mechanisms appear to be adequate on Federal lands. However, 
because we find that existing regulatory mechanisms are not adequate to 
protect habitat for tree voles on the nearly 80 percent of the DPS that 
is made up of State or private lands, we conclude that overall, 
existing regulatory mechanisms are not adequate to protect the DPS from 
the threats discussed under Factors A and E and, in conjunction with 
these additional factors, pose a significant threat to the persistence 
of the North Oregon Coast DPS of the red tree vole.
    We have evaluated the best available scientific and commercial data 
on the inadequacy of existing regulatory mechanisms, and determined 
that this factor poses a significant threat to the viability of the 
North Oregon Coast DPS of the red tree vole, when we consider this 
factor in concert with the other factors impacting the DPS.

Factor E. Other Natural or Manmade Factors Affecting the Species' 
Continued Existence

Fragmentation and Isolation of Older Forest Habitats
    Tree voles in the northern Oregon Coast Range evolved in vast, 
well-distributed expanses of primarily late-successional forest. By 
1936, the amount of large-conifer forest was already below the 
historical range of 52 to 85 percent of the Coast Range estimated to 
contain late-successional forest (greater than 80 years old) over the 
past 1,000 years (Wimberly et al. 2000, p. 175; Wimberly and Ohmann 
2004, p. 642). In 1936, extensive patches of large-conifer Douglas-fir 
forest connected much of the central and southern portions of the Coast 
Range Province. In the northern quarter of the province, patches of 
large Douglas-fir combined with large spruce-hemlock forest and 
intermingled with large patches of open and very young stands (Wimberly 
and Ohmann 2004, pp. 635, 639). Most of those open and young stands 
encompassed the 300,000 acres (121,410 ha) burned in the 1933 Tillamook 
fire. By 1996, large blocks of the remaining large-conifer forest were 
restricted to Federal and State lands in the central portion of the 
Coast Range Province, having been eliminated from most private lands 
(Wimberly and Ohmann 2004, p. 635). Elsewhere, large-conifer forests 
were primarily isolated in scattered fragments on public land. The 1936 
area of the Coast Range Province covered by large Douglas-fir (2,052 
square mi (5,315 square km)) and large spruce-hemlock (344 square mi 
(891 square km)) cover types declined by 1996, primarily as a result of 
timber harvest, resulting in a 58 percent reduction in the total area 
of large-conifer forest. Conversely, the combined area of small 
Douglas-fir and spruce-

[[Page 63748]]

hemlock forests increased by 87 percent (Wimberly and Ohmann 2004, pp. 
639-641).
    Not only have amounts of older forest decreased, but the spatial 
distribution of those forests has changed. Prior to European 
settlement, vegetation simulations indicate that mature (80-200 years) 
and old-growth forest (greater than 200 years) patches had the highest 
densities of all successional stages within the Coast Range Province. 
In addition, old-growth patches were large, ranging from 810 to 3,280 
square mi (2,100 to 8,500 square km), with a median of 1,660 square mi 
(4,300 square km), while patches of less than 80-year-old forests were 
generally less than 770 square mi (2,000 square km) (Wimberly 2002, p. 
1322). In the Coast Range Province today, the largest old-growth patch 
is 2.5 square mi (6.5 square km), while the largest patch of early-
seral forest (less than 30 years old) is larger than 1,900 square mi 
(5,000 square km), and the largest patch of 30 to 80-year-old forest is 
larger than 1,150 square mi (3,000 square km) (Wimberly et al. 2004, p. 
152).
    Within the DPS, we analyzed data compiled as part of the NWFP 
effectiveness monitoring program (USDA/USDI 2010, unpublished data) for 
the distribution of late-successional and old-growth (LSOG) patches 
within the DPS. As part of our analysis, we wanted to see what 
proportion of the LSOG habitat comprised patches large enough to 
support tree voles, and how close these patches were to other suitable 
patches. There is little information on minimum stand sizes used by 
tree voles and a complete lack of information on what is needed to 
sustain tree vole populations (USDA and USDI 2000b, p. 7). In Polk and 
Tillamook Counties, Hopkins (2010, pers. comm.) found vole nests in 
forest patches as small as 5 to 10 acres (2 to 4 ha) in the oldest 
(350-400 years), most structurally complex stands available. Huff et 
al. (1992, pp. 6-7) compiled data on actual red tree vole presence and 
found the mean age of stands in which tree voles were found in the 
Coast Range was 340 years and the minimum stand size was 75 ac (30 ha), 
with mean and median stand sizes of 475 and 318 ac (192 and 129 ha), 
respectively. Whether a minimum patch size of 5 to 10 ac (2 to 4 ha) or 
even 75 ac (30 ha) can sustain a population of red tree voles over the 
long term is unknown and is influenced by such things as habitat 
quality within and surrounding the stand, the position of the stand 
within the landscape, and the ability of individuals to move among 
stands (Huff et al. 1992, p. 7; Martin and McComb 2003, pp. 571-579). 
However, in the absence of better information on the stand size needed 
to sustain tree vole populations (USDA and USDI 2000b, p. 7), we 
consider the 75-ac (30-ha) minimum patch size identified by Huff et al. 
(1992, pp. 6-7) the best available information to use for our analysis 
because it represents actual tree vole occurrence and not just presence 
of a nest. As part of our analysis, we found that 59 percent of the 
area mapped as LSOG occurred in patches larger than 75 ac (30 ha). If 
we extrapolate this proportion to Dunk's (2009, p. 7) analysis showing 
only 11 percent of the DPS containing actual tree vole habitat (418,000 
ac (169,165 ha)), we find the suitability potentially further reduced 
to only 246,620 ac (99,807 ha), or 6 percent of the DPS. This is 
consistent with Dunk (2009, p. 9), who noted that his work did not take 
into account habitat fragmentation, connectivity, and metapopulation 
dynamics that may influence whether populations or individual tree 
voles could occur within his area of analysis.
    It is important to note that even the forested areas identified as 
individual ``patches'' through a geographic information systems (GIS) 
program do not necessarily represent areas of forest with continuous 
canopy cover. Although these patches of forest are technically 
connected at some level, inspection of the data reveal that they are 
for the most part highly porous and discontinuous, and we performed no 
analysis to filter out stands that may be so porous or discontinuous as 
to provide no interior habitat. Furthermore, the LSOG definition used 
as part of the NWFP monitoring program (mean tree DBH of 20 in (50.8 
cm) or greater; canopy cover 10 percent or greater; all tree species 
included) can include stands that do not necessarily equate to red tree 
vole habitat and represents a substantial overestimate. For example, 
while the LSOG dataset identified 759,968 ac (307,559 ha) of LSOG 
within the DPS, Dunk (2009, pp. 4, 7) found red tree vole habitat to 
comprise approximately 425,000 ac (172,000 ha) of the DPS (see 
Continuing Modification and Current Condition of Red Tree Vole Habitat 
in Factor A, above). There are several reasons why the LSOG database 
represents a liberal (i.e., overly generous) description of red tree 
vole habitat. First, the dataset included stands with canopy cover as 
low as 10 percent, which is well below the minimum canopy cover of 53 
percent and even further below the mean of 78 percent for stands in 
which Swingle (2005, p. 39), as one example, found tree vole nests. The 
dataset also included hardwood species as part of the canopy cover 
component allowing for the possibility of LSOG patches comprising 
primarily hardwood stands with scattered large conifers. While tree 
voles have been found in mixed conifer/hardwood stands, their exclusive 
diet of conifer needles would limit the habitat capability of stands 
that are primarily hardwood. Therefore, our analysis of remaining older 
forest patches in the DPS provides an overestimate in terms of 
remaining potential tree vole habitat, given that the LSOG data used 
provide a liberal characterization of tree vole habitat. Furthermore, 
the GIS pixel aggregation used likely characterized some of the data as 
patches that would in reality be too porous to function as tree vole 
habitat, increasing the potential for overestimation. Applying the 
proportion of this LSOG data set that meets the minimum forest patch 
size to the area of DPS considered suitable tree vole habitat (Dunk 
2009, p. 7), an analysis considered a likely overestimate of tree vole 
occupancy (see Factor A. Continuing Modification and Current Condition 
of Red Tree Vole Habitat, above), we find only 6 percent of the DPS may 
be in suitable habitat that is of a large enough patch size to sustain 
tree voles. This suggests that the remaining potentially suitable 
habitat for tree voles is highly fragmented, which further lessens the 
probability of long-term persistence of red tree voles under current 
conditions in the DPS.
    In simulated pre-European settlement forests of the Coast Range 
Province, most forests less than 200 years old were within 0.4 mi (1 
km) of an old-growth forest patch. This pattern has reversed, with a 
considerable increase in isolation of old-growth forest patches 
(Wimberly et al. 2004, p. 152). Our analysis of the LSOG forest data 
provided by the NWFP effectiveness monitoring program indicates that in 
the DPS, the average distance between LSOG forest patches greater than 
75 ac (30 ha) in size was 1,745 ft (532 m). Larger patches greater than 
500 ac (202 ha) in size were separated by 6,158 ft (1,877 m) on 
average. This increasing isolation of LSOG forest patches due to 
maintenance of younger stands in the intervening areas poses a threat 
to the red tree vole, as the dispersal capability of this species is so 
limited. As noted earlier, the greatest known dispersal distance for an 
individual red tree vole is 1,115 ft (340 m) (Biswell and Meslow, 
unpublished data referenced in USDA and USDI 2000b, p. 8), but shorter 
distances from 10 to 246 ft (3 to 75 m) appear to be more the norm for 
dispersing subadults (Swingle 2005, p.

[[Page 63749]]

63). The current average distance between patches of LSOG forest in the 
DPS thus exceeds the known dispersal distances of red tree voles. A 
matrix of surrounding younger forest is not entirely inhospitable 
habitat for dispersing red tree voles, but survivorship in such 
habitats is likely reduced. Whether red tree voles can successfully 
disperse between remaining patches of fragmented habitat depends on 
their vagility and tolerance for the intervening matrix habitat 
(Pardini 2004, p. 2581).
    Historically, dispersal between trees in areas of more contiguous 
older forest would not have been a limiting factor for red tree voles, 
but under the current conditions of fragmentation, the ability of 
individuals to disperse between patches of remaining high quality 
habitat is restricted. Limited dispersal can translate into a lack of 
sufficient gene flow to maintain diversity and evolutionary potential 
within the population, possible inbreeding depression, Allee effects 
(e.g., failure to locate a mate), and other problems (e.g., 
Soul[eacute] 1980, entire; Terborgh and Winter 1980, pp. 129-130; 
Shaffer 1981, p. 131; Gilpin and Soul[eacute] 1986, pp. 26-27; Lande 
1988, pp. 1457-1458). The potential for the local loss of populations 
is high, as remnant habitat patches formerly occupied by tree voles may 
not be recolonized due to the distance between habitat fragments and 
the short-distance dispersal of the species, leading to local 
extirpation and further isolation of the remaining small populations, 
and possibly eventual extinction (see Isolation of Populations and 
Small Population Size, below). As noted above, although we do not have 
standardized, quantitative survey data, the fact that red tree voles 
are increasingly difficult to find and have apparently disappeared from 
some areas where they were formerly known to occur suggests that 
current habitat conditions are not conducive to the successful 
dispersal or maintenance of red tree vole populations within the DPS.
    Highly suitable red tree vole habitat (that with the greatest 
strength of selection) is quite rare throughout the range of the red 
tree vole (Dunk and Hawley 2009, p. 632) and is even more restricted 
within the North Oregon Coast DPS (Dunk 2009, pp. 4-5). Moreover, large 
blocks of older forest (greater than 1,000 ac (400 ha)) are restricted 
primarily to Federal lands, with contiguous blocks separated by great 
distances (Moeur et al. 2005, p. 77). Fragmentation complicates habitat 
availability for red tree voles, which select for patches of large tree 
structure where fragmentation is minimized (Martin and McComb 2002, p. 
262); having evolved in extensive areas of relatively more contiguous 
late-successional forest, tree voles are especially vulnerable to the 
negative effects of fragmentation and isolation due to their limited 
dispersal capability. Within the DPS, virtually all of the Federal land 
lies in two widely separated clusters (Figure 2). Much of the southern 
portion of the DPS, south of U.S. Highway 20, is Federal land, with the 
other cluster of Federal land lying north of Highway 20, mainly between 
Lincoln City and Tillamook. As most of the remaining high-quality 
habitat for red tree voles within the DPS is restricted to these two 
clusters of Federal lands, there is little redundancy for tree vole 
populations within the DPS, and loss of either cluster would result in 
the single remaining cluster and its associated tree vole population 
being highly vulnerable to extirpation through some stochastic event, 
such as wildfire. These two blocks of Federal ownership are separated 
by primarily private and some State lands. Except for a small patch of 
checkerboard BLM ownership in southeast Columbia and northeast Yamhill 
Counties, along with a few small State parks, ownership north of 
Tillamook consists almost entirely of private timberland and lands 
managed by the Oregon Department of Forestry (Tillamook and Clatsop 
State Forests).
    Implementing current land management policies in the Coast Range is 
projected to provide a modest increase (approximately 20 percent) in 
red tree vole habitat over the next 100 years, primarily on public 
lands (Spies et al. 2007b, p. 53). However, red tree vole populations 
appear to be decreasing in the face of current threats to their 
habitat. Therefore, we conclude that this limited increase in suitable 
habitat that may develop on public lands over an extended length of 
time will not be sufficient to address the lack of connectivity that 
currently exists between Federal lands, due to land management 
practices on the intervening lands (USDA and USDI 2007, p. 291). 
Furthermore, currently small, isolated populations of tree voles may 
not be capable of persisting over the length of time required to enjoy 
the benefits of this projected increase in suitable habitat, but may 
more likely be subject to local extirpations in the intervening time 
period. The Final Environmental Impact Statement analyzing the effects 
of discontinuing the NWFP Survey and Manage program concluded that the 
combination of small amounts of Federal land, limited connectivity 
between these lands, and few known vole sites north of Highway 20 would 
result in habitat insufficient to support stable populations of red 
tree voles (USDA and USDI 2007, pp. 291-292). The authors of the report 
further concluded that due to these vulnerabilities, ``every site is 
critical for persistence'' for the red tree vole in Oregon's North 
Coast Range north of Highway 20 (USDA and USDI 2007, p. 292). Given the 
fragmented nature of Federal lands providing late-successional 
conditions in the DPS and the limited connectivity between these 
remaining blocks, it is unlikely that the small projected increase in 
suitable habitat that may develop over the next 100 years on Federal 
lands will be sufficient to offset the more immediate threats of 
habitat destruction, modification, and fragmentation that threaten the 
North Oregon Coast population of the red tree vole.

Summary of Fragmentation and Isolation of Older Forest Habitats

    Red tree voles are considered habitat specialists and are strongly 
associated with large, relatively more contiguous areas of conifer 
forests with late-successional characteristics; they are not adapted to 
fragmented or patchy habitats (Martin and McComb 2002, p. 262). The 
older forest habitat associated with red tree voles has been 
significantly reduced through historical timber harvest, and as 
discussed under Factor A, above, ongoing management for timber 
production maintains much of the remaining older forest habitat in a 
fragmented and isolated condition, surrounded by younger forests of 
lower quality habitat for tree voles. We analyzed data compiled as part 
of the NWFP effectiveness monitoring program (USDA/USDI 2010, 
unpublished data) and found that of the remaining older forest within 
the DPS, 59 percent is in patches greater than 75 ac (30 ha), but these 
patches comprise only 6 percent of the entire DPS. The average distance 
between the remaining patches that are at least 75 ac (30 ha) in size 
exceeds the known dispersal distances of red tree voles. This suggests 
that red tree voles are unlikely to persist over the long term in most 
of the remaining patches of older forest habitats within the DPS, 
because most of them are likely too small or too isolated to support 
tree vole populations. Although the surrounding younger forests may 
serve as interim or dispersal habitat, the evidence suggests that such 
forest conditions are unlikely to support persistent populations of red 
tree voles. Furthermore, our evaluation suggests that the remaining 
older forest

[[Page 63750]]

habitat for tree voles is highly fragmented, which further lessens the 
probability of long-term persistence of red tree voles under current 
conditions in the DPS due to the limited dispersal capability of the 
species, and other consequences of isolation (see Isolation of 
Populations and Small Population Size, below).
    Most of the remaining high-quality habitat for red tree voles in 
the DPS is restricted to Federal lands; however, these lands make up 
only 22 percent of the area within the DPS, and they occur in two 
widely spaced clusters, one north of Highway 20 and one south of 
Highway 20. Thus, there is little redundancy for tree vole populations 
within the DPS, and loss of either cluster on Federal lands would 
result in the single remaining cluster and its associated tree vole 
population being highly vulnerable to extirpation or even extinction 
through some stochastic event, such as wildfire (see Climate Change, 
below). Under present conditions, the Federal lands north of Highway 20 
are already considered insufficient to support stable populations of 
red tree voles (USDA and USDI 2007, pp. 291-292).
    Under the current conditions of habitat fragmentation within the 
DPS, the ability of red tree voles to disperse between patches of 
remaining high-quality habitat are extremely restricted, and the 
evidence suggests that any remaining tree vole populations within the 
DPS are likely relatively small. The potential for the local loss of 
populations is therefore high, as remnant habitat patches formerly 
occupied by tree voles may not be recolonized due to the distance 
between habitat fragments and the short-distance dispersal capabilities 
of the species, leading to local extirpation and further isolation of 
the remaining small populations, and possibly eventual extinction (see 
Isolation of Populations and Small Population Size, below). 
Furthermore, ongoing timber harvest in surrounding areas of younger 
forests contributes to the threat of habitat fragmentation and 
isolation, as discussed above in Factors A and D. Therefore, based on 
the above evaluation, we conclude that the fragmentation and isolation 
of older forest habitats pose a significant threat to the North Oregon 
Coast DPS of the red tree vole.
Climate Change
    General Impacts. Climate change presents substantial uncertainty 
regarding future vegetation and habitat conditions in the North Oregon 
Coast DPS. Reduction and isolation of red tree vole habitat has been 
identified as a substantial threat to their persistence. Changing 
climate could further reduce tree vole habitat in ways that are 
difficult to predict.
    Globally, poleward and upward elevational shifts in the ranges of 
plant and animal species are being observed and evidence indicates 
recent warming is influencing this change in distribution (Parmesan 
2006, pp. 648-649; IPCC 2007, p. 8; Marris 2007, entire). In North 
America, and specifically in the Pacific Northwest, effects of forest 
pathogens, insects, and fire on forests are expected to increase, 
resulting in an extended period of high fire risk and large increases 
in area burned (IPCC 2007, p. 14; Karl et al. 2009, pp. 136-137; OCCRI 
2010, pp. 16-18; Shafer et al. 2010, pp. 183-185). The pattern of 
higher summer temperatures and earlier spring snowmelt, leading to 
greater summer moisture deficits and consequent increased fire risk, 
has already been observed in the forests of the Pacific Northwest (Karl 
et al. 2009, p. 136). Ecosystem resilience is expected to be exceeded 
by the unprecedented combination of climate change, its associated 
disturbances, and other ecosystem pressures such as land-use change and 
resource over-exploitation (IPCC 2007, p. 11). These projections 
discussed above indicate further reduction and isolation of red tree 
vole habitat over the next century.
    Red tree voles in the North Oregon Coast DPS cannot shift their 
range farther north due to the existing barrier of the Columbia River, 
which defines the northern boundary of their current and historical 
range. In addition, their range already occupies the summit of the 
Oregon Coast Range, so a shift to higher elevations is also not 
possible. Climate change assessments predict possible extinctions of 
such local populations if they cannot shift their ranges in response to 
environmental change (Karl et al. 2009, p. 137).
    Increased Frequency and Magnitude of Wildfire due to Climate 
Change. In the western hemlock and Sitka spruce plant series that 
dominates the Coast Range, fires tend to be rare but are usually stand-
replacing events when they take place, although low and moderate 
severity fires also occur (Impara 1997, p. 92). Sediment core data show 
mean fire return intervals of 230 to 240 years over the past 2,700 
years (Long et al. 1998, p. 786; Long and Whitlock 2002, p. 223). Three 
large fires, ranging from 300,000 to 800,000 acres (120,000 to 325,000 
ha), occurred in the DPS in the 1800s, in addition to the Tillamook 
fires of 1933-1951 (Morris 1934, pp. 317-322, 328; Pyne 1982, pp. 336-
337; Agee 1993, p. 212; Wimberly et al. 2000, p. 172). Starting in the 
mid-1800s, climate change, combined with Euro-American settlement, may 
have influenced the onset of large-scale fires (Weisberg and Swanson 
2003, p. 25). Another complication in these wetter forests has been a 
pattern of multiple reburns that occurred, such as the Tillamook burns 
of 1933, 1939, 1945, and 1951. Reburns may or may not add large amounts 
of additional area to the original burn, but they have the potential to 
impede the development of the stand for decades, delaying the ultimate 
return to older forest habitat suitable for red tree voles (Agee 1993, 
p. 213). Forests in the Pacific Northwest face a possible increased 
risk of large-scale fires within the foreseeable future; under the 
conditions of anticipated climate change, the effects of forest 
pathogens and fire on forests are expected to increase, resulting in an 
extended period of high fire risk and large increases in area burned 
(IPCC 2007, p. 14; Karl et al. 2009, pp. 136-137). Most recently, the 
Oregon Climate Change Research Institute predicted that large fires 
will become more common in the forests west of the Cascades, which 
includes the forests of the North Oregon Coast Range; estimated 
increases in regional forest areas burned over the next century ranged 
from 180 to 300 percent (OCCRI 2010, p. 16).
    Considering that the majority of the remaining tree vole habitat in 
the DPS is limited to Federal land, which comprises a total of roughly 
850,000 ac (344,000 ha) and is restricted to two separate clusters in 
the DPS, it is certainly possible to lose much of the Federal land in 
either of these blocks to a single stand-replacement fire, further 
limiting habitat and restricting the range of the tree vole in the DPS. 
Fire suppression organization and tactics have improved since the large 
fires of the last two centuries, resulting in a reduction in stand-
replacement fires (Wimberly et al. 2000, p. 178), although Weisberg and 
Swanson (2003, p. 25) note that suppression success may have been 
influenced by the reduction in fuel accumulations that these extensive 
fires accomplished. Regardless, the intense, large, high-severity fires 
that can occur in the Coast Range are driven by severe weather events 
(droughts or east wind patterns) (Agee 1997, p. 154), conditions under 
which fire suppression is severely hampered at best and ineffectual at 
worst (Impara 1997, pp. 262-263). Although large fires occurred within 
the DPS historically, in the past there were many additional areas of 
older forest

[[Page 63751]]

that were less isolated from other older forest stands and could serve 
as refugia for tree voles displaced from forests that burned; under 
current conditions, there are few such refugia available (Wimberly 
2002, p. 1322; Wimberly et al. 2004, p. 152) (see Modification of 
Oregon Coast Range Vegetation above). Given that we have evidence of 
past fires in the Coast Range that burned areas of up to 800,000 ac 
(325,000 ha), an amount roughly twice as large as either of the 
remaining clusters of Federal land within the DPS, and that projections 
under anticipated conditions of climate change point to the increased 
risk and magnitude of fire in this region (e.g., OCCRI 2010, p. 16), we 
believe it is reasonably likely that a single stand-replacing fire 
could occur within the foreseeable future that would eliminate much of 
the remaining suitable habitat for tree voles within the DPS.

Summary of Climate Change

    The uncertainty in climate change models prevents a specific 
assessment of potential future threats to the North Oregon Coast DPS of 
the red tree vole as a consequence of projected warming trends and the 
various environmental and ecological changes associated with increasing 
temperatures. However, the direction of these future trends indicate 
that climate change will likely exacerbate some of the key threats to 
the DPS, such as an increased probability of large wildfires which may 
result in the further destruction, modification, fragmentation, and 
isolation of older forest habitats, and evidence suggests that such 
changes may already be occurring. High-quality habitat for red tree 
voles within the DPS is largely restricted to two clusters of Federal 
lands, and these areas are small enough that a single stand-replacing 
fire could potentially concentrate the remaining red tree voles to 
primarily a single population that would be highly vulnerable to 
extirpation or extinction from future stochastic events. Furthermore, 
red tree voles within the DPS are restricted in their ability to shift 
their range in response to changes that may take place as a consequence 
of climate change. We therefore conclude that the environmental effects 
resulting from climate change, by itself or in combination with other 
factors, exacerbate threats to the North Oregon Coast DPS of the red 
tree vole.
Swiss Needle Cast
    A large-scale disturbance event currently ongoing in the Oregon 
Coast Range is the spread of Swiss needle cast, a foliage disease 
specific to Douglas-fir caused by the fungus Phaeocryptopus gaeumannii. 
It is typically found in Douglas-fir grown outside of its native range, 
but in western Oregon it is primarily found, and is more consistently 
severe, along the western slope of the central and northern Oregon 
Coast Range, which overlaps both the Sitka spruce and western hemlock 
plant series. Douglas-fir accounted for less than 20 percent of the 
forest composition prior to the 1940s in this portion of the Coast 
Range, but timber harvest and large-scale planting of Douglas-fir on 
cutover areas make it the dominant species today. The wetter, milder 
weather, combined with a uniform distribution of the host species, 
favor the fungus and help spread the disease (Hansen et al. 2000, p. 
777; Shaw 2008, pp. 1, 3). In Oregon, Swiss needle cast is 
geographically limited to western Oregon and there is no evidence of it 
expanding. Even so, it has affected about 1 million ac (405,000 ha), 
much of that in the northern and central Oregon Coast Range of the DPS. 
It is roughly estimated that about half of the land base is moderately 
afflicted by Swiss needle cast, and about 10 percent of the area is 
severely afflicted by this disease (Filip 2009, pers. comm.).
    Swiss needle cast causes premature needle loss which, although 
rarely lethal, reduces tree growth rates by 20 to 55 percent (Shaw 
2008, pp. 1-2). Most of the research on this disease has occurred in 
managed plantations less than 40 years old (Shaw 2009, pers. comm.), 
although it is known to limit growth in established overstory trees 
greater than 100 years old, even within mixed-species stands (Black et 
al. 2010, p. 1680). Forest pathologists are just beginning to 
understand how to manage this disease. Thinning treatments to improve 
tree vigor in infected stands do not appear to exacerbate the spread of 
the disease or its effects on tree health. However, young Douglas-firs 
infected with the pathogen are not expected to outgrow the disease 
(Black et al. 2010, p. 1680) and may never develop the large structures 
that are integral features of older forests. Given our current 
knowledge, a likely scenario in these stands is that the non-host Sitka 
spruce and western hemlock will become the dominant cover, moving these 
sites closer to the historical species composition present before 
earlier forest management converted them to Douglas-fir (Filip 2009, 
pers. comm.). Where these non-host species are deficient or absent in 
infected stands, reestablishing them in the stand is the only known 
treatment certain to reduce the spread and extent of the disease. There 
is still much uncertainty in our understanding of this pathogen to 
project future trends in vegetation. While it could result in a return 
of western hemlock and Sitka spruce that were removed as a result of 
conversion to Douglas-fir plantations, the commercial value of Douglas-
fir is a major incentive to continue research to develop pathogen 
treatments that would allow continued existence of healthy Douglas-fir 
stands. In addition, projected effects of climate change (see Increased 
Frequency and Magnitude of Wildfire due to Climate Change, above) could 
alter the extent of the fog zone in which Swiss needle cast is 
prevalent.

Summary of Swiss Needle Cast

    Swiss needle cast is a foliage disease specific to Douglas-fir, and 
is found in western Oregon along the western slope of the central and 
northern Oregon Coast Range. Some of the most severe infestations of 
Swiss needle cast occur in the Sitka spruce plant series, which is the 
plant series in the DPS where tree voles forage primarily on western 
hemlock and Sitka spruce. However, the disease also occurs in the 
western hemlock plant series on the western slope of the Oregon Coast 
Range, where most of the voles that forage on Douglas-fir tend to 
occur. Thus, while the disease may ultimately improve foraging sources 
for some red tree voles over the long term, it may remove forage for 
others. In addition, Swiss needle cast may affect forest 
characteristics in mixed species stands that affect tree voles and are 
unrelated to foraging, such as canopy closure and structural components 
that may provide cover. Therefore, the potential impact that this 
disease may have on the tree vole population is not well understood at 
this time. Although Swiss needle cast may potentially have some 
negative effects on red tree voles, at this point in time we do not 
have evidence that the impacts of Swiss needle cast are so severe as to 
pose a significant threat to the North Oregon Coast DPS of the red tree 
vole.
Isolation of Populations and Small Population Size
    There are multiple features of red tree vole biology and life 
history that limit their ability to respond to habitat loss and 
alteration, as well as to stochastic environmental events. Due to their 
current restricted distribution within the DPS, stochastic events could 
further isolate individuals and consequently limit their recolonization 
capability. Small home ranges and limited dispersal distances of red 
tree voles, as well as their apparent reluctance to

[[Page 63752]]

cross large openings, likely make it difficult for them to recolonize 
isolated habitat patches. As discussed above in the section 
``Fragmentation and Isolation of Older Forest Habitats,'' within the 
DPS, forests with the late-successional characteristics that represent 
high-quality habitat for red tree voles presently exist in a highly 
fragmented state, the average distance between the minimum patch sizes 
associated with nesting exceeded the known maximum dispersal distance 
of red tree voles. Based on this information, we conclude that high-
quality older forest habitats for red tree voles within the DPS are in 
a highly fragmented and isolated condition.
    Without the ability to move between isolated patches of occupied 
habitat, local populations act essentially as islands vulnerable to 
local extirpation, resulting from a disequilibrium between local 
extinction and immigration events (Brown and Kodric-Brown 1977, p. 
445). Some species are adapted to living in patchy environments and may 
exist as a series of local populations connected by occasional movement 
of individuals between them, known as ``metapopulations'' (e.g., Hanski 
and Gilpin 1991, p. 7). However, it is presumed that the red tree vole 
was formerly more continuously distributed throughout the late-
successional forests of the Oregon Coast Range and has only recently 
become ``insularized'' (isolated into islands of habitat) through 
habitat fragmentation. The limited dispersal ability of the red tree 
vole indicates this species is not adapted to living in a patchy 
environment, where long-distance movements between populations are 
occasionally required. Although in many cases the tree voles within the 
DPS are not separated by completely inhospitable matrix habitat, but 
may only be isolated by surrounding areas of forest in earlier seral 
stages, the apparent disappearance of red tree voles from many areas 
where they were formerly found leads us to believe that successful 
recolonization of formerly occupied areas is likely infrequent, if it 
occurs at all (see discussion of Past and Current Range and Abundance 
under Factor A, above). As noted above, the average distance between 
patches of potentially suitable habitat at a minimum of 75 ac (30 ha) 
in size in the DPS exceeds the greatest known dispersal distance for a 
red tree vole. The apparent disappearance of red tree voles from areas 
where they were formerly found, combined with the isolation of 
remaining habitat patches at distances on average greater than the 
known dispersal capability of red tree voles, leads us to conclude that 
movement of individuals between patches of older forest habitat is 
infrequent at best. Therefore, we conclude that at present, the red 
tree vole most likely persists as a set of relatively isolated 
populations in discrete patches of older forest habitat and surrounding 
lower quality, younger forest, with little if any interaction between 
these populations.
    Although we do not have direct evidence of red tree vole population 
sizes within the DPS, the evidence before us suggests that remaining 
local tree vole populations are likely relatively small and isolated. 
We base this conclusion on the limited amount of tree vole habitat 
remaining within the DPS, on the fragmented and isolated nature of the 
remaining habitat, and on evidence from recent search efforts, which 
have yielded few voles relative to historical search efforts, 
suggesting that red tree vole numbers are greatly reduced in the DPS 
compared to historical conditions (see Background and Past and Current 
Range and Abundance under Factor A, above, for details). That isolated 
populations are more likely to decline than those that are not isolated 
(e.g., Davies et al. 2000, p. 1456) is discussed above. In addition to 
isolation, population size also plays an important role in extinction 
risk. Small, isolated populations place species at greater risk of 
local extirpation or extinction due to a variety of factors, including 
loss of genetic variability, inbreeding depression, demographic 
stochasticity, environmental stochasticity, and natural catastrophes 
(Franklin 1980, entire; Shaffer 1981, p. 131; Gilpin and Soul[eacute] 
1986, pp. 25-33; Soul[eacute] and Simberloff 1986, pp. 28-32; Lehmkuhl 
and Ruggiero 1991, p. 37; Lande 1994, entire). Stochastic events that 
put small populations at risk of extinction include, but are not 
limited to, variation in birth and death rates, fluctuations in gender 
ratio, inbreeding depression, and random environmental disturbances 
such as fire, wind, and climatic shifts (e.g., Shaffer 1981, p. 131; 
Gilpin and Soul[eacute] 1986, p. 27; Blomqvist et al. 2010, entire). 
The isolation of populations and consequent loss of genetic interchange 
may lead to genetic deterioration, for example, that has negative 
impacts on the population at different timescales. In the short term, 
populations may suffer the deleterious consequences of inbreeding; over 
the long term, the loss of genetic variability diminishes the capacity 
of the species to evolve by adapting to changes in the environment 
(e.g., Franklin 1980, pp. 140-144; Soul[eacute] and Simberloff 1986, 
pp. 28-29; Nunney and Campbell 1993, pp. 236-237; Reed and Frankham 
2003, pp. 233-234; Blomqvist et al. 2010, entire). Although we do not 
have any information on relative levels of genetic variability in red 
tree vole populations, Swingle (2005, p. 82) suggested that genetic 
inbreeding may be maintaining cream-colored and melanistic tree vole 
pelage polymorphisms at a few populations within the red tree vole's 
range. Swingle (2005, p. 82) did not elaborate on his suggestion, nor 
account for the possibility that alternative processes may be 
maintaining these different color forms.
    Based on this evaluation, we conclude that the isolation of red 
tree vole populations due to fragmentation of their remaining older 
forest habitat, independent of the total area of suitable habitat that 
may be left, poses a significant threat to the red tree vole within the 
DPS.

Summary of Isolation of Populations and Small Population Size

    Remaining red tree vole populations in the North Oregon Coast DPS 
likely persist primarily in isolated patches of fragmented, older 
forest habitat, and the surrounding younger forest habitats are subject 
to continuing habitat modification due to timber harvest that tends to 
maintain the forest in this highly fragmented condition (see Factor A 
discussion and Fragmentation and Isolation of Older Forest Habitats, 
above). Red tree voles are considered highly vulnerable to local 
extirpations due to habitat fragmentation or loss (Huff et al. 1992, p. 
1). Species that have recently become isolated through habitat 
fragmentation do not necessarily function as a metapopulation and, 
especially in the case of species with poor dispersal abilities, local 
populations run a high risk of extinction when extirpations outpace 
dispersal and immigration (Gilpin 1987, pp. 136, 138; Hanski and Gilpin 
1991, p. 13; Hanski et al. 1996, p. 539; Harrison 2008, pp. 82-83; 
Sodhi et al. 2009, p. 518). Some conservation biologists suggest that 
for species with poor dispersal abilities, habitat fragmentation is 
likely more important than habitat area as a determinant of extinction 
probability (Shaffer and Sansom 1985, p. 146). The low reproductive 
rate and lengthy development period of young, relative to other vole 
species, adds further to the inherent vulnerabilities of the red tree 
vole and may limit population growth; the isolation of tree voles 
through insularization likely exacerbates these inherent 
vulnerabilities (Bolger et al. 1997, p. 562).

[[Page 63753]]

    For the reasons given above, based on the observed level of habitat 
fragmentation and isolation that has occurred within the DPS, the 
presumed small size of remaining tree vole populations, and the 
inherent vulnerabilities of the red tree vole to local extirpation or 
extinction due to its life history characteristics, we conclude that 
the isolation of populations and the consequences of small population 
size pose a significant threat to the red tree vole within the North 
Oregon Coast DPS.

Summary of Factor E

    Population isolation, presumed small local population size, and 
potential loss of populations to large-scale disturbance events 
exacerbated by climate change, combined with the life-history traits 
that put red tree voles at a disadvantage in moving between and 
recolonizing new habitats in an already fragmented landscape, are the 
principal threats considered under this factor that significantly 
affect the species. Although precise quantitative estimates are not 
available, recent surveys suggest that populations have substantially 
declined in the DPS, and that red tree voles are likely at greatly 
reduced numbers relative to their historical abundance. Furthermore, 
our analysis of LSOG data from the NWFP effectiveness monitoring 
program indicates that, within the DPS, any remaining highly suitable 
habitat is highly fragmented and patchy in occurrence. Patches of 
forest meeting older forest standards that are overly generous for red 
tree voles, and thus are likely overestimating the size and number of 
remaining patches that provide suitable habitat, indicate that the 
average distance between the remaining patches that are at least 75 ac 
(30 ha) in size exceeds the known dispersal distances of red tree 
voles, and the difference is even greater for patches that are more 
than 500 ac (202 ha) in size.
    The narrow habitat requirements, low mobility, low reproductive 
potential, and low dispersal ability of red tree voles limits their 
movement among existing patches of remnant habitat, and analysis of 
remaining large patches of potentially suitable habitat suggests that 
populations of red tree voles in the DPS likely are largely isolated 
from one another. This information, in conjunction with evidence that 
the older forest habitats associated with red tree voles are highly 
fragmented and restricted in size, leads us to conclude that remaining 
populations of red tree voles are likely small in size. Furthermore, 
with little or no exchange of individuals between them, these small, 
isolated populations are at risk of local extirpation due to a variety 
of factors, including loss of genetic variability, inbreeding 
depression, demographic stochasticity, environmental stochasticity, and 
disturbance events. The lack of redundancy in red tree vole populations 
within the North Oregon Coast DPS renders these populations highly 
vulnerable to large-scale catastrophes or disturbance events, such as 
wildfire, and this vulnerability is exacerbated by climate change.

Conclusion for Factor E

    Red tree voles are considered highly vulnerable to local 
extirpations due to habitat fragmentation or loss, and the evidence 
suggests that the vast majority of forest with potentially suitable 
characteristics for tree voles persists in very small, disconnected 
patches in the DPS. The continuing modification of forest habitats, as 
discussed under Factor A, maintains the older forest habitats 
associated with red tree voles in this fragmented and isolated 
condition. The narrow habitat requirements, low mobility, relatively 
low reproductive potential, and low dispersal ability of red tree voles 
limits their movement among existing patches of remnant habitat. This 
fragmentation of habitat, resulting in small, isolated populations of 
tree voles, can have significant negative impacts on the North Oregon 
Coast DPS of the red tree vole, including potential inbreeding 
depression, loss of genetic diversity, and vulnerability to extirpation 
as a consequence of various stochastic events. Although large-scale 
disturbance events such as fire are not common in the Coast Range, we 
have historical evidence of occasional very large fires in this region, 
and climate change projections indicate a likely increase in both fire 
risk and fire size. At present, red tree voles are thus largely without 
available refugia to sustain the population in the face of events such 
as severe, large-scale fires. Under these conditions, red tree voles in 
the North Oregon Coast DPS are unlikely to experience the habitat 
connectivity and redundancy needed to sustain their populations over 
the long term. Based on the above evaluation, we conclude that the 
threats of continued fragmentation and isolation of older forest 
habitats, as potentially exacerbated by the environmental effects of 
climate change, and the isolation of populations and consequences of 
small population size pose a significant threat to the red tree vole 
within the North Oregon Coast DPS. We did not have sufficient evidence 
to suggest that Swiss needle cast poses a significant threat to the DPS 
at this point in time.
    We have evaluated the best available scientific and commercial data 
on other natural or manmade factors affecting the continued existence 
of the North Oregon Coast DPS of the red tree vole, including the 
effects of habitat fragmentation, as exacerbated by the environmental 
effects of climate change, isolation of small populations, and 
consequences of small population size, and determined that this factor 
poses a significant threat to the viability of the North Oregon Coast 
DPS of the red tree vole, when we consider this factor in concert with 
the other factors impacting the DPS.

Finding

    As required by the Act, we considered the five factors in assessing 
whether the North Oregon Coast DPS of the red tree vole is threatened 
or endangered throughout all of its range. We have carefully assessed 
the best scientific and commercial data available regarding the past, 
present, and future threats faced by the North Oregon Coast DPS of the 
red tree vole. We reviewed the petition, information available in our 
files, and other published and unpublished information submitted to us 
by the public following our 90-day petition finding, and we consulted 
with recognized experts on red tree vole biology, habitat, and 
genetics, as well as with experts on the vegetation of the northern 
Oregon Coast Range. In addition, we consulted with other Federal and 
State resource agencies and completed our own analyses of the available 
data.
    On the basis of the best scientific and commercial data available, 
we find that the population segment satisfies the discreteness and 
significance elements of the DPS policy and therefore qualifies as a 
DPS under our policy. We further find that listing the North Oregon 
Coast DPS of the red tree vole is warranted. However, listing the North 
Oregon Coast DPS of the red tree vole is precluded by higher priority 
listing actions at this time, as discussed in the Preclusion and 
Expeditious Progress section below.
    Although quantitative data are not available to estimate red tree 
vole populations, comparing past collection efforts with recent surveys 
leads us to conclude that tree voles are substantially more difficult 
to find now than they were historically. In some areas within the DPS, 
red tree voles are now not found, or are scarce, where they were 
formerly relatively abundant. This information, in conjunction with the 
knowledge that red tree voles are closely associated with older forest 
habitats and strong quantitative data

[[Page 63754]]

showing an unprecedented loss of older forest habitat in the Oregon 
Coast Range Province, insufficient area of remaining late-successional 
old-growth habitat, and large distances between those remaining older 
forest patches that exceed known dispersal distances of tree voles, 
leads us to conclude that tree vole populations have substantially 
declined from past levels. Whereas, the literature provides multiple 
examples of voles nesting in younger stands, virtually all analyses 
comparing vole nest presence or relative abundance of nests in younger 
versus older stands have shown an increased use or selection of older 
stands. Alhough the role of younger stands is unclear, in weighing the 
available evidence, including a recent modeling effort specific to 
habitat suitability for red tree voles, we conclude that older forests 
are necessary habitat for red tree voles and that younger stands will 
rarely substitute as habitat in the complete absence of older stands. 
However, we recognize that younger stands may facilitate dispersal or 
short-term persistence in landscapes where older forests are isolated 
or infrequent.
    Amounts of older forest habitat within the Coast Range Province 
have been reduced below historical levels, primarily through timber 
harvest (Wimberley et al. 2000, p. 176). The occurrence of forest 
structural conditions outside of the historical range of variability 
may not in itself be a problem with respect to red tree vole 
persistence, considering their persistence through historical large-
scale fires that removed habitat. However, the frequency and duration 
of those conditions outside the historical range of variability will 
ultimately affect the persistence of the red tree vole. Historically, 
old-growth forest (greater than 200 years old) was well dispersed 
(Wimberly et al. 2004, p. 152) within the Oregon Coast Province and 
there were large tracts of suitable habitat that served as refugia in 
which tree voles could persist while adjacent disturbed areas grew into 
habitat (Wimberley et al. 2000, p. 177). Such areas likely served as 
source areas to recolonize newly developed habitats (Pulliam 1988, pp. 
658-660; Dias 1996, p. 326). However, if the amount or duration of 
unsuitable habitat exceeds the ability of the species to persist in 
refugia and ultimately recolonize available areas, the species may 
eventually be extirpated. Hence, the longer habitat stays in an 
unsuitable condition, the greater the risk to the population (Wimberly 
et al. 2000, p. 177).
    Under current management conditions, the vast majority of remaining 
red tree vole habitat in the DPS is, and will continue to be, limited 
to Federal lands. Federal lands make up less than a quarter of the area 
within the DPS, and are limited to two disparate clusters of land. 
Although 62 percent of the Federal ownership in the DPS is currently 
managed under the NWFP and the WOPR to develop and maintain late-
successional conditions that would be conducive to red tree vole 
habitat, only 30 percent of these Federal lands are currently estimated 
to provide suitable habitat for red tree voles (Dunk 2009, pp. 5, 7). 
Even if the entire Federal ownership provided older forest habitat 
conducive to red tree vole occupation, this would still represent a 
significant reduction of older forest habitat based on estimates from 
simulations of forest conditions in the Coast Range Province during the 
past 3,000 years (Wimberly et al. 2000, pp. 173-175; Nonaka and Spies 
2005, p. 1740). Although much of this loss was historical, it led to 
the present condition of insufficient habitat for red tree voles today; 
at present, less than 1 percent of the habitat within the DPS is in the 
condition for which red tree voles showed the greatest strength of 
selection for nesting, and nearly 90 percent of the DPS is in a 
condition avoided by red tree voles. Most of the lands in the nearly 80 
percent of the DPS under State and private ownership are managed for 
timber production. Although regulatory mechanisms exist that are 
intended to provide for the conservation of wildlife and habitats 
during the course of timber harvest activities on private and State 
lands, the habitat requirements and life-history characteristics of the 
red tree vole are such that these regulatory mechanisms are inadequate 
to prevent the ongoing modification, fragmentation, and isolation of 
red tree vole habitat on these lands.
    Our own analysis of NWFP data demonstrates the fragmentation and 
isolation of large patches of older forest remain within the DPS. 
Fifty-nine percent of the LSOG within the DPS comprised patches greater 
than 75 ac (30 ha), the minimum stand size in which tree voles are 
found, and the average distance between these patches exceeds the known 
dispersal limits of tree voles (USFWS 2010, unpublished data). 
Furthermore, the criteria used to define the initial dataset of late-
successional forest used in our analysis includes forest conditions 
that are not suitable for red tree voles (e.g., low canopy cover, 
predominant hardwood cover), so these results are overestimates of 
habitat remaining for red tree voles. Finally, applying the proportion 
of large patches within the DPS onto the amount of tree vole habitat 
estimated within the DPS (Dunk 2009, p. 7) indicates only about 6 
percent of the DPS is in a condition of suitable habitat in patches 
large enough to provide for tree voles, and this analysis is considered 
a likely overestimate of tree vole habitat. Clearly, existing and 
projected amounts of older conifer forest habitat conducive to red tree 
vole persistence are less than the amounts projected to have occurred 
historically and with which tree voles have evolved. High-quality older 
forest habitat remains in isolated fragments, most of which are too 
small to support tree voles, and are so widely separated as to be 
likely well beyond the dispersal capability of the species. Unlike 
historical conditions, which were highly stochastic, these changes are 
likely to be permanent. Based on our analysis of best available 
information, we conclude the remaining high-quality habitat within the 
DPS is likely insufficient to support red tree voles over the long 
term, and persists in a fragmented and isolated condition that renders 
local populations of red tree voles vulnerable to extirpation or 
extinction through a variety of processes, including genetic 
stochasticity, demographic stochasticity, environmental stochasticity, 
and natural catastrophes.
    The significant historical losses of older forest with the late-
successional characteristics selected by red tree voles, in conjunction 
with ongoing practices that maintain the remaining patches of older 
forest in a highly fragmented and isolated condition by managing the 
surrounding younger forest stands on short-rotation schedules, pose a 
threat to the persistence of the North Oregon Coast DPS of the red tree 
vole through the destruction, modification, or curtailment of its 
habitat or range.
    Furthermore, barring a significant change in the Oregon Forest 
Practices Rules and Act, loss, modification, and fragmentation of red 
tree vole habitat is likely to continue on most of the 62 percent of 
the DPS that is privately owned. Forecasts for State forest land, which 
makes up almost all of the 16 percent of the DPS in State ownership, 
are to manage 15 to 25 percent of their land in older forest structure, 
with another 15 to 25 percent to be managed as layered forest 
structure. However, it is expected to take 70 years before reaching 
these amounts, with only 8 percent of the State lands currently 
existing in these structural conditions. Active management via thinning 
to reach these targeted structures, while potentially developing 
suitable tree vole habitat in the long term, may further

[[Page 63755]]

limit the potential for well-connected tree vole populations in the 
ensuing 70 years. Current regulations on private and State lands 
provide for timber harvest on relatively short rotation schedules; this 
contributes to the modification of older forest habitat, and maintains 
forest in a low-quality condition for red tree voles. Although some 
incidental benefits may accrue to individual red tree voles from the 
buffers put in place to protect habitat and targeted wildlife species 
under the Forest Practices Rules, in general the patches of forest 
remaining under these guidelines are too small and isolated to provide 
for the persistence of red tree voles. In some harvest units, the 
regulations require the retention of only two trees per ac (0.8 trees 
per ha), and the size of these trees is well below that normally used 
by red tree voles. The linear perpendicular extent of tree retention 
along fishbearing streams under the State regulations is dramatically 
less (about one-fifteenth) than that conserved under Federal 
regulations. The scarcity of red tree voles throughout much of the DPS 
where they were formerly found with ease further suggests the forest 
areas retained under the existing regulatory mechanisms are 
insufficient to support persistent tree vole populations or successful 
dispersal and recolonization. Finally, unlike on Federal lands, there 
are no mechanisms in place on private or State lands to survey for tree 
voles and manage for sites that are located. We have therefore found 
existing regulatory mechanisms on private and State lands inadequate to 
provide for the conservation of the red tree vole within the DPS.
    The current presumed limited population size and distribution of 
the red tree vole within a small portion of the DPS makes the species 
particularly vulnerable to random environmental disturbances such as 
fires. Evidence from past fire events indicates that stand replacement 
fires have historically occurred in this area large enough that, if 
fires of similar size were to occur now or in the foreseeable future, 
could eliminate most, if not all, of the largest patches of remaining 
high-quality older forest habitat in the DPS. This is of particular 
concern since the stronghold of the red tree vole population in this 
DPS is likely concentrated in a single cluster of Federal lands south 
of Highway 20, and the potential loss of the high quality habitat on 
these lands to an event such as a fire would remove the greatest source 
population of red tree voles in the DPS. Other populations are more 
fragmented and isolated and have little potential to contribute to the 
overall persistence of the DPS under current conditions of habitat 
fragmentation. Population connectivity is thus a particular concern 
given the species' reduced numbers, habitat specialization and limited 
dispersal capabilities, combined with the limited distribution of older 
forests located primarily on Federal land within the range of the red 
tree vole (USDA and USDI 2000a, p. 186). Even on the cluster of Federal 
lands north of Highway 20, remaining habitat has been deemed 
insufficient to support stable populations of red tree voles (USDA and 
USDI 2007, pp. 291-292).
    Finally, though the precise effects of environmental changes 
resulting from climate change on red tree vole habitat are unknown, the 
projected increase in size and severity of forest disturbance vectors 
such as fire and pathogens are expected to further reduce and isolate 
habitat and tree vole populations. In addition, projected shifts in the 
range of species to the north and to increased elevations would further 
reduce the available habitat for the red tree vole, given that it is 
already at its northern and elevational limit within the North Oregon 
Coast DPS. Therefore, we have additionally found that the North Oregon 
Coast DPS of the red tree vole is threatened by the exacerbating 
effects of other natural or manmade factors affecting its continued 
existence.
    Given the threats described above, we find that the North Oregon 
Coast DPS of the red tree vole is in danger of extinction now or in the 
foreseeable future and therefore warrants listing. We have considered 
time spans of several projections of forest conditions and associated 
tree vole response and other measures of biodiversity to determine how 
far into the future is reasonably foreseeable. Trends in timber harvest 
and biodiversity in the Oregon Coast Range are projected for the next 
century (Johnson et al. 2007, entire; Spies et al. 2007a, b, entire). 
Although older forest structure is expected to develop on some areas of 
State land and in those Federal land allocations managed for late-
successional conditions, existing stands are in a variety of age and 
structural stages and it will be several decades before those stands 
develop older forest structure and late-successional conditions. For 
example, on State lands, it is estimated that it will take at least 70 
years to develop the targeted amounts of forest complexity (ODF 2010c, 
p. I-13). Congruent with the time spans stated above, we have 
determined the foreseeable future for the red tree vole to be 
approximately 70 to 100 years.
    In summary, several threats, combined with the limited ability of 
the red tree vole to respond to those threats, contribute to our 
finding that the North Oregon Coast DPS of the red tree vole is in 
danger of extinction now or in the foreseeable future. Older forest 
habitats that provide for red tree voles are limited and highly 
fragmented, while ongoing forest practices in much of the DPS maintain 
the remaining patches of older forest in a highly fragmented and 
isolated condition by managing the surrounding younger forest stands on 
short-rotation schedules. Existing regulatory mechanisms on private and 
State lands result in the maintenance of this condition on most of 
their ownership. Although a portion of the State forest land will be 
managed towards older forest structure, it is expected to take 70 years 
before reaching these conditions. Red tree vole populations within the 
North Oregon Coast DPS appear to be relatively small and isolated. 
Multiple features of red tree vole biology and life history limit their 
ability to respond to the above noted habitat loss and alteration. 
These features include small home ranges, limited dispersal distances, 
low reproductive potential relative to other closely related rodents, a 
reluctance to cross large openings, and likely increased exposure to 
predation in certain habitat conditions (e.g. younger stands or in 
areas with insufficient canopy cover that forces voles to leave trees 
and travel on the ground). Such life history characteristics make it 
difficult for red tree voles to persist in or recolonize already 
isolated habitat patches. Although some land management allocations 
within the DPS call for developing older forest conditions that may 
provide habitat for the red tree vole, it will be decades before those 
areas attain those conditions. In the interim, the red tree vole 
remains vulnerable to random environmental disturbances that may remove 
or further isolate large blocks of already limited habitat (e.g. large 
wind storms or stand-replacing fire events). Finally, small and 
isolated populations such as the red tree vole are more vulnerable to 
extirpation within the DPS due to a variety of factors including loss 
of genetic variability, inbreeding depression, and demographic 
stochasticity. Because of the existing habitat conditions, the limited 
ability of the red tree vole to persist in much of the DPS, and its 
vulnerability in the foreseeable future until habitat conditions 
improve, we find that the North Oregon Coast DPS of the red tree

[[Page 63756]]

vole is in danger of extinction now or in the foreseeable future.
    We reviewed the available information to determine if the existing 
and foreseeable threats render the DPS at risk of extinction now such 
that issuing an emergency regulation temporarily listing the species 
under section 4(b)(7) of the Act is warranted. We have determined that 
issuing an emergency regulation temporarily listing the species is not 
warranted for the North Oregon Coast DPS of the red tree vole at this 
time, because voles are currently distributed across multiple areas 
within the DPS and we do not believe there are any potential threats of 
such great immediacy, severity, or scope that would simultaneously 
threaten all of the known populations with the imminent risk of 
extinction. However, if at any time we determine that an emergency 
regulation temporarily listing of the North Oregon Coast DPS of the red 
tree vole is warranted, we will initiate this action at that time.

Listing Priority Number

    The Service adopted guidelines on September 21, 1983 (48 FR 43098) 
to establish a rational system for utilizing available appropriations 
to the highest priority species when adding species to the Lists of 
Endangered or Threatened Wildlife and Plants or reclassifying 
threatened species to endangered status. These guidelines, titled 
``Endangered and Threatened Species Listing and Recovery Priority 
Guidelines'' address the immediacy and magnitude of threats, and the 
level of taxonomic distinctiveness by assigning priority in descending 
order to monotypic genera (genus with one species), full species, and 
subspecies (or equivalently, distinct population segments of 
vertebrates). The lower the listing priority number (LPN), the higher 
the listing priority (that is, a species with an LPN of 1 would have 
the highest listing priority).
    As a result of our analysis of the best available scientific and 
commercial information, we assigned the North Oregon Coast DPS of the 
red tree vole an LPN of 9, based on our finding that the DPS faces 
threats that are imminent and of moderate to low magnitude, including 
the present or threatened destruction, modification, or curtailment of 
its habitat; the inadequacy of existing regulatory mechanisms; and the 
impacts of chance environmental and demographic events on an already 
isolated population. We consider the threat magnitude moderate because, 
although the entire population is experiencing threats, the impact of 
those threats is more pronounced on private and State ownerships than 
on Federal lands, where more of the existing tree vole habitat is 
likely to remain. For example, our analysis indicates that remaining 
forested habitat on Federal lands provides a measure of security to 
extant vole populations. Although timber harvest across the DPS is a 
concern, the loss of suitable vole habitat to timber harvest has 
declined, and the current status of the species may reflect a lag 
effect from previous timber harvest. At the same time, much of the 
Federal forested lands are growing toward older conditions and 
management of these lands is targeted toward increasing the older 
forest condition of the landscape. In consideration of all these 
factors, we find the magnitude of threats to be moderate to low. We 
consider all of these threats imminent because they are currently 
occurring within the DPS.

Preclusion and Expeditious Progress

    Preclusion is a function of the listing priority of a species in 
relation to the resources that are available and the cost and relative 
priority of competing demands for those resources. Thus, in any given 
fiscal year (FY), multiple factors dictate whether it will be possible 
to undertake work on a listing proposal regulation or whether 
promulgation of such a proposal is precluded by higher priority listing 
actions.
    The resources available for listing actions are determined through 
the annual Congressional appropriations process. The appropriation for 
the Listing Program is available to support work involving the 
following listing actions: Proposed and final listing rules; 90-day and 
12-month findings on petitions to add species to the Lists of 
Endangered and Threatened Wildlife and Plants (Lists) or to change the 
status of a species from threatened to endangered; annual 
``resubmitted'' petition findings on prior warranted-but-precluded 
petition findings as required under section 4(b)(3)(C)(i) of the Act; 
critical habitat petition findings; proposed and final rules 
designating critical habitat; and litigation-related, administrative, 
and program-management functions (including preparing and allocating 
budgets, responding to Congressional and public inquiries, and 
conducting public outreach regarding listing and critical habitat). The 
work involved in preparing various listing documents can be extensive 
and may include, but is not limited to: Gathering and assessing the 
best scientific and commercial data available and conducting analyses 
used as the basis for our decisions; writing and publishing documents; 
and obtaining, reviewing, and evaluating public comments and peer 
review comments on proposed rules and incorporating relevant 
information into final rules. The number of listing actions that we can 
undertake in a given year also is influenced by the complexity of those 
listing actions; that is, more complex actions generally are more 
costly. The median cost for preparing and publishing a 90-day finding 
is $39,276; for a 12-month finding, $100,690; for a proposed rule with 
critical habitat, $345,000; and for a final listing rule with critical 
habitat, $305,000.
    We cannot spend more than is appropriated for the Listing Program 
without violating the Anti-Deficiency Act (see 31 U.S.C. 
1341(a)(1)(A)). In addition, in FY 1998 and for each fiscal year since 
then, Congress has placed a statutory cap on funds that may be expended 
for the Listing Program, equal to the amount expressly appropriated for 
that purpose in that fiscal year. This cap was designed to prevent 
funds appropriated for other functions under the Act (for example, 
recovery funds for removing species from the Lists), or for other 
Service programs, from being used for Listing Program actions (see 
House Report 105-163, 105th Congress, 1st Session, July 1, 1997).
    Since FY 2002, the Service's budget has included a critical habitat 
subcap to ensure that some funds are available for other work in the 
Listing Program (``The critical habitat designation subcap will ensure 
that some funding is available to address other listing activities'' 
(House Report No. 107-103, 107th Congress, 1st Session, June 19, 
2001)). In FY 2002 and each year until FY 2006, the Service has had to 
use virtually the entire critical habitat subcap to address court-
mandated designations of critical habitat, and consequently none of the 
critical habitat subcap funds have been available for other listing 
activities. In some FYs since 2006, we have been able to use some of 
the critical habitat subcap funds to fund proposed listing 
determinations for high-priority candidate species. In other FYs, while 
we were unable to use any of the critical habitat subcap funds to fund 
proposed listing determinations, we did use some of this money to fund 
the critical habitat portion of some proposed listing determinations so 
that the proposed listing determination and proposed critical habitat 
designation could be combined into one rule, thereby being more 
efficient in our work. At this time, for FY 2011, we plan to use some 
of the critical habitat subcap funds to fund proposed listing 
determinations.

[[Page 63757]]

    We make our determinations of preclusion on a nationwide basis to 
ensure that the species most in need of listing will be addressed first 
and also because we allocate our listing budget on a nationwide basis. 
Through the listing cap, the critical habitat subcap, and the amount of 
funds needed to address court-mandated critical habitat designations, 
Congress and the courts have in effect determined the amount of money 
available for other listing activities nationwide. Therefore, the funds 
in the listing cap, other than those needed to address court-mandated 
critical habitat for already listed species, set the limits on our 
determinations of preclusion and expeditious progress.
    Congress identified the availability of resources as the only basis 
for deferring the initiation of a rulemaking that is warranted. The 
Conference Report accompanying Public Law 97-304 (Endangered Species 
Act Amendments of 1982), which established the current statutory 
deadlines and the warranted-but-precluded finding, states that the 
amendments were ``not intended to allow the Secretary to delay 
commencing the rulemaking process for any reason other than that the 
existence of pending or imminent proposals to list species subject to a 
greater degree of threat would make allocation of resources to such a 
petition [that is, for a lower-ranking species] unwise.'' Although that 
statement appeared to refer specifically to the ``to the maximum extent 
practicable'' limitation on the 90-day deadline for making a 
``substantial information'' finding, that finding is made at the point 
when the Service is deciding whether or not to commence a status review 
that will determine the degree of threats facing the species, and 
therefore the analysis underlying the statement is more relevant to the 
use of the warranted-but-precluded finding, which is made when the 
Service has already determined the degree of threats facing the species 
and is deciding whether or not to commence a rulemaking.
    In FY 2011, on April 15, 2011, Congress passed the Full-Year 
Continuing Appropriations Act (Pub. L. 112-10), which provides funding 
through September 30, 2011. The Service has $20,902,000 for the listing 
program. Of that, $9,472,000 is being used for determinations of 
critical habitat for already listed species. Also $500,000 is 
appropriated for foreign species listings under the Act. The Service 
thus has $10,930,000 available to fund work in the following 
categories: Compliance with court orders and court-approved settlement 
agreements requiring that petition findings or listing determinations 
be completed by a specific date; section 4 (of the Act) listing actions 
with absolute statutory deadlines; essential litigation-related, 
administrative, and listing program-management functions; and high-
priority listing actions for some of our candidate species. In FY 2010, 
the Service received many new petitions and a single petition to list 
404 species. The receipt of petitions for a large number of species is 
consuming the Service's listing funding that is not dedicated to 
meeting court-ordered commitments. Absent some ability to balance 
effort among listing duties under existing funding levels, the Service 
is only able to initiate a few new listing determinations for candidate 
species in FY 2011.
    In 2009, the responsibility for listing foreign species under the 
Act was transferred from the Division of Scientific Authority, 
International Affairs Program, to the Endangered Species Program. 
Therefore, starting in FY 2010, we used a portion of our funding to 
work on the actions described above for listing actions related to 
foreign species. In FY 2011, we anticipate using $1,500,000 for work on 
listing actions for foreign species, which reduces funding available 
for domestic listing actions; however, currently only $500,000 has been 
allocated for this function. Although there are no foreign species 
issues included in our high-priority listing actions at this time, many 
actions have statutory or court-approved settlement deadlines, thus 
increasing their priority. The budget allocations for each specific 
listing action are identified in the Service's FY 2011 Allocation Table 
(part of our record).
    For the above reasons, funding a proposed listing determination for 
the North Oregon Coast DPS of the red tree vole is precluded by court-
ordered and court-approved settlement agreements, listing actions with 
absolute statutory deadlines, and work on proposed listing 
determinations for those candidate species with a higher listing 
priority (i.e., candidate species with LPNs of 1-8).
    Based on our September 21, 1983, guidelines for assigning an LPN 
for each candidate species (48 FR 43098), we have a significant number 
of species with a LPN of 2. Using these guidelines, we assign each 
candidate an LPN of 1 to 12, depending on the magnitude of threats 
(high or moderate to low), immediacy of threats (imminent or 
nonimminent), and taxonomic status of the species (in order of 
priority: monotypic genus (a species that is the sole member of a 
genus); species; or part of a species (subspecies, or distinct 
population segment)). The lower the listing priority number, the higher 
the listing priority (that is, a species with an LPN of 1 would have 
the highest listing priority).
    Because of the large number of high-priority species, we have 
further ranked the candidate species with an LPN of 2 by using the 
following extinction-risk type criteria: International Union for the 
Conservation of Nature and Natural Resources (IUCN) Red list status/
rank, Heritage rank (provided by NatureServe), Heritage threat rank 
(provided by NatureServe), and species currently with fewer than 50 
individuals, or 4 or fewer populations. Those species with the highest 
IUCN rank (critically endangered), the highest Heritage rank (G1), the 
highest Heritage threat rank (substantial, imminent threats), and 
currently with fewer than 50 individuals, or fewer than 4 populations, 
originally comprised a group of approximately 40 candidate species 
(``Top 40''). These 40 candidate species have had the highest priority 
to receive funding to work on a proposed listing determination. As we 
work on proposed and final listing rules for those 40 candidates, we 
apply the ranking criteria to the next group of candidates with an LPN 
of 2 and 3 to determine the next set of highest priority candidate 
species. Finally, proposed rules for reclassification of threatened 
species to endangered species are lower priority, because as listed 
species, they are already afforded the protections of the Act and 
implementing regulations. However, for efficiency reasons, we may 
choose to work on a proposed rule to reclassify a species to endangered 
if we can combine this with work that is subject to a court-determined 
deadline.
    With our workload so much bigger than the amount of funds we have 
to accomplish it, it is important that we be as efficient as possible 
in our listing process. Therefore, as we work on proposed rules for the 
highest priority species in the next several years, we are preparing 
multi-species proposals when appropriate, and these may include species 
with lower priority if they overlap geographically or have the same 
threats as a species with an LPN of 2. In addition, we take into 
consideration the availability of staff resources when we determine 
which high-priority species will receive funding to minimize the amount 
of time and resources required to complete each listing action.
    As explained above, a determination that listing is warranted but 
precluded must also demonstrate that expeditious progress is being made 
to add and

[[Page 63758]]

remove qualified species to and from the Lists of Endangered and 
Threatened Wildlife and Plants. As with our ``precluded'' finding, the 
evaluation of whether progress in adding qualified species to the Lists 
has been expeditious is a function of the resources available for 
listing and the competing demands for those funds. (Although we do not 
discuss it in detail here, we are also making expeditious progress in 
removing species from the list under the Recovery program in light of 
the resource available for delisting, which is funded by a separate 
line item in the budget of the Endangered Species Program. So far 
during FY 2011, we have completed delisting rules for three species.) 
Given the limited resources available for listing, we find that we are 
making expeditious progress in FY 2011 in the Listing Program. This 
progress included preparing and publishing the following 
determinations:

                                        FY 2011 Completed Listing Actions
----------------------------------------------------------------------------------------------------------------
     Publication date                  Title                   Actions                      FR pages
----------------------------------------------------------------------------------------------------------------
10/6/2010.................  Endangered Status for the   Proposed Listing       75 FR 61664-61690.
                             Altamaha Spinymussel and    Endangered.
                             Designation of Critical
                             Habitat.
10/7/2010.................  12-Month Finding on a       Notice of 12-month     75 FR 62070-62095.
                             Petition to list the        petition finding,
                             Sacramento Splittail as     Not warranted.
                             Endangered or Threatened.
10/28/2010................  Endangered Status and       Proposed Listing       75 FR 66481-66552.
                             Designation of Critical     Endangered
                             Habitat for Spikedace and   (uplisting).
                             Loach Minnow.
11/2/2010.................  90-Day Finding on a         Notice of 90-day       75 FR 67341-67343.
                             Petition to List the Bay    Petition Finding,
                             Springs Salamander as       Not substantial.
                             Endangered.
11/2/2010.................  Determination of            Final Listing          75 FR 67511-67550.
                             Endangered Status for the   Endangered.
                             Georgia Pigtoe Mussel,
                             Interrupted Rocksnail,
                             and Rough Hornsnail and
                             Designation of Critical
                             Habitat.
11/2/2010.................  Listing the Rayed Bean and  Proposed Listing       75 FR 67551-67583.
                             Snuffbox as Endangered.     Endangered.
11/4/2010.................  12-Month Finding on a       Notice of 12-month     75 FR 67925-67944.
                             Petition to List Cirsium    petition finding,
                             wrightii (Wright's Marsh    Warranted but
                             Thistle) as Endangered or   precluded.
                             Threatened.
12/14/2010................  Endangered Status for       Proposed Listing       75 FR 77801-77817.
                             Dunes Sagebrush Lizard.     Endangered.
12/14/2010................  12-Month Finding on a       Notice of 12-month     75 FR 78029-78061.
                             Petition to List the        petition finding,
                             North American Wolverine    Warranted but
                             as Endangered or            precluded.
                             Threatened.
12/14/2010................  12-Month Finding on a       Notice of 12-month     75 FR 78093-78146.
                             Petition to List the        petition finding,
                             Sonoran Population of the   Warranted but
                             Desert Tortoise as          precluded.
                             Endangered or Threatened.
12/15/2010................  12-Month Finding on a       Notice of 12-month     75 FR 78513-78556.
                             Petition to List            petition finding,
                             Astragalus microcymbus      Warranted but
                             and Astragalus schmolliae   precluded.
                             as Endangered or
                             Threatened.
12/28/2010................  Listing Seven Brazilian     Final Listing          75 FR 81793-81815.
                             Bird Species as             Endangered.
                             Endangered Throughout
                             Their Range.
1/4/2011..................  90-Day Finding on a         Notice of 90-day       76 FR 304-311.
                             Petition to List the Red    Petition Finding,
                             Knot subspecies Calidris    Not substantial.
                             canutus roselaari as
                             Endangered.
1/19/2011.................  Endangered Status for the   Proposed Listing       76 FR 3392-3420.
                             Sheepnose and               Endangered.
                             Spectaclecase Mussels.
2/10/2011.................  12-Month Finding on a       Notice of 12-month     76 FR 7634-7679.
                             Petition to List the        petition finding,
                             Pacific Walrus as           Warranted but
                             Endangered or Threatened.   precluded.
2/17/2011.................  90-Day Finding on a         Notice of 90-day       76 FR 9309-9318.
                             Petition To List the Sand   Petition Finding,
                             Verbena Moth as             Substantial.
                             Endangered or Threatened.
2/22/2011.................  Determination of            Final Listing          76 FR 9681-9692.
                             Threatened Status for the   Threatened.
                             New Zealand-Australia
                             Distinct Population
                             Segment of the Southern
                             Rockhopper Penguin.
2/22/2011.................  12-Month Finding on a       Notice of 12-month     76 FR 9722-9733.
                             Petition to List Solanum    petition finding,
                             conocarpum (marron          Warranted but
                             bacora) as Endangered.      precluded.
2/23/2011.................  12-Month Finding on a       Notice of 12-month     76 FR 9991-10003.
                             Petition to List Thorne's   petition finding,
                             Hairstreak Butterfly as     Not warranted.
                             Endangered.
2/23/2011.................  12-Month Finding on a       Notice of 12-month     76 FR 10166-10203.
                             Petition to List            petition finding,
                             Astragalus hamiltonii,      Warranted but
                             Penstemon flowersii,        precluded & Not
                             Eriogonum soredium,         Warranted.
                             Lepidium ostleri, and
                             Trifolium friscanum as
                             Endangered or Threatened.
2/24/2011.................  90-Day Finding on a         Notice of 90-day       76 FR 10299-10310.
                             Petition to List the Wild   Petition Finding,
                             Plains Bison or Each of     Not substantial.
                             Four Distinct Population
                             Segments as Threatened.
2/24/2011.................  90-Day Finding on a         Notice of 90-day       76 FR 10310-10319.
                             Petition to List the        Petition Finding,
                             Unsilvered Fritillary       Not substantial.
                             Butterfly as Threatened
                             or Endangered.
3/8/2011..................  12-Month Finding on a       Notice of 12-month     76 FR 12667-12683.
                             Petition to List the Mt.    petition finding,
                             Charleston Blue Butterfly   Warranted but
                             as Endangered or            precluded.
                             Threatened.
3/8/2011..................  90-Day Finding on a         Notice of 90-day       76 FR 12683-12690.
                             Petition to List the        Petition Finding,
                             Texas Kangaroo Rat as       Substantial.
                             Endangered or Threatened.
3/10/2011.................  Initiation of Status        Notice of Status       76 FR 13121-13122.
                             Review for Longfin Smelt.   Review.
3/15/2011.................  Withdrawal of Proposed      Proposed rule          76 FR 14210-14268.
                             Rule to List the Flat-      withdrawal.
                             tailed Horned Lizard as
                             Threatened.
3/15/2011.................  Proposed Threatened Status  Proposed Listing       76 FR 14126-14207.
                             for the Chiricahua          Threatened; Proposed
                             Leopard Frog and Proposed   Designation of
                             Designation of Critical     Critical Habitat.
                             Habitat.
3/22/2011.................  12-Month Finding on a       Notice of 12-month     76 FR 15919-15932.
                             Petition to List the        petition finding,
                             Berry Cave Salamander as    Warranted but
                             Endangered.                 precluded.
4/1/2011..................  90-Day Finding on a         Notice of 90-day       76 FR 18138-18143.
                             Petition to List the        Petition Finding,
                             Spring Pygmy Sunfish as     Substantial.
                             Endangered.
4/5/2011..................  12-Month Finding on a       Notice of 12-month     76 FR 18684-18701.
                             Petition to List the        petition finding,
                             Bearmouth Mountainsnail,    Not Warranted and
                             Byrne Resort                Warranted but
                             Mountainsnail, and          precluded.
                             Meltwater Lednian
                             Stonefly as Endangered or
                             Threatened.

[[Page 63759]]

 
4/5/2011..................  90-Day Finding on a         Notice of 90-day       76 FR 18701-18706.
                             Petition To List the        Petition Finding,
                             Peary Caribou and Dolphin   Substantial.
                             and Union population of
                             the Barren-ground Caribou
                             as Endangered or
                             Threatened.
4/12/2011.................  Proposed Endangered Status  Proposed Listing       76 FR 20464-20488.
                             for the Three Forks         Endangered; Proposed
                             Springsnail and San         Designation of
                             Bernardino Springsnail,     Critical Habitat.
                             and Proposed Designation
                             of Critical Habitat.
4/13/2011.................  90-Day Finding on a         Notice of 90-day       76 FR 20613-20622.
                             Petition To List Spring     Petition Finding,
                             Mountains Acastus           Substantial.
                             Checkerspot Butterfly as
                             Endangered.
4/14/2011.................  90-Day Finding on a         Notice of 90-day       76 FR 20911-20918.
                             Petition to List the        Petition Finding,
                             Prairie Chub as             Substantial.
                             Threatened or Endangered.
4/14/2011.................  12-Month Finding on a       Notice of 12-month     76 FR 20918-20939.
                             Petition to List Hermes     petition finding,
                             Copper Butterfly as         Warranted but
                             Endangered or Threatened.   precluded.
4/26/2011.................  90-Day Finding on a         Notice of 90-day       76 FR 23256-23265.
                             Petition to List the        Petition Finding,
                             Arapahoe Snowfly as         Substantial.
                             Endangered or Threatened.
4/26/2011.................  90-Day Finding on a         Notice of 90-day       76 FR 23265-23271.
                             Petition to List the        Petition Finding,
                             Smooth-Billed Ani as        Not substantial.
                             Threatened or Endangered.
5/12/2011.................  Withdrawal of the Proposed  Proposed Rule,         76 FR 27756-27799.
                             Rule to List the Mountain   Withdrawal.
                             Plover as Threatened.
5/25/2011.................  90-Day Finding on a         Notice of 90-day       76 FR 30082-30087.
                             Petition To List the Spot-  Petition Finding,
                             tailed Earless Lizard as    Substantial.
                             Endangered or Threatened.
5/26/2011.................  Listing the Salmon-Crested  Final Listing          76 FR 30758-30780.
                             Cockatoo as Threatened      Threatened.
                             Throughout its Range with
                             Special Rule.
5/31/2011.................  12-Month Finding on a       Notice of 12-month     76 FR 31282-31294.
                             Petition to List Puerto     petition finding,
                             Rican Harlequin Butterfly   Warranted but
                             as Endangered.              precluded.
6/2/2011..................  90-Day Finding on a         Notice of 90-day       76 FR 31903-31906.
                             Petition to Reclassify      Petition Finding,
                             the Straight-Horned         Substantial.
                             Markhor (Capra falconeri
                             jerdoni) of Torghar Hills
                             as Threatened.
6/2/2011..................  90-Day Finding on a         Notice of 90-day       76 FR 31920-31926.
                             Petition to List the        Petition Finding,
                             Golden-winged Warbler as    Substantial.
                             Endangered or Threatened.
6/7/2011..................  12-Month Finding on a       Notice of 12-month     76 FR 32911-32929.
                             Petition to List the        petition finding,
                             Striped Newt as             Warranted but
                             Threatened.                 precluded.
6/9/2011..................  12-Month Finding on a       Notice of 12-month     76 FR 33924-33965.
                             Petition to List Abronia    petition finding,
                             ammophila, Agrostis         Not Warranted and
                             rossiae, Astragalus         Warranted but
                             proimanthus, Boechera       precluded.
                             (Arabis) pusilla, and
                             Penstemon gibbensii as
                             Threatened or Endangered.
6/21/2011.................  90-Day Finding on a         Notice of 90-day       76 FR 36049-36053.
                             Petition to List the Utah   Petition Finding,
                             Population of the Gila      Not substantial.
                             Monster as an Endangered
                             or a Threatened Distinct
                             Population Segment.
6/21/2011.................  Revised 90-Day Finding on   Notice of 90-day       76 FR 36053-36068.
                             a Petition To Reclassify    Petition Finding,
                             the Utah Prairie Dog From   Not substantial.
                             Threatened to Endangered.
6/28/2011.................  12-Month Finding on a       Notice of 12-month     76 FR 37706-37716.
                             Petition to List Castanea   petition finding,
                             pumila var. ozarkensis as   Not warranted.
                             Threatened or Endangered.
6/29/2011.................  90-Day Finding on a         Notice of 90-day       76 FR 38095-38106.
                             Petition to List the        Petition Finding,
                             Eastern Small-Footed Bat    Substantial.
                             and the Northern Long-
                             Eared Bat as Threatened
                             or Endangered.
6/30/2011.................  12-Month Finding on a       Notice of 12-month     76 FR 38504-38532.
                             Petition to List a          petition finding,
                             Distinct Population         Not warranted.
                             Segment of the Fisher in
                             Its United States
                             Northern Rocky Mountain
                             Range as Endangered or
                             Threatened with Critical
                             Habitat.
7/12/2011.................  90-Day Finding on a         Notice of 90-day       76 FR 40868-40871.
                             Petition to List the Bay    Petition Finding,
                             Skipper as Threatened or    Substantial.
                             Endangered.
7/19/2011.................  12-Month Finding on a       Notice of 12-month     76 FR 42631-42654.
                             Petition to List Pinus      petition finding,
                             albicaulis as Endangered    Warranted but
                             or Threatened with          precluded.
                             Critical Habitat.
7/19/2011.................  Petition To List Grand      Notice of 12-month     76 FR 42654-42658.
                             Canyon Cave                 petition finding,
                             Pseudoscorpion.             Not warranted.
7/26/2011.................  12-Month Finding on a       Notice of 12-month     76 FR 44547-44564.
                             Petition to List the        petition finding,
                             Giant Palouse Earthworm     Not warranted.
                             (Drilolerius americanus)
                             as Threatened or
                             Endangered.
7/26/2011.................  12-Month Finding on a       Notice of 12-month     76 FR 44566-44569.
                             Petition to List the        petition finding,
                             Frigid Ambersnail as        Not warranted.
                             Endangered.
7/27/2011.................  Determination of            Final Listing          76 FR 45054-45075.
                             Endangered Status for       Endangered,
                             Ipomopsis polyantha         Threatened.
                             (Pagosa Skyrocket) and
                             Threatened Status for
                             Penstemon debilis
                             (Parachute Beardtongue)
                             and Phacelia submutica
                             (DeBeque Phacelia).
7/27/2011.................  12-Month Finding on a       Notice of 12-month     76 FR 45130-45162.
                             Petition to List the        petition finding,
                             Gopher Tortoise as          Warranted but
                             Threatened in the Eastern   precluded.
                             Portion of its Range.
8/2/2011..................  Proposed Endangered Status  Proposed Listing       76 FR 46218-46234.
                             for the Chupadera           Endangered.
                             Springsnail (Pyrgulopsis
                             chupaderae) and Proposed
                             Designation of Critical
                             Habitat.
8/2/2011..................  90-Day Finding on a         Notice of 90-day       76 FR 46238-46251.
                             Petition to List the        Petition Finding,
                             Straight Snowfly and        Not substantial.
                             Idaho Snowfly as
                             Endangered.
8/2/2011..................  12-Month Finding on a       Notice of 12-month     76 FR 46251-46266.
                             Petition to List the        petition finding,
                             Redrock Stonefly as         Not warranted.
                             Endangered or Threatened.

[[Page 63760]]

 
8/2/2011..................  Listing 23 Species on Oahu  Proposed Listing       76 FR 46362-46594.
                             as Endangered and           Endangered.
                             Designating Critical
                             Habitat for 124 Species.
8/4/2011..................  90-Day Finding on a         Notice of 90-day       76 FR 47123-47133.
                             Petition To List Six Sand   Petition Finding,
                             Dune Beetles as             Not substantial and
                             Endangered or Threatened.   substantial.
8/9/2011..................  Endangered Status for the   Final Listing          76 FR 48722-48741.
                             Cumberland Darter, Rush     Endangered.
                             Darter, Yellowcheek
                             Darter, Chucky Madtom,
                             and Laurel Dace.
8/9/2011..................  12-Month Finding on a       Notice of 12-month     76 FR 48777-48788.
                             Petition to List the        petition finding,
                             Nueces River and Plateau    Not warranted.
                             Shiners as Threatened or
                             Endangered.
8/9/2011..................  Four Foreign Parrot         Proposed Listing       76 FR 49202-49236.
                             Species [crimson shining    Endangered and
                             parrot, white cockatoo,     Threatened; Notice
                             Philippine cockatoo,        of 12-month petition
                             yellow-crested cockatoo].   finding, Not
                                                         warranted.
8/10/2011.................  Proposed Listing of the     Proposed Listing       76 FR 49408-49412.
                             Miami Blue Butterfly as     Endangered
                             Endangered, and Proposed    Similarity of
                             Listing of the Cassius      Appearance.
                             Blue, Ceraunus Blue, and
                             Nickerbean Blue
                             Butterflies as Threatened
                             Due to Similarity of
                             Appearance to the Miami
                             Blue Butterfly.
8/10/2011.................  90-Day Finding on a         Notice of 90-day       76 FR 49412-49417.
                             Petition To List the        Petition Finding,
                             Saltmarsh Topminnow as      Substantial.
                             Threatened or Endangered
                             Under the Endangered
                             Species Act.
8/10/2011.................  Emergency Listing of the    Emergency Listing      76 FR 49542-49567.
                             Miami Blue Butterfly as     Endangered
                             Endangered, and Emergency   Similarity of
                             Listing of the Cassius      Appearance.
                             Blue, Ceraunus Blue, and
                             Nickerbean Blue
                             Butterflies as Threatened
                             Due to Similarity of
                             Appearance to the Miami
                             Blue Butterfly.
8/11/2011.................  Listing Six Foreign Birds   Final Listing          76 FR 50052-50080.
                             as Endangered Throughout    Endangered.
                             Their Range.
8/17/2011.................  90-Day Finding on a         Notice of 90-day       76 FR 50971-50979.
                             Petition to List the        Petition Finding,
                             Leona's Little Blue         Substantial.
                             Butterfly as Endangered
                             or Threatened.
----------------------------------------------------------------------------------------------------------------

    Our expeditious progress also includes work on listing actions that 
we funded in FY 2010 and FY 2011 but have not yet been completed to 
date. These actions are listed below. Actions in the top section of the 
table are being conducted under a deadline set by a court. Actions in 
the middle section of the table are being conducted to meet statutory 
timelines, that is, timelines required under the Act. Actions in the 
bottom section of the table are high-priority listing actions. These 
actions include work primarily on species with an LPN of 2, and, as 
discussed above, selection of these species is partially based on 
available staff resources, and when appropriate, include species with a 
lower priority if they overlap geographically or have the same threats 
as the species with the high priority. Including these species together 
in the same proposed rule results in considerable savings in time and 
funding, when compared to preparing separate proposed rules for each of 
them in the future.

                           Actions Funded in FY 2010 and FY 2011 But Not Yet Completed
----------------------------------------------------------------------------------------------------------------
                          Species                                                  Action
----------------------------------------------------------------------------------------------------------------
                               Actions Subject to Court Order/Settlement Agreement
----------------------------------------------------------------------------------------------------------------
4 parrot species (military macaw, yellow-billed parrot,     12-month petition finding.
 red-crowned parrot, scarlet macaw) \5\.
4 parrot species (blue-headed macaw, great green macaw,     12-month petition finding.
 grey-cheeked parakeet, hyacinth macaw) \5\.
Longfin smelt.............................................  12-month petition finding.
----------------------------------------------------------------------------------------------------------------
                                        Actions with Statutory Deadlines
----------------------------------------------------------------------------------------------------------------
Casey's june beetle.......................................  Final listing determination.
5 Bird species from Colombia and Ecuador..................  Final listing determination.
Queen Charlotte goshawk...................................  Final listing determination.
Ozark hellbender \4\......................................  Final listing determination.
Altamaha spinymussel \3\..................................  Final listing determination.
6 Birds from Peru & Bolivia...............................  Final listing determination.
Loggerhead sea turtle (assist National Marine Fisheries     Final listing determination.
 Service) \5\.
2 mussels (rayed bean (LPN = 2), snuffbox No LPN) \5\.....  Final listing determination.
CA golden trout \4\.......................................  12-month petition finding.
Black-footed albatross....................................  12-month petition finding.
Mojave fringe-toed lizard \1\.............................  12-month petition finding.
Kokanee--Lake Sammamish population \1\....................  12-month petition finding.
Cactus ferruginous pygmy-owl \1\..........................  12-month petition finding.
Northern leopard frog.....................................  12-month petition finding.
Tehachapi slender salamander..............................  12-month petition finding.
Coqui Llanero.............................................  12-month petition finding/Proposed listing.
Dusky tree vole...........................................  12-month petition finding.

[[Page 63761]]

 
Leatherside chub (from 206 species petition)..............  12-month petition finding.
Platte River caddisfly (from 206 species petition) \5\....  12-month petition finding.
3 Texas moths (Ursia furtiva, Sphingicampa blanchardi,      12-month petition finding.
 Agapema galbina) (from 475 species petition).
3 South Arizona plants (Erigeron piscaticus, Astragalus     12-month petition finding.
 hypoxylus, Amoreuxia gonzalezii) (from 475 species
 petition).
5 Central Texas mussel species (3 from 475 species          12-month petition finding.
 petition).
14 parrots (foreign species)..............................  12-month petition finding.
Mohave Ground Squirrel \1\................................  12-month petition finding.
Western gull-billed tern..................................  12-month petition finding.
OK grass pink (Calopogon oklahomensis) \1\................  12-month petition finding.
Ashy storm-petrel \5\.....................................  12-month petition finding.
Honduran emerald..........................................  12-month petition finding.
Eagle Lake trout \1\......................................  90-day petition finding.
32 Pacific Northwest mollusks species (snails and slugs)    90-day petition finding.
 \1\.
42 snail species (Nevada & Utah)..........................  90-day petition finding.
Spring Mountains checkerspot butterfly....................  90-day petition finding.
10 species of Great Basin butterfly.......................  90-day petition finding.
404 Southeast species.....................................  90-day petition finding.
Franklin's bumble bee \4\.................................  90-day petition finding.
American eel \4\..........................................  90-day petition finding.
Aztec gilia \5\...........................................  90-day petition finding.
White-tailed ptarmigan \5\................................  90-day petition finding.
San Bernardino flying squirrel \5\........................  90-day petition finding.
Bicknell's thrush \5\.....................................  90-day petition finding.
Sonoran talussnail \5\....................................  90-day petition finding.
2 AZ Sky Island plants (Graptopetalum bartrami & Pectis     90-day petition finding.
 imberbis) \5\.
I'iwi \5\.................................................  90-day petition finding.
Humboldt marten...........................................  90-day petition finding.
Desert massasauga.........................................  90-day petition finding.
Western glacier stonefly (Zapada glacier).................  90-day petition finding.
Thermophilic ostracod (Potamocypris hunteri)..............  90-day petition finding.
Sierra Nevada red fox \5\.................................  90-day petition finding.
Boreal toad (eastern or southern Rocky Mtn population) \5\  90-day petition finding.
----------------------------------------------------------------------------------------------------------------
                                          High-Priority Listing Actions
----------------------------------------------------------------------------------------------------------------
20 Maui-Nui candidate species \2\ (17 plants, 3 tree        Proposed listing.
 snails) (14 with LPN = 2, 2 with LPN = 3, 3 with LPN = 8).
8 Gulf Coast mussels (southern kidneyshell (LPN = 2),       Proposed listing.
 round ebonyshell (LPN = 2), Alabama pearlshell (LPN = 2),
 southern sandshell (LPN = 5), fuzzy pigtoe (LPN = 5),
 Choctaw bean (LPN = 5), narrow pigtoe (LPN = 5), and
 tapered pigtoe (LPN = 11)) \4\.
Umtanum buckwheat (LPN = 2) and white bluffs bladderpod     Proposed listing.
 (LPN = 9) \4\.
Grotto sculpin (LPN = 2) \4\..............................  Proposed listing.
2 Arkansas mussels (Neosho mucket (LPN = 2) & Rabbitsfoot   Proposed listing.
 (LPN = 9)) \4\.
Diamond darter (LPN = 2) \4\..............................  Proposed listing.
Gunnison sage-grouse (LPN = 2) \4\........................  Proposed listing.
Coral Pink Sand Dunes Tiger Beetle (LPN = 2) \5\..........  Proposed listing.
Lesser prairie chicken (LPN = 2)..........................  Proposed listing.
4 Texas salamanders (Austin blind salamander (LPN = 2),     Proposed listing.
 Salado salamander (LPN = 2), Georgetown salamander (LPN =
 8), Jollyville Plateau (LPN = 8)) \3\.
5 SW aquatics (Gonzales Spring Snail (LPN = 2), Diamond Y   Proposed listing.
 springsnail (LPN = 2), Phantom springsnail (LPN = 2),
 Phantom Cave snail (LPN = 2), Diminutive amphipod (LPN =
 2)) \3\.
2 Texas plants (Texas golden gladecress (Leavenworthia      Proposed listing.
 texana) (LPN = 2), Neches River rose-mallow (Hibiscus
 dasycalyx) (LPN = 2)) \3\.
4 AZ plants (Acuna cactus (Echinomastus erectocentrus var.  Proposed listing.
 acunensis) (LPN = 3), Fickeisen plains cactus
 (Pediocactus peeblesianus fickeiseniae) (LPN = 3), Lemmon
 fleabane (Erigeron lemmonii) (LPN = 8), Gierisch mallow
 (Sphaeralcea gierischii) (LPN = 2)) \5\.
FL bonneted bat (LPN = 2) \3\.............................  Proposed listing.
3 Southern FL plants (Florida semaphore cactus (Consolea    Proposed listing.
 corallicola) (LPN = 2), shellmound applecactus (Harrisia
 (=Cereus) aboriginum (=gracilis)) (LPN = 2), Cape Sable
 thoroughwort (Chromolaena frustrata) (LPN = 2)) \5\.
21 Big Island (HI) species \5\ (includes 8 candidate        Proposed listing.
 species--6 plants & 2 animals; 4 with LPN = 2, 1 with LPN
 = 3, 1 with LPN = 4, 2 with LPN = 8).
12 Puget Sound prairie species (9 subspecies of pocket      Proposed listing.
 gopher (Thomomys mazama ssp.) (LPN = 3), streaked horned
 lark (LPN = 3), Taylor's checkerspot (LPN = 3), Mardon
 skipper (LPN = 8)) \3\.
2 TN River mussels (fluted kidneyshell (LPN = 2), slabside  Proposed listing.
 pearlymussel (LPN = 2)) \5\.
Jemez Mountain salamander (LPN = 2) \5\...................  Proposed listing.
----------------------------------------------------------------------------------------------------------------
\1\ Funds for listing actions for these species were provided in previous FYs.
\2\ Although funds for these high-priority listing actions were provided in FY 2008 or 2009, due to the
  complexity of these actions and competing priorities, these actions are still being developed.
\3\ Partially funded with FY 2010 funds and FY 2011 funds.
\4\ Funded with FY 2010 funds.
\5\ Funded with FY 2011 funds.


[[Page 63762]]

    We have endeavored to make our listing actions as efficient and 
timely as possible, given the requirements of the relevant law and 
regulations, and constraints relating to workload and personnel. We are 
continually considering ways to streamline processes or achieve 
economies of scale, such as by batching related actions together. Given 
our limited budget for implementing section 4 of the Act, these actions 
described above collectively constitute expeditious progress.
    The North Oregon Coast DPS of the red tree vole will be added to 
the list of candidate species upon publication of this 12-month 
finding. We will continue to monitor the status of this species as new 
information becomes available. This review will determine if a change 
in status is warranted, including the need to make prompt use of 
emergency listing procedures.
    We intend that any proposed listing action for the North Oregon 
Coast DPS of the red tree vole will be as accurate as possible. 
Therefore, we will continue to accept additional information and 
comments from all concerned governmental agencies, the scientific 
community, industry, or any other interested party concerning this 
finding.

References Cited

    A complete list of all references cited is available on the 
internet at http://www.regulations.gov and on request from the Oregon 
Fish and Wildlife Office (see ADDRESSES).

Authors

    The primary authors of this document are the staff members of the 
Oregon Fish and Wildlife Office.

Authority

    The authority for this action is the Endangered Species Act of 
1973, as amended (16 U.S.C. 1531 et seq.).

    Dated: September 19, 2011.
Daniel M. Ashe,
Director, Fish and Wildlife Service.
[FR Doc. 2011-25818 Filed 10-12-11; 8:45 am]
BILLING CODE 4310-55-P