[Federal Register Volume 68, Number 2 (Friday, January 3, 2003)]
[Proposed Rules]
[Pages 331-348]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-19]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AI51


Endangered and Threatened Wildlife and Plants; Withdrawal of the 
Proposed Rule To List the Flat-tailed Horned Lizard as Threatened

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule; withdrawal.

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SUMMARY: We, the Fish and Wildlife Service (Service), have determined 
that the action of listing the flat-tailed horned lizard (Phrynosoma 
mcallii) as threatened, pursuant to the Endangered Species Act (Act) of 
1973, as amended, is not warranted, and we consequently withdraw our 
proposed rule. We have made this determination because threats to the 
species as identified in the proposed rule are not as significant as 
earlier believed, and current available data do not indicate that the 
threats to the species and its habitat, as analyzed under the five 
listing factors described in section 4(a)(1) of the Act, are likely to 
endanger the species in the foreseeable future throughout all or a 
significant portion of its range.

ADDRESSES: Supporting documentation for this rulemaking is available 
for public inspection, by appointment, during normal business hours at 
the U.S. Fish and Wildlife Service, Carlsbad Fish and Wildlife Office, 
6010 Hidden Valley Road, Carlsbad, CA 92009.

FOR FURTHER INFORMATION CONTACT: Jim Bartel, Field Supervisor, at the 
above address (telephone, 760-431-9440, or fax, 760-431-9618).

SUPPLEMENTARY INFORMATION:

Background

    The flat-tailed horned lizard (Phrynosoma mcallii) is a small 
phrynosomatid lizard that reaches a maximum adult body length of 8.4 
centimeters (cm) (3.3 inches [in]) (Muth and Fisher 1992). The flat-
tailed horned lizard has a dorso-ventrally flattened body; long, broad 
flattened tail; and dagger-like head spines common to horned lizards. 
The species is cryptic in color, ranging from pale gray to light rust 
brown dorsally, and white or cream ventrally. It can be distinguished 
from the only other horned lizard known to occur within its range, the 
desert horned lizard (Phrynosoma platyrhinos), by its dark vertebral 
stripe, two rows of fringed scales on each side of the body, lack of 
external ear openings, and unmarked white ventral surface in most 
individuals (Foreman 1997). Apparent hybrids between the two species, 
exhibiting a mix of morphological characteristics, have been observed 
in the vicinity of Ocotillo, California (Stebbins 1985), and southeast 
of Yuma, Arizona (K. Young, Utah State University, pers. comm. 2002).
    The flat-tailed horned lizard is endemic (restricted) to the 
Sonoran Desert in southern California, southwestern Arizona, and 
adjoining portions of Sonora and Baja California, Mexico (Turner and 
Medica 1982). Within California, the flat-tailed horned lizard ranges 
from the Coachella Valley, the northernmost extent of its range, south 
along both sides of the Salton Sea and Imperial Valley. On the west 
side of the Salton Sea and Imperial Valley, the species ranges into the 
Borrego Valley, Ocotillo Wells area, West Mesa, and the Yuha Desert 
(Yuha Basin). On the east side of Imperial Valley, the species occurs 
in the vicinity of the Dos Palmas Bureau of Land Management (BLM)

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Area of Critical Environmental Concern (ACEC), but predominantly occurs 
in East Mesa and in areas adjoining the Algodones Dunes (i.e., Imperial 
Sand Dunes, Glamis Sand Dunes). In Arizona, the flat-tailed horned 
lizard is found in the Yuma Desert south of the Gila River and west of 
the Gila and Butler Mountains (Rorabaugh et al. 1987). The flat-tailed 
horned lizard is patchily distributed throughout its range, and has 
been recorded at elevations as high as 520 meters (m) (1,706 feet [ft]) 
above sea level, but is more commonly found below 250 m (820 ft) in 
areas with flat-to-modest slopes (Turner et al. 1980).
    The range of the flat-tailed horned lizard extends into Mexico from 
the international border in the Yuha Desert in California, south to 
Laguna Salada in Baja California, and from the international border in 
the Yuma Desert in Arizona, south and east through the Pinacate Region 
to the sandy plains around Puerto Penasco and Bahia de San Jorge, 
Sonora (Johnson and Spicer 1985, Gonzales-Romero and Alvarez-Cardenas 
1989).
    The distribution of the flat-tailed horned lizard is not contiguous 
across its range, because of fragmentation by large-scale agricultural 
and urban development, primarily in the Imperial Valley and the 
Coachella Valley. In addition, the Salton Sea, Colorado River, East 
Highline Canal, New Coachella Canal, and All American Canal are 
barriers to movement of flat-tailed horned lizards.
    Due to this habitat fragmentation and existing geographic barriers, 
the distribution of flat-tailed horned lizards appears to be currently 
divided on a broad scale into at least four geographically discrete 
populations: three in California and one in Arizona. The three 
populations in California are located in the Coachella Valley, the west 
side of the Salton Sea/Imperial Valley, and the east side of the 
Imperial Valley.
    The Coachella Valley population of flat-tailed horned lizards was 
likely much more extensive and connected to other populations in 
California in the past. Now it is isolated by extensive agricultural 
development in the southern half of the Coachella Valley and by the 
Salton Sea. The other two populations of flat-tailed horned lizards, on 
the west side of the Salton Sea/Imperial Valley and the east side of 
the Imperial Valley, are isolated from the Coachella Valley population 
and each other by agricultural and urban development of the Imperial 
Valley and by the Salton Sea. The Arizona population is isolated from 
populations in California by agricultural and urban development around 
Yuma, and ultimately by the Colorado River.
    Hodges (1997) estimated that the flat-tailed horned lizard 
historically (prior to agricultural or urban development of either the 
Coachella or Imperial Valleys) occupied up to 979,037 hectares (ha) 
(2,419,200 acres [ac]) in Arizona and California. Approximately 51 
percent (503,173 ha [1,243,340 ac]) of this historical habitat remains 
in the United States, with about 56,770 ha (140,300 ac) in Arizona and 
446,390 ha (1,103,040 ac) in California (Hodges 1997). The Salton Sea 
area could arguably be considered ephemeral historical habitat, present 
at some points and absent at others, as the area changed through time. 
Hodges (1977) included the Salton Sea as historical habitat. If the 
area the Salton Sea currently occupies is not considered historical 
habitat, then approximately 57 percent (557,072 ha [1,376,525 ac]) of 
historical habitat remains in the United States.
    Johnson and Spicer (1985) estimated that in 1981 approximately 59 
percent of the species range occurred in Mexico, with the majority of 
the range in Mexico occurring in the state of Sonora. However, the 
distribution of the species in Mexico is poorly understood because few 
surveys have been conducted to determine where the species occurs in 
Mexico (CEDO 2001). In Sonora, about 14 percent of the habitat was 
estimated to be threatened by urban, agricultural or recreational use, 
and habitat degradation in 1981 (Johnson and Spicer 1985). In Baja 
California Norte, considerable habitat loss has occurred in the 
Mexicali Valley, where urban and agricultural development extends from 
Mexicali to the Colorado River (Johnson and Spicer 1985, Foreman 1997).
    The majority (about 60 percent) of the species' range in Mexico 
lies within two federally protected areas: (1) The Upper Gulf of 
California and Colorado Delta Biosphere Reserve, and (2) the Pinacate 
and Gran Desierto de Altar Biosphere Reserve (CEDO 2001). The National 
Park of Pinacate is an area administered by the Mexican government with 
use restrictions similar to those in a national park in the United 
States. The Pinacate area is primarily a volcanic zone within which 
flat-tailed horned lizard habitat is probably limited to the sandy 
perimeters of Volcan Pinacate. The Upper Gulf of California Biosphere 
Reserve includes flat-tailed horned lizard habitat in the vicinity of 
the Colorado River Delta in Sonora, Mexico.
    The flat-tailed horned lizard is most commonly found in sandy flats 
and valleys in a creosote (Larrea tridentata)--white bursage (Ambrosia 
dumosa) plant association (Turner et al. 1980; Muth and Fisher 1992; 
Foreman 1997). Turner et al. (1980) stated the best habitats are 
generally low-relief areas with surface soils of fine packed sand or 
pavement, overlain with loose, fine sand. Flat-tailed horned lizards 
are also known to occur at the edges of vegetated sand dunes, on barren 
clay soils, and sparse saltbush communities, but Turner et al. (1980) 
suspected that these recorded occurrences were actually individuals 
that had dispersed from more suitable habitats. Within a creosote plant 
community in West Mesa, California, Muth and Fisher (1992) found that 
flat-tailed horned lizards preferred sandy substrates with white 
bursage and Emory dalea (Psorothamnus emoryi), and avoided creosote and 
Tequilia plicata. In Arizona, Rorabaugh et al. (1987) found flat-tailed 
horned lizard abundance correlated with big galleta grass (Hilaria 
rigida) and sandy substrates, but suggested that the presence of sandy 
substrates were more important than that of big galleta grass.
    Several researchers have investigated the relationship between 
density of perennial plants and flat-tailed horned lizard abundance. 
The relationships observed varied among studies (Altman et al. 1980, 
Turner and Medica 1982, Beauchamp et al. 1998). Altman et al. (1980) 
and Turner and Medica (1982) found the relative abundance of horned 
lizards was significantly and positively correlated with perennial 
plant density in creosote-white bursage plant communities. However, 
Beauchamp et al. (1998) found flat-tailed horned lizards to be present 
in higher relative densities in sparsely vegetated areas with large 
patches of concretions, gravel, and silt, than they were in sandy or 
densely vegetated areas. Altman et al. (1980) also reported finding 
flat-tailed horned lizards in desert pavement areas. Foley (2002) found 
little correlation in substrate texture and distribution of flat-tailed 
horned lizards when using three experimental treatments consisting of 
sandy, rocky and mixed substrates. However, Grant and Wright (2002) 
found flat-tailed horned lizard abundance was positively correlated 
with percentage of sand cover.
    Information concerning population dynamics of flat-tailed horned 
lizard populations is limited and inconclusive. Since 1979, population 
trends were monitored using a combination of scat counts and lizards 
observed along transects (Wright 2002). Different methods of transect 
selection, numbers and experience of observers, numbers of repetitions, 
and lengths and shapes of transects have been used from year to year 
(Wright 2002).

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    The relationship between scat counts and lizard abundance is 
unclear, or weak at best (Wright 2002). Wright (2002) states that while 
differences in scat abundance could indicate differences in lizard 
abundance, the observed decline in the rate at which scat is found 
could also be a result of an increase in Off-Highway Vehicle (OHV) 
activity resulting in crushed or buried scat, lower deposition rates, 
greater wind eradication, different observers, or additional factors. 
Furthermore, the use of scat counts does not account for variations in 
lizard activity, misidentification of scat from other species, scat 
production due to fluctuating food resources, weather conditions that 
affect scat production or longevity in the field, observer differences, 
and small sample sizes (Muth and Fisher 1992, Rorabaugh 1994). 
Consequently, scat abundance may not be positively correlated with 
lizard abundance under varying conditions (Rorabaugh 1994, Beauchamp et 
al. 1998). In addition, the use of a relative index, such as scat 
counts, to indicate population trends is not reliable due to 
uncorrected bias that exists (discussed further below). Relative index 
techniques assume that any changes or differences in survey results are 
proportional to true changes or differences in the populations of 
interest (Thompson et al. 1998). Thus, due to the significant 
limitations of scat count data, we consider the use of scat count 
information useful primarily in determining the distribution and 
presence of flat-tailed horned lizards.
    Two measures of abundance trends (i.e., lizards detected per 10 
hours, and lizards per transect) used between 1979 and 2001 for the 
East Mesa, West Mesa, and Yuha Basin, did not include scat data (Wright 
2002). No statistically significant trends were found in the rate at 
which lizards were detected or the number of lizards per transect on 
any of the areas from 1979 to 2001 (Wright 2002). The measure of 
lizards per transect has inherent error due to differences in transect 
lengths surveyed among years. More importantly, the methodologies used 
between 1979 and 2001 have varied and the data have not incorporated 
detection probabilities (see Thompson et al. 1998). Because flat-tailed 
horned lizards are very difficult to find in the field due to their 
cryptic coloration and behavioral characteristics, incorporating the 
probability of detecting them into survey results is very important.
    Detectability is a common source of bias that is ignored for 
relative index techniques, such as the techniques used to collect the 
data between 1979 and 2001. Numerous factors may affect the 
detectability of animals within selected sampling plots. These include 
physical structure and cover, weather, individual behavior, and survey 
methodology. However, it is possible that differences in relative 
abundance found using uncorrected data may result from only a 
difference in detectability of animals between areas or within the same 
area across time (Thompson et al. 1998). Uncorrected bias could 
seriously affect the validity and usefulness of data in indicating 
abundance trends (Thompson et al. 1998).
    The BLM recently estimated the population size on the Yuha Basin 
Management Area (MA) (one of five management areas identified in a 
management strategy for the species) by using capture-mark-recapture 
(CMR) techniques incorporating detection probabilities (see Thompson et 
al. 1998, Williams et al. 2002). In the summer (June to August) of 
2002, the population of flat-tailed horned lizards for the Yuha Basin 
MA (24,122 ha [59,605 ac]) was estimated at 18,494 adults (95 percent 
CI = 14,596 to 22,391) (Grant and Wright 2002) and 8,685 juveniles (95 
percent CI = 6,860 to 10,510) (derived from Grant and Wright 2002). 
``Adults'' included all lizards greater than 60 millimeters (mm) (Young 
and Young 2000), while ``juveniles'' included all lizards 60 mm or less 
in snout-to-vent length. Population estimates for the other four MAs 
using a CMR methodology will be conducted soon, for the first time 
(Gavin Wright, BLM biologist, pers. comm. 2002).
    Greater than 95 percent of the diet of flat-tailed horned lizards 
consists of ants of the genera Messor, Pogonomyrmex, Conomyrma, and 
Myrmecocystus (Turner and Medica 1982, Pianka and Parker 1975). Flat-
tailed horned lizards are oviparous (egg-laying), early maturing, and 
may produce multiple clutches within a breeding season (Howard 1974). 
Flat-tailed horned lizards produce relatively small egg clutches (N = 
31; mean clutch size = 4.7; range = 3 to 7; Howard 1974), compared to 
most other horned lizards (Pianka and Parker 1975). The first cohort 
hatches in July to August (Muth and Fisher 1992; Young and Young 2000), 
and in some years a second cohort may be produced (Howard 1974, Young 
and Young 2000). Hatchlings from the first cohort may reach sexual 
maturity after their first winter season, whereas hatchlings born later 
may require an additional growing season to mature (Howard 1974, Young 
and Young 2000). Flat-tailed horned lizards can live up to at least 6 
years in the wild (FTHL-ICC 2002), and up to 9 years in captivity (Baur 
1986).
    Flat-tailed horned lizards can have relatively large home ranges 
(Foreman 1997). Muth and Fisher (1992) found the mean home range for 
lizards (N = 22) was 2.7 ha (6.7 ac) from a minimum of 19 locations in 
West Mesa. In the Yuma Desert of Arizona, Young and Young (2000) found 
mean home ranges for males differed between drought and wet years, 
while those of females did not. The mean home range for males was 2.5 
ha (6.2 ac) during a dry year versus 10.3 ha (25.5 ac) during a wet 
year. Female mean home ranges were smaller at 1.3 ha (3.2 ac) and 1.9 
ha (4.7 ac) in dry and wet years, respectively (Young and Young 2000). 
Young and Young (2000) noted a wide variation in movement patterns, 
with a few home ranges estimated at greater than 34.4 ha (85 ac).
    Flat-tailed horned lizards generally lie close to the ground and 
remain motionless when approached (Wone 1995); however, but on occasion 
they may bury themselves in loose sand if it is available (Norris 
1949). More rarely they may flee. Their propensity to remain motionless 
and bury themselves in the sand, along with their cryptic coloration 
and flattened body, make them very difficult to find in the field 
(Foreman 1997). During the summer, a flat-tailed horned lizard may 
escape extreme surface temperatures either by burying the main part of 
its body below the surface layer (Norris 1949) or by retreating to a 
burrow (Rorabaugh 1994, Young and Young 2000).
    Adult flat-tailed horned lizards are reported to be obligatory 
hibernators (Mayhew 1965), although individuals have been noted on the 
surface during January and February (Eric Hollenbeck, Ocotillo Wells 
SVRA biologist, pers. comm. 2002). Hibernation may begin as early as 
October and end as late as March (Muth and Fisher 1992). Hibernation 
burrows appear to be self-constructed (constructed by the lizards 
themselves versus using burrows constructed by other animals) and are 
within 10 cm (3.9 in) of the surface (Muth and Fisher 1992). Mayhew 
(1965) found that the majority of lizards hibernated within 5 cm (2.0 
in) of the surface. The greatest depth recorded was 20 cm (7.9 in) 
below the surface. While most adults apparently hibernate during winter 
months, some juveniles may remain active (Muth and Fisher 1992).
    In June of 1997, seven Federal and State agencies signed a Flat-
Tailed Horned Lizard Conservation Agreement (CA) to implement a Flat-
tailed Horned Lizard Rangewide Management Strategy (Management 
Strategy). The purpose of

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the Management Strategy is to provide a framework for conserving 
sufficient habitat to maintain several viable populations of the flat-
tailed horned lizard throughout the range of the species in the United 
States. The Management Strategy was developed by an interagency working 
group over a two-year period. As part of the CA, agencies delineated 
specific areas under their jurisdiction as Management Areas (MAs). 
Approximately 181,100 ha (447,600 ac) of the remaining flat-tailed 
horned lizard habitat managed by signatories of the CA exists within 
five MAs, which occur in the Borrego Badlands, West Mesa, Yuha Desert, 
East Mesa, and the Yuma Desert. These managed areas are believed to 
represent approximately 35 percent of flat-tailed horned lizard habitat 
remaining in the United States.
    The five MAs were designed to identify large areas of public land 
where flat-tailed horned lizards have been found, as well as to include 
most flat-tailed horned lizard habitat identified as key areas in 
previous studies (Turner et al. 1980, Turner and Medica 1982, Rorabaugh 
et al. 1987, Foreman 1997). MAs were proposed based on accepted 
principles of good preserve design, utilizing the best information 
available at the time (FTHL-ICC 2002). Furthermore, the MAs were 
delineated to include areas as large as possible, while avoiding 
extensive, existing and predicted management conflicts (e.g., OHV open 
areas). The MAs are meant to be the core areas for maintaining self-
sustaining populations of flat-tailed horned lizards in the U.S. (FTHL-
ICC 2002).
    The flat-tailed horned lizard commonly occurs in additional areas 
outside of the MAs. These areas include the Ocotillo Wells State 
Vehicle Recreation Area (Ocotillo Wells SVRA), Coachella Valley, the 
areas adjoining the Algodones Dunes, and east of the Algodones Dunes 
between Ogilby and the Mexican border (Norris 1949, Turner et al. 1980, 
Turner and Medica 1982). The Ocotillo Wells SVRA is currently a 
Research Area under the Management Strategy, and studies on the flat-
tailed horned lizard have been encouraged and funded by the California 
Department of Parks and Recreation (CDPR) Division of Off-Highway Motor 
Vehicle Recreation (Foreman 1997).
    The majority of the potential flat-tailed horned lizard habitat is 
within and adjacent to the Algodones Dunes is within the Imperial Sand 
Dunes Recreation Area. Over 47,754 ha (118,000 ac) of the Imperial Sand 
Dunes Recreation Area is used as an OHV open area. The majority of the 
Algodones Dunes north of Highway 78 is a designated wilderness area.
    The Coachella Valley has been developed to a much larger extent 
than any other geographic area within the flat-tailed horned lizard's 
current range, and does not have nearly as much Federal land as the 
other areas in which the MAs were established. There are only about 
16,610 ha (41,040 ac) of flat-tailed horned lizard habitat remaining, 
representing 19 percent of the approximately 86,820 ha (214,540 ac) of 
historical habitat in the Coachella Valley (Katie Barrows, pers. comm. 
2002), about 3 percent of the current habitat rangewide in the U.S., 
and roughly 1 percent of the species range overall, including Mexico 
(we derive these figures using Hodges' 1997 figure for current habitat 
within the U.S., and Johnson and Spicer's [1985] estimate of overall 
range). Of the remaining habitat in the Coachella Valley, only about 
2,150 ha (5,314 ac) of suitable flat-tailed horned lizard habitat is 
estimated to be protected as part of the Coachella Valley Fringe-Toed 
Lizard Preserve System (Coachella Valley Mountains Conservancy 2001).
    Approximately 75 percent of the flat-tailed horned lizard habitat 
in the Coachella Valley is either private or Tribal land and subject to 
development in the near future. An area with the largest amount of 
remaining habitat outside the fringe-toed lizard preserve system is the 
Big Dune area between Palm Springs and Indian Wells, south of I-10. 
However, this area is fragmented with major roads and new development 
(e.g., residential housing, shopping centers, Agua Caliente Casino, and 
California State University of San Bernardino Extension) and is 
increasingly subject to new development because of its central location 
within the Coachella Valley.
    Signatories of the CA, which include the Service, Bureau of 
Reclamation (BOR), BLM, U.S. Marine Corps, U.S. Navy, Arizona Game and 
Fish Department (AGFD), California Department of Fish and Game (CDFG), 
and CDPR, committed to implementation of conservation measures for the 
species over the life of the CA. These measures included: (1) Continued 
monitoring of lizard populations and new surface disturbance within 
MAs; (2) limitation of new surface-disturbing projects within MAs to 1 
percent of the area of MAs between 1997-2002; (3) collection of 
compensation fees from project proponents who conduct activities within 
and outside of MAs; (4) reduction in off-highway vehicle (OHV = all 
vehicles used off-road, including automobiles, dune buggies, 
motorcycles, all-terrain-cycles, four-wheelers, etc.) routes within 
MAs; (5) prohibition of off-highway competitive events within MAs; (6) 
support of continued flat-tailed horned lizard monitoring and research; 
(7) mitigation for surface-disturbing activities in lizard habitat; and 
(8) attempting to acquire all private inholdings within MAs. An 
Interagency Coordination Committee (ICC) and a Management Oversight 
Group, composed of biologists and managers from CA signatory agencies, 
respectively, were established to formulate and oversee implementation 
of the Management Strategy. The signatories agreed to review the CA and 
its effectiveness annually to determine whether it should be revised. 
Within a year of completing the tasks identified in the implementation 
schedule, the involved parties shall review the CA and either modify, 
renew, or terminate it. The CA may at any time be amended, extended, 
modified, supplemented, or terminated by mutual concurrence. 
Participation in the CA/Management Strategy is voluntary, and agencies 
may withdraw from participation with 60 days' notice. The Management 
Strategy is currently being revised.
    A flat-tailed horned lizard Population Viability Analysis (PVA) was 
conducted by a conservation team convened both to share research 
results involving this species and to evaluate the Management Strategy. 
The preliminary PVA provided no estimate of the minimum viable 
population size and did not determine whether populations contained 
within the MAs were viable, due to a lack of population demographic and 
stochastic (i.e., random events relevant to a population) information. 
However, the analysis illustrated the sensitivity of flat-tailed horned 
lizard population viability to certain factors, particularly changes in 
mortality and fecundity. Recommendations in the PVA report included 
controlling activities that result in mortality of flat-tailed horned 
lizards and degradation of their habitat. Large management areas were 
found to be desirable as a conservative approach to ensuring the long-
term population persistence.
    Based on information obtained since the withdrawal of the proposed 
listing rule in 1997 and information documented in the proposed rule, 
we have identified potential threats to the flat-tailed horned lizard, 
including the following: urban development, agricultural development, 
OHV activity, energy developments, military activities, introduction of 
non-native plants, pesticide use, and habitat degradation due to Border 
Patrol and

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illegal drive-through traffic along the United States-Mexico border. 
These threats and their effects on flat-tailed horned lizards and their 
habitat are discussed in further detail in the section ``Summary of 
Factors Affecting the Species.''

Previous Federal Action

    In 1982, we first identified the flat-tailed horned lizard as a 
category 2 candidate species for listing under the Act (47 FR 58454). 
Service regulations defined category 2 candidate species as ``taxa for 
which information in the possession of the Service indicated that 
proposing to list as endangered or threatened was possibly appropriate, 
but for which sufficient data on biological vulnerability and threats 
were not currently available to support proposed rules.'' In 1989, we 
elevated the species to category 1 status (54 FR 554). Category 1 
included species ``for which the Service has on file sufficient 
information on biological vulnerability and threat(s) to support 
issuance of a proposed rule.'' Subsequently, on November 29, 1993, we 
published a proposed rule to list the flat-tailed horned lizard as a 
threatened species pursuant to the Act (58 FR 62624).
    On May 16, 1997, in response to a lawsuit filed by the Defenders of 
Wildlife to compel us to make a final listing determination on the 
flat-tailed horned lizard, the District Court in Arizona ordered us to 
issue a final listing decision within 60 days. A month after the 
District Court's order, several State and Federal agencies signed a CA 
implementing a recently completed rangewide management strategy to 
protect the flat-tailed horned lizard. Pursuant to the CA, cooperating 
parties agreed to take voluntary steps aimed at ``reducing threats to 
the species, stabilizing the species'' populations, and maintaining its 
ecosystem.''
    On July 15, 1997, we issued a final decision to withdraw the 
proposed rule to list the flat-tailed horned lizard as a threatened 
species (62 FR 37852). We based the withdrawal on three factors: (1) 
Population trend data did not conclusively demonstrate significant 
population declines; (2) some of the threats to the flat-tailed horned 
lizard habitat had grown less serious since the proposed rule was 
issued; and (3) we believed that the recently approved ``conservation 
agreement w[ould] ensure further reductions in threats.''
    Six months following our withdrawal of the proposed listing rule, 
the Defenders of Wildlife filed a lawsuit challenging our decision. On 
June 16, 1999, the District Court for the Southern District of 
California granted summary judgement in our favor upholding our 
decision not to list the flat-tailed horned lizard. However, on July 
31, 2001, the Ninth Circuit Court of Appeals reversed the lower court's 
ruling and directed the District Court to remand the matter back to us 
for further consideration in accordance with the legal standards 
outlined in its opinion. The case was remanded back to us because (1) 
the withdrawal did not expressly consider whether the flat-tailed 
horned lizard is likely to become an endangered species within the 
foreseeable future in a significant portion of its range; and (2) the 
withdrawal did not ``address the lizard's viability in a site-specific 
manner with regard to the putative benefits of the Conservation 
Agreement.''
    On October 24, 2001, the District Court ordered us to reinstate the 
previously effective proposed listing rule within 60 calendar days and, 
thereafter, commence a 12-month statutory time schedule for a final 
listing decision, and render our final listing determination in 
compliance with the mandate of the Ninth Circuit Court's order. 
Accordingly, we published a notice on December 26, 2001, announcing the 
reinstatement of the 1993 proposed listing of the flat-tailed horned 
lizard as threatened and the opening of a 120-day public comment period 
on the reinstated proposed rule (66 FR 66384).
    In compliance with our requirements and for the purpose of 
adequately soliciting public comment, we published legal notices of the 
reinstatement of the 1993 proposed rule and the opening of the public 
comment period in the San Diego Union Tribune on January 7, 2002; 
Imperial Valley Press on January 7, 2002; The Desert Sun on January 8, 
2002; and The Yuma Daily Sun on January 7, 2002; inviting the general 
public to comment. On May 30, 2002, we published a notice reopening the 
public comment period for an additional 60 days (67 FR 37752) and 
announced that we would be holding public hearings from 1 to 3 p.m. and 
from 6 to 8 p.m. on June 19, 2002, in El Centro, California. 
Additionally, on May 30, 2002, we published public notices in the San 
Diego Union Tribune, Imperial Valley Press, and The Desert Sun, 
announcing the June 19, 2002, public hearings in El Centro, California.
    On September 24, 2002, we published an additional notice (67 FR 
59809) announcing the reopening of the public comment period for 15 
days to allow for peer review, additional public comment on the 
proposed rule, and submittal of information that has become available 
since our 1997 withdrawal. In this current final determination to 
withdraw our proposal to list the flat-tailed horned lizard as 
threatened, we address the Court's order that we determine: (1) Whether 
the flat-tailed horned lizard is likely to become an endangered species 
within the foreseeable future in a significant portion of its range; 
and (2) the lizard's viability in a site-specific manner with regard to 
the putative benefits of the CA.

Summary of Comments and Recommendations

    In the 3 notices announcing the public comment periods, we 
requested all interested parties to submit the following types of 
information pertaining to the flat-tailed horned lizard: current 
status, ecology, distribution, threats, and management/conservation 
efforts in place. We requested this information in order to make a new 
final listing determination based on the best scientific and commercial 
data currently available. During the three public comment periods, we 
received written comments from a total of 58 entities, and 10 speakers 
gave verbal comments at the public hearings.
    Substantive information provided in all public comments either has 
been incorporated directly into this withdrawal or is addressed below. 
Similar comments are grouped together.
    Comment 1: One commenter supported the listing of several 
populations of flat-tailed horned lizards, including the population in 
the Coachella Valley and Arizona. The commenter further stated that 
independent of the proposal to list the flat-tailed horned lizard as a 
threatened species rangewide, the Coachella Valley population must be 
listed as an endangered species.
    Our Response: In our 1993 proposed rule, we proposed to list the 
flat-tailed horned lizard as a threatened species throughout its range.
    However, under the Act and our regulations, a species will still 
warrant listing if it is threatened or endangered in a significant 
portion of its range. As discussed in the ``Finding'' section of this 
withdrawal, we have determined that the flat-tailed horned lizard is 
not threatened throughout all or a significant portion of its range.
    We considered whether the flat-tailed horned lizard population in 
the Coachella Valley would warrant listing pursuant to our joint 
Service and National Marine Fisheries Service Policy Regarding the 
Recognition of Distinct Vertebrate Population Segments (61 FR 4722). 
According to this policy,

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to be listed as distinct vertebrate population segments populations 
have to qualify as both ``discrete'' and ``significant.''
    A population segment of a vertebrate species may be considered 
discrete if it satisfies either one of the following conditions: (1) It 
is markedly separated from other populations of the same taxon as a 
consequence of physical, physiological, ecological, or behavioral 
factors; or (2) it is delineated by international government boundaries 
within which differences in control of exploitation, management of 
habitat, conservation status, or regulatory mechanisms exist that are 
significant in light of section 4(a)(1)(D) of the Act. If a population 
segment is considered discrete under one or more of the above 
conditions, its biological and ecological significance will then be 
considered. Significance is determined by the importance or 
contribution, or both, of a discrete population to the species 
throughout its range. The policy (61 FR 4722) lists four examples of 
factors that may be used to determine significance: (1) Persistence of 
the discrete population segment in an ecological setting 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 
known surviving natural occurrence of a taxon that may be more abundant 
elsewhere as an introduced population outside its historic range; and 
(4) evidence that the discrete population segment differs markedly from 
other populations of the taxon in genetic characteristics. In carrying 
out this analysis, the Service will consider available scientific 
evidence of the discrete population segment's importance to the species 
as a whole.
    If a population segment is found to be discrete and significant 
(i.e., it is a DPS) its evaluation for endangered or threatened status 
will be based on the Act's definitions of those terms and on a review 
of the species' status relative to the factors described in section 
4(a)(1) of the Act for listing a species as endangered or threatened.
    As outlined in this withdrawal, we currently believe there are four 
disjunct geographic areas occupied by flat-tailed horned lizards. They 
are disjunct due to fragmentation of habitat by agricultural and urban 
development, the Salton Sea, and the Colorado River. We recognize that 
of the four geographically discrete populations, the Coachella Valley 
population is the smallest and most fragmented by development and 
roads, and faces existing and future threats to the remaining habitat. 
Current scientific evidence does not suggest that the Coachella Valley 
population is genetically, behaviorally, or ecologically unique; is a 
large population of flat-tailed horned lizards; or contributes 
individuals to other geographic areas through emigration. Therefore, we 
conclude that this population, even if discrete, is not significant 
within the meaning of the DPS policy. If additional information becomes 
available that indicates the Coachella Valley population is 
biologically or ecologically significant pursuant to the Policy 
Regarding the Recognition of Distinct Vertebrate Population Segments 
(61 FR 4722), we may reconsider the status of the Coachella Valley 
population for the purpose of listing under the Act. At this time, the 
threats to the remaining populations (as described below) do not 
suggest that they warrant consideration for listing as a separate DPS.
    Comment 2: One commenter noted that the population of flat-tailed 
horned lizards in the Coachella Valley is isolated from all other 
populations and is at the northern limit of the species range, and that 
preliminary genetic work being conducted at Utah State University 
suggests that the Coachella Valley population has a unique genetic 
structure.
    Our Response: We agree that the population of flat-tailed horned 
lizards in the Coachella Valley is isolated from all other populations, 
and is at the northern limit of the species range. We have contacted 
the Utah State University scientist who is conducting the genetic 
research on the species, and he indicated that the work is still 
ongoing and that no conclusions have been drawn yet on the genetic 
structure of flat-tailed horned lizard populations.
    Comment 3: Several commenters have remarked on the apparent lack of 
implementation of the planning actions in the Management Strategy, and 
its overall ineffectiveness with regards to conservation of flat-tailed 
horned lizard populations.
    Our Response: There are nine planning actions with associated 
subactions. The Management Strategy states that it is understood among 
the signatories that implementation of these actions is subject to 
availability of funds and compliance with all applicable regulations. 
The implementation of the planning actions from May 1997 through June 
2002 was as follows.
    Planning Action 1: Delineate and designate five flat-tailed horned 
lizard MAs and one flat-tailed horned lizard research area. Management 
Areas have not been fully designated, although participating agencies 
have continued to recognize the boundaries of MAs. Precise boundary 
descriptions have been completed. Naval Air Facility-El Centro has 
designated the portions of the MAs under Department of Defense 
jurisdiction through the Naval Air Facility-El Centro Integrated 
Natural Resources Management Plan. In order to implement the Management 
Strategy, the Yuma and El Centro BLM field offices have drafted a 
document entitled ``The Proposed Amendment to the California Desert 
Conservation Area Plan and the Yuma District Resource Management Plan 
to Expand the East Mesa ACEC, West Mesa ACEC, and Gran Desierto Dunes 
ACEC Boundaries and To Implement the Flat-Tailed Horned Lizard 
Rangewide Management Strategy in Imperial County, California and Yuma 
County, Arizona.'' An Environmental Assessment (EA No. CA-067-EA-1998-
023) was associated with the proposed amendment, and is still in the 
process of being finalized. Public scoping meetings concerning the 
proposed amendment were held. While the environmental assessment has 
not been completed, the Conservation Agreement has been signed and the 
Management Strategy has been implemented to the degree mentioned below.
    Planning Action 2: Define and implement management actions 
necessary to minimize loss or degradation of habitat. Most subactions 
were implemented as follows. Appropriate mitigation measures were 
enforced for all authorized projects that impacted flat-tailed horned 
lizards or their habitat. Compensation funds were required for most 
projects that had residual impacts to flat-tailed horned lizard 
habitat. The limit of discretionary land use authorizations (not 
including impacts from OHV activity) to 1 percent cumulatively for each 
MA was not exceeded. No disposal of lands within MAs occurred. No new 
roads were authorized in MAs. Members of the ICC for the Management 
Strategy held several flat-tailed horned lizard orientation sessions 
with Border Patrol agents in the Yuma and El Centro sectors to reduce 
impacts to flat-tailed horned lizard habitat along the international 
border. The BLM El Centro office implemented an aggressive education 
strategy with Border Patrol to reduce impacts to flat-tailed horned 
lizard habitat. Competitive off-highway vehicle races have not been 
permitted in MAs. No new recreation facilities were allowed in MAs. A 
camping closure was implemented and enforced as mitigation in the East 
Mesa MA. However,

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important subactions to designate routes ``open,'' ``closed,'' or 
``limited;'' to reduce route density; and to limit camping to within 15 
m (50 ft) from the centerline of a designated open route in MAs were 
not implemented; or were implemented to a limited degree. The effects 
of this inaction are discussed under Factor A of the section ``Summary 
of Factors Affecting the Species.''
    Planning Action 3: Rehabilitate damaged and degraded habitat in 
MAs. BLM staff have been rehabilitating routes inside the Yuha Basin 
MA. They have focused on proliferation (unauthorized development of new 
routes by users) and parallel routes off of designated routes; and have 
rehabilitated approximately 32 to 40 km (20 to 25 mi) of non-designated 
routes.
    Planning Action 4: Attempt to acquire through exchange, donation, 
or purchase from willing sellers all private lands within MAs. Lists 
prioritizing parcels for acquisition have been maintained by the 
California OHV Division office headquarters in Sacramento and by BLM's 
El Centro office. BLM's El Centro office has contacted all landowners 
within the East Mesa MA to advise them of BLM's desire to acquire their 
lands through purchase or exchange. Approximately 6,273 ha (15,500 ac) 
of Arizona State land within the Yuma Desert MA was acquired by the 
Department of Defense, a signatory to the Management Strategy. 
Consequently, all land within this MA is owned by signatory agencies. 
Anza Borrego Desert State Park acquired private lands totaling 299 ha 
(740 ac) within and adjacent to the Borrego Badlands MA. BLM-El Centro 
acquired 97 ha (240 ac) within the East Mesa MA and 32 ha (80 ac) 
within the West Mesa MA. California Department of Transportation has 
purchased one section (259 ha [640 ac]) in the northern portion of the 
West Mesa MA as compensation for a project outside the MAs. This 
section may be conveyed to BLM in the future.
    Planning Action 5: Maintain or establish effective habitat 
corridors between naturally adjacent populations. No new corridors have 
been established, but no new projects were authorized that would block 
movement across existing corridors between MAs. Currently, MAs that may 
still be connected by corridors include the Borrego Badlands MA, West 
Mesa MA, and Yuha MA. An OHV open area and I-8 lie between West Mesa 
and the Yuha MAs, but two underpasses may facilitate some movement 
between these MAs. All corridors across the U.S.-Mexico border are 
currently intact, according to the ICC.
    Planning Action 6: Coordinate activities and funding among the 
participating agencies and Mexican agencies. The signatory agencies 
formed the ICC, which has met quarterly to discuss implementation of 
planning actions under the Management Strategy. The signatory agencies 
also formed a Management Oversight Group to provide management-level 
leadership, coordination, and oversight in the implementation of the 
Management Strategy. A study to investigate the distribution of flat-
tailed horned lizards in Sonora and Baja California, Mexico, was 
initiated with funding from BOR and BLM.
    Planning Action 7: Promote the purposes of the strategy through law 
enforcement and public education. Annual reports (ICC 1999a, ICC 1999b, 
ICC 2002) stated that insufficient law enforcement personnel were 
available to prevent most of the illegal off-highway vehicle traffic 
and illegal dumping that occurs in the West Mesa, Yuha Basin, and East 
Mesa MAs. The annual reports state that given the funding situation of 
most of the agencies involved, sufficient law enforcement is unlikely 
to occur. Information pamphlets addressing the flat-tailed horned 
lizard were prepared by the CDPR staff at Ocotillo Wells SVRA and Naval 
Air Facility El Centro and distributed to relevant agencies and the 
public. Flat-tailed horned lizard signs were posted on most access 
points into the Yuma Desert and East Mesa MAs. BLM's El Centro office 
produced range-user brochures and wallet cards to educate all range 
users of the presence of flat-tailed horned lizards and procedures to 
avoid impacting lizards and to report any accidental impacts to 
lizards.
    Planning Action 8: Encourage and support research that will promote 
the conservation of flat-tailed horned lizards or desert ecosystems and 
will effectively define and implement necessary management actions, 
both within and outside of MAs and the Research Area. Ocotillo Wells 
SVRA funded four studies (Young 1999, Setser and Young 2000, Setser 
2001, and Gardner 2002) to collect information on flat-tailed horned 
lizard demographics, habitat use, and the effects of OHV activity. 
Various sampling methodologies to assess population trends were tested. 
ICC members consulted with Colorado State University regarding 
monitoring population trends. Flat-tailed horned lizard life history 
and demographic data were collected by several researchers from Utah 
State University. In 2001, BLM's El Centro office conducted a pilot CMR 
study that led to a population estimate study in 2002 for the Yuha 
Basin MA. Tissue samples were taken from the disjunct populations 
throughout the range of the flat-tailed horned lizard and are to be 
analyzed by Utah State University to determine any genetic differences 
between populations.
    Planning Action 9: Continue Inventory and Monitoring. BLM's Palm 
Springs office conducted surveys in the Coachella Valley. Surveys were 
also conducted across Baja Norte and Sonora, Mexico, with the help of 
ICC personnel and funding from BOR and BLM. Additional surveys were 
conducted along the peripheral areas of the Borrego Badlands MA. 
Surveys of flat-tailed horned lizards and their scat continued on MAs 
each year between 1997 and 2001. ICC annual reports monitored the 
habitat loss authorized by Management Strategy/CA signatories. The Navy 
contracted Tierra Data Systems in 1997 to take aerial photographs and 
digitally map the five MAs and the Research Area to document habitat 
loss and disturbance. The El Centro BLM office quantified vehicular 
impacts at a finer resolution than Tierra Data Systems by using a step-
point method on the West Mesa, Yuha Basin, and East Mesa MAs. A similar 
analysis was conducted in the Yuma MA by the Service and the Arizona 
Game and Fish Department.
    In conclusion, while the Management Strategy has resulted in 
actions that provide protections for the flat-tailed horned lizard and 
has contributed to reductions in particular threats to the species (see 
Factor D below), the stated objectives of the Management Strategy have 
not yet been fully achieved. Specifically, the four of the Management 
Strategy's priority 1 planning subactions have not been fully 
implemented. These are the following: (1) Finalizing the designations 
of the MAs; (2) reducing route densities in MAs; (3) signing routes 
closed, limited, or open; and (4) providing adequate law enforcement.
    Comment 4: One commenter stated that one of the management areas is 
within the boundaries of an ORV Open Area (Ocotillo Wells SVRA) and 
asked what has been done on the ground in the Ocotillo Wells SVRA to 
actually protect the lizard's habitat.
    Our Response: None of the Management Areas contains OHV open areas. 
The Ocotillo Wells SVRA is designated as a Research Area and is not a 
designated Management Area under the Management Strategy. The Ocotillo 
Wells SVRA was not established to protect the flat-tailed horned 
lizard's habitat. It is one of six State Vehicular Recreation Areas 
within California that

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serve as OHV parks for the public. While OHV freeplay, racing, and 
touring are permitted, the Ocotillo Wells SVRA prohibits most permanent 
surface disturbing activities. In order to encourage studies on the 
flat-tailed horned lizard, the Ocotillo Wells SVRA was proposed as a 
Research Area in the Management Strategy. Funding was to be provided by 
the California Department of Parks and Recreation Division of Off-
Highway Motor Vehicle Recreation.
    Comment 5: One commenter stated that large areas within the BLM-
managed deserts of California and Arizona, as well as significant 
portions of Anza-Borrego Desert State Park and the Ocotillo Wells SVRA, 
have been closed to protect the flat-tailed horned lizard and its 
habitat from OHV intrusion.
    Our Response: No areas have been closed to OHV use to protect the 
flat-tailed horned lizard or its habitat. Within the Anza-Borrego 
Desert State Park, OHV activity is limited to designated routes. Most 
of the BLM managed lands within the range of the flat-tailed horned 
lizard are currently open to OHV use in some capacity. The entire 
Ocotillo Wells SVRA is open to OHV use in some form, and the majority 
is completely open to freeplay (unlimited access and use). The Ocotillo 
Wells SVRA is in fact the largest of the State Vehicular Recreation 
Areas in California, comprising approximately 85 percent of land in the 
program. In addition, there are two BLM Open Areas that have 
unrestricted OHV use, the BLM's Plaster City (16,592 ha [41,000 ac]) 
and Superstition Hills (5,261 ha [13,000 ac]) Open Areas.
    Comment 6: One commenter mentioned that the data show a weak, 
almost nonexistent correlation between OHV use and alleged declines in 
flat-tailed horned lizard populations, and that by contrast, other 
threats such as predation by ravens, shrikes, and round-tailed 
squirrels have been substantiated with hard evidence.
    Our Response: Past indices of population abundance of the flat-
tailed horned lizard have not used similar methodologies, nor have they 
incorporated detection probabilities. Population trends based on such 
data potentially include error related to numerous variables, including 
variation in detectability, scat counts, sampling methods, study areas 
sampled, number of transects surveyed, number of observers, 
temperature, year, etc. The BLM (Wright 2002) reported data that can be 
used as an indication of abundance from 1979 to 2001 and the 
correlation of OHV activity and population abundance, conditional on a 
number of assumptions.
    Wright (2002) reported that flat-tailed horned lizards were 
encountered at the highest rates in the Navy and Limited use areas of 
West Mesa, at intermediate rates in the Yuha Desert and East Mesa, and 
at the lowest rates in the West Mesa ACEC, Plaster City, and 
Superstition Mountains Open Areas. If detection rates were assumed to 
be equal across all variables involved, then an inference could be made 
that the areas used most by OHVs, the open areas, have the lowest 
abundance of flat-tailed horned lizards. If we assume that the main 
difference between open and the other areas is a higher rate of use of 
open areas by OHVs, we could reasonably conclude that OHV impacts were 
responsible for this difference. However, the previously mentioned bias 
and error associated with the data collection make this inference weak 
and unreliable.
    Further hypothesis testing of the relationship of OHV use and flat-
tailed horned lizard abundance incorporating detection probabilities in 
a rigorous sampling design would be valuable. The BLM has recognized 
the importance of incorporating detection probability into their flat-
tailed horned lizard sampling designs and has recently employed such a 
design to estimate population size in the Yuha Basin MA, referred to 
previously in the ``Background'' section of this notice.
    OHV activity has also been documented as the direct cause of 
mortality of individual flat-tailed horned lizards (Luckenbach 1975; 
Luckenbach and Bury 1983; Muth and Fisher 1992). However, the number of 
documented flat-tailed horned lizard mortalities due to OHVs is 
limited.
    The fact that ravens, shrikes, and round-tailed squirrels have been 
documented as predators of flat-tailed horned lizards does not make 
them threats to the survival of the species. We assume that flat-tailed 
horned lizards have coevolved in a predator-prey relationship with most 
of the predators they encounter in the Sonoran Desert. There are no 
data showing that round-tailed ground squirrels or other predators 
depend on flat-tailed horned lizards as a primary food source. To the 
contrary, round-tailed ground squirrels are omnivorous and rely on 
plant material for a major part of their diet (Ernest and Mares 1987).
    Anthropogenic threats (i.e., human caused habitat destruction and 
degradation; e.g., OHV activity) and introduced predators or 
competitors are generally regarded as more severe threats to the 
survival of native species than are predators or interspecific 
competition with which the species has coevolved (Pimm et al. 1995). 
There is also the potential for natural predators to increase their 
predation rate on certain prey given human subsidies available. For 
example, increased predation rates on flat-tailed horned lizards by 
loggerhead shrikes and American kestrels have been reported in 
localized areas where human-provided perches (e.g., power lines or 
planted palm trees) have been used by shrikes and kestrels as points 
from which to hunt (Young and Young 2000, Cameron Barrows pers. comm, 
2002). However, areas in which these increased predation rates occur 
are small in size and occur within relatively short distances of the 
perches in the abovementioned examples.
    Comment 7: One commenter stated that it is absolutely critical that 
we not issue a final decision until after we have conducted the studies 
necessary to address flat-tailed horned lizard abundance and viability 
on private lands. The commenter further recommended that all future 
studies do the following: (1) Abandon scat counts as a way of deriving 
species densities, (2) use different, more reliable methods for 
counting flat-tailed horned lizards, and (3) be repeatable over time, 
so that trend data on the lizard can be developed.
    Our Response: The schedule for the final listing determination was 
mandated by the Southern District Court of California under the 
direction of the Ninth Circuit Court of Appeals, to be made within 12 
months of reinstating the proposed listing. A notice announcing the 
reinstatement of the 1993 proposed rule was published in the Federal 
Register on December 26, 2001. Consequently, on the basis of the best 
scientific and commercial data currently available, we must make a 
final listing determination for the flat-tailed horned lizard by 
December 26, 2002.
    While our listing determination undoubtedly would be aided by 
further studies on flat-tailed horned lizards, we can not delay the 
decision. Additionally, we do not currently have the funding to conduct 
additional research prior to making our decision. Despite this 
shortcoming, several of the commenter's recommendations have already 
been enacted. We have not used any scat count information to derive 
lizard density or abundance estimates, and the BLM has begun to use the 
previously mentioned CMR methodology to conduct population estimates on 
the MAs, which can then be replicated in the future to gain information 
on population trends.

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    Comment 8: One commenter remarked that a large flaw in the 
management strategy was that little or no baseline data were gathered 
on the abundance of the lizard or the condition of its habitat at the 
time the conservation agreement was put in place.
    Our Response: While there were no data leading to population 
estimates, there were data gathered on flat-tailed horned lizard 
abundance using transects between 1979 and 1997, as discussed 
previously. In addition, the U.S. Navy (signatory agency) funded aerial 
photography of the MAs, and Tierra Data Systems subsequently analyzed 
the photographs to establish baseline levels of surface disturbance 
within MAs. We have since analyzed aerial photos taken in 2002 in an 
attempt to document disturbance on MAs using a methodology similar to 
that used by Tierra Data Systems in 1997. We then compared the 1997 
disturbance information to that of 2002 to assess the change in amount 
of disturbance during that time period. The results of this comparative 
analysis can be found under our discussion of Factor A in the Summary 
of Factors Affecting the Species.
    Comment 9: Several commenters have expressed concern that Border 
Patrol is not a signatory to the Conservation Agreement associated with 
the Management Strategy, and that its activities pose one of the main 
threats to the flat-tailed horned lizard.
    Our Response: The Border Patrol declined the opportunity to sign 
the CA, but has encouraged education of new agents and continues to 
coordinate with signatory agencies to identify ways to reduce the 
impacts of Border Patrol activities. ICC members held several flat-
tailed horned lizard orientation sessions with Border Patrol agents in 
the Yuma and El Centro sectors to reduce impacts to flat-tailed horned 
lizard habitat along the international border. These briefings were 
designed to familiarize Border Patrol agents with flat-tailed horned 
lizard natural history, habitat requirements, and the importance of 
minimizing vehicular traffic off of designated patrol routes/roads, and 
were well received by Border Patrol personnel. However, the Border 
Patrol's OHV activities and their impacts on flat-tailed horned lizard 
conservation have not been monitored and assessed.
    Comment 10: One commenter remarked that while the MAs may be large 
enough to ensure viability of the species, because only approximately 
35 percent of the current range of the flat-tailed horned lizard is 
included in the MAs, the species will at some point cease to be a part 
of the ecological community.
    Our Response: Assessing a species' role in an ecosystem is often a 
complex task. We believe that the flat-tailed horned lizard will 
continue to be a self-sustaining, functioning component of their 
ecosystem into the foreseeable future. The roughly 65 percent of the 
current range of the flat-tailed horned lizard found outside of the 
MAs, if not developed, may continue to serve as habitat for flat-tailed 
horned lizard populations.
    Much of the habitat outside the MAs is managed by Federal agencies 
such as the BLM, or the State. These agencies have the capacity to 
manage their lands to conserve flat-tailed horned lizard habitat into 
the future. The Management Strategy is applied to lands owned or 
managed by Federal signatories outside MAs as well, albeit to a lesser 
degree than is done for lands inside MAs. BLM lands outside of 
designated open areas are managed for limited use under the California 
Desert Conservation Area Plan. The flat-tailed horned lizard is also a 
sensitive species in the California Desert Conservation Area Plan, 
which states the goal for such designated species is to manage the 
species and their habitats so that the potential for Federal or State 
listing is minimized. In addition, the BLM must adhere to directives 
such as Executive Orders 11644 and 11989, which established policies 
and provided for procedures to control and direct, among other things, 
the use of OHVs on Federal lands in order to protect the resources of 
those lands.
    Any habitat within the current range of the flat-tailed horned 
lizard that is in the Anza-Borrego Desert State Park is managed 
favorably for the conservation of the flat-tailed horned lizard, 
because of the emphasis placed on resource protection and regulations 
limiting OHV activity to designated trails. Some of the California 
state land outside the MAs is in the Ocotillo Wells SVRA. The mission 
of the Off-Highway Motor Vehicle Recreation Division (CSDPR 2002) 
includes insuring ``that quality recreational opportunities remain 
available for future generations by providing for education, 
conservation, and enforcement efforts that balance OHV recreation 
impact with programs that conserve and protect cultural and natural 
resources.'' In addition, projects on State lands must adhere to the 
California Environmental Quality Act (CEQA). CEQA requires a full 
public disclosure of the potential environmental impact of proposed 
projects. Moreover, there is no evidence of private lands in flat-
tailed horned lizard habitat being developed at a rate that would pose 
a significant threat to the species or its habitat, except in the 
Coachella Valley.
    In the Coachella Valley, Regional Habitat Conservation Plans in 
preparation by the Coachella Valley Association of Governments and the 
Agua Caliente Band of Cahuilla Indians would conserve a yet-to-be-
determined amount of flat-tailed horned lizard habitat, leaving the 
rest subject to development. However, these Habitat Conservation Plans 
are in progress and are subject to approval in the future; therefore, 
their completion and implementation cannot be relied upon for 
conservation purposes.
    Comment 11: One commenter responded that BLM studies have shown 
that flat-tailed horned lizard populations have remained at levels 
found in the 1970s, regardless of the increased use of the desert by 
Border Patrol, OHVs, and other development.
    Our Response: The BLM population trend data from the 1970s until 
2001 used scat counts, which have been acknowledged to be unreliable 
indicators of lizard abundance (Muth and Fisher 1992, Rorabaugh 1994, 
Beauchamp et al. 1998) that should not be used to analyze population 
trends. Other problems associated with these studies have been stressed 
in our response to comment 6. In 2002, the BLM started to use the CMR 
methodology (described previously) incorporating detection probability 
to estimate population sizes on the MAs. This is a much more reliable 
and promising methodology that BLM will continue using in the future to 
monitor population trends. The increased use of the desert by Border 
Patrol, OHVs, and other development and the resulting effects on flat-
tailed horned lizard populations has been difficult to monitor. 
Intuitively, we know these impacts cannot keep increasing without 
resulting in negative impacts to habitat. However, based on the best 
available information, we have determined that such possible negative 
impacts do not currently, or in the foreseeable future, pose a threat 
to the species. Land use thresholds resulting in population declines 
can only be derived through sound research and monitoring. See also 
discussion in Factor A below.
    Comment 12: Several commenters stated that we should take economic 
impacts into consideration when we decide whether to list the flat-
tailed horned lizard, because the areas surrounding the lizard's 
habitat are in danger of suffering economic harm

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should the listing and any resulting land use restrictions occur.
    Our Response: The Act requires us to make listing determinations 
solely on the basis of the best scientific and commercial data 
available after conducting a review of the status of the species 
(section 4(b) of the Act). Congress also made it clear in the 
Conference Report accompanying the 1982 amendments to the Act that 
``economic considerations have no relevance to determinations regarding 
the status of species.'' We do not consider economic impacts in the 
listing process, except when designating critical habitat; during this 
latter process, we conduct an economic analysis.
    Comment 13: One commenter noted that reported habitat loss 
resulting from urbanization may not be accurate, because cities such as 
Imperial, El Centro, and Brawley have alkali, heavy clay, and silty 
clay soils, respectively; and these soil types are not preferred 
habitat for the flat-tailed horned lizard.
    Our Response: These soils and habitats in Imperial Valley may not 
have been preferred or high quality habitat for the flat-tailed horned 
lizard, but they still more than likely provided habitat of some 
quality. Historically, the Imperial Valley may not have consisted of 
contiguous habitat quality but probably consisted of a patchy mosaic of 
different qualities of flat-tailed horned lizard habitat, as is seen 
today in the different geographic areas. Flat-tailed horned lizards do 
not require fine sandy habitats as was described in the past, but 
appear to be more flexible in their use of different soil types 
(Beauchamp et al. 1998). They have been found to occur on clay soils 
(Turner et al. 1980); concretions, gravel, and silt (Beauchamp et al. 
1998); and desert pavement areas (Altman et al. 1980); in addition to 
the fine sandy habitats in which they are commonly found. They have 
even been found on the rocky lower slopes of Superstition Mountain 
coexisting with chuckwallas (Turner et al. 1980). Furthermore, the 
areas the commenter notes above may have been beneficial to populations 
for reasons other than providing quality habitat (e.g., corridors or 
``stepping stones'' providing gene flow among populations). Flat-tailed 
horned lizards have been documented in what are now the towns of 
Westmorland, Seeley, and Holtville (Klauber 1932).
    Comment 14: A few commenters noted that although the Management 
Strategy and Conservation Agreement were produced in 1997, an 
environmental assessment to officially authorize the Management Areas 
has not been completed.
    Our Response: While this is true, the Yuma and El Centro BLM field 
offices drafted a document to implement the Management Strategy. This 
document is ``The Proposed Amendment to the California Desert 
Conservation Area Plan and the Yuma District Resource Management Plan 
to Expand the East Mesa ACEC, West Mesa ACEC, and Gran Desierto Dunes 
ACEC Boundaries and to Implement the Flat-tailed Horned Lizard 
Rangewide Management Strategy in Imperial County, California, and Yuma 
County, Arizona.'' An environmental assessment (EA No. CA-067-EA-1998-
023) is attached to this proposed amendment. Public scoping meetings 
concerning this proposed amendment have been held, and work is in 
progress to finalize the environmental assessment. While the 
environmental assessment has not been completed, the Conservation 
Agreement has been signed, and the Management Strategy has been 
implemented to the degree mentioned previously.

Peer Review

    In accordance with our July 1, 1994, Interagency Cooperative Policy 
for Peer Review in Endangered Species Act Activities (59 FR 34270), we 
solicited the expert opinions of six independent specialists. The 
Policy for Peer Review states that it is the policy of the Service to 
incorporate independent peer review in listing decisions during the 
public comment period in the following manner: (1) Solicit the expert 
opinions of a minimum of three appropriate and independent specialists 
regarding pertinent scientific and commercial data and assumptions 
relating to the taxonomy, population models, and supportive biological 
and ecological information for species under consideration for listing; 
and (2) summarize in the final decision document the opinions of all 
independent peer reviewers received on the species under consideration. 
The purpose of such review is to ensure that listing decisions are 
based on scientifically sound data, assumptions, and analyses, 
including input of appropriate experts and specialists.
    We specifically asked the reviewers to review both our proposal to 
list the flat-tailed horned lizard as threatened (58 FR 62624) and our 
subsequent withdrawal of the proposed rule (62 FR 37852), and also to 
provide comments and information on the following issues: (1) Any 
additional data that may assist us in making our listing decision, (2) 
the status and threats to the species--in particular, the four 
geographic areas in which the species occurs in the United States, and 
(3) the effectiveness of the conservation strategy to provide adequate 
protection and management for the species. Four peer reviewers 
responded to our solicitation.
    One reviewer noted that his comments are limited to the Coachella 
Valley population and stated that the Coachella Valley has experienced 
higher levels of urbanization and habitat fragmentation than any of the 
five MAs identified in the Management Strategy. The reviewer mentioned 
that the Coachella Valley historically had a substantial flat-tailed 
horned lizard population and that the largest remaining unfragmented 
habitat patch represents just 3 to 4 percent of its original extent. 
The reviewer stated that the Management Strategy has had no apparent 
benefit within the Coachella Valley, because there is no MA established 
within the Coachella Valley due to the lack of public land containing 
flat-tailed horned lizard habitat.
    Two reviewers recommended the species be listed as threatened, as 
proposed in 1993, and the fourth reviewer recommended the species not 
be listed. The two reviewers who recommended listing the species stated 
that more research was necessary on the demographics of flat-tailed 
horned lizard populations.
    One reviewer's opinion was that if immediate and strong action is 
not taken, the species is likely to disappear in most or all of its 
range in the immediate future. However, this reviewer noted that 
critical demographic data necessary to demonstrate population stability 
are still lacking. The reviewer remarked that the quality of data on 
flat-tailed horned lizards is so poor that all analyses are suspect. 
The following recommendations for continued research relevant to 
developing the necessary information to make a convincing argument for 
listing this species were offered: (1) Long-term capture-recapture 
data; (2) phylogeography studies to determine historic patterns of 
dispersal and present effects of fragmentation; (3) comparative 
ecological studies in areas impacted by chemicals that might affect ant 
populations versus areas where no detectable affects of insecticide 
exist; (4) physiological studies to determine whether dietary shifts 
(away from ants) might negatively effect growth rates and size at 
sexual maturity; and (5) close examination of the illegal OHV threat 
with the intent of developing a strategy of effective enforcement.
    One reviewer, who has conducted research on flat-tailed horned 
lizards in

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Arizona and California, expressed that the designated MAs and the 
current protective measures are adequate, and the species does not 
warrant Federal listing as threatened. This reviewer stated that the 
main reason that the species does not warrant Federal listing is that 
even without population estimates for the MAs, it is reasonable to 
believe there are large, viable, self-sustaining populations that are 
being protected in the MAs.
    We respectfully disagree with the two reviewers who recommended 
listing the flat-tailed horned lizard rangewide, because we do not feel 
the available data indicate that the species is likely to become 
endangered within the foreseeable future throughout all or a 
significant portion of its range. While one reviewer stated that 
critical demographic data necessary to demonstrate population stability 
are still lacking, reliable demographic data showing population 
declines are also lacking.

Summary of Factors Affecting the Species

    Section 4 of the Act (16 U.S.C. 1531 et seq.) and the regulations 
(50 CFR part 424) that implement the listing provisions of the Act set 
forth the procedures for adding species to the Federal list of 
endangered and threatened species. A species may be determined to be an 
endangered or threatened species due to one or more of the five factors 
described in section 4(a)(1) of the Act. These factors and their 
application to the flat-tailed horned lizard rangewide are discussed 
below.

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

United States
    There were some threats of habitat loss and modification identified 
in the 1993 proposed rule that have been reduced since 1993 or for 
which we have limited new information since 1993. The proposed rule 
stated that 95 percent of the remaining optimal habitat in California 
is threatened by one or more impacts, and that urban growth is an 
important component of these threats. At this time, habitat loss due to 
urbanization does not appear to be a significant threat in the 
foreseeable future, due to Federal and State land ownership of most of 
the remaining habitat, with the exception of that in the Coachella 
Valley and Borrego Valley. The Imperial Valley has been developed up 
against the borders of MAs, and additional BLM lands on both sides of 
the Imperial Valley largely prevent further urban and agricultural 
development. The proposed rule also mentioned gold mining as a 
potential threat. There are currently no gold mines in flat-tailed 
horned lizard habitat, and gold mines are not expected to become a 
threat in the foreseeable future.
    The relative abundance index that was used in the 1993 proposed 
rule to document a decline in the Yuha Desert has since been found to 
be based on erroneous assumptions and inconclusive data. The 
information on population trends presented in the proposed rule was 
derived in part from scat count data collected between 1979 and 1991. 
The use of scat counts for this purpose has problems that were 
previously mentioned in the Background section of this rule, and 
therefore we do not consider scat counts scientifically reliable as 
indicators of population abundance. At this time, the available data do 
not indicate that populations of flat-tailed horned lizard are 
declining or threatened in any of the geographic areas, with the 
exception of the Coachella Valley, discussed later.
    The distribution of the flat-tailed horned lizard was described by 
Turner and Medica (1982) as the desert areas of southeastern California 
and southwestern Arizona and adjoining portions of Sonora and Baja 
California Norte, Mexico. The historical distribution of the flat-
tailed horned lizard in California was arguably connected to an unknown 
extent from the Imperial Valley north through the Coachella Valley. 
Locality records report flat-tailed horned lizards occurring within the 
Imperial Valley in the towns of Westmorland, Seeley, and Holtville 
(Klauber 1932). Bryant (1911) reported locality records from Mecca 
(southern end of Coachella Valley) and ``Salton Lake.'' The development 
of the Imperial Valley and southern half of the Coachella Valley for 
agriculture and urbanization, and the filling up of the Salton Sea, 
have essentially fragmented the range of the flat-tailed horned lizard 
in California into the following disjunct areas: (1) Coachella Valley, 
(2) west side of Salton Sea and Imperial Valley, and (3) the east side 
of the Imperial Valley. Additionally, the Colorado River separates the 
Arizona population of flat-tailed horned lizards from populations in 
California. Consequently, we will further analyze Factor A using the 
four disjunct areas within the United States: (1) Coachella Valley, (2) 
west side of Salton Sea/Imperial Valley, (3) east side of Imperial 
Valley, and (4) Arizona.
Coachella Valley (California)
    There has been substantial loss and fragmentation of flat-tailed 
horned lizard habitat within the Coachella Valley. We use the term 
fragmentation to refer to the breaking up of a habitat or ecosystem 
into smaller parcels (Foreman 1997). Fragmentation stems from 
Interstate 10 (I-10), which runs through the middle of the Coachella 
Valley; an associated network of roads south of I-10; and associated 
urban and agricultural development. An important effect of habitat 
fragmentation is the decreased movement of a species (i.e., the flat-
tailed horned lizard) across a landscape. Some highways, such as I-10, 
act as complete barriers to movement of flat-tailed horned lizards. 
Other roads may decrease the probability that flat-tailed horned 
lizards will cross the road, or may result in increased mortality rates 
for flat-tailed horned lizards within an unknown distance of roads. The 
decrease in movement of flat-tailed horned lizards due to roads can 
have negative impacts to local populations, including: (1) Decreased 
dispersal rates of juveniles, (2) decreased likelihood for rescue of 
small populations due to immigration, (3) decreased genetic flow 
between local populations, and (4) other unknown impacts to a 
population's spatial structure.
    The amount of contiguous and total habitat remaining in the 
Coachella Valley is far less than that found in the other three 
geographic areas. There are about 16,610 ha (41,040 ac) remaining, 
which represent 19 percent of the approximately 86,820 ha (214,540 ac) 
of historical habitat in the Coachella Valley (Barrows, pers. comm. 
2002), and about 3 percent of the current habitat rangewide in the U.S. 
(We derive these figures using Hodges 1997 figure for current habitat 
within the U.S.) Approximately 75 percent of the flat-tailed horned 
lizard habitat in the Coachella Valley is either private or Tribal land 
and subject to development in the near future. The remainder is either 
in Federal or State ownership. Between 1996 and 2002, an estimated 
2,428 ha (6,000 ac) of flat-tailed horned lizard habitat was developed 
in the Coachella Valley (Kim Nicol, CDFG biologist, pers. comm. 2002).
    The largest patch of habitat is on the Coachella Valley Preserve 
and consists of about 1,480 ha (3,660 ac). In total, there are about 
2,150 hectares (5,314 acres) of suitable flat-tailed horned lizard 
habitat that are protected as part of the Coachella Valley Fringe-Toed 
Lizard Preserve System (Coachella Valley Mountains Conservancy 2001).

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An area with the largest amount of remaining habitat outside the 
fringe-toed lizard Preserve System is the Big Dune area between Palm 
Springs and Indian Wells, south of I-10. However, this area is 
fragmented with major roads and new development (e.g., residential 
housing, shopping centers, Agua Caliente Casino, and California State 
University of San Bernardino Extension) and is increasingly subject to 
new development because of its central location within the Coachella 
Valley.
    Regional Habitat Conservation Plans in preparation by the Coachella 
Valley Association of Governments and the Agua Caliente Band of 
Cahuilla Indians would conserve a yet-to-be-determined amount of flat-
tailed horned lizard habitat and the rest would be subject to 
development. However, these Habitat Conservation Plans are in progress 
and are subject to approval in the future; therefore their completion 
and implementation cannot be relied upon for conservation purposes.
West Side of Salton Sea/Imperial Valley (California)
    This geographic area spans from Borrego Valley east to Salton Sea, 
and south to the border with Mexico, bounded on the west by the 
Peninsular Mountain ranges and to the east by the Salton Sea and 
agricultural development of the Imperial Valley. The majority of the 
private land that is potential flat-tailed horned lizard habitat is in 
the Borrego Valley and Ocotillo Wells area just south of State Route 
(SR) 78, west of the West Mesa MA. The geographic area contains three 
MAs (Borrego Badlands, West Mesa, and Yuha Basin) and the Ocotillo 
Wells SVRA research area.
    This geographic area is fragmented from north to south by SR22, 
SR78, Interstate 8 (I-8), and SR98. Habitat loss has also resulted from 
the towns of Borrego Springs, Salton City, Ocotillo Wells, and 
Ocotillo. The largest of these towns is Borrego Springs, with a 
population of approximately 3,000 people. Due to the small size of 
these towns, it is unlikely that urban or agricultural development in 
or around these small towns is a significant threat to the flat-tailed 
horned lizard or its habitat in the foreseeable future.

Borrego Badlands MA

    The Borrego Badlands MA is composed of about 17,159 ha (42,400 ac), 
of which 14,771 ha (36,500 ac) is habitat managed by signatories to the 
Management Strategy/CA, and 2,388 ha (5,900 ac) are private land. When 
we compared habitat disturbance and loss from aerial photographs taken 
in 2002 with the habitat loss and disturbance documented by Tierra Data 
Systems in 1997, we found that the length of dirt roads had slightly 
increased from 154 kilometers (km) (96 miles [mi]) to 192 km (120 mi), 
and the area disturbed had increased from 142 ha (351 ac) to 761 ha 
(1,881 ac). However, this increase in disturbed area may have been an 
artifact of what we designated disturbed versus what Tierra Data 
Systems called disturbed. The majority of the increase in disturbed 
habitat was attributed to an area that appeared to be an abandoned 
airfield.

West Mesa MA

    The West Mesa MA consists of approximately 55,079 ha (136,100 ac), 
of which 46,257 ha (114,300 ac) is habitat managed by signatories to 
the Management Strategy/CA, and 8,822 ha (21,800 ac) are private land. 
No geothermal activity was found during BLM disturbance surveys, but 
about 2 percent of the surface has been affected by mining. In 2001, 
the BLM estimated that 11.4 percent of the West Mesa MA was covered 
with vehicle tracks (Wright 2002). Wright (2002) reported that the West 
Mesa and Yuha Basin MAs have relatively high levels of vehicular 
disturbance throughout and lack protected core habitats when compared 
with the East Mesa MA. The number of OHV routes in the West Mesa MA 
increased roughly fourfold from 1985 to 2001 (Wright 2002).

Yuha Basin MA

    The Yuha Basin MA consists of about 24,363 ha (60,200 ac), of which 
23,149 ha (57,200 ac) of habitat is managed by signatories to the 
Management Strategy/CA. This MA is bounded by I-8 to the north and 
fragmented by SR98 running east to west across the entire MA. In 2001, 
the BLM estimated that 10.5 percent of the eastern Yuha Basin MA was 
covered with vehicle tracks (Wright 2002). Wright (2002) estimated 
there was a 23 percent increase in routes and graded roads on this MA 
from 1994 to 2001, and commented that the vehicle track levels along 
SR98 in the eastern Yuha Basin MA are more consistent with an Open Area 
than they are with a limited area. Part of the high level of vehicle 
track disturbance in this area can be attributed to the increase in 
illegal drive-through traffic in the recent past from the border into 
the U.S. (BLM 2002). Drive-through traffic consists of vehicles that 
drive illegally across the International boundary, the majority off-
road, without being inspected by Federal officers. The Border Patrol is 
planning to erect an ``Anti-Vehicle Barrier System'' along the 
international order that will decrease this specific OHV threat in the 
future. This system has been effective in reducing illegal drive-
through traffic near the Algodones Dunes.
    The primary reason for the proliferation of trails in limited use 
areas is most likely due to the lack of route signing and law 
enforcement available not only on the Yuha Basin MA, but across all 
MAs. ``Federal Lands: Information on the Use and Impact of Off-highway 
Vehicles,'' a U.S. General Accounting Office (USGAO) report to Congress 
(USGAO 1995), reported that BLM has ``not completed inventories of 
their OHV areas, roads, and trails, and they have not finished 
preparing maps and posting signs to indicate where OHVs may or may not 
be used. Without such inventories, maps, and signs, neither the public 
nor the staff can be certain whether specific areas, roads, or trails 
are available for OHV use.'' The report did not specifically look at 
the resource areas containing flat-tailed horned lizard habitat, but it 
does illustrate the difficulty BLM offices across the western United 
States have in complying with their agency's own regulations requiring 
the designation of lands for OHV use be communicated to the public. 
Without maps and signs to identify OHV routes, the USGAO (1995) 
concluded that restricted-use areas are, in effect, used and managed as 
open-use areas.
    Our analysis showed that, between 1997 to 2002, the percentage of 
area disturbed increased from 6.6 to 9.7, the area of disturbance 
increased from 1,376 ha (3,400 ac) to 2,145 ha (5,300 ac), and the 
length of roads increased from 394 km (246 mi) to 655 km (409 mi). We 
consider the BLM figures for vehicle track coverage to be more accurate 
for strictly measuring vehicle tracks, because of the finer resolution 
in sampling. BLM measured track coverage on the ground, while our 
measurements were derived from aerial photographs with obviously much 
coarser resolution.

Outside MAs

    The Ocotillo Wells SVRA manages about 31,040 ha (76,700 ac) between 
the Borrego Badlands MA and the West Mesa MA, west of SR86. The 
Ocotillo Wells SVRA allows unrestricted use by OHVs across 
approximately 20,640 ha (51,000 ac) of this area, while the remaining 
land is a restricted area zone limited to OHV use on designated trails 
only (Hollenbeck, pers. comm. 2002). In addition to the Ocotillo Wells 
SVRA, in this geographic area unrestricted OHV use is also allowed in 
the BLM's Plaster City (approximately 6,070 ha [15,000 ac]) and 
Superstition Hills

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(approximately 14,164 ha [35,000 ac]) Open Areas.
    The California State Department of Parks and Recreation (CSDPR 
2002) has reported an increasing popularity of OHV activity in 
California, with a 30 percent increase in dirt bike registrations, a 96 
percent increase in the number of All-Terrain Vehicle registrations, 
and a 96 percent increase in Dune Buggy and Sand Rail registrations 
from 1983 to 2000. The number of 4 wheel-drive vehicles registered in 
the state increased 74 percent from 1994 to 2001. The visitation rate 
to State Vehicular Recreation Areas in California increased 52 percent 
from 1985 to 2000. The Ocotillo Wells SVRA contains the majority of the 
greater than 36,423 ha (90,000 ac) in California's six SVRAs. These 
upward trends in OHV use in California can be expected to continue as 
the U.S. Census Bureau estimates California's population to increase by 
39 percent, from 32 million to 45 million people by the year 2020.
    OHV activity can result in direct mortality of flat-tailed horned 
lizards and other sand dwelling lizards (Luckenbach 1975; Luckenbach 
and Bury 1983; Muth and Fisher 1992). Road mortality has also been 
documented to occur (Turner and Medica 1982, Muth and Fisher 1992, ICC 
1999b, Young and Young 2000). Flat-tailed horned lizards may be more 
prone to road and OHV caused mortality than other lizards due their 
tendency to remain motionless when approached. OHV activity can also 
crush burrows used by flat-tailed horned lizards and modify habitat 
because of impacts to vegetation (Luckenbach 1975, Vollmer et al. 1976, 
Bury et al. 1977, Luckenbach and Bury 1983, Wilshire 1983), soil 
disturbance (Luckenbach 1975, Bury et al. 1977, Webb 1983, Strittholt 
et al. 2000); and introduction of non-native plants.
    Past studies of OHV impacts on lizards (Busack and Bury 1974, Bury 
et al. 1977, Luckenbach and Bury 1983, Klinger et al. 1990, Beauchamp 
et al. 1998, Setser and Young 2000, Setser 2001, Gardner 2002, Grant 
and Wright 2002, Knauf 2002) have been largely inconclusive or cannot 
be readily applied across the species' range (i.e., have limited 
inference space; Ratti and Garton 1994). Luckenbach and Bury (1983) 
reported that a pronounced reduction in flat-tailed horned lizard 
abundance around the Algodones Dunes had been anecdotally noted by 
scientists. Marked declines in herbaceous and perennial plants, 
arthropods, lizards and mammals in OHV-used areas compared with nearby 
control areas were also reported by Luckenbach and Bury (1983). The 
declines, however, were for the Colorado Desert fringe-toed lizard (Uma 
notata) and beetles, and did not include flat-tailed horned lizards or 
ants. Similarly, the BLM (Knauf 2002) found that preliminary results 
from a comparative study on fringe-toed lizard abundance in OHV open 
and closed areas showed that abundance of fringe-toed lizards in the 
OHV-used areas of the Algodones Dunes was significantly lower than in 
areas closed to OHVs.
    Research was conducted in creosote-dominated habitats in the Mojave 
Desert. Researchers compared reptile metrics (measures) between sites 
used differentially by OHVs and control sites (Bury et al. 1977). Bury 
et al. (1977) found a significant decrease in numbers of reptiles on 
ORV-used areas compared with numbers on control sites in the Mojave 
Desert. However, the highest number of desert horned lizards 
(Phrynosoma platyrhinos) on any one plot occurred on a moderately used 
OHV site. In research conducted by both Busack and Bury (1974) and Bury 
et al. (1977), there appeared to be an inverse relationship between 
increased use of OHVs and the abundance of lizards. Grant and Wright 
(2002) reported that OHV use was negatively correlated with flat-tailed 
horned lizard abundance on 12 plots on the Yuha Basin MA; however, the 
correlation was not statistically significant.
    Research in the Ocotillo Wells SVRA found flat-tailed horned 
lizards at higher densities in non-sandy habitats than sandy habitats 
within the SVRA, which differed from most other research findings 
(Beauchamp et al. (1998). It was unclear, however, if flat-tailed 
horned lizards were found in these atypical habitat types because they 
are more plastic in habitat use than previously thought, these habitat 
types are more available in the Ocotillo Wells SVRA than other areas in 
which flat-tailed horned lizards have been studied, or as a response to 
OHV activity (Beauchamp et al. 1998). Beauchamp et al. (1998) stated 
that most of the sandy areas were heavily affected by OHV activity 
compared to the habitat types where flat-tailed horned lizards were 
more dense.
    Setser and Young (2000) and Setser (2001) found flat-tailed horned 
lizards avoided OHV disturbed areas. However, there was no difference 
in flat-tailed horned lizard habitat use between areas within 10 m (33 
ft) of OHV trails and sites further away from OHV trails (Setser and 
Young 2000, Setser 2001). Setser and Young (2000) and Setser (2001) 
concluded that (1) OHV use might render sites less suitable to flat-
tailed horned lizard use, because of the impacts of OHV activity on 
vegetation and soil characteristics; or (2) OHV trails occur on sites 
not preferred by flat-tailed horned lizards (e.g., barren ground with 
no plants or rocks). However, Gardner (2002) suggested that OHV 
activity did not have an effect on flat-tailed horned lizards at two 
different areas in the Ocotillo Wells SVRA, on the basis of 
observations. Similarly, Grant and Wright (2002) found that abundance 
of flat-tailed horned lizards was more correlated with percentage of 
sand cover than level of OHV disturbance.
    In conclusion, while there has been some research on the adverse 
effects of OHV activity on vegetation, soils, and flat-tailed horned 
lizards, its applicability to flat-tailed horned lizard populations is 
limited and unreliable, because of the lack of scientific rigor 
associated with the research designs. Additionally, the effects of OHV 
activity on flat-tailed horned lizard populations were not the primary 
research questions. Nevertheless, these studies have utility in 
generating hypotheses concerning variation in degree of OHV use and 
flat-tailed horned lizard abundance. At this time, we feel that the 
available studies do not collectively show that OHV activity causes 
declines in flat-tailed horned lizard populations in the four different 
geographic areas in the United States, or that adverse OHV impacts pose 
a significant threat to these populations. Management activities, 
including efforts to reduce conflicts with actions that impact flat-
tailed horned lizard habitats, would be enhanced by focused research. 
Impacts of OHV activity on flat-tailed horned lizard populations should 
be studied using rigorous research designs to yield conclusions with 
high degrees of certainty (Ratti and Garton 1994) regarding the effects 
of OHV activity on flat-tailed horned lizard populations across the 
geographic areas previously mentioned.
    The Management Strategy includes specific planning actions to 
``Maintain information exchange and coordination of monitoring, 
management activities, and research'' and ``Encourage and support 
research that will promote the conservation of [flat-tailed horned 
lizards] or desert ecosystems.'' Research priorities include techniques 
for assessing abundance, life history, demographics, and effects of 
activities (including OHV use and associated activities). The research 
is conducted by the appropriate land management agency. We expect that 
future studies on these research priorities will provide the Service 
with the information necessary

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to reevaluate the status of the flat-tailed horned lizard and threats 
at a population level.
East Side of Imperial Valley (California)
    This geographic area is fragmented north to south by the New 
Coachella Canal, which separates the East Mesa populations from 
peripheral Algodones Dunes populations. Additional fragmentation is 
caused by SR78, I-8, and the All American Canal running mostly in an 
east to west direction. On the east side of the Algodones Dunes, Ogilby 
Road further fragments the area, although to a far lesser degree, 
running from I-8 to SR78.

East Mesa MA

    The East Mesa MA is 46,661 ha (115,300 ac) in size, and consists of 
43,869 ha (108,400 ac) managed by signatories to the Management 
Strategy/CA, and 2,792 ha (6,900 ac) of private land. In 2001, BLM 
estimated that about 4.8 percent of the surface area in the southern 
portion of the East Mesa MA was covered with OHV tracks (Wright 2002). 
Our disturbance analysis showed that, between 1997 and 2002, the 
percentage area disturbed increased from 7.3 to 7.8, acreage of 
disturbance increased from 3,278 ha (8,099 ac) to 3,311 ha (8,181 ac), 
and length of roads increased from 224 km (140 mi) to 944 km (590 mi).
    In 2001, BLM disturbance surveys detected about 5 percent of the 
surface area in the southern East Mesa MA to be affected by 
agriculture, mining, and geothermal activity (Wright 2002). A live 
bombing area controlled by the U.S. Navy, El Centro Naval Air Facility 
is located in the northernmost portion of the MA. Based on our review 
of currently available information, we believe the limited nature of 
the activities discussed above, do not individually or collectively 
pose a significant threat to the species and/or its habitat such that 
the species warrants listing under the Act.

Outside MA

    The Imperial Sand Dunes Recreation Area is over 60,704 ha (150,000 
ac) of habitat directly to the east of the East Mesa MA. Unrestricted 
OHV activity is permitted on more than 47,754 ha (118,000 ac) of the 
area, while about 12,950 ha (32,000 ac) are designated as a wilderness 
area, with no vehicle use allowed. Habitat has been degraded in the 
open area of the Imperial Sand Dunes Recreation Area by OHV activity 
and associated camping. The main impacts to the population in this area 
are most likely along the western periphery of the Dunes, where people 
camp and ride OHVs to and from the Dunes and around camp, and to a 
lesser extent on the eastern periphery. The Dunes have heavy OHV use; 
however, surveys have shown that the Dunes have a low abundance of 
flat-tailed horned lizards (Turner et al. 1980, Luckenbach and Bury 
1983, Wright 2002), even in the wilderness area of the Dunes 
(Luckenbach and Bury 1983, Wright, pers. comm. 2002).
    There has been loss of flat-tailed horned lizard habitat on the 
west side of East Mesa due to geothermal development on both BLM and 
private land in an area termed the Known Geothermal Resource Area 
(KGRA). Historically, approximately 28,240 ha (69,760 ac) of potential 
flat-tailed horned lizard habitat were subject to geothermal 
development in the form of construction, maintenance and operation of 
geothermal powerplants within the KGRA. Ormesa LLC currently operates 
six geothermal power plants and 80 geothermal wells on nearly 5,463 ha 
(13,500 ac) of BLM land in the KGRA (D. Campbell, Ormesa LLC Plant 
Manager, in litt. 2002).
    Based on our review of currently available information, we believe 
the limited nature of the geothermal activities discussed above and 
their location on the periphery of East Mesa, do not constitute a 
significant threat to the species and/or its habitat such that the 
species warrants listing under the Act.
Yuma Desert (Arizona)
    The historic range of the species in Arizona was estimated at 
approximately 82,360 ha (203,520 ac) by Hodges (1997), and 89,455 ha 
(221,043 ac) by the AGFD (Duane Shroufe, AGFD Director, in litt. 2002). 
By 1997, Hodges (1997) estimated about 69 percent (56,780 ha [140,301 
ac]) of the species' historic range remained. Habitat losses resulted 
from conversion to agriculture, urbanization, and military use. AGFD 
similarly estimates about 72 percent (64,283 ha [158,844 ac]) of the 
historic range currently remains in Arizona. AGFD reported that 
approximately 3.7 percent of historic habitat has been lost since 1996. 
Conversion of habitat to agriculture has been the primary land use 
responsible for the loss of habitat in Arizona, eliminating about 17.5 
percent of historic habitat by 1997. Conversion of habitat for urban 
and military use accounted for the loss of approximately 11.1 percent 
and 2.5 percent of historic habitat, respectively (Hodges 1997). The 
1993 proposed rule noted that urban and agricultural expansion into 
flat-tailed horned lizard habitat on the part of the communities of San 
Luis, Yuma, and the Foothills was a threat. While the expansion of 
these communities will convert some flat-tailed horned lizard habitat, 
77 percent of the remaining habitat is within the MA and 87 percent is 
managed by signatories to the CA. The remaining private land subject to 
development is adjacent to existing urban and agricultural areas and is 
fragmented. In addition, the potential development of this land will 
not fragment or degrade the contiguous habitat remaining in the Yuma 
Desert MA, which comprises the majority of the flat-tailed horned 
lizard habitat in Arizona. For these reasons, the remaining private 
land does not constitute a significant portion of the range of the 
flat-tailed horned lizard in this geographic area.

Yuma Desert MA

    Of the current habitat, 50,384 ha (124,500 ac) are within the MA. 
Recently, 6,273 ha (15,500 ac) of suitable habitat owned by the State 
of Arizona within the Yuma Desert MA was acquired by the Department of 
Defense, a signatory to the Conservation Agreement. Consequently, the 
Management Area is completely owned by signatories to the Management 
Strategy.
    A proposal for an Area Service Highway on the west side of the MA 
would reduce the MA by about 405 ha (1,000 ac), because it would revise 
the MA boundary. The Area Service Highway would further fragment 
habitat on the west side of the MA by dividing it from the adjoining 
habitat outside the MA. Because the Area Service Highway will only 
contract the MA boundary on one side by less than 1 percent, leaving 
the habitat in the MA contiguous, this impact does not constitute a 
significant threat to the species or its habitat such that the species 
warrants listing under the Act.
    The Yuma Desert MA is relatively undisturbed compared to the 
Management Areas in California. Rorabaugh et al. (2002) randomly 
surveyed the Management Area to assess human disturbance and found the 
most common form was off-road-vehicle tracks, which covered 2.9 to 3.4 
percent of the surface area. The Marine Corps Air Station-Yuma has a 66 
ha (162 ac) target area called the ``Moving Sands Target'' within the 
MA. Based on our review of currently available information, we believe 
the limited nature of the activities discussed above, do not 
individually or collectively pose a significant threat to the species 
and/or its habitat such that the species warrants listing under the 
Act.

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Outside MA

    Currently, there is an estimated 14,876 ha (36,758 ac) of flat-
tailed horned lizard habitat outside the MA. Of this habitat, 8,376 ha 
(20,697 ac) are owned by either the Arizona State Land Department, 
private interests, or the Cocopah Tribe. No immediate plans for 
development of this land are known; however, AGFD considers the land to 
be vulnerable to development. The other 44 percent is owned primarily 
by the BOR, which is a signatory agency of the Conservation Agreement, 
so the land is less likely to be developed (Shroufe in litt. 2002). 
However, approximately 6,475 ha (16,000 ac) of habitat managed by the 
BOR are within the ``5-Mile Zone'' of the international border with 
Mexico, which has been identified by the City of San Luis in their 
General Management Plan for potential development (Robert Kritzstein, 
BLM, in litt. 2002). These lands do not comprise a significant 
percentage of the flat-tailed horned lizard habitat in this geographic 
area, and the potential development of this land will not fragment or 
degrade the contiguous habitat remaining in the Yuma Desert MA. 
Therefore, these activities do not constitute a significant threat to 
the species or its habitat such that the species warrants listing under 
the Act.
    Invasion of non-native plants into the desert systems has been 
noted as a threat (Hodges 1997, Shroufe in litt. 2002). Non-native 
species that have become prevalent in certain areas of the Sonoran 
Desert include Schismus barbatus (Mediterranean grass) and Brassica 
spp. (mustard). In Arizona, high densities of Mediterranean grass 
currently appear limited to disturbed areas in proximity to Yuma 
(Shroufe in litt. 2002). These species can become dense and effectively 
stabilize substrates that were once loose sand, likely reducing flat-
tailed horned lizard habitat quality. Increased fuel load for fire is 
also a concern with these non-native plant species, and the effects of 
a new fire regime on the desert ecosystems and ultimately the flat-
tailed horned lizard is unknown. Because of the limited extent to which 
non-native plants have established themselves in flat-tailed horned 
lizard habitat in this geographic area, this threat does not warrant 
listing the species under the Act.
Mexico
    At this time, much less is known about the threats of habitat loss 
and modification in Mexico. Urban and agricultural farming are the most 
immediate threats to the species in Mexico (CEDO 2001). Considerable 
habitat loss has occurred in the Mexicali Valley in Baja California 
Norte where urban and agricultural development extends from Mexicali to 
the Colorado River (Johnson and Spicer 1985, Foreman 1997). This 
development from Mexicali to the Colorado River together with the All 
American Canal, has isolated flat-tailed horned lizard habitat on the 
Andrade Mesa in Mexico from East Mesa in the U.S. and also from the 
Yuha Desert in Mexico. Habitat fragmentation also has resulted from a 
variety of human activities, such as the creation of roads and 
highways. Other potential threats to the habitat of the flat-tailed 
horned lizard include invasion of non-native plants such as Russian 
thistle (Salsola kali), mustards (Brassica spp.), and salt cedar; 
cattle grazing in the Gran Desierto/Pinacate region; and the increasing 
use of OHVs in sandy plains, dunes, and back-roads (CEDO 2001). 
However, the effects of these threats have not been adequately 
documented (CEDO 2001).
    In conclusion, after considering all the current available 
information, we have determined that the threats identified under 
Factor A are not significant enough to conclude that the flat-tailed 
horned lizard is likely to become endangered throughout all or a 
significant portion of its range in the foreseeable future. However, 
the Coachella Valley has experienced a significant amount of habitat 
curtailment and there is the potential for significant habitat 
destruction in the immediate future, because of the predominant private 
ownership of habitat and the rate of development in the Coachella 
Valley. The available data do not suggest that habitat modification by 
OHV use threatens the flat-tailed horned lizard on the west side of the 
Salton Sea/Imperial Valley and east side of the Imperial Valley. We 
conclude that the Arizona population is not likely to become endangered 
within the foreseeable future, because the low percentage of lands in 
private ownership makes for a low degree of threat from development. 
Further, OHV use has not been shown to be a threat to populations here 
and this geographic area experiences a relatively low level of OHV 
activity.

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

    In the past, scientists have reported on collection of flat-tailed 
horned lizards. The most noted example was the collection of 381 flat-
tailed horned lizards along an 11.3 km (7 mi) stretch of SR78 between 
the Coachella and East Highline Canals between 1961 to 1964 (Bolster 
and Nicol 1989). Norris (1949) noted that near Palm Springs the capture 
of flat-tailed horned lizards was not a common occurrence, and that 
collecting was good if it yielded two flat-tailed horned lizards in one 
day. Collection of flat-tailed horned lizards has not been reported 
since 1964. Because of the difficulty in locating these lizards, due to 
their cryptic coloration and tendency to remain motionless when 
approached, no threat of overutilization of this species is known or 
expected in the future on either public or private lands. Collection 
for the pet trade has not been identified as a threat to the species.

C. Disease or Predation

    While disease is not known to be a threat to flat-tailed horned 
lizard persistence, flat-tailed horned lizards are depredated by a 
variety of predators. Flat-tailed horned lizard predators include 
loggerhead shrikes, round-tailed ground squirrels, grasshopper mice, 
snakes, canids, American kestrels, common ravens, and burrowing owls 
(Muth and Fisher 1992, Duncan et al. 1994, Young and Young 2000). 
Round-tailed ground squirrels were documented as the main predator of 
flat-tailed horned lizards during research conducted in California (N = 
19; Muth and Fisher 1992) and Arizona (N = 26; Young and Young 2000), 
with loggerhead shrikes being the second most common predator. The 1993 
proposed rule noted that Bolster and Nicol (1989) suggested that 
predation of flat-tailed horned lizards near agricultural areas and 
urban areas may be elevated because of the presence of house cats in 
urban areas and the abundance of loggerhead shrikes and other predatory 
birds in croplands. We were unable to find any documentation suggesting 
that house cats increased mortality rates for flat-tailed horned 
lizards adjacent to urban areas. Increased predation rates on flat-
tailed horned lizards by loggerhead shrikes and American kestrels have 
been reported in localized areas where human-provided perches (e.g., 
power lines or palm trees) have been used by shrikes and kestrels as 
points from which to hunt (Young and Young 2000, Barrows pers. comm. 
2002). Despite this, available evidence does not suggest that predation 
has caused a significant threat to the persistence of the species in 
any part of its range, public or private.

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D. The Inadequacy of Existing Regulatory Mechanisms

    Existing mechanisms that could provide some protection for the 
flat-tailed horned lizard include the following: (1) State laws, 
including the California Endangered Species Act (CESA) and CEQA, and 
the Arizona State List of Wildlife of Special Concern and Arizona Game 
and Fish Commission Order 43; (2) Federal laws and regulations, 
including the National Environmental Policy Act (NEPA), the Endangered 
Species Act in those cases where this species occurs in habitat 
occupied by other listed species, and the Fish and Wildlife 
Coordination Act; (3) local land use processes and ordinances; (4) the 
Flat-Tailed Horned Lizard Rangewide Management Strategy and associated 
Conservation Agreement; (5) regional planning efforts such as the 
Coachella Valley Multi-Species Habitat Conservation Plan; and (6) 
foreign laws and regulations in Mexico, including the Mexican 
Endangered Species List.
    The State of California considers the flat-tailed horned lizard a 
species of special concern, but it is not listed as threatened or 
endangered under CESA. Consequently, the species receives no protection 
under CESA. In California, the management of Anza-Borrego Desert State 
Park is favorable for the conservation of the flat-tailed horned lizard 
because of the emphasis placed on resource protection and regulations 
limiting OHV activity to designated trails.
    The States of California and Arizona prohibit the collection of 
flat-tailed horned lizards pursuant to California Code of Regulations, 
Title 14, Section 5.60, and Arizona Game and Fish Commission Order 43, 
except by permit. The AGFD has included the species on the draft List 
of Wildlife of Special Concern in Arizona, which Arizona uses to 
prioritize species for planning and funding purposes. No state 
regulations in Arizona protect the habitat of this species at this 
time.
    CEQA requires review of any project that is undertaken, funded, or 
permitted by a State or local governmental agency. If a project with 
potential impacts on the flat-tailed horned lizard were reviewed, CDFG 
personnel could determine that, although not listed, the lizard is a de 
facto endangered, threatened, or rare species under section 15380 of 
CEQA. Once significant effects are identified, the lead agency has the 
option of requiring mitigation for effects through changes in the 
project or deciding that overriding considerations make mitigation 
infeasible (CEQA Sec. 21002). In the latter case, projects may be 
approved that cause significant environmental damage, such as 
destruction of listed endangered species or their habitat. Protection 
of listed species through CEQA is, therefore, dependent upon the 
discretion of the agency involved.
    The flat-tailed horned lizard may receive some level of protection 
through the Act because of overlapping ranges or proximity to other 
federally listed species in California. These species include Coachella 
Valley fringe-toed lizard (Uma inornata), Coachella Valley milk-vetch 
(Astragalus lentiginosus var. coachellae), Pierson's milk-vetch 
(Astragalus magdalenae var. peirsonii), bighorn sheep in the Peninsular 
Ranges (Ovis canadensis), and desert tortoise (Gopherus agassizii).
    The federally threatened Coachella Valley fringe-toed lizard is 
restricted to the Coachella Valley, but its distribution overlaps with 
the northern portion of the flat-tailed horned lizard's range in the 
Coachella Valley. However, the flat-tailed horned lizard may use 
additional habitat within the Coachella Valley in which the fringe-toed 
lizard does not occur. In addition, the majority of suitable habitat in 
the Coachella Valley in which both the fringe-toed lizard and flat-
tailed horned lizard occur is not protected. Only 2,150 ha (5,314 ac) 
of suitable flat-tailed horned lizard habitat is protected as part of 
the Coachella Valley Fringe-toed Lizard Preserve System (Coachella 
Valley Mountains Conservancy 2001). The federally endangered Coachella 
Valley milk-vetch also co-occurs with the flat-tailed horned lizard 
only within the Coachella Valley and offers no additional conservation 
beyond that provided by the fringe-toed lizard. However, projects in 
which there is a Federal action that may affect one or both these 
species are subject to Section 7 consultation with the Service under 
the Act. Section 7 consultations on the Coachella Valley fringe-toed 
lizard and/or Coachella Valley milk-vetch may indirectly provide ways 
to avoid or minimize adverse impacts to the flat-tailed horned lizard 
in addition to the targeted species.
    The federally endangered bighorn sheep of the Peninsular Ranges and 
flat-tailed horned lizards may overlap in habitat use at the edge of 
both of their ranges, where there is suitable habitat for both species 
in close proximity to the toe of slope of the mountains. However, the 
benefit to the flat-tailed horned lizard provided by the protection of 
bighorn sheep in the Peninsular Ranges is inconsequential.
    The federally endangered Pierson's milk-vetch is restricted to the 
Algodones Dunes, in which the flat-tailed horned lizard occurs in low 
numbers (Wright 2002), therefore offering little protection to the 
flat-tailed horned lizard. The range of the federally threatened desert 
tortoise may marginally overlap with the flat-tailed horned lizard in 
certain parts of the Coachella Valley, near the east side of the Salton 
Sea and the east side of the Algodones Dunes; however, no conservation 
value to the flat-tailed horned lizard should be expected.
    Through NEPA and the Fish and Wildlife Coordination Act, we may 
recommend discretionary conservation measures to avoid, minimize, and 
offset impacts to fish and wildlife resources resulting from Federal 
projects and water development projects authorized by the U.S. Army 
Corps of Engineers.
    The Management Strategy/CA has been the main regulatory mechanism 
established for the conservation of the flat-tailed horned lizard 
throughout its range. The Management Strategy/CA was signed in 1997 and 
included an extensive list of planning actions developed as 
recommendations to management agencies to ensure population viability 
within each MA (Foreman 1997). A caveat of the Management Strategy, 
however, was that the implementation of these actions is subject to 
availability of funds and compliance with all applicable regulations. 
In addition, the CA is a voluntary agreement to implement the 
Management Strategy; a signatory agency may withdraw from the CA after 
giving the other signatories 60 days' notice.
    Some of the planning actions have not yet been implemented. The 
planning action to ``limit vehicle access and limit route proliferation 
within MAs,'' has not been achieved. No action has been taken regarding 
the planning subactions to designate all routes either open, closed, or 
limited; and to reduce open and limited route density in MAs (Shroufe 
in litt. 2002, Wright in litt. 2002), despite these subactions' being 
``priority 1'' actions. Priority 1 actions are defined in the 
Management Strategy (Foreman 1997) as ``action[s] that must be taken in 
the near term to conserve the species and prevent irreversible 
population declines.'' The lack of enforcement to ensure closed and 
limited use areas is the primary deficiency of Management Strategy 
implementation. Should future research demonstrate that OHV use poses a 
significant threat to the species, these deficiencies may need to be 
corrected to avoid the species being listed in the future.
    While some important planning actions in the Management Strategy 
have not yet been implemented, the

[[Page 347]]

actions that have been and are being implemented do provide protection 
for the flat-tailed horned lizard and its habitat and have contributed 
to reductions in specific threats to the species. Most planning actions 
listed in the Management Strategy were implemented between the period 
of May 1997 and June 2002 (see our response to comment 3). The 
Management Strategy actions that contributed the most to the 
conservation of flat-tailed horned lizards were the exclusion of 
pesticide spraying within MAs, exclusion of competitive recreational 
events within MAs, efforts to develop and implement a monitoring 
strategy, and compensation for project impacts to flat-tailed horned 
lizard habitat.
    The actions that have been and are being implemented on the MAs do 
provide protection for the flat-tailed horned lizard and its habitat in 
each of the four geographic areas, except the Coachella Valley, in 
which the flat-tailed horned lizard occurs. Additionally, the 
Management Strategy has contributed to reductions in specific threats 
to the species, and to the viability of the flat-tailed horned lizard 
in each of the five MAs and ultimately the four geographic areas. 
Current available information does not indicate that the viability of 
the flat-tailed horned lizard in each of the geographic areas in which 
it occurs, with the exception of the Coachella Valley, is dependent on 
full implementation of the Management Strategy.
    Regional Habitat Conservation Plans in preparation by the Coachella 
Valley Association of Governments and the Agua Caliente Band of 
Cahuilla Indians would conserve a yet-to-be-determined amount of flat-
tailed horned lizard habitat, leaving the rest subject to development. 
These Habitat Conservation Plans are in progress and are subject to 
approval in the future; therefore, their completion and implementation 
cannot be relied upon for conservation purposes.
    The species is listed in the official Mexican Endangered Species 
List as threatened (CEDO 2001). Consequently, the species is protected 
from collection, sale, and commerce, and its habitat is afforded 
special protection in Mexico. The majority (about 60 percent) of the 
species' range in Mexico lies within two Mexican Federal natural 
protected areas: The Upper Gulf of California and Colorado Delta 
Biosphere Reserve, and the Pinacate and Gran Desierto de Altar 
Biosphere Reserve (CEDO 2001). The National Park of Pinacate is an area 
administered by the Mexican government with use restrictions similar to 
those of a national park in the United States. However, the boundaries 
are not well established, and enforcement of regulations is minimal.
    In conclusion, currently available information does not indicate 
that inadequate regulatory mechanisms necessitate listing the species 
under the Act. However, if flat-tailed horned lizard populations are 
found to be declining in the future, it would be prudent to revisit the 
adequacy of the regulatory mechanisms mentioned above, including the 
Management Strategy.

E. Other Natural or Manmade Factors Affecting Its Continued Existence

    Pesticide spraying associated with the Curlytop Virus Control 
Program to control the beet leafhopper (Circulifer tenellus) (Curlytop 
Program) on the east and west sides of the Salton Sea and Imperial 
Valley, is a threat because of its effects on the ant prey base for 
flat-tailed horned lizards. In the 1993 proposed rule, this threat was 
identified as having an impact mainly the East Mesa and Yuha Desert. 
Since the proposed rule, the threat from pesticide spraying has been 
reduced by a BLM Record of Decision on the Curlytop Program in 1997 and 
2002 to prohibit pesticide spraying within MAs. The Curlytop Program or 
a similar program has not been conducted in the Arizona geographic area 
of the species range (Minch, Arizona Department of Food and 
Agriculture, pers. comm. 2002). However, the Curlytop Program persists 
outside MAs and its direct, and indirect effects on flat-tailed horned 
lizard populations outside the MAs are not known in any detail. Foreman 
(1997) stated that the effects of applying broad-spectrum insecticide 
to desert scrub communities over many years are potentially many and 
complex. Pesticide/herbicide drift from croplands also has the 
potential to adversely affect plant communities adjacent to 
agricultural areas (Foreman 1997).
    The California Department of Food and Agriculture's Joint 
Environmental Assessment proposed that the Curlytop Program is likely 
to have no direct adverse effect to flat-tailed horned lizard 
populations, because studies (Hall and Clark 1982, Peterle and Giles 
1964, and Giles 1970; all cited in CDFA 2000) have shown various lizard 
species have a high tolerance of malathion. However, indirect effects 
of the Curlytop Program to ant populations were noted as being a 
concern in the associated Biological Opinion (11430-2002-7FCC-2365.1). 
The Curlytop Program included monitoring of ant colonies in 1991. 
Malathion was found to negatively affect ant colonies temporarily; 
however, ant colonies rapidly recovered (Peterson in litt. 1991). The 
Biological Opinion estimated the program could affect up to 141,643 ha 
(350,000 ac) of flat-tailed horned lizard habitat outside the MAs; 
however, most treatments are localized.
    Historically, treatments in the Imperial Valley are necessary 1 out 
of every 3 years, and the area treated may vary from 50 to a few 
thousand hectares (100 to several thousand acres) (CDFA 2000). The most 
recent treatments in the Imperial Valley were in 1998 and 1991, when 
2,388 ha (5,900 ac) and 2,891 ha (7,143 ac), respectively, of flat-
tailed horned lizard habitat were sprayed (CDFA 2000).
    Because of the limited extent of area sprayed, the prohibition of 
spraying on MAs, the long intervals between applications, and the 
apparently temporary nature of the adverse affects, we do not believe 
the Curlytop Program to be a threat to the species throughout all or a 
significant portion of its range to the extent that the flat-tailed 
horned lizard would be likely to become in danger of extinction in the 
foreseeable future. However, because the study conducted by CDFA 
(mentioned earlier) was cursory, we recommend further monitoring of ant 
colonies and flat-tailed horned lizard populations in treated and 
adjacent areas.
    The potential adverse impacts associated with drought were 
mentioned in the 1993 proposed rule. The threat that localized areas 
may experience long-term drought resulting in decreased local flat-
tailed horned lizard populations still exists.
    In our 1993 proposal to list the flat-tailed horned lizard as 
threatened, we identified numerous potential threats to the species and 
its habitat as the rationale for believing that the listing of the 
flat-tailed horned lizard was warranted. In this withdrawal, we have 
spoken directly to many of the threats discussed in our 1993 proposal 
in addition to other information that has become available since the 
publication of that proposal. We did not, however, speak directly to 
all threats because we believe, based on our review of currently 
available and credible information, that the threats not directly 
discussed here no longer pose a significant threat to the species and/
or its habitat individually or in combination such that the species 
warrants listing under the Act.

Finding

    The species was proposed as threatened in 1993 because much of the 
habitat of this species was reported to have been lost, fragmented, or 
degraded

[[Page 348]]

by human use; and relative densities were reported to have declined in 
at least one of five optimal habitat areas. Much of the species' 
habitat has been lost, fragmented, or degraded, but available data 
concerning population abundance, trends, and threats do not indicate 
that because of this habitat loss and degradation the species is likely 
to become endangered within the foreseeable future throughout all or a 
significant portion of its range.
    The information on population trends presented in the 1993 proposed 
rule was derived in part from scat count data collected between 1979 
and 1991. We no longer consider the use of these scat counts reliable 
for this purpose, as previously discussed in this rule. Therefore, we 
do not consider scat counts useful or reliable indicators of population 
abundance. Currently available data do not suggest that flat-tailed 
horned lizard populations are declining in any of the geographic areas.
    On the basis of the analysis of the five factors for the four 
different geographic areas in which the flat-tailed horned lizard 
occurs in the U.S., we conclude that the species is in danger of 
extirpation within the Coachella Valley, because of the large amount of 
habitat loss, the drastic curtailment of its range, a high degree of 
fragmentation of remaining habitat, and the threat of habitat loss in 
the foreseeable future.
    While we have determined that the population of flat-tailed horned 
lizards in the Coachella Valley is endangered with extinction within 
the foreseeable future, we have concluded that the current distribution 
of the flat-tailed horned lizard in the Coachella Valley does not 
constitute a significant portion of the species' range. We have made 
this determination based on the following: (1) Small extent of flat-
tailed horned lizard habitat in the Coachella Valley relative to the 
overall range of the species (approximately 3 percent of the range in 
the U.S., and roughly 1 percent of the species range overall, including 
Mexico); and (2) high level of habitat fragmentation. In addition, 
current scientific evidence does not suggest that the Coachella Valley 
population is genetically, behaviorally, or ecologically unique; nor 
does it appear to be a large population of flat-tailed horned lizards 
or contribute individuals to other geographic areas through emigration.
    Currently, the only geographic areas that have relatively large 
amounts of flat-tailed horned lizard habitat on private lands are the 
Coachella Valley and the west side of Salton Sea/Imperial Valley. The 
Coachella Valley is discussed above. Currently available information 
does not suggest that development of private lands on the west side of 
Salton Sea/Imperial Valley poses a threat in the foreseeable future. 
The only towns in this geographic area are Borrego Springs, Ocotillo, 
Ocotillo Wells, and Salton City. The largest of these towns is Borrego 
Springs with a population of approximately 3,000 people. It is likely 
the size of these towns will not change significantly in the 
foreseeable future. Therefore, we conclude that the threat of 
development of private lands in areas other than the Coachella Valley 
is not significant enough to endanger the species within the 
foreseeable future throughout a significant portion of its range.
    In addition, currently available data do not suggest that the flat-
tailed horned lizard is likely to become an endangered species within 
the foreseeable future on the west side of the Salton Sea/Imperial 
Valley and east side of Imperial Valley. The primary potential threat 
to the flat-tailed horned lizard identified for these areas is OHV use. 
As discussed under Factor A in the ``Summary of Factors Affecting the 
Species'' section, we believe the available studies do not collectively 
show that OHV activity causes declines in flat-tailed horned lizard 
populations, or that adverse OHV impacts pose a significant threat to 
these populations.
    We conclude the Arizona population is not likely to become 
endangered within the foreseeable future, because of the relatively low 
level of OHV activity in this geographic area and the low degree of 
threats from development due to the low percentage of lands in private 
ownership.
    Following our above analysis and discussion, we have determined 
that the action of listing the flat-tailed horned lizard as threatened 
throughout its range as proposed in 1993 is not warranted. We have made 
this determination because the threats to the species, as identified in 
the proposed rule, are not as significant as earlier believed, and 
current available data do not indicate that the threats to the species 
and its habitat are likely to endanger the species in the foreseeable 
future throughout all or a significant portion of its range. 
Consequently, we withdraw our 1993 proposal to list the flat-tailed 
horned lizard as threatened throughout its range.

References Cited

    A complete list of all references cited is available at the 
Carlsbad Fish and Wildlife Office (see ADDRESSES above).

Author

    The primary author of this document is the Carlsbad Fish and 
Wildlife Office (see ADDRESSES above).

Authority

    The authority for this action is section 4(b)(6)(B)(ii) of the 
Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).

    Dated: December 24, 2002.
Steve Williams,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 03-19 Filed 1-2-03; 8:45 am]
BILLING CODE 4310-55-P