[Federal Register Volume 86, Number 187 (Thursday, September 30, 2021)]
[Proposed Rules]
[Pages 54298-54338]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-21219]



[[Page 54297]]

Vol. 86

Thursday,

No. 187

September 30, 2021

Part II





Department of the Interior





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Fish and Wildlife Service





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50 CFR Part 17





Endangered and Threatened Wildlife and Plants; Removal of 23 Extinct 
Species From the Lists of Endangered and Threatened Wildlife and 
Plants; Proposed Rule

  Federal Register / Vol. 86, No. 187 / Thursday, September 30, 2021 / 
Proposed Rules  

[[Page 54298]]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[FF09E22000 FXES11130900000 201]
RIN 1018-BC98


Endangered and Threatened Wildlife and Plants; Removal of 23 
Extinct Species From the Lists of Endangered and Threatened Wildlife 
and Plants

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to 
remove 23 species from the Federal Lists of Endangered and Threatened 
Wildlife and Plants due to extinction. This proposal is based on a 
review of the best available scientific and commercial information, 
which indicates that these species are no longer extant and, as such, 
no longer meet the definition of an endangered species or a threatened 
species under the Endangered Species Act of 1973, as amended (Act). We 
are seeking information and comments from the public regarding this 
proposed rule.

DATES: We will accept comments received or postmarked on or before 
November 29, 2021. Comments submitted electronically using the Federal 
eRulemaking Portal (see ADDRESSES, below) must be received by 11:59 
p.m. Eastern Time on the closing date. We must receive requests for a 
public hearing, in writing, at the address shown in FOR FURTHER 
INFORMATION CONTACT by November 15, 2021.

ADDRESSES: You may submit comments by one of the following methods:
    (1) Electronically: Go to the Federal eRulemaking Portal: http://www.regulations.gov. In the Search box, enter the appropriate docket 
number (see table under Public Comments in SUPPLEMENTARY INFORMATION). 
Then, click on the Search button. On the resulting page, in the Search 
panel on the left side of the screen, under the Document Type heading, 
check the Proposed Rule box to locate this document. You may submit a 
comment by clicking on ``Comment Now!''
    (2) By hard copy: Submit by U.S. mail to: Public Comments 
Processing, Attn: [Insert appropriate docket number; see table under 
Public Comments in SUPPLEMENTARY INFORMATION], U.S. Fish and Wildlife 
Service, MS: PRB/3W, 5275 Leesburg Pike, Falls Church, VA 22041-3803.
    We request that you send comments only by the methods described 
above. We will post all comments on http://www.regulations.gov. This 
generally means that we will post any personal information you provide 
us (see Public Comments, below, for more information).

FOR FURTHER INFORMATION CONTACT: 

------------------------------------------------------------------------
                Species                        Contact information
------------------------------------------------------------------------
Bridled white-eye, Kauai akialoa, Kauai  Earl Campbell, Field
 nukupuu, Kauai `o`o (honeyeater),        Supervisor, Pacific Islands
 large Kauai thrush (kama), little        Fish and Wildlife Office, 808-
 Mariana fruit bat, Maui akepa, Maui      792-9400, 300 Ala Moana
 nukupuu, Molokai creeper (kakawahie),    Boulevard, Suite 3-122,
 Phyllostegia glabra var. lanaiensis      Honolulu, HI 96850.
 (no common name), and po`ouli
 (honeycreeper).
Bachman's warbler......................  Thomas McCoy, Field Supervisor,
                                          South Carolina Field Office,
                                          843-300-0431, 176 Croghan
                                          Spur, Charleston, SC 29407.
Flat pigtoe, southern acornshell,        Stephen Ricks, Field
 stirrupshell, and upland combshell.      Supervisor, Mississippi Field
                                          Office, 601-321-1122, 6578
                                          Dogwood View Parkway, Suite A,
                                          Jackson, MS 39213.
Green blossom (pearly mussel),           Daniel Elbert, Field
 tubercled blossom (pearly mussel),       Supervisor, Tennessee Field
 turgid blossom (pearly mussel), and      Office, 931-528-6481, Interior
 yellow blossom (pearly mussel).          Region 2--South Atlantic-Gulf
                                          (Tennessee), 446 Neal Street,
                                          Cookeville, TN 38506.
Ivory-billed woodpecker................  Joe Ranson, Field Supervisor,
                                          Louisiana Field Office, 337-
                                          291-3113, 200 Dulles Dr.,
                                          Lafayette, LA 70506.
San Marcos gambusia....................  Adam Zerrenner, Field
                                          Supervisor, Austin Ecological
                                          Services Field Office, 512-490-
                                          0057 (ext. 248), 10711 Burnet
                                          Rd., Suite 200, Austin, Texas
                                          78758.
Scioto madtom..........................  Patrice Ashfield, Field
                                          Supervisor, Ohio Ecological
                                          Services Field Office, 614-416-
                                          8993, 4625 Morse Road, Suite
                                          104, Columbus, OH 43230.
------------------------------------------------------------------------

    Persons who use a telecommunications device for the deaf (TDD) may 
call the Federal Relay Service at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Executive Summary

    Why we need to publish a rule. Section 4 of the Act (16 U.S.C. 
1533) and its implementing regulations in title 50 of the Code of 
Federal Regulations (50 CFR part 424) set forth the procedures for 
adding species to, removing species from, or reclassifying species on 
the Federal Lists of Endangered and Threatened Wildlife and Plants 
(List or Lists) in 50 CFR part 17. Under our regulations at 50 CFR 
424.11(e)(1), a species shall be delisted if, after conducting a status 
review based on the best scientific and commercial data available, we 
determine that the species is extinct. The 23 species within this 
proposed rule are currently listed as endangered or threatened; we are 
proposing to delist them due to extinction. We can only delist a 
species by issuing a rule to do so.
    What this document does. We propose to remove 23 species from the 
Lists due to extinction.
    The basis for our action. We may determine that a species should be 
removed from the List because it no longer meets the definition of an 
endangered species or a threatened species, including whether the best 
available information indicates that a species is extinct.

Information Requested

Public Comments

    We intend that any final rule resulting from this proposal will be 
based on the best available scientific and commercial data and will be 
as accurate and effective as possible. Therefore, we request comments 
or information from other concerned governmental agencies, Native 
American Tribes, the scientific community, industry, or any other 
interested parties concerning this proposed rule. Comments should be as 
specific as possible. We are specifically requesting comments on any 
additional information on whether these species

[[Page 54299]]

are extant or extinct. This information can include:
    (1) Any information that indicates whether the best available 
information supports a determination that one of the species is or is 
not extinct, including:
    (a) Biological or ecological requirements as it relates to the 
detectability of the species, including but not limited to: Lifespan, 
life stage, maturation period, physical description and ease of 
identification, vocalization, and habitat requirements for feeding, 
breeding, and sheltering;
    (b) Survey efforts past and current including information on how 
extensive the surveys were, the methodology used in the survey, and how 
effective were the methods used to detect the species (i.e., were the 
surveys designed to effectively detect the species if it is present in 
the area?); or
    (c) Last sighting of the species including a description of 
location of the sighting, the type of sighting (e.g., visual or 
auditory), length of time since last detection, and the frequency of 
last sightings.
    (2) Factors that may have resulted in the extinction of the 
species, which may include habitat modification or destruction, 
overutilization, disease, predation, the inadequacy of existing 
regulatory mechanisms, or other natural or manmade factors.
    Please include sufficient information with your submission (such as 
scientific journal articles or other publications) to allow us to 
verify any scientific or commercial information you include.
    Please note that submissions merely stating support for, or 
opposition to, the action under consideration without providing 
supporting information, although noted, will not be considered in 
making a determination, as section 4(b)(1)(A) of the Act directs that 
determinations as to whether any species is an endangered or a 
threatened species must be made ``solely on the basis of the best 
scientific and commercial data available.''
    You may submit your comments and materials concerning this proposed 
rule by one of the methods listed in ADDRESSES. We request that you 
send comments only by the methods described in ADDRESSES.
    You may submit your comments or materials electronically, or view a 
detailed description of the basis for a species determination, on the 
internet at http://www.regulations.gov under the following docket 
numbers:

------------------------------------------------------------------------
                  Species                            Docket No.
------------------------------------------------------------------------
Kauai akialoa.............................           FWS-R1-ES-2020-0104
Kauai nukupuu.............................           FWS-R1-ES-2020-0104
Kauai `o`o (honeyeater)...................           FWS-R1-ES-2020-0104
Large Kauai thrush (kam'a)................           FWS-R1-ES-2020-0104
Maui akepa................................           FWS-R1-ES-2020-0104
Maui nukupuu..............................           FWS-R1-ES-2020-0104
Molokai creeper (kakawahie)...............           FWS-R1-ES-2020-0104
Po`ouli (honeycreeper)....................           FWS-R1-ES-2020-0104
Bridled white-eye.........................           FWS-R1-ES-2020-0104
Little Mariana fruit bat..................           FWS-R1-ES-2020-0104
Phyllostegia glabra var. lanaiensis (no              FWS-R1-ES-2020-0104
 common name).............................
San Marcos gambusia.......................           FWS-R2-ES-2020-0105
Scioto madtom.............................           FWS-R3-ES-2020-0106
Flat pigtoe...............................           FWS-R4-ES-2020-0107
Southern acornshell.......................           FWS-R4-ES-2020-0107
Stirrupshell..............................           FWS-R4-ES-2020-0107
Upland combshell..........................           FWS-R4-ES-2020-0107
Green blossom (pearly mussel).............           FWS-R4-ES-2020-0108
Tubercled blossom (pearly mussel).........           FWS-R4-ES-2020-0108
Turgid blossom (pearly mussel)............           FWS-R4-ES-2020-0108
Yellow blossom (pearly mussel)............           FWS-R4-ES-2020-0108
Ivory-billed woodpecker...................           FWS-R4-ES-2020-0109
Bachman's warbler.........................           FWS-R4-ES-2020-0110
------------------------------------------------------------------------

    Supporting information used to prepare the determinations, as well 
as comments and materials we receive, will be available for public 
inspection on http://www.regulations.gov, or by contacting the 
appropriate person, as specified under FOR FURTHER INFORMATION CONTACT.
    If you submit information via http://www.regulations.gov, your 
entire submission--including any personal identifying information--will 
be posted on the website. If your submission is made via a hardcopy 
that includes personal identifying information, you may request at the 
top of your document that we withhold this information from public 
review. However, we cannot guarantee that we will be able to do so. We 
will post all hardcopy submissions on http://www.regulations.gov.
    Because we will consider all comments and information we receive 
during the comment period, our final determinations may differ from 
this proposal. Based on the new information we receive (and any 
comments on that new information), we may conclude that the species 
should remain listed as endangered or threatened, or reclassify from 
threatened to endangered, instead of being delisted because new 
evidence indicates that it is not extinct.

Public Hearing

    Section 4(b)(5) of the Act provides for a public hearing on this 
proposal, if requested. Requests must be received by the applicable 
date specified in DATES. Such requests must be sent to the address 
shown in FOR FURTHER INFORMATION CONTACT. We will schedule a public 
hearing on this proposal, if requested, and announce the date, time, 
and place of the hearing, as well as how to obtain reasonable 
accommodations, in the Federal Register and local newspapers at least 
15 days before the hearing. For the immediate future, we will provide 
these public hearings using webinars that will be announced on the 
Service's website, in addition to the Federal Register. The use of 
these virtual public hearings is consistent with our regulations at 50 
CFR 424.16(c)(3).

Peer Review

    In accordance with our policy, ``Notice of Interagency Cooperative 
Policy for Peer Review in Endangered Species Act Activities,'' which 
was published on July 1, 1994 (59 FR 34270)

[[Page 54300]]

and our August 22, 2016, Director's Memorandum ``Peer Review Process,'' 
we will seek, or have sought, the expert opinion of at least three 
appropriate and independent specialists regarding scientific data and 
interpretations contained in this proposed rule for each species or 
group of species. In certain cases, species will be grouped together 
for peer review based on similarities in biology or geographic 
occurrences. We will send copies of the five-year species status 
reviews to the peer reviewers immediately following publication in the 
Federal Register. We will ensure that the opinions of peer reviewers 
are objective and unbiased by following the guidelines set forth in the 
Director's Memo, which updates and clarifies Service policy on peer 
review (U.S. Fish and Wildlife Service 2016). The purpose of such 
review is to ensure that our decisions are based on scientifically 
sound data, assumptions, and analysis. Accordingly, our final decisions 
may differ from this proposal.

Background

    Section 4(c) of the Act requires the Service to maintain and 
publish Lists of Endangered and Threatened Species. This includes 
delisting species that are extinct or presumed extinct based on the 
best scientific and commercial data available. The Service can decide 
to delist a species presumed extinct on its own initiative, as a result 
of a 5-year review under section 4(c)(2) of the Act, or because we are 
petitioned to delist due to extinction. Congress made clear that an 
integral part of the statutory framework is for the Service to make 
delisting decisions when appropriate and revise the Lists accordingly. 
For example, section 4(c)(1) of the Act requires the Service to revise 
the Lists to reflect recent determinations, designations, and 
revisions. Similarly, section 4(c)(2) requires the Service to review 
the lists at least every 5 years; determine, based on those reviews, 
whether any species should be delisted or reclassified; and, if so, 
apply the same standards and procedures as for listings under sections 
4(a) and 4(b). Finally, to make a finding that a particular action is 
warranted but precluded, the Service must make two determinations: (1) 
That the immediate proposal and timely promulgation of a final 
regulation is precluded by pending proposals to determine whether any 
species is endangered or threatened; and (2) that expeditious progress 
is being made to add qualified species to either of the Lists and to 
remove species from the Lists (16 U.S.C. 1533(b)(3)(B)(iii)). Delisting 
species that will not benefit from the Act's protections because they 
are extinct allows us to allocate resources responsibly for on-the-
ground conservation efforts, recovery planning, 5-year reviews, and 
other protections for species that are extant and will therefore 
benefit from those actions.

Regulatory and Analytical Framework

    Section 4 of the Act (16 U.S.C. 1533) and its implementing 
regulations (50 CFR part 424) set forth the procedures for adding 
species to, removing species from, or reclassifying species on the 
Lists. Our regulations (50 CFR 424.11(e)) state that the Secretary 
shall delist a species if the Secretary finds that, after conducting a 
status review based on the best scientific and commercial data 
available:

    (1) The species is extinct;
    (2) The species does not meet the definition of an endangered 
species or a threatened species. In making such a determination, we 
consider the same five factors and apply the same standards set 
forth as for listing and reclassification; or
    (3) The listed entity does not meet the statutory definition of 
a species.

    In this proposed rule, we use the commonly understood biological 
definition of ``extinction'' as meaning that no living individuals of 
the species remain in existence. A determination of extinction will be 
informed by the best available information to indicate that no 
individuals of the species remain alive, either in the wild or 
captivity. This is in contrast to ``functional extinction,'' where 
individuals of the species remain alive but the species is no longer 
viable and/or no reproduction will occur (e.g., any remaining females 
cannot reproduce, only males remain, etc.).
    In our analyses, we attempted to minimize the possibility of either 
(1) prematurely determining that a species is extinct where individuals 
exist but remain undetected, or (2) assuming the species is extant when 
extinction has already occurred. Our determinations of whether the best 
available information indicates that a species is extinct included an 
analysis of the following criteria: Detectability of the species, 
adequacy of survey efforts, and time since last detection. All three 
criteria require taking into account applicable aspects of species' 
life history. Other lines of evidence may also support the 
determination and be included in our analysis.
    In conducting our analyses of whether these species are extinct, we 
considered and thoroughly evaluated the best scientific and commercial 
data available. We reviewed the information available in our files, and 
other available published and unpublished information. These 
evaluations may include information from recognized experts; Federal, 
State, and Tribal governments; academic institutions; foreign 
governments; private entities; and other members of the public.
    The 5-year reviews of these species contain more detailed 
biological information on each species. This supporting information can 
be found on the internet at http://www.regulations.gov under the 
appropriate docket number (see table under Public Comments, above). The 
following information summarizes the analyses for each of the species 
proposed for delisting by this rule.

Summary of Biological Status and Threats

Mammals

Little Mariana Fruit Bat (Pteropus tokudae)

I. Background
    The little Mariana fruit bat (Pteropus tokudae) was listed as 
endangered on August 27, 1984 (49 FR 33881), and was included in the 
Recovery Plan for Mariana Fruit Bat (Pteropus mariannus, or fanihi in 
the Chamorro language) and the Little Mariana Fruit Bat (USFWS 1990). 
Last observed in 1968, the little Mariana fruit bat was ``among the 
most critically endangered species of wildlife under U.S. 
jurisdiction,'' as noted in the 1984 final listing rule (49 FR 33881, 
August 27, 1984, p. 49 FR 33882), which cited hunting and loss of 
habitat as the primary factors contributing to its rarity. Three 5-year 
status reviews have been completed; the 2009 (initiated on March 8, 
2007; see 72 FR 10547) and 2015 (initiated on February 5, 2013; see 78 
FR 8185) reviews did not recommend a change in status (USFWS 2009b, 
2015). The 5-year status review completed in 2019 (initiated on May 7, 
2018; see 83 FR 20088) recommended delisting due to extinction likely 
resulting from habitat loss, poaching, and predation by the brown tree 
snake (Boiga irregularis). This recommendation was based on a 
reassessment of all available information for the species, coupled with 
an evaluation of population trends and threats affecting the larger, 
extant Mariana fruit bat, which likely shares similar behavioral and 
biological traits and provides important context for the historical 
decline of the little Mariana fruit bat. (USFWS 2019).
    The little Mariana fruit bat was first described from a male type 
specimen collected in August 1931 (Tate 1934, p. 1). Its original 
scientific name, Pteropus tokudae, remains current. Only three 
confirmed observations of the little Mariana fruit bat existed in the

[[Page 54301]]

literature based on collections of three specimens: Two males in 1931 
(Tate 1934, p. 3), and a female in 1968 (Perez 1972, p. 146), all on 
the island of Guam where it was presumably endemic. Despite the dearth 
of confirmed collections and observations, two relatively recent 
studies have confirmed the taxonomic validity of the little Mariana 
fruit bat, via morphology (Buden et al. 2013, entire) and genetics 
(Almeida et al. 2014, entire). A study of the physical morphology of 
several Micronesia Pteropus spp., including all three known little 
Mariana fruit bat specimens, concluded that the species was a distinct 
taxon (Buden et al. 2013, entire). Subsequently, genetic analysis of 
skin samples from 50 of the 63 described Pteropus species supported the 
Mariana little fruit bat's taxonomic distinctness (Almeida et al. 2014, 
entire).
    The little Mariana fruit bat belonged to a primarily tropical group 
of bats in the Megachiroptera suborder characterized by relatively 
large size, frugivorous diet (fruit-eating), and lack of echolocation. 
Its genus, Pteropus, comprises 63 species, including many coastal 
species endemic to Pacific islands (Almeida et al. 2014, pp. 83-84). 
Given the homogeneity of life-history traits within the Pteropus genus, 
we expect that the little Mariana fruit bat exhibited similar behavior 
and life history to other members of the genus, including group 
roosting and foraging within forest habitat, lengthy care of few 
offspring, and slow population growth (USFWS 1990, p. 7; Wiles 1987, p. 
154). Lifespan for the little Mariana fruit bat is unknown, but the 
Mariana fruit bat may survive for 30 years in captivity (USFWS 2020, 
unpaginated) and other bats within the genus live between 14 and 40 
years. In the most recent 5-year review completed in 2019, we drew upon 
our knowledge of the larger and still extant Mariana fruit bat's 
biology to extrapolate a likely timeline and explanation for the little 
Mariana fruit bat's rarity, decline, and eventual extinction.
    The earliest available scientific literature indicates that the 
little Mariana fruit bat was always likely rare, as suggested by 
written accounts of the species first recorded in the early 1900s 
(Baker 1948, p. 54; Perez 1972, pp. 145-146; Wiles 1987, p 154). In 
addition to possibly having been inherently rare, as suggested by the 
literature, a concurrent decline in the little Mariana fruit bat 
population likely occurred during the well-documented decrease in 
Mariana fruit bat abundance on Guam in the 1900s. In 1920, it was ``not 
an uncommon sight'' to see fruit bats flying over the forest during the 
daytime in Guam (Wiles 1987, p. 150). Just 10 years later (when the 
first two little Mariana fruit bat specimens were collected), fruit 
bats were uncommon on the island (Wiles 1987, p. 150), and were found 
mostly in northern Guam; introduced firearms may have been a 
contributing factor in their decline because they increased the 
efficiency of hunting (Wiles 1987, p. 150).
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    The little Mariana fruit bat was much smaller than the related 
Mariana fruit bat (Tate 1934, p. 2; Perez 1972, p. 146; Buden et al. 
2013, pp. 109-110). Adult bats measured approximately 5.5 to 5.9 inches 
(in) (14 to 15.1 centimeters (cm)) in head-body length, with a wingspan 
of approximately 25.6 to 27.9 in (650 to 709 mm). The adults weighed 
approximately 5.36 ounces (152 grams). Although primarily dark brown in 
color, the little Mariana fruit bat showed some variation on the neck 
and head which could appear pale gold and grayish or yellowish-brown in 
color. Because of their small size (O'Shea and Bogan 2003, pp. 49, 254; 
USFWS 2009, p. 55), it is possible that adult little Mariana fruit bats 
were historically confused with juvenile fruit bats. Therefore, 
historical accounts of the species may have been underrepresented 
(Perez 1972, p. 143; Wiles 1987, p. 15).
    The challenges of surveying for the Mariana fruit bat and most 
Pteropus spp. (including in theory, the little Mariana fruit bat) are 
numerous. Mariana fruit bats sleep during the day in canopy emergent 
trees, either solitarily or within colonial aggregations that may occur 
across several acres (O'Shea and Bogan 2003, p. 254; Utzurrum et al. 
2003, p. 49; USFWS 2009, p. 269). The tropical islands where many 
tropical fruit bats (Pteropus spp.) are located have widely diverse and 
steeply topographical habitat, making surveys difficult. Additionally, 
most Pteropus spp. choose roost sites (both colonial and individual) 
that occur in locations difficult for people to reach, such as adjacent 
to steep cliffsides in remote forest areas (Wilson and Graham 1992, p. 
65). The selection of roost sites in these areas is likely both a 
result of their evolved biology (for example to take advantage of 
updrafts for flight (Wilson and Graham 1992, p. 4)) and learned 
behavior to avoid poachers (USFWS 2009, pp. 24-25; Mildenstein and 
Johnson 2017, p. 36). To avoid triggering this avoidance behavior, 
surveyors must generally keep a distance of 164 feet (50 meters) and 
survey only downwind of roost sites (Mildenstein and Boland 2010, pp. 
12-13; Mildenstein and Johnson 2017, pp. 55, 86). Additionally, 
Pteropus spp. typically sleep during the day and do not vocalize, and 
flying individuals may be easily counted twice due to their foraging 
patterns (Utuzurrum et al. 2003, p. 54).
Survey Effort
    Historically, surveys to estimate colonial fruit bat numbers have 
generally involved two relatively simple and inexpensive methods, 
direct counts and station counts (or departure, or exit counts) 
(Utuzurrum et al. 2003, pp. 53-54). With direct counts, surveyors 
attempt to determine the number of bats in a roosting colony (or 
individual bats) at a single site during the day. Direct counts usually 
involve use of binoculars or a spotting scope, depending on the 
observation distance from the colony or individuals (Kunz et al. 1996; 
Eby et al. 1999; Garnett et al. 1999; Worthington et al. 2001 as cited 
in Mildenstein and Boland 2010, pp. 2-3). Conversely, surveyors conduct 
exit counts in the late afternoon to early evening when bats begin to 
depart from the roost site for evening foraging. Exit counts are 
typically conducted at locations with wide and unimpeded views of 
either areas known to contain colonies, or forested areas that would 
likely serve as roost sites for bats. Occasionally, surveyors may 
conduct both exit and direct counts by boat or by air with a 
helicopter. More recently, direct and exit count surveys involve use of 
computers and digital photography to aid the process (Mildenstein and 
Boland 2010, pp. 2-3).
    By 1945, fruit bats were difficult to locate even in the northern 
half of Guam, where they were largely confined to forested cliff lines 
along the coasts (Baker 1948, p. 54). During surveys conducted between 
1963 and 1968, the Guam Division of Aquatic and Wildlife Resources 
(DAWR) confirmed that bats were declining across much of Guam and were 
absent in the south. It was also during these same field studies that 
the third and last little Mariana fruit bat was collected in northern 
Guam in 1968 (Baker 1948, p. 146).
    Increased survey efforts during the late 1970s and early 1980s 
reported no confirmed sightings of the little Mariana fruit bat 
(Wheeler and Aguon 1978, entire; Wheeler 1979, entire; Wiles 1987, 
entire; Wiles 1987, pp. 153-154). When the little Mariana fruit bat was 
listed as endangered (49 FR 33881; August 27, 1984), we noted that the 
species was on the verge of extinction

[[Page 54302]]

and had not been verifiably observed after 1968. When we published a 
joint recovery plan for the little Mariana fruit bat and the Mariana 
fruit bat in 1990, we considered the little Mariana fruit bat already 
extinct based upon the available literature (USFWS 1990, p. 7).
    During the 1990s, researchers recorded decreasing Mariana fruit bat 
numbers on Guam and increasing fatalities of immature bats. They 
hypothesized the decline was due to predation by the brown tree snake 
(Wiles et al. 1995, pp. 33-34, 39-42). With bat abundance continuing to 
decline in the 2000s, researchers now estimate the island's Mariana 
fruit bat population currently fluctuates between 15 and 45 individuals 
(Mildenstein and Johnson 2017, p. 24; USFWS 2017, p. 54). Even if the 
little Mariana fruit bat persisted at undetectable numbers for some 
time after its last confirmed collection in 1968, it is highly likely 
the little Mariana fruit bat experienced the same pattern of decline 
that we are now seeing in the Mariana fruit bat.
Time Since Last Detection
    As stated above, the little Mariana fruit bat was last collected in 
northern Guam in 1968 (Baker 1948, p. 146). Intensive survey efforts 
conducted by Guam DAWR and other researchers in subsequent decades have 
failed to locate the species. Decades of monthly (and, later, annual) 
surveys for the related Mariana fruit bat by qualified personnel in 
northern Guam have failed to detect the little Mariana fruit bat 
(Wheeler and Aguon 1978, entire; Wheeler 1979, entire; Wiles 1987, 
entire; Wiles 1987, pp. 153-154; USFWS 1990, p. 7).
III. Analysis
    Like the majority of bat species in the genus Pteropus, specific 
biological traits likely exacerbated the little Mariana fruit bat's 
susceptibility to human activities and natural events (Wilson and 
Graham 1992, pp. 1-8). For example, low fecundity in the genus due to 
late reproductive age and small broods (1 to 2 young annually) inhibits 
population rebound from catastrophic events such as typhoons, and from 
slow progression of habitat loss and hunting pressure that we know 
occurred over time. The tendency of Pteropus bats to roost together in 
sizeable groups or colonies in large trees rising above the surrounding 
canopy makes them easily detected by hunters (Wilson and Graham 1992, 
p. 4). Additionally, Pteropus bats show a strong tendency for roost 
site fidelity, often returning to the same roost tree year after year 
to raise their young (Wilson and Graham 1992, p. 4; Mildenstein and 
Johnson 2017, pp. 54, 68). This behavior likely allowed hunters and 
(later) poachers to easily locate and kill the little Mariana fruit bat 
and, with the introduction of firearms, kill them more efficiently 
(Wiles 1987, pp. 151, 154; USFWS 2009, pp. 24-25; Mildenstein and 
Johnston 2017, pp. 41-42). The vulnerability of the entire genus 
Pteropus is evidenced by the fact that 6 of the 62 species in this 
genus have become extinct in the last 150 years (including the little 
Mariana fruit bat). The International Union for Conservation of Nature 
(IUCN) categorizes an additional 37 species in this genus at risk of 
extinction (Almeida et al. 2014, p. 84).
    In discussing survey results for the Mariana fruit bat in the late 
1980s, experts wrote that the level of illegal poaching of bats on Guam 
remained extremely high, despite the establishment of several legal 
measures to protect the species beginning in 1966 (Wiles 1987, p. 154). 
They also wrote about the effects of brown tree snake predation on 
various fruit bats species (Savidge, 1987, entire; Wiles 1987, pp. 155-
156). To date, there is only one documented instance of brown tree 
snake actually preying on the Mariana fruit bat; in that case, three 
young bats were found within the stomach of a snake (Wiles 1987, p. 
155). However, immature Pteropus pups are particularly vulnerable to 
predators between approximately 3 weeks and 3 months of age. During 
this timeframe, the mother bats stop taking their young with them while 
they forage in the evenings, leaving them alone to wait at their roost 
tree (Wiles 1987, p. 155).
    Only three specimens of little Mariana fruit bat have ever been 
collected, all on the island of Guam, and no other confirmed captures 
or observations of this species exist. Based on the earliest records, 
the species was already rare in the early 1900s. Therefore, since its 
discovery, the little Mariana fruit bat likely experienced greater 
susceptibility to a variety of factors because of its small population 
size. Predation by the brown tree snake, alteration and loss of 
habitat, increased hunting pressure, and possibly competition with the 
related Mariana fruit bat for the same resources under the increasingly 
challenging conditions contributed to the species' decreased ability to 
persist.
    It is highly likely the brown tree snake, the primary threat 
thought to be the driver of multiple bird and reptile species 
extirpations and extinctions on Guam, has been present throughout the 
little Mariana fruit bat's range for at least the last half-century, 
and within the last northern refuge in northern Guam since at least the 
1980s. Because of its life history and the challenges presented by its 
small population size, we conclude that the little Mariana fruit bat 
was extremely susceptible to predation by the brown tree snake.
IV. Conclusion
    At the time of listing in 1984, hunting and loss of habitat were 
considered the primary threats to the little Mariana fruit bat. The 
best available information now indicates that the little Mariana fruit 
bat is extinct. The species appears to have been vulnerable to 
pervasive, rangewide threats including habitat loss, poaching, and 
predation by the brown tree snake. Since its last detection in 1968, 
qualified observers have conducted surveys and searches throughout the 
range of the little Mariana fruit bat but have not detected the 
species. Available information indicates that the species was not able 
to persist in the face of anthropogenic and environmental stressors, 
and we conclude that the best available scientific and commercial 
information indicates that the species is extinct.

Birds

Bachman's Warbler (Vermivora bachmanii)

I. Background
    The Bachman's warbler (Vermivora bachmanii) was listed on March 11, 
1967 (32 FR 4001), as endangered under the Endangered Species 
Preservation Act of 1966, as a result of the loss of breeding and 
wintering habitat. Two 5-year reviews were completed for the species on 
February 9, 2007 (initiated on July 26, 2005; see 70 FR 43171), and May 
6, 2015 (initiated on September 23, 2014; see 79 FR 56821). Both 5-year 
reviews recommended that if the species was not detected within the 
following 5 years, it would be appropriate to delist due to extinction.
    The Bachman's warbler was first named in 1833 as Sylvia bachmanii 
based on a bird observed in a swamp near Charleston, South Carolina 
(AOU 1983, pp. 601-602). The Bachman's warbler was among the smallest 
warblers with a total length of 11.0 to 11.5 centimeters (cm) (4.3 to 
4.5 inches (in)). The species was found in the southeastern portions of 
the United States from the south Atlantic and Gulf Coastal Plains, 
extending inland in floodplains of major rivers (eastern Texas, 
Louisiana, Arkansas, bootheel of Missouri, Alabama, Georgia, North and 
South Carolinas, Virginia, and flyovers in Florida). However, breeding 
was documented only in northeast Arkansas, southeast Missouri, 
southwest Kentucky, central Alabama, and

[[Page 54303]]

southeast South Carolina. Bachman's warbler was a neotropical migrant; 
historically, the bulk of the species' population left the North 
American mainland each fall for Cuba and Isle of Pines (Dingle 1953, 
pp. 67-68, 72-73).
    Available information indicates that migratory habitat preferences 
differed from winter and breeding habitat preferences in that the bird 
used or tolerated a wider range of conditions and vegetative 
associations during migration. Historical records indicate the 
Bachman's warbler typically nested in low, wet, forested areas 
containing variable amounts of water, but usually with some permanent 
water. While it is not definitively known, it is thought that they 
preferred small edges created by fire or storms with a dense understory 
of the cane species Arundinaria gigantea and palmettos. Nests were 
typically found in shrubs low to the ground from late March through 
June, and average known clutch size was 4.2 +/-0.7 (with a range of 3 
to 5) (Hamel 2018, pp. 14-15). During the winter in Cuba, it was found 
in a wider variety of habitats across the island including forests, 
ranging from dry, semi-deciduous forests to wetlands, and even in 
forested urban spaces (Hamel 1995, p. 5). Life expectancy is unknown, 
but other warbler species live for 3 to 11 years (Klimkiewicz et al. 
1983, pp. 292-293).
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    The Bachman's warbler was one of the smallest warblers with a total 
length of 11.0 to 11.5 cm. The bill was slender with a slight downward 
curve in both sexes and was a unique feature within the genus. The male 
was olive-green above with yellow forehead, lores, eye-ring, chin, and 
underparts; a black throat and crown; and dusky wings and tail. Males 
also had a yellow shoulder patch and bright rump. Generally, while 
similar, plumage of females was paler. Females lacked any black 
coloration and had olive green upperparts with yellow forehead and 
underparts. The eye-ring was whiter than in the males, and the crown 
was grayish. The dark patch on the throat was usually missing and the 
eye-ring was pale. Females had a buffy or bright yellowish forehead and 
a gray crown with no black; a whitish or white crissum; and less 
pronounced white spots on the tail (Hamel and Gauthreaux 1982, pp. 235-
239; Hamel 1995, p. 2). Immature males resembled females. Males were 
easy to distinguish from other warblers. However, the drab coloration 
of the females and immature birds made positive identification 
difficult (Hamel and Gauthreaux 1982, p. 235). Additionally, females 
were much more difficult to identify because variability in plumage was 
greater. Immature females were also most likely to be confused with 
other similarly drab warblers. The song of the Bachman's warbler was a 
zeep or buzzy zip given by both sexes (Hamel 2020, Sounds and Vocal 
Behavior). This species may have been difficult to differentiate on 
call alone, as its call was somewhat reminiscent of the pulsating trill 
of the northern parula (Parula americana) (Curson et al. 1994, p. 95), 
and only two recordings exist from the 1950s (Hamel 2018, p. 32) to 
guide ornithologists on distinguishing it this way. Despite the fact 
that it could be mistaken for the northern parula, Bachman's warbler 
was of high interest to birders, and guides have been published 
specifically to aid in field identification (Hamel and Gauthreaux 1982, 
entire). As a result, substantial informal and formal effort has been 
expended searching for the bird and verifying potential sightings as 
outlined below (see ``Survey Effort'').
Survey Effort
    Although Bachman's warbler was first described in 1833, it remained 
relatively unnoticed for roughly the next 50 years. Population 
estimates are qualitative in nature and range from rare to abundant 
(Service 1999, pp. 4-448). Populations were probably never large and 
were found in ``some numbers'' between 1890 and 1920, but afterwards 
populations appeared to be very low (Hamel 2018, pp. 16-18). For 
instance, several singing males were reported in Missouri and Arkansas 
in 1897 (Widmann 1897, p. 39), and Bachman's warbler was seen as a 
migrant along the lower Suwannee River in flocks of several species 
(Brewster and Chapman 1891, p. 127). The last confirmed nest was 
documented in 1937 (Curson et al. 1994, p. 96). A dramatic decline 
occurred sometime between the early 1900s and 1940 or 1950. Recognition 
of this decline resulted in the 1967 listing of the species (32 FR 
4001; March 11, 1967) under the Endangered Species Preservation Act of 
1966.
    Between 1975 and 1979, an exhaustive search was conducted in South 
Carolina, Missouri, and Arkansas. No Bachman's warblers were located 
(Hamel 1995, p. 10). The last (though unconfirmed) sighting in Florida 
was from a single bird observed near Melbourne in 1977. In 1989, an 
extensive breeding season search was conducted on Tensas National 
Wildlife Refuge in Louisiana. Six possible Bachman's warbler 
observations occurred, but could not be documented sufficiently to meet 
acceptability criteria established for the study (Hamilton 1989, as 
cited in Service 2015, p. 4).
    An experienced birder reported multiple, possible sightings of 
Bachman's warbler at Congaree National Park, South Carolina, in 2000 
and 2001. These included hearing a male and seeing a female. In 2002, 
the National Park Service partnered with the Service and the Atlantic 
Coast Joint Venture to investigate these reports. Researchers searched 
over 3,900 acres of forest during 166 hours of observation in March and 
April; however, no Bachman's warbler sightings or vocalizations were 
confirmed. As noted previously, females and immature birds are 
difficult to positively identify. Males (when seen) are more easily 
distinguishable from other species. Researchers trying to verify the 
sightings traced several promising calls back to northern parulas and 
finally noted that they were confident the species would have been 
detected had it been present (Congaree National Park 2020, p. 3).
    In several parts of the Bachman's warbler's range, relatively 
recent searches (since 2006) for ivory-billed woodpecker also prompted 
more activity in appropriate habitat for Bachman's warbler. Although 
much of the search period for ivory-billed woodpecker is during the 
winter, the searches usually continue until the end of April, when 
Bachman's warbler would be expected in the breeding range. Therefore, 
because Bachman's warbler habitat overlaps ivory-billed woodpecker 
habitat, the probability that Bachman's warbler would be detected, if 
present, has recently increased (Service 2015, pp. 5-6). Further, in 
general, substantial informal effort has been expended searching for 
Bachman's warbler because of its high interest among birders (Service 
2015, p. 5). In spite of these efforts, Bachman's warbler has not been 
observed in the United States in more than three decades.
    In Cuba, the species' historical wintering range, the last 
ornithologist to see the species noted that the species was observed 
twice in the 1960s in the Zapata Swamp: One sighting in the area of a 
modern-day hotel in Laguna del Tesoro and the other one in the Santo 
Tomas, Zanja de la Cocodrila area. Some later potential observations 
(i.e., 1988) in the same areas were thought to be a female common 
yellowthroat (Navarro 2020, pers. comm.). A single bird was reported in 
Cuba in 1981 at Zapata Swamp (Garrido 1985, p. 997; Hamel 2018, p. 20). 
However, additional surveys in Cuba by Hamel and Garrido in 1987 
through 1989 did not confirm

[[Page 54304]]

additional birds (Navarro 2020, pers. comm.). There have been no 
sightings or bird surveys in recent years in Cuba, and all claimed 
sightings of Bachman's warbler from 1988 onwards have been rejected by 
the ornithological community (Navarro 2020, pers. comm.). Curson et al. 
(1994, p. 96) considers all sightings from 1978 through 1988 in Cuba as 
unconfirmed.
Time Since Last Detection
    After 1962, reports of the Bachman's warbler in the United States 
have not been officially accepted, documented observations (Chamberlain 
2003, p. 5). Researchers have been thorough and cautious in 
verification of potential sightings, and many of the more recent ones 
could not be definitively verified. Bachman's warbler records from 
1877-2001 in North America are characterized as either relying on 
physical evidence or on independent expert opinion, or as controversial 
sightings (Elphick et al. 2010, pp. 8, 10). In Cuba, no records have 
been verified since the 1980s (Navarro 2020, pers. comm.).
Other Considerations Applicable to the Species' Status
    At breeding grounds, the loss of habitat from clearing of large 
tracts of palustrine (i.e., having trees, shrubs, or emergent 
vegetation) wetland beginning in the 1800s was a major factor in the 
decline of the Bachman's warbler. Most of the palustrine habitat in the 
Mississippi Valley (and large proportions in Florida) was historically 
converted to agriculture or affected by other human activities 
(Fretwell et al. 1996, pp. 8, 10, 124, 246). Often the higher, drier 
portions of land that the Bachman's warbler required for breeding were 
the first to be cleared because they were more accessible and least 
prone to flooding (Hamel 1995, pp. 5, 11; Service 2015, p. 4). During 
World Wars I and II, many of the remaining large tracts of old growth 
bottomland forest were cut, and the timber was used to support the war 
effort (Jackson 2020, Conservation and Management, p. 2). At the 
wintering grounds of Cuba, extensive loss of primary forest wintering 
habitat occurred due to the clearing of large areas of the lowlands for 
sugarcane production (Hamel 2018, p. 24). Hurricanes also may have 
caused extensive damage to habitat and direct loss of overwintering 
Bachman's warblers. Five hurricanes occurred between November 1932 and 
October 1935. Two storms struck western Cuba in October 1933, and the 
November 1932 hurricane is considered one of the most destructive ever 
recorded. These hurricanes, occurring when Bachman's warblers would 
have been present at their wintering grounds in Cuba, may have resulted 
in large losses of the birds (Hamel 2018, p. 19).
III. Analysis
    As early as 1953, Bachman's warbler was reported as one of the 
rarest songbirds in North America (Dingle 1953, p. 67). The species may 
have gone extinct in North America by 1967 (Elphick et al. 2010, p. 
619). Despite extensive efforts to document presence of the species, no 
new observations of the species have been verified in the United States 
or Cuba in several decades (Elphick et al. 2010, supplement; Navarro 
2020, pers. comm.). Given the likely lifespan of the species, it has 
not been observed in several generations.
IV. Conclusion
    As far back as 1977, Bachman's warbler has been described as being 
on the verge of extinction (Hooper and Hamel 1977, p. 373) and the 
rarest songbird native to the United States (Service 1999, pp. 4-445). 
The species has not been seen in the United States or Cuba since the 
1980s, despite extensive efforts to locate it and verify potential 
sightings. Therefore, we conclude that the best available scientific 
and commercial information indicates that the species is extinct.

Bridled White-eye (Zosterops conspicillatus conspicillatus)

I. Background
    The bridled white-eye (Zosterops conspicillatus conspicillatus, or 
Nossa in the Chamorro language), was listed as endangered in 1984 (49 
FR 33881; August 27, 1984), and was included in the Recovery Plan for 
the Native Forest Birds of Guam and Rota of the Commonwealth of the 
Northern Mariana Islands (USFWS 1990, entire). The species was last 
observed in 1983, and the 1984 final listing rule for the bridled 
white-eye noted that the species ``may be the most critically 
endangered bird under U.S. jurisdiction'' (49 FR 33881, August 27, 
1984, p. 49 FR 33883) and cited disease and predation by nonnative 
predators, including the brown tree snake (Boiga irregularis), as the 
likely factors contributing to its rarity (49 FR 33881, August 27, 
1984, p. 49 FR 33884). Three 5-year status reviews were completed for 
the bridled white-eye; the 2009 (initiated on March 8, 2007; see 72 FR 
10547) and 2015 (initiated on March 6, 2012; see 77 FR 13248) reviews 
did not recommend a change in status (USFWS 2009a, 2015). After 
reevaluation of all available information, the 5-year status review 
completed in 2019 (initiated on May 7, 2018; see 83 FR 20088) 
recommended delisting due to extinction, based on continued lack of 
detections and the pervasive rangewide threat posed by the brown tree 
snake (USFWS 2019, p. 10).
    At the time of listing, the bridled white-eye on Guam was 
classified as one subspecies within a complex of bridled white-eye 
(Zosterops conspiculatus) populations found in the Mariana Islands. The 
most recent taxonomic work (Slikas et al. 2000, p. 360) continued to 
classify the Guam subspecies within the same species as the bridled 
white-eye populations currently found on Saipan, Tinian, and Aguiguan 
in the Commonwealth of the Northern Mariana Islands (Z. c. saypani) but 
considered the Rota population (Z. rotensis; now separately listed as 
endangered under the Act) to be a distinct species.
    Endemic only to Guam, within the Mariana Islands, the bridled 
white-eye was a small (0.33 ounce or 9.3 grams), green and yellow, 
warbler-like forest bird with a characteristic white orbital ring 
around each eye (Jenkins 1983, p. 48). The available information about 
the life history of the species is sparse, based on a few early 
accounts in the literature (Seale 1901, pp. 58-59; Stophet 1946, p. 
540; Marshall 1949, p. 219; Baker 1951, pp. 317-318; Jenkins 1983, pp. 
48-49). Nonterritorial and often observed in small flocks, the species 
was a canopy-feeding insectivore that gleaned small insects from the 
twigs and branches of trees and shrubs (Jenkins 1983, p. 49). Although 
only minimal information exists about the bridled white-eye's nesting 
habits and young, observations of nests during several different months 
suggests the species bred year-round (Marshall 1949, p. 219; Jenkins 
1983, p. 49). No information is available regarding longevity of the 
bridled white-eye, but lifespans in the wild for other white-eyes in 
the same genus range between 5 and 13 years (Animal Diversity Web 2020; 
The Animal Aging and Longevity Database 2020; WorldLifeExpectancy.com 
2020).
    The bridled white-eye was reported to be one of the more common 
Guam bird species between the early 1900s and the 1930s (Jenkins 1983, 
p. 5). However, reports from the mid- to late-1940s indicated the 
species had perhaps become restricted to certain areas on Guam (Baker 
1951, p. 319; Jenkins 1983, p. 50). By the early- to mid-1970s, the 
bridled white-eye was found only in the forests in the very northern 
portion of Guam (Wiles et al. 2003, p. 1353). It was considered rare by 
1979, causing experts

[[Page 54305]]

to conclude that the species was nearing extinction (Jenkins 1983, p. 
50).
    By 1981, the bridled white-eye was known to inhabit only a single 
395-acre (160-hectare) limestone bench known as Pajon Basin in a 
limestone forest at Ritidian Point, an area that later became the Guam 
National Wildlife Refuge. Nestled at the base of towering limestone 
cliffs of about 426 feet (130 meters), the site was bordered by 
adjoining tracts of forest on three sides, and ocean on the northern 
side (Wiles et al. 2003, p. 1353). Pajon Basin was also the final 
refuge for many of Guam's native forest bird species and was the last 
place where 10 of Guam's forest bird species were still observed 
together in one locality at historical densities (Savidge 1987, p. 661; 
Wiles et al. 2003, p. 1353).
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    The bridled white-eye has been described as active and occurred in 
small flocks of 3 to 12 individuals (Jenkins 1983, p. 48). Although 
apparently not as vocal as its related subspecies on the other Mariana 
Islands, the bridled white-eye was observed singing and typically 
vocalized with ``chipping calls'' while flocking, less so during 
foraging (Jenkins 1983, p. 48). Although perhaps not correctly 
identified as a ``secretive'' or ``cryptic'' species (Amidon in litt. 
2000, pp. 14-15), the detectability of the related Rota bridled white-
eye (Zosterops rotensis) is greatest during surveys when it is close to 
the observer, relative to other species of birds that are detected at 
further distances. While we are unaware of surveys for the bridled 
white-eye using alternative methodologies specific for rare or 
secretive bird species, we conclude there is still sufficient evidence 
of extinction based upon the large body of literature confirming the 
impacts of the brown tree snake on Guam (see discussion below under 
``III. Analysis'').
Survey Effort
    Variable circular plot (VCP) studies are surveys conducted at pre-
established stations along transects. Surveyor counts all birds seen 
and heard during an 8-minute count period and estimates the distance 
from the count station to each bird seen or heard. From this 
information, an estimate of the number of birds in a surveyed area is 
determined and the confidence interval for the estimate is derived. 
During a multi-year VCP study at Pajon Basin consisting of annual 
surveys between 1981 and 1987, observations of the bridled white-eye 
drastically declined in just the first 3 years of the study. In 1981, 
54 birds were observed, and in 1982, 49 birds were documented, 
including the last observation of a family group (with a fledging) of 
the species. One year later, during the 1983 survey, only a single 
individual bridled white-eye was sighted. Between 1984 and 1987, 
researchers failed to detect the species within this same 300-acre 
(121-hectare) site (Beck 1984, pp. 148-149).
    Between the mid- and late-1980s, experts had already begun to 
hypothesize that the bridled white-eye had become extinct (Jenkins 
1983, p. 50; Savidge 1987, p. 661). Although human access has become 
more restricted within portions of Andersen Air Force Base since 1983, 
the Guam DAWR has, to date, continued annual roadside counts across the 
island as well as formal transect surveys in northern Guam in areas 
previously inhabited by the bridled white-eye. The species remains 
undetected since the last observation in Pajon Basin in 1983 (Wiles 
2018, pers. comm.; Quitugua 2018, pers. comm.; Aguon 2018, pers. 
comm.).
Time Since Last Detection
    Researchers failed to observe the species at the Pajon Basin during 
the annual surveys between 1984 and 1987, and during subsequent 
intermittent avian surveys in northern Guam in areas where this species 
would likely occur (Savidge 1987, p. 661; Wiles et al. 1995, p. 38; 
Wiles et al. 2003, entire).
III. Analysis
    The brown tree snake is estimated to be responsible for the 
extinction, extirpation, or decline of 2 bat species, 4 reptiles, and 
13 of Guam's 22 (59 percent) native bird species, including all of the 
native forest bird species with the exception of the Micronesian 
starling (Aplonis opaca) (Wiles et al. 2003, p. 1358; Rodda and Savidge 
2007, p. 307). The most comprehensive study of the decline (Wiles et 
al. 2003, entire) indicated that 22 bird species were severely impacted 
by the brown tree snake.
    The study also found that in areas newly invaded by the snake, 
observed declines of avian species were greater than or equal to 90 
percent and occurred rapidly, with the average duration just 8.9 years. 
The study also examined traits of the birds that made them more or less 
susceptible to predation by the brown tree snake, and determined that 
the ability and tendency to nest and roost in locations where snakes 
were less common (e.g., cave walls) correlated with greater likelihood 
of coexistence with the snake. Large clutch size and large body size 
correlated with a species' greater persistence, although large body 
size appeared to only delay, but not prevent, extirpation. Measuring a 
mere 0.33 ounces (9.3 grams), the bridled white-eye was relatively 
small in size, and its nests were located in areas accessible to brown 
tree snakes (Baker 1951, pp. 316-317; Jenkins 1983, pp. 49-50).
    We used a recent analytical tool that assesses information on 
threats to infer species extinction based on an evaluation of whether 
identified threats are sufficiently severe and prolonged to cause local 
extinction, as well as sufficiently extensive in geographic scope to 
eliminate all occurrences (Keith et al. 2017, p. 320). Applying this 
analytical approach to the bridled white-eye, we examined years of 
research and dozens of scientific publications and reports that 
indicate that the effects of predation by the brown tree snake have 
been sufficiently severe, prolonged, and extensive in geographic scope 
to cause widespread range contraction, extirpation, and extinction for 
several birds and other species. Based on this analysis, we conclude 
that the bridled white-eye is extinct and brown tree snake predation 
was the primary causal agent.
IV. Conclusion
    At the time of its listing in 1984, disease and predation by 
nonnative predators, including the brown tree snake, were considered 
the primary threats to the bridled white-eye. The best available 
information now indicates that the bridled white-eye is extinct. The 
species appears to have been vulnerable to the pervasive, rangewide 
threat of predation from the brown tree snake. Since its last detection 
in 1983, qualified observers have conducted surveys and searches 
throughout the range of the bridled white-eye and have not detected the 
species. Available information indicates that the species was not able 
to persist in the face of environmental stressors, and we conclude that 
the best available scientific and commercial information indicates that 
the species is extinct.

Ivory-Billed Woodpecker (Campephilus principalis)

I. Background
    The ivory-billed woodpecker (Campephilus principalis) was first 
described by Mark Catesby in 1731 (Tanner 1942, p. xv), under a 
different taxonomic nomenclature. It was the

[[Page 54306]]

largest woodpecker in the United States and the second largest in North 
America with an overall length of approximately 48-51 centimeters (cm) 
(18-20 inches), an estimated wingspan of 76-80 cm (29-31 inches), and a 
weight of 454-567 grams (g) (16-20 ounces); however, data from live 
birds are lacking, so these estimates were based on observations by 
ornithologists from the late 19th century who collected specimens 
(Service 2010, pp. 1-2).
    The ivory-billed woodpecker was listed as endangered throughout its 
range on March 11, 1967 (32 FR 4001) under the Endangered Species 
Preservation Act of 1966. Although no threats were identified at the 
time of listing, land clearing and timber harvesting were known at the 
time as threats acting on the species. A status review was announced on 
April 10, 1985 (50 FR 14123) to determine if the species was extinct 
and should therefore be proposed for delisting. We did not receive any 
confirmed reports of live birds as a result of that review. In 1986, we 
funded a large-scale survey that included coverage of potential sites 
throughout the species' historical range (Jackson 1989, p. 74; Jackson 
2006, p. 1-2, USFWS 2010, p. 69). The study also included soliciting 
requests for new sightings and investigating those reports for 
validity, as well as researching historical sources (Jackson 1989, p. 
74). No conclusive evidence of ivory-billed woodpeckers was obtained 
during that study.
    Another status review was announced on November 6, 1991 (56 FR 
56882) for all species (foreign and domestic listings) listed before 
1991. In this review, the status of many species was simultaneously 
evaluated with no in-depth assessment of the five factors or threats as 
they pertain to the individual species. The document stated that the 
Service was seeking any new or additional information reflecting the 
necessity of a change in the status of the species under review. The 
document indicated that if significant data were available warranting a 
change in a species' classification, the Service would propose a rule 
to modify the species' status. No change in the bird's listing 
classification was found to be warranted. Each year, the Service 
reviews and updates listed species information for inclusion in the 
required Recovery Report to Congress. While considerable effort was 
placed on confirming reported sightings after 2004 (details provided 
below), no further sightings occurred. By 2013, the ornithological 
community determined that these sightings could not be confirmed. Since 
2013, our annual recovery data call included status recommendations 
such as ``presumed extinct'' for the ivory-billed woodpecker.
    A 5-year review was most recently announced on May 7, 2018 (83 FR 
20092), with a 60-day public comment period ending July 6, 2018. During 
the public comment period, the Service received and considered four 
public comments describing reported, but not verifiable, encounters as 
well as indications that the inability to conclusively document 
existence does not mean that the species is extinct (Trahan 2020, pers. 
comm.). The Service also reviewed a variety of additional resources, 
including published and unpublished scientific information provided by 
other Service offices, State wildlife agencies, stakeholders, and other 
partners. Specific sources included the final rule listing this species 
under the Act (32 FR 4001; March 11, 1967); the recovery plan (Service 
2010, entire); peer-reviewed scientific publications; unpublished field 
observations by Federal, State, and other experienced biologists; 
unpublished studies and survey reports; and notes and communications 
from other qualified individuals. The 5-year review was also sent to 
four independent peer reviewers; one responded with comments. This 5-
year review was finalized on June 3, 2019, and recommended that the 
ivory-billed woodpecker be delisted due to extinction (USFWS 2019, 
entire).
    Much of what we know about the ivory-billed woodpecker comes from 
research in Louisiana during the late 1930s (Service 2010, pp. xv, vii, 
10-22, 67). Suitable habitat for the ivory-billed woodpecker is thought 
to be extensive forested areas with old-growth characteristics and a 
naturally high volume of dead and dying wood, particularly in virgin 
bottomland hardwoods that may sustain the species between disturbance 
events (e.g., fires, storms, or other events expected to kill or stress 
trees) (Tanner 1942, pp. 46-47, 52). The home range for the ivory-
billed woodpecker is thought to have been fairly large due to their 
ability to fly long distances, up to at least several kilometers a day 
between favored roost sites and feeding areas. The estimated ivory-
billed woodpecker density historically ranged from one breeding pair 
per 6.25 square miles to one breeding pair per 17 square miles (Tanner 
1942, p. 32).
    Breeding was thought to occur between January and April (Tanner 
1942, pp. 95-96). Clutch size reportedly ranged from 1 to 5 eggs with 
an estimated incubation period of approximately 20 days (Service 2010, 
p. 11). Both sexes of ivory-billed woodpecker incubated the eggs as 
well as fed the young for a period of about 5 weeks until the young 
fledged (Tanner 1942, pp. 101, 104). The young may have been fed by the 
parents for an additional 2 months and roosted near and foraged with 
the parents into the next breeding season. Dead or dying portions of 
live trees, and sometimes dead trees, may have been excavated for nest 
cavities. These cavities ranged from 4.6 meters (m) (15.1 feet (ft)) to 
over 21 m (69 ft) up a nest tree, although rarely below 9 m (29.5 ft) 
from a tree's base (Service 2010, p. 11). Ivory-billed woodpeckers not 
only used nest cavities but excavated roost cavities as well, which are 
similar in appearance to nest cavities. Pairs or group members were 
found to roost in trees near each other, and they also were reported to 
leave the roost after sunrise (Tanner 1942, pp. 57-59). The roosting 
area is known to have been the center of activity for ivory-billed 
woodpeckers; however, insect abundance (i.e., food availability) was 
thought to be important to distribution as well (Tanner 1942, pp. 33-
36, 46, 52). Although it is not known for certain, lifespan for the 
species was estimated to be in excess of 10 years (USFWS 2020, p. 24).
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    The ivory-billed woodpecker had a black and white plumage with a 
white chisel-tipped beak, yellow eyes, and a pointed crest. It was 
sexually dimorphic, with the sexes exhibiting different characteristics 
(i.e., sizes, coloring, etc.). Females had a solid black crest, and 
males were red from the nape to the top of the crest with an outline of 
black on the front of the crest (Service 2010, p. 1). This large 
woodpecker produced distinctive sounds and had distinctive markings 
(e.g., large white patch on the wing that can be seen from long 
distances (Tanner 1942, p. 1)), indicating a certain degree of 
detectability during surveys, if present.
Survey Effort
    The last commonly agreed-upon sighting of the species was on the 
Singer Tract in the Tensas River region of northeast Louisiana in April 
of 1944 (Service 2019, p. 9). Since this sighting, the most compelling 
evidence of the existence of the ivory-billed woodpecker was in 2004 in 
Arkansas (Fitzpatrick et al. 2005, pp. 1460-1462). From 2004 to 2005, 
within the same area of Bayou DeView, located in the

[[Page 54307]]

Cache River National Wildlife Refuge (NWR) in Arkansas, observers 
reported sightings, audio recordings, and a video interpreted to be an 
ivory-billed woodpecker (Service 2010, p. 13). The original 2004 
encounter as well as the other reports and video from Arkansas spurred 
an extensive search effort in the area that was led by the Cornell 
Laboratory of Ornithology and the Arkansas Nature Conservancy beginning 
in 2005. Multiple approaches were used, including visual methods, aural 
methods, and playback methods (alone and in combination), as well as 
helicopter surveys. However, after completing analysis of detection 
probabilities associated with all of the methods, researchers noted 
few, if any, ivory-billed woodpeckers could have remained undetected in 
the Big Woods of Arkansas during the period from 2005 to 2009 
(Rohrbaugh and Lammertink 2016, p. 40). Further, although the bird in 
the video was first interpreted as an ivory-billed woodpecker, there is 
dispute among the ornithological community as to whether it was an 
actual ivory-billed woodpecker or instead a pileated woodpecker 
(Dryocopus pileatus). No conclusive videos gathered since then that 
confirm the persistence of the ivory-billed woodpecker. After 
additional extensive analysis of the recordings, it was determined that 
these recordings do not constitute evidence of the presence of ivory-
billed woodpeckers (Charif et al. 2005, p. 1489; Fitzpatrick et al. 
2005, p. 1462; Jackson 2006, p. 3).
    Since the reported ivory-billed woodpecker in 2004/2005 at the 
Cache River NWR, a survey design was developed and implemented during 
search efforts throughout the species' historical range. Many State, 
Federal, and private partners (e.g., State wildlife agencies, the 
Service, and the Cornell Laboratory of Ornithology) collaborated over a 
5-year period to conduct extensive searches for evidence of the 
species' presence within the historical range; however, no individuals 
were reliably located, and no conclusive evidence confirmed the 
species' persistence (Service 2010, pp. V, VII, 2-9, 75-89). Since the 
5-year survey effort was completed, other survey efforts based on 
sightings and vocalizations reported by wildlife professionals and 
other individuals have continued throughout the range through present 
day. These efforts include:
     2005-2013: Pearl River swamp, Louisiana and 
Choctawhatchee River swamp, Florida--Approximately 1,500 hours were 
spent surveying these two swamps with a kayak and video cameras. Three 
video clips were produced from both areas; however, the blurred images 
are inconclusive as to whether they are ivory-billed woodpeckers or not 
(Collins 2017, entire; Donahue 2017, p. 2).
     2007-2011: 30 additional areas in the 
southeastern United States (Pascagoula Basin of Mississippi, Mobile 
Basin of Alabama, Congaree and Coastal Basins of South Carolina, 
Apalachicola Basin of north Florida, and Everglades/Big Cypress Complex 
of south Florida) were surveyed with no presence of ivory-billed 
woodpeckers found (Lammertink and Rohrbaugh 2016, p. 7).
     2011: White River NWR, Arkansas--Searches were 
completed a year and a half after a tornado; no evidence of ivory-
billed woodpecker presence was observed, further adding to negative 
outcome of the 2005-2009 search efforts in this NWR (Lammertink and 
Rohrbaugh 2016, p. 7).
     2011: Avoyelles Parish, Louisiana--Survey on 
private property and Pomme de Terre Wildlife Management Area (WMA). No 
observations of ivory-billed woodpeckers were made (Lammertink and 
Rohrbaugh 2016, p. 7).
     2011: Lee River State Natural Area, South 
Carolina--No evidence of ivory-billed woodpecker presence was found 
during surveys (Lammertink and Rohrbaugh 2016, p. 7).
     2009-present: Louisiana--A search group, Project 
Coyote, was founded to search for ivory-billed woodpeckers in 
Louisiana; no evidence has been offered that constitutes undeniable 
confirmation that the species persists (Michaels 2018, p. 79).
     2016: Cuba--An expedition to Cuba was initiated 
in search of the ivory-billed woodpecker; no presence found (McClelland 
2016, pp. 13-15).
    Although there have been many sightings reported over the years 
since the last unrefuted sighting in 1944, there is much debate over 
the validity of these reports. Furthermore, there is no objective 
evidence (e.g., clear photographs, feathers of demonstrated recent 
origin, specimens, etc.) of the continued existence of the species.
    Additionally, researchers analyzed the temporal pattern of the 
collection dates of museum specimens from 1853 to 1932 throughout the 
historical range to estimate the probability of the persistence of the 
species into the 21st century, as well as the probability that the 
species would be found at survey sites with continued efforts. The 
probability of persistence in a 2011 analysis was less than 0.000064, 
and this analysis estimated the probable extinction date to be between 
1960 and 1980 (Gotelli et al. 2011, entire). While differing in 
assumptions, treatment of data, and statistical methods used, other 
analyses had qualitatively similar conclusions (e.g., Roberts et al. 
2009, entire; Solow et al. 2011, entire).
Time Since Last Detection
    The last unrefuted sighting of the ivory-billed woodpecker occurred 
in April 1944 on the Singer Tract in the Tensas River region of 
northeast Louisiana (Service 2015, p. 9).
III. Analysis
    The decline of mature forested habitat with a high percentage of 
recently dead or dying trees and widespread collection of the species 
likely led to the extirpation of the population sometime after the 
1940s. Although there have been potential sightings reported over the 
years since the last agreed-upon sighting in 1944, there is much debate 
over the validity of these reports. Furthermore, there is no objective 
evidence (e.g., clear photographs, feathers of demonstrated recent 
origin, specimens, etc.) of the continued existence of the species 
despite extensive searches. Given the likely lifespan of the species, 
this means it has not been indisputably observed in more than seven 
generations.
IV. Conclusion
    The ivory-billed woodpecker has not been definitively sighted since 
1944, despite decades of extensive survey effort. The loss of mature 
forest habitat and widespread collection of the species likely led to 
its extirpation in the 1940s or soon thereafter. Therefore, we conclude 
that the best available scientific and commercial information indicates 
that the species is extinct.

Kauai akialoa (Akialoa stejnegeri)

I. Background
    Kauai akialoa (Akialoa stejnegeri; listed as Hemignathus 
stejnegeri), a Hawaiian honeycreeper, was listed as endangered on March 
11, 1967 (32 FR 4001). It was included in the Kauai Forest Birds 
Recovery Plan (USFWS 1983), and the Revised Recovery Plan for Hawaiian 
Forest Birds (USFWS 2006, p. 2-86). At the time of listing, we 
considered Kauai akialoa to have very low population numbers and to be 
threatened by habitat loss, avian disease, and predation by rats 
(Rattus spp.). The last confirmed observation of the species was in 
1965, although there was an unconfirmed sighting in 1969 (Reynolds and 
Snetsinger 2001, p. 142). Two 5-year status reviews have been 
completed, in 2009 (initiated on July 6, 2005; see 70 FR 38972) and 
2018 (initiated on February 13, 2015; see 80

[[Page 54308]]

FR 8100). The 2009 review did not recommend a change in status, though 
there was some information indicating the species was already extinct. 
The 5-year status review completed in 2019 recommended delisting due to 
extinction based on consideration of additional information about the 
biological status of the species, included in the discussion below 
(USFWS 2019, pp. 5, 10).
    The life history of Kauai akialoa is poorly known and based mainly 
on observations from the end of the 19th century (USFWS 2006, p. 2-86). 
There is no information on the lifespan of the Kauai akialoa nor its 
threats when it was extant. The species was widespread on Kauai and 
occupied all forest types above 656 feet (200 meters) elevation 
(Perkins 1903, pp. 369, 422, 426). Its historical range included nearly 
all Kauai forests visited by naturalists at the end of the 19th 
century. After a gap of many decades, the species was seen again in the 
1960s, when one specimen was collected (Richardson and Bowles 1964, p. 
30). It has not been seen since, despite efforts by ornithologists 
(Conant et al. 1998, p. 15) and birders, and intensive survey efforts 
by wildlife biologists spanning 1968 to 2018 (USFWS 1983, p. 2; Hawaii 
Department of Land and Natural Resources unpubl. data; Reynolds and 
Snetsinger 2001, entire; Crampton et al. 2017 entire; Crampton 2018, 
pers. comm.).
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    The Kauai akialoa was a large (6.7 to 7.5 inches, or 17 to 19 
centimeters, total length), short-tailed Hawaiian honeycreeper with a 
very long, thin, curved bill, the longest bill of any historically 
known Hawaiian passerine. The plumage of both sexes was olive-green; 
males were more brightly colored, were slightly larger, and had a 
somewhat longer bill (USFWS 2006, p. 2-86). The Kauai akialoa's 
relatively large size and distinctive bill suggest that if it were 
extant, it would be detectable by sight and recognized.
Survey Effort
    A comprehensive survey of Hawaiian forest birds was initiated in 
the 1970s using the VCP method (Scott et al. 1986, entire). VCP surveys 
in Hawaii are conducted at pre-established stations along transects. 
The surveyor counts all birds seen and heard during an 8-minute count 
period and estimates the distance from the count station to each bird 
seen or heard. From this information, an estimate of the number of 
birds in area surveyed is determined and the confidence interval for 
this estimate derived. VCP surveys have been the primary method used to 
count birds in Hawaii; however, it is not appropriate for all species 
and provides poor estimates for extremely rare birds (Camp et al. 2009, 
p. 92). In recognition of this problem, the Rare Bird Search (RBS) was 
undertaken from 1994 to 1996, to update the status and distribution of 
13 ``missing'' Hawaiian forest birds (Reynolds and Snetsinger 2001, pp. 
134-137). The RBS was designed to improve efficiency in the search for 
extremely rare species, using the method of continuous observation 
during 20- to 30-minute timed searches in areas where target species 
were known to have occurred historically, in conjunction with audio 
playback of species vocalizations (when available). Several recent 
surveys and searches, including the RBS, have been unsuccessful in 
detecting Kauai akialoa despite intensive survey efforts by wildlife 
biologists from 1968 to 1973, and in 1981, 1989, 1993, 1994, 2000, 
2005, and 2011 to 2018 (Hawaii Department of Land and Natural Resources 
unpubl. data; Reynolds and Snetsinger 2001, entire; Crampton et al. 
2017, entire; Crampton 2018 pers. comm.). An unconfirmed 1969 report 
may have been the last sighting of Kauai akialoa (Conant et al. 1998, 
p. 15). Kauai akialoa has been presumed likely extinct for some time 
(Reynolds and Snetsinger 2001, p. 142).
    In addition, extensive time has been spent by qualified observers 
in the historical range of the Kauai akialoa searching for the small 
Kauai thrush (Myadestes palmeri), akekee (Loxops caeruleirostris), and 
Kauai creeper (Oreomystis bairdi). Hawaii Forest Bird Surveys (HFBS) 
were conducted in 1981, 1989, 1994, 2000, 2005, 2007, 2008, 2012, and 
2018 (Paxton et al. 2016, entire). The Kauai Forest Bird Recovery 
Project (KFBRP) conducted occupancy surveys for the small Kauai thrush 
in Kokee State Park, Hono O NaPali Natural Area Reserve, Na Pali Kona 
Forest Reserve, and Alakai Wilderness Preserve, from 2011 to 2013 
(Crampton et al. 2017, entire), and spent over 1,500 person-hours per 
year from 2015 to 2018 searching for Kauai creeper and akekee nests. 
During the HFBS in 2012 and 2018, occupancy surveys and nest searches 
did not yield any new detections of Kauai akialoa. The KFBRP conducted 
mist-netting in various locations within the historical range for Kauai 
akialoa from 2006 through 2009, and from 2011 through 2018, and no 
Kauai akialoa were caught or encountered (Crampton 2018, pers. comm.).
Time Since Last Detection
    Another approach used to determine whether extremely rare species 
are likely extinct or potentially still extant is to calculate the 
probability of a species' extinction based on time (years) since the 
species was last observed (Elphick et al. 2010, p. 620). This approach, 
when applied to extremely rare species, has the drawback that an 
incorrect assignment of species extinction may occur due to inadequate 
survey effort and/or insufficient time by qualified observers spent in 
the area where the species could still potentially exist. Using 1969 as 
the last credible sighting of Kauai akialoa, the authors' estimated 
date for the species' extinction is 1973, with 95 percent confidence 
that the species was extinct by 1984.
III. Analysis
    The various bird species in the subfamily Drepanidinae (also known 
as the Hawaiian honeycreepers), which includes Kauai akialoa, are 
highly susceptible to introduced avian disease. They are particularly 
susceptible to avian malaria (Plasmodium relictum), which results in 
high rates of mortality. At elevations below approximately 4,500 feet 
(1,372 meters) in Hawaii, the key factor driving disease epizootics 
(outbreaks) of pox virus (Avipoxvirus) and avian malaria is the 
seasonal and altitudinal distribution and density of the primary vector 
of these diseases, Culex quinquefasciatus (Atkinson and Lapointe 2009a, 
pp. 237-238, 245-246).
    A recent analytic tool was consulted using information on threats 
to infer species extinction based on an evaluation of whether 
identified threats are sufficiently severe and prolonged to cause local 
extinction, and sufficiently extensive in geographic scope to eliminate 
all occurrences (Keith et al. 2017, p. 320). The disappearance of many 
Hawaiian honeycreeper species over the last century from areas below 
approximately 4,500 feet elevation points to effects of avian disease 
having been sufficiently severe and prolonged, and extensive in 
geographic scope, to cause widespread species' range contraction and 
possible extinction. It is highly likely avian disease is the primary 
causal factor for the disappearance of many species of Hawaiian 
honeycreepers from forested areas below 4,500 feet on the islands of 
Kauai, Oahu, Molokai, and Lanai (Scott et al. 1986, p. 148; Banko and 
Banko 2009, pp. 52-53; Atkinson and Lapointe 2009a, pp. 237-238).

[[Page 54309]]

    It is widely established that small populations of animals are 
inherently more vulnerable to extinction because of random demographic 
fluctuations and stochastic environmental events (Mangel and Tier 1994, 
p. 607; Gilpin and Soul[eacute] 1986, pp. 24-34). Formerly widespread 
populations that become small and isolated often exhibit reduced levels 
of genetic variability, which diminishes the species' capacity to adapt 
and respond to environmental changes, thereby lessening the probability 
of long-term persistence (e.g., Barrett and Kohn 1991, p. 4; Keller and 
Waller 2002, p. 240; Newman and Pilson 1997, p. 361). As populations 
are lost or decrease in size, genetic variability is reduced, resulting 
in increased vulnerability to disease and restricted potential 
evolutionary capacity to respond to novel stressors (Spielman et al. 
2004, p. 15261; Whiteman et al. 2006, p. 797). As numbers decreased 
historically, effects of small population size were very likely to have 
negatively impacted Kauai akialoa, reducing its potential for long-term 
persistence.
    Several recent surveys and searches (1981 to 2018), including the 
RBS, have been unsuccessful in detecting Kauai akialoa despite efforts 
by ornithologists (Conant et al. 1998, p. 15) and birders, and 
intensive survey efforts by wildlife biologists in 1968 to 1973, 1981, 
1989, 1994, 2000, 2005, and from 2011 to 2018 (Hawaii Department of 
Land and Natural Resources unpubl. data; USFWS 1983, p. 2; Reynolds and 
Snetsinger 2001, entire; Crampton et al. 2017, entire; Crampton 2018, 
pers. comm.). Using 1969 as the last credible sightings, based on 
independent expert opinion, the estimated date for the species' 
extinction is 1973, with 95 percent confidence of the species having 
become extinct by 1984 (Elphick et al. 2010, p. 620).
IV. Conclusion
    At the time of listing in 1967, the Kauai akialoa faced threats 
from habitat loss, avian disease, and predation by introduced mammals. 
The best available information now indicates that the Kauai akialoa is 
extinct. The species appears to have been vulnerable to introduced 
avian disease. In addition, the effects of small population size likely 
limited the species' genetic variation and adaptive capacity, thereby 
increasing the vulnerability of the species to environmental stressors 
including habitat loss and degradation. Since its last detection in 
1969, qualified observers have conducted extensive surveys and searches 
but have not detected the species. Available information indicates that 
the species was not able to persist in the face of environmental 
stressors, and we conclude that the best available scientific and 
commercial information indicates that the species is extinct.

Kauai nukupuu (Hemignathus hanapepe)

I. Background
    The Kauai nukupuu (Hemignathus hanapepe) was listed as endangered 
on March 11, 1967 (32 FR 4001), and was included in the Kauai Forest 
Birds Recovery Plan (USFWS 1983), as well as the Revised Recovery Plan 
for Hawaiian Forest Birds (USFWS 2006). At the time of listing, 
observations of only two individuals had been reported during that 
century (USFWS 1983, p. 3). The last confirmed observation (based on 
independent expert opinion and physical evidence) of the species was in 
1899 (Eliphick et al. 2010, p. 620). Two 5-year status reviews have 
been completed, in 2010 (initiated on April 11, 2006; see 71 FR 18345) 
and 2019 (initiated on February 13, 2015; see 80 FR 8100). The 2010 
review did not recommend a change in status, though there was some 
information indicating the species was already extinct. The 5-year 
status review completed in 2019 recommended delisting due to extinction 
based on consideration of additional information about the biological 
status of the species, included in the discussion below (USFWS 2019, 
pp. 4-5, 10).
    The historical record provides little information on the life 
history of Kauai nukupuu (USFWS 2006, p. 2-89). There is no specific 
information on the lifespan or breeding biology of Kauai nukupuu, 
although it is presumed to be similar to its closest relative, 
akiapolaau (Hemignathus munroi, listed as Hemignathus wilsoni), a 
honeycreeper from the island of Hawaii. Similar to the akiapolaau, the 
Kauai nukupuu uses its bill to extract invertebrates from epiphytes, 
bark, and wood. The last confirmed observation (based on independent 
expert opinion and physical evidence) of Kauai nukupuu was in 1899 
(Eliphick et al. 2010, p. 620); however, there was an unconfirmed 
observation in 1995 (Conant et al. 1998, p. 14).
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    Kauai nukupuu was a medium-sized, approximately 23-gram (0.78-
ounce), Hawaiian honeycreeper (family Fringillidae, subfamily 
Drepanidinae) with an extraordinarily thin, curved bill, slightly 
longer than the bird's head. The lower mandible was half the length of 
the upper mandible. Adult male plumage was olive-green with a yellow 
head, throat, and breast, whereas adult female and immature plumage 
consisted of an olive-green head and yellow or yellowish gray under-
parts (USFWS 2006, p. 2-89). The long, curved, and extremely thin bill 
of Kauai nukupuu, in combination with its brightly colored plumage, 
would have made this bird highly detectable to ornithologists and 
birders had it persisted (USFWS 2006, p. 2-89). No subsequent sightings 
or vocalizations have been documented since the unconfirmed sighting in 
1995, despite extensive survey efforts.
Survey Effort
    In the absence of early historical surveys, the extent of the 
geographical range of the Kauai nukupuu is unknown. A comprehensive 
survey of Hawaiian forest birds was initiated in the 1970s using the 
VCP method (Scott et al. 1986, entire) (see Survey Effort section for 
the Kauai akialoa, above, for the description of the VCP surveys). 
Several recent surveys and searches, including the RBS, have been 
unsuccessful in detecting Kauai nukupuu despite intensive survey 
efforts by wildlife biologists from 1968 to 1973, and in 1981, 1989 
1993, 1994, 2000, 2005, and 2011 to 2018 (Hawaii Department of Land and 
Natural Resources unpubl. data; Reynolds and Snetsinger 2001, entire; 
Crampton et al. 2017, entire; Crampton 2018 pers. comm.). During the 
RBS, Kauai nukupuu were not detected. The lack of detections combined 
with analysis of detection probability (P >= 0.95) suggested that the 
possible population count was fewer than 10 birds in 1996 (Reynolds and 
Snetsinger 2001, p. 142).
    Extensive time has been spent by qualified observers in the 
historical range of the Kauai nukupuu searching for the small Kauai 
thrush (Myadestes palmeri), akekee (Loxops caeruleirostris), and Kauai 
creeper (Oreomystis bairdi). Hawaii Forest Bird Surveys (HFBS) were 
conducted in 1981, 1989, 1994, 2000, 2005, 2007, 2008, 2012, and 2018 
(Paxton et al. 2016, entire). During the HFBS in 2012 and 2018, 
occupancy surveys and nest searches did not yield any new detections of 
the Kauai nukupuu. The KFBRP conducted mist-netting in various 
locations within the historical range for the Kauai nukupuu from 2006 
through 2009, and from 2011 through 2018, and no Kauai nukupuu were 
caught or encountered (Crampton 2018, pers. comm.). Despite 
contemporary

[[Page 54310]]

search efforts, the last credible sighting of Kauai nukupuu occurred in 
1899.
Time Since Last Detection
    Using 1899 as the last credible sighting of Kauai nukupuu based on 
independent expert opinion and physical evidence, the estimated date 
for the species' extinction was 1901, with 95 percent confidence that 
the species was extinct by 1906 (Elphick et al. 2010, p. 620).
III. Analysis
    Some of the reported descriptions of this species better match the 
Kauai amakihi (Chlorodrepanis stejnegeri) (USFWS 2006, p. 2-90). 
Although skilled observers reported three unconfirmed sightings of 
Kauai nukupuu in 1995 (Reynolds and Snetsinger 2001, p. 142), extensive 
hours of searching within the historical range failed to detect any 
individuals. The last credible sightings of Kauai nukupuu was in 1899, 
based on independent expert opinion and physical evidence (Elphick et 
al. 2010, p. 620). It was estimated that 1901 was the year of 
extinction, with 95 percent confidence that the species was extinct by 
1906. The species was likely vulnerable to the persistent threats of 
avian disease combined with habitat loss and degradation, which remain 
drivers of extinction for Hawaiian forest birds.
V. Conclusion
    At the time of listing in 1967, the Kauai nukupuu had not been 
detected for almost 70 years. Since its last detection in 1899, 
qualified observers have conducted extensive surveys and searches 
throughout the range of the Kauai nukupuu and have not detected the 
species. Available information indicates that the species was not able 
to persist in the face of environmental stressors, and we conclude that 
the best available scientific and commercial information indicates that 
the species is extinct.

Kauai `o`o (Moho braccatus)

I. Background
    The Kauai `o`o (Moho braccatus) was listed as endangered on March 
11, 1967 (32 FR 4001), and was included in the Kauai Forest Birds 
Recovery Plan (USFWS 1983), as well as the Revised Recovery Plan for 
Hawaiian Forest Birds (USFWS 2006). At the time of listing, the 
population size was estimated at 36 individuals (USFWS 1983, p. 3). 
Threats to the species included the effects of low population numbers, 
habitat loss, avian disease, and predation by introduced mammals. The 
last plausible record of a Kauai `o`o was a vocal response to a 
recorded vocalization played by a field biologist on April 28, 1987, in 
the locality of Halepaakai Stream. Two 5-year status reviews have been 
completed, in 2009 (initiated on July 6, 2005; see 70 FR 38972) and 
2018 (initiated on February 13, 2015; see 80 FR 8100). The 2009 review 
did not recommend a change in status, though there was some information 
indicating the species was already extinct. The 5-year status review 
completed in 2018 recommended delisting due to extinction based on 
consideration of new information about the biological status of the 
species, included in the discussion below (USFWS 2019, pp. 5, 10).
    The Kauai `o`o measured 7.7 inches (19.5 centimeters) and was 
somewhat smaller than the Moho species on the other islands. It was 
glossy black on the head, wings, and tail; smoky brown on the lower 
back, rump, and abdomen; and rufous-brown on the upper tail coverts. It 
had a prominent white patch at the bend of the wing. The thigh feathers 
were golden yellow in adults and black in immature birds (Berger 1972, 
p. 107). The Kauai `o`o is one of four known Hawaiian species of the 
genus Moho and one of five known Hawaiian bird species within the 
family Mohoidae (Fleischer et al. 2008, entire). Its last known habitat 
was the dense ohia forest in the valleys of Alakai Wilderness Preserve. 
It reportedly fed on various invertebrates and the fruits and nectar 
from ohia, lobelia, and other flowering plants. There is no information 
on the lifespan of the Kauai `o`o.
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    The vocalizations of this species were loud, distinctive, and 
unlikely to be overlooked. The song consisted of loud whistles that 
have been described as flute-like, echoing, and haunting, suggesting 
that detectability would be high in remaining suitable habitat if the 
Kauai `o`o still existed (USFWS 2006 p. 2-47).
Survey Effort
    In the absence of early historical surveys, the extent of the 
geographical range of the Kauai `o`o cannot be reconstructed. The 
comprehensive surveys of Hawaiian forest birds are described in the 
Survey Effort section of the Kauai akialoa. Several recent surveys and 
searches, including the VCP and RBS, have been unsuccessful in 
detecting Kauai `o`o despite intensive survey efforts by wildlife 
biologists from 1968 to 1973, and in 1981, 1989 1993, 1994, 2000, 2005, 
and 2011 to 2018 (Hawaii Department of Land and Natural Resources 
unpubl. data; Reynolds and Snetsinger 2001, entire; Crampton et al. 
2017, entire; Crampton 2018 pers. comm.). During the RBS, coverage of 
the search area was extensive; therefore, there was a high probability 
of detecting a Kauai `o`o. None were detected, and it was concluded the 
Kauai `o`o was likely extinct (P >= 0.95) (Reynolds and Snetsinger 
2001, p. 142).
    Extensive time has been spent by qualified observers in the 
historical range of the Kauai `o`o searching for the small Kauai thrush 
(Myadestes palmeri), akekee (Loxops caeruleirostris), and Kauai creeper 
(Oreomystis bairdi). Hawaii Forest Bird Surveys (HFBS) were conducted 
in 1981, 1989, 1994, 2000, 2005, 2007, 2008, 2012, and 2018 (Paxton et 
al. 2016, entire). During the HFBS in 2012 and 2018, occupancy surveys 
and nest searches did not yield any new detections of Kauai `o`o. The 
KFBRP conducted mist-netting in various locations within the historical 
range for Kauai `o`o from 2006 through 2009 and 2011 through 2018, and 
no Kauai `o`o were caught or encountered (Crampton 2018, pers. comm.). 
The last credible sighting was in 1987.
Time Since Last Detection
    Using 1987 as the last credible sighting of the Kauai `o`o based on 
independent expert opinion, the estimated date for the species' 
extinction was 1991, with 95 percent confidence that the species was 
extinct by 2000 (Elphick et al. 2010, p. 620).
III. Analysis
    The various bird species in the subfamily Drepanidinae (also known 
as the Hawaiian honeycreepers), which includes Kauai `o`o, are highly 
susceptible to introduced avian disease, particularly avian malaria 
(Plasmodium relictum). At elevations below approximately 4,500 feet 
(1,372 meters) in Hawaii, the key factor driving disease epizootics of 
pox virus (Avipoxvirus) and avian malaria is the seasonal and 
altitudinal distribution and density of the primary vector of these 
diseases, Culex quinquefasciatus (Atkinson and Lapointe 2009a, pp. 237-
238, 245-246). Because they occur at similar altitudes and face similar 
threats, please refer to the Analysis section for the Kauai akialoa, 
above, for more information.
IV. Conclusion
    At the time of listing in 1967, the Kauai `o`o faced threats from 
effects of

[[Page 54311]]

low population numbers, habitat loss, avian disease, and predation by 
introduced mammals. The best available information now indicates that 
the Kauai `o`o is extinct. The species appears to have been vulnerable 
to introduced avian disease. In addition, the effects of small 
population size likely limited the species' genetic variation and 
adaptive capacity, thereby increasing the vulnerability of the species 
to environmental stressors including habitat loss and degradation. 
Since its last detection in 1987, qualified observers have conducted 
extensive surveys and searches and have not detected the species. 
Available information indicates that the species was not able to 
persist in the face of environmental stressors, and we conclude that 
the best available scientific and commercial information indicates that 
the species is extinct.

Large Kauai Thrush (Myadestes myadestinus)

I. Background
    The large Kauai thrush (Myadestes myadestinus, or kama`o in the 
Hawaiian language) was listed as endangered on October 13, 1970 (35 FR 
16047), and was included in the Kauai Forest Birds Recovery Plan (USFWS 
1983), as well as the Revised Recovery Plan for Hawaiian Forest Birds 
(USFWS 2006). At the time of listing, the population size was estimated 
at 337 individuals (USFWS 1983, p. 3). Threats to the species included 
effects of low population numbers, habitat loss, avian disease, and 
predation by introduced mammals. Two 5-year status reviews were 
completed in 2009 (initiated on July 6, 2005; see 70 FR 38972) and 2019 
(initiated on February 13, 2015; see 80 FR 8100). The 2009 review did 
not recommend a change in status, though there was some information 
indicating the species was already extinct. The 5-year status review 
completed in 2019 recommended delisting due to extinction based on 
consideration of additional information about the biological status of 
the species, included in the discussion below (USFWS 2019, pp. 5, 10).
    The large Kauai thrush was a medium-sized (7.9 inches, or 20 
centimeters, total length) solitaire. Its plumage was gray-brown above, 
tinged with olive especially on the back, and light gray below with a 
whitish belly and undertail coverts. The large Kauai thrush lacked the 
white eye-ring and pinkish legs of the smaller puaiohi (small Kauai 
thrush, Myadestes palmeri) (USFWS 2006, p. 2-19). There is no specific 
information on the life history of the large Kauai thrush; however, it 
is presumed that it is similar to the more common and closely related 
Hawaii thrush (Myadestes obscurus). Nests of the large Kauai thrush 
have not been described but may be a cavity or low platform, similar to 
those of the Hawaii thrush. Nesting likely occurred in the spring. The 
diet of the large Kauai thrush was reported to include fruits and 
berries, as well as insects and snails. The last (unconfirmed) 
observation of the large Kauai thrush was made during the February 1989 
Kauai forest bird survey (Hawaii Department of Land and Natural 
Resources unpubl. data). However, the last credible sighting of the 
large Kauai thrush occurred in 1987.
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    The large Kauai thrush was often described for its habit of rising 
into the air, singing a few vigorous notes and then suddenly dropping 
down into the underbrush. The vocalizations of this species varied 
between sweet and melodic to lavish and flute-like, often given just 
before dawn and after dusk (USFWS 2006 p. 2-19). These behaviors 
suggest that detectability would be high in remaining suitable habitat 
if the large Kauai thrush still existed. No subsequent sightings or 
vocalizations have been documented despite extensive survey efforts by 
biologists and birders.
Survey Effort
    Several recent surveys and searches, including the VCP and RBS, 
have been unsuccessful in detecting the large Kauai thrush despite 
intensive survey efforts by wildlife biologists from 1968 to 1973, and 
in 1981, 1989, 1993, 1994, 2000, 2005, and 2011 to 2018 (Hawaii 
Department of Land and Natural Resources unpubl. data; Reynolds and 
Snetsinger 2001, entire; Crampton et al. 2017, entire; Crampton 2018, 
pers. comm.). During the RBS in 2001, coverage of the search area was 
extensive; therefore, they had a high probability of detecting the 
large Kauai thrush. None were detected, and it was concluded that the 
large Kauai thrush was likely extinct (P >= 0.95) (Reynolds and 
Snetsinger 2001, p. 142).
    Extensive time has been spent by qualified observers in the 
historical range of the large Kauai thrush searching for the small 
Kauai thrush (Myadestes palmeri), akekee (Loxops caeruleirostris), and 
Kauai creeper (Oreomystis bairdi). Hawaii Forest Bird Surveys (HFBS) 
were conducted in 1981, 1989, 1994, 2000, 2005, 2007, 2008, 2012, and 
2018 (Paxton et al. 2016, entire). During the HFBS in 2012 and 2018, 
occupancy surveys and nest searches did not yield any new detections of 
the large Kauai thrush. The KFBRP conducted mist-netting in various 
locations within the historical range for the large Kauai thrush from 
2006 through 2009, and from 2011 through 2018, and no large Kauai 
thrush were caught or encountered (Crampton 2018, pers. comm.). The 
last credible sighting of the large Kauai thrush occurred in 1987.
Time Since Last Detection
    Using 1987 as the last credible sighting of the large Kauai thrush 
based on independent expert opinion, the estimated date for the 
species' extinction was 1991, with 95 percent confidence that the 
species was extinct by 1999 (Elphick et al. 2010, p. 620).
III. Analysis
    Several recent surveys and searches, including the RBS and HFBS, 
have been unsuccessful in detecting the large Kauai thrush despite 
intensive survey efforts by wildlife biologists in 1993, 1994, 2000, 
2005, and 2011 to 2018 (Hawaii Department of Land and Natural Resources 
unpubl. data; Reynolds and Snetsinger 2001, entire; Crampton et al. 
2017, entire; Crampton 2018, pers. comm.). Using 1987 as the last 
credible sighting based on independent expert opinion and the species' 
observational record, the estimated date for the species' extinction 
was 1991, with 95 percent confidence the species was extinct by 1999 
(Elphick et al. 2010, p. 620). Another analysis determined that the 
large Kauai thrush was probably extinct at the time of the RBS in 1994 
(P >= 0.95) (Reynolds and Snetsinger 2001, p. 142).
IV. Conclusion
    At the time of listing in 1970, the large Kauai thrush faced 
threats from low population numbers, habitat loss, avian disease, and 
predation by introduced mammals. The best available information now 
indicates that the large Kauai thrush is extinct. The species appears 
to have been vulnerable to the effects of small population size, which 
likely limited its genetic variation, disease resistance, and adaptive 
capacity, thereby increasing the vulnerability of the species to the 
environmental stressors of habitat degradation and predation by 
nonnative mammals. Since its last credible detection in 1987, qualified 
observers have conducted extensive surveys and searches throughout the 
range of the

[[Page 54312]]

species but have not detected the species. Available information 
indicates that the species was not able to persist in the face of 
environmental stressors, and we conclude that the best available 
scientific and commercial information indicates that the species is 
extinct.

Maui Akepa (Loxops coccineus ochraceus)

I. Background
    The Maui akepa (Loxops coccineus ochraceus, listed as Loxops 
ochraceus) was listed as endangered on October 13, 1970 (35 FR 16047), 
and was included in the Maui-Molokai Forest Birds Recovery Plan (USFWS 
1984, pp. 12-13), and the Revised Recovery Plan for Hawaiian Forest 
Birds (USFWS 2006, pp. 2-94, 2-134-2-137). At the time of listing, we 
considered Maui akepa to have very low population numbers, and to face 
threats from habitat loss, avian disease, and predation by introduced 
mammals. Three 5-year status reviews have been completed; the 2010 
(initiated on April 11, 2006; see 71 FR 18345) and 2015 (initiated on 
March 6, 2012; see 77 FR 13248) reviews did not recommend a change in 
status, though there was some information indicating the species was 
already extinct (USFWS 2010, p. 12; USFWS 2015, p. 10). The 5-year 
status review completed in 2018 (initiated on February 12, 2016; see 81 
FR 7571) recommended delisting due to extinction, based in part on 
continued lack of detections and consideration of extinction 
probability (USFWS 2018, pp. 5, 10).
    The Maui akepa was known only from the island of Maui in the 
Hawaiian Islands. Maui akepa were found in small groups with young in 
the month of June when the birds were molting (Henshaw 1902, p. 62). 
The species was observed preying on various insects including small 
beetles, caterpillars, and small spiders, as well as drinking the 
nectar of ohia (Metrosideros polymorpha) flowers (Rothschild 1893 to 
1900, pp. 173-176; Henshaw 1902, p. 62; Perkins 1903, pp. 417-420). The 
species appeared to also use the ohia tree for nesting as a pair of 
Maui akepa was observed building a nest in the terminal foliage of a 
tall ohia tree (Perkins 1903, p. 420).
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    Maui akepa adult males varied from dull brownish orange to 
ochraceus (light brownish yellow), while females were duller and less 
yellowish (USFWS 2006, p. 2-134). Although the species was easily 
identifiable by sight, its small body size (less than 5 inches (13 
centimeters) long) and habitat type (dense rain forest) made visual 
detection difficult. Songs and calls of Maui akepa could be confused 
with those of other Maui forest bird species; therefore, detection of 
the species requires visual confirmation of the individual producing 
the songs and calls (USFWS 2006, p. 2-135).
Survey Effort
    In the absence of early historical surveys, the extent of the 
geographical range of the Maui akepa is unknown. Because the species 
occupied Maui Island, one might expect that it also inhabited Molokai 
and Lanai Islands like other forest birds in the Maui Nui group, but 
there are no fossil records of Maui akepa from either of these islands 
(USFWS 2006, p. 2-135). All historical records of the Maui akepa in the 
late 19th and early 20th century were from high-elevation forests most 
accessible to naturalists, near Olinda and Ukulele Camp on the 
northwest rift of Haleakala, and from mid-elevation forests in Kipahulu 
Valley (USFWS 2006, p. 2-134). This range suggests that the birds were 
missing from forests at lower elevations, perhaps due to the 
introduction of disease-transmitting mosquitoes to Lahaina in 1826 
(USFWS 2006, p. 2-135). From 1970 to 1995, there were few credible 
sightings of Maui akepa (USFWS 2006, p. 2-136).
    The population of Maui akepa was estimated at 230 individuals, with 
a 95 percent confidence interval of plus or minus 290 individuals 
(Scott et al. 1986, pp. 37, 154) during VCP surveys in 1980. In other 
words, the estimate projects a maximum population of 520 individuals 
and a minimum population of zero. However, confidence intervals were 
large, and this estimate was based on potentially confusing auditory 
detections, and not on visual observation (USFWS 2006, p. 2-136). On 
Maui, VCP surveys are conducted at survey stations spaced 328 to 820 
feet (100 to 250 meters) apart, on transect lines spaced 1 to 2 miles 
(1.6 to 3.2 kilometers) apart (Scott et al. 1986, pp. 34-40). It is 
estimated that 5,865 8-minute point counts would be needed to determine 
with 95 percent confidence the absence of Maui akepa on Maui (Scott et 
al. 2008, p. 7). In 2008, only 84 VCP counts had been conducted on Maui 
in areas where this species was known to have occurred historically. 
Although the results of the 1980 VCP surveys find Maui akepa extant at 
that time, tremendous effort is required using the VCP method to 
confirm this species' extinction (Scott et al. 2008). For Maui akepa, 
nearly 70 times more VCP counts than conducted up to 2008 would be 
needed to confirm the species' extinction with 95 percent confidence.
    Songs identified as Maui akepa were heard on October 25, 1994, 
during the RBS in Hanawi Natural Area Reserve (Hanawi NAR) and on 
November 28, 1995, from Kipahulu Valley at 6,142 feet (1,872 meters) 
elevation, but the species was not confirmed visually. Auditory 
detections of Maui akepa require visual confirmation because of 
possible confusion or mimicry with similar songs of Maui parrotbill 
(Pseudonestor xanthophrys) (Reynolds and Snetsinger 2001, p. 140). The 
last confirmed record, as defined above, of Maui akepa was from Hanawi 
NAR in 1988 (Engilis 1990, p. 69).
    Qualified observers spent extensive time searching for Maui akepa, 
po`ouli (Melamprosops phaeosoma), and Maui nukupuu (Hemignathus lucidus 
affinis, listed as Hemignathus affinis) in the 1990s. Between September 
1995 and October 1996, 1,730 acres (700 hectares) in Hanawi NAR were 
searched during 318 person-days (Baker 2001, p. 147), including the 
area with the most recent confirmed sightings of Maui akepa. During 
favorable weather conditions (good visibility and no wind or rain) 
teams would stop when ``chewee'' calls given by Maui parrotbill, or 
when po`ouli and Maui nukupuu were heard, and would play either Maui 
parrotbill or akiapolaau (Hemignathus munroi, listed as Hemignathus 
wilsoni) calls and songs to attract the bird for identification. Six 
po`ouli were found, but no Maui akepa were detected (Baker 2001, p. 
147). The Maui Forest Bird Recovery Project (MFBRP) conducted searches 
from 1997 through 1999 from Hanawi NAR to Koolau Gap (west of Hanawi 
NAR), for a total of 355 hours at three sites with no detections of 
Maui akepa (Vetter 2018, pers. comm.). The MFBRP also searched Kipahulu 
Valley on northern Haleakala from 1997 to 1999, for a total of 320 
hours with no detections of Maui akepa. However, the Kipahulu searches 
were hampered by bad weather, and playback was not used (Vetter 2018, 
pers. comm.). Despite over 10,000 person-hours of searches in the 
Hanawi NAR and nearby areas from October 1995 through June 1999, 
searches failed to confirm earlier detections of Maui akepa (Pratt and 
Pyle 2000, p. 37). While working on Maui parrotbill recovery from 2006 
to 2011, the MFBRP spent extensive time in the area of the last Maui 
akepa sighting. The MFBRP project coordinator concluded that if Maui 
akepa were present, they would have been detected (Mounce 2018, pers. 
comm.).

[[Page 54313]]

Time Since Last Detection
    The last confirmed sighting (as defined for the RBS) of the Maui 
akepa was in 1988 (Engilis 1990, p. 69). Surveys conducted during the 
late 1980s to the 2000s failed to locate the species (Pratt and Pyle 
2000, p. 37; Baker 2001, p. 147). Using 1980 as the last documented 
observation record for Maui akepa (the 1988 sighting did not meet the 
author's criteria for a ``documented'' sighting), 1987 was estimated to 
be the year of extinction of Maui akepa, with 2004 as the upper 95 
percent confidence bound on that estimate (Elphick et al. 2010, p. 
620).
III. Analysis
    Reasons for decline presumably are similar to threats faced by 
other endangered forest birds on Maui, including small populations, 
habitat degradation by feral ungulates and introduced invasive plants, 
and predation by introduced mammalian predators, including rats (Rattus 
spp.), cats (Felis catus), and mongoose (Herpestes auropunctatus) 
(USFWS 2006, p. 2-136). Rats may have played an especially important 
role as nest predators of Maui akepa. While the only nest of Maui akepa 
ever reported was built in tree foliage, the birds may also have 
selected tree cavities as does the very similar Hawaii akepa (Loxops 
coccineus coccineus). In Maui forests, nest trees are of shorter 
stature than where akepa survive on Hawaii Island. Suitable cavity 
sites on Maui are low in the vegetation, some near or at ground level, 
and thus more accessible to rats. High densities of both black and 
Polynesian rats (Rattus rattus and R. exulans) are present in akepa 
habitat on Maui (USFWS 2006, p. 2-136).
    The population of Maui akepa was estimated at 230 birds in 1980 
(Scott et al. 1986, p. 154); however, confidence intervals on this 
estimate were large. In addition, this may have been an overestimate 
because it was based on audio detections that can be confused with 
similar songs of Maui parrotbill. The last confirmed sighting of Maui 
akepa was in 1988, from Hanawi NAR (Engilis 1990, p. 69). Over 10,000 
search hours in Hanawi NAR and nearby areas including Kipahulu Valley 
from October 1995 through June 1999 failed to confirm presence of Maui 
akepa (Pratt and Pyle 2000, p. 37). Field presence by qualified 
observers from 2006 to 2011 in the area Maui akepa was last known 
failed to detect this species, and the MFBRP project coordinator 
concluded that if Maui akepa were present they would have been detected 
(Mounce 2018, pers. comm.). Further, using the method to determine 
probability of species extinction based on time (years) since the 
species was last observed (using 1980 as the last documented 
observation record, as described above), the estimated year the Maui 
akepa became extinct is 1987, with 2004 as the upper 95 percent 
confidence bound on that estimate (Elphick et al. 2010, p. 620).
IV. Conclusion
    At the time of listing in 1970, we considered the Maui akepa to be 
facing threats from habitat loss, avian disease, and predation by 
introduced mammals. The best available information now indicates that 
the Maui akepa is extinct. The species appears to have been vulnerable 
to the effects of small population size, which likely limited its 
genetic variation, disease resistance, and adaptive capacity, thereby 
increasing the vulnerability of the species to the environmental 
stressors of habitat degradation and predation by nonnative mammals. 
Since the last detection in 1988, qualified observers have conducted 
extensive surveys in that same area with no additional detections of 
the species. Available information indicates that the species was not 
able to persist in the face of environmental stressors, and we conclude 
that best available scientific and commercial information indicates 
that the species is extinct.

Maui Nukupuu (Hemignathus lucidus affinis)

I. Background
    The Maui nukupuu (Hemignathus lucidus affinis, listed as 
Hemignathus affinis) was listed as endangered on October 13, 1970 (35 
FR 16047), and was included in the Maui-Molokai Forest Birds Recovery 
Plan (USFWS 1984, pp. 8, 10-12), and the Revised Recovery Plan for 
Hawaiian Forest Birds (USFWS 2006, pp. 2-92-2-96). At the time of 
listing, we considered Maui nukupuu to have very low population numbers 
and to be threatened by habitat loss, avian disease, and predation by 
introduced mammals. The 5-year status review completed in 2018 
(initiated on February 12, 2016; see 81 FR 7571) recommended delisting 
due to extinction (USFWS 2018, p. 11).
    The Maui nukupuu was known only from the island of Maui in the 
Hawaiian Islands. The historical record provides little information on 
the life history of the Maui nukupuu (Rothschild 1893 to 1900, pp. 103-
104; Perkins 1903, pp. 426-430). Nothing is known of its breeding 
biology, which likely was similar to its closest relative, the 
akiapolaau (Hemignathus munroi) on Hawaii Island. The Maui nukupuu was 
insectivorous and probed bark, lichen, and branches to extract insects, 
foraging behaviors that resembled those of akiapolaau. Diet of the Maui 
nukupuu was reported to be small weevils and larvae of orders 
Coleoptera and Lepidoptera (Perkins 1903, p. 429). There is scant 
evidence that Maui nukupuu took nectar from flowers. Maui nukupuu often 
joined mixed-species foraging flocks (Perkins 1903, p. 429).
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    The Maui nukupuu was a medium-sized (approximately 0.78 ounce, or 
23 gram) Hawaiian honeycreeper with an extraordinarily thin, curved 
bill that was slightly longer than the bird's head. The lower mandible 
was half the length of the upper mandible and followed its curvature 
rather than being straight (as in the related akiapolaau) (USFWS 2006, 
p. 2-92). Adult males were olive green with a yellow head, throat, and 
breast, whereas adult females and juveniles had an olive-green head and 
yellow or yellowish gray under-parts. The species' coloration and bill 
shape were quite distinctive, making visual identification of Maui 
nukupuu relatively easy. The Maui nukupuu's song resembled the warble 
of a house finch (Carpodacus mexicanus), but was lower in pitch. Both 
the song and the ``kee-wit'' call resembled those of Maui parrotbill 
(Pseudonestor xanthophrys), and audio detection required visual 
confirmation (USFWS 2006, p. 2-92).
Survey Effort
    Historically, the Maui nukupuu was known only from Maui, but 
subfossil bones of a probable Maui nukupuu from Molokai show that the 
species likely formerly inhabited that island (USFWS 2006, p. 2-92). 
All records from late 19th and early 20th centuries were from locations 
most accessible to naturalists, above Olinda on the northwest rift of 
Haleakala, and from mid-elevation forests in Kipahulu Valley (USFWS 
2006, pp. 2-134). Observers at the time noted the restricted 
distribution and low population density of Maui nukupuu. As on Kauai, 
introduced mosquitoes and avian diseases may have already limited these 
birds to forests at higher elevations, and we can presume that the Maui 
nukupuu once had a much wider geographic range (USFWS 2006, pp. 2-92). 
In 1967, Maui nukupuu were rediscovered in the upper reaches of 
Kipahulu Valley on the eastern slope of Haleakala, east Maui (Banko 
1968, pp.

[[Page 54314]]

65-66; USFWS 2006, pp. 2-95). Since then, isolated sightings have been 
reported on the northern and eastern slopes of Haleakala, but these 
reports are uncorroborated by behavioral information or follow-up 
sightings (USFWS 2006, pp. 2-95).
    Based on a single sighting of an immature bird during VCP surveys 
in 1980, the population of Maui nukupuu was estimated to be 28 
individuals, with a 95 percent confidence interval of plus or minus 56 
individuals (Scott et al. 1986, pp. 37, 131). On Maui, VCP surveys are 
conducted at survey stations spaced 328 to 820 feet (100 to 250 meters) 
apart, on transect lines spaced 1 to 2 miles (1.6 to 3.2 kilometers) 
apart (Scott et al. 1986, pp. 34-40). It was estimated that 1,357 8-
minute point counts would be needed to determine with 95 percent 
confidence the absence of Maui nukupuu on Maui (Scott et al. 2008, p. 
7). In 2008, only 35 VCP counts had been conducted on Maui in areas 
where Maui nukupuu could still potentially exist. Although the results 
of VCP surveys in 1980 find Maui nukupuu extant at that time, a 
tremendous effort is required to confirm this species' extinction using 
VCP method (Scott et al. 2008). For Maui nukupuu, nearly 39 times more 
VCP counts than conducted up to 2008 would be needed to confirm this 
species' extinction with 95 percent confidence. The RBS reported an 
adult male Maui nukupuu with bright yellow plumage at 6,021 feet (1,890 
meters) elevation in 1996 from Hanawi Natural Area Reserve (Hanawi NAR) 
(Reynolds and Snetsinger 2001, p. 140). Surveys and searches have been 
unsuccessful in finding Maui nukupuu since the last confirmed sighting 
by RBS. Based on these results, the last reliable record of Maui 
nukupuu was from Hanawi NAR in 1996 (24 years ago).
    Qualified observers spent extensive time searching for Maui 
nukupuu, po`ouli (Melamprosops phaeosoma), and Maui akepa (Loxops 
coccineus ochraceus, listed as Loxops ochraceus) in the 1990s. Between 
September 1995 and October 1996, 1,730 acres (700 hectares) of Hanawi 
NAR were searched during 318 person-days (Baker 2001, p. 147). Please 
refer to the Maui akepa Survey Effort section above for the method used 
in this survey. The Maui Forest Bird Recovery Project (MFBRP) conducted 
searches from 1997 to 1999, from Hanawi NAR to Koolau Gap (west of the 
last sighting of Maui nukupuu) for a total of 355 hours of searches at 
three sites with no detections of Maui nukupuu (Vetter 2018, pers. 
comm.). The MFBRP also searched Kipahulu Valley on northern Haleakala 
from 1997 to 1999, for a total of 320 hours, with no detections of Maui 
nukupuu. The Kipahulu searches were hampered, however, by bad weather, 
and playback was not used (Vetter 2018, pers. comm.). Despite over 
10,000 person-hours of searching in the Hanawi NAR and nearby areas 
from October 1995 through June 1999, searches failed to confirm 
detection in 1996 of Maui nukupuu, or produce other sightings (Pratt 
and Pyle 2000, p. 37). While working on Maui parrotbill recovery from 
2006 to 2011, the MFBRP spent extensive time in the area of the last 
Maui nukupuu sighting. The MFBRP project coordinator concluded that if 
Maui nukupuu were still present they would have been detected (Mounce 
2018, pers. comm.).
Time Since Last Detection
    The Maui nukupuu was last sighted in the Hanawi NAR in 1996 
(Reynolds and Snetsinger 2001, p. 140). Surveys conducted during the 
late 1990s and early 2000s were unable to locate the species (Pratt and 
Pyle 2000, p. 37; Baker 2001, p. 147).
    Elphick et al 2010 (p. 630) attempted to apply their method to 
predict the probability of species extinction for the Maui nukupuu 
based on time (years) since the species was last observed (see Time 
Since Last Detection section for Kauai akialoa, above). Basing 
extinction probability solely on the sighting record without physical 
evidence has the drawback that an incorrect assignment of species 
extinction may occur due to inadequate survey effort and/or 
insufficient time spent by qualified observers in areas where the 
species could still potentially exist. Therefore, observations in 1967, 
1980, and 1996 were not considered for this analysis because they did 
not meet the researchers' criteria for a confirmed sighting. Therefore, 
using 1896 as the last observation of Maui nukupuu, under their 
stringent criteria, the authors were unable to determine an estimated 
date for species extinction.
III. Analysis
    The Maui nukupuu is also affected by small population sizes and 
other threats, as discussed above under the Analysis section for the 
Maui akepa. The population of Maui nukupuu was estimated to be 28 birds 
in 1980 (Scott et al. 1986, pp. 37, 131); however, confidence intervals 
on this estimate were large. This population was vulnerable to negative 
effects of small population size, including stochastic effects and 
genetic drift that can accelerate the decline of small populations. 
However, even rare species can persist despite having low numbers. The 
last confirmed sighting of Maui nukupuu was in 1996, from Hanawi NAR 
(Reynolds and Snetsinger 2001, p. 140). Over 10,000 person-search hours 
in Hanawi NAR and nearby areas, including Kipahulu Valley, from October 
1995 through June 1999 failed to confirm this sighting or to detect 
other individuals (Pratt and Pyle 2000, p. 37). While working on Maui 
parrotbill recovery from 2006 to 2011, the MFBRP spent extensive time 
in the area of the last Maui nukupuu sighting; however, no Maui nukupuu 
were observed, and the MFBRP project coordinator concluded that if Maui 
nukupuu were still present they would have been detected (Mounce 2018, 
pers. comm.).
IV. Conclusion
    At the time of listing in 1970, Maui nukupuu had very low 
population numbers and faced threats from habitat loss, avian disease, 
and predation by introduced mammals. The species appears to have been 
vulnerable to avian disease and the effects of small population size. 
The latter likely limited the species' genetic variation and adaptive 
capacity, thereby increasing the vulnerability of the species to the 
environmental stressors of habitat degradation and predation by 
nonnative mammals. Since its last detection in 1996, qualified 
observers have conducted extensive searches in the area where the 
species was last sighted and other native forest habitat where the 
species occurred historically, but have not detected the species. 
Available information indicates that the species was not able to 
persist in the face of environmental stressors, and we conclude that 
the best available scientific and commercial data indicate that the 
species is extinct.

Molokai Creeper (Paroeomyza flammea)

I. Background
    The Molokai creeper (Paroreomyza flammea, or k[amacr]k[amacr]wahie 
in the Hawaiian language) was listed as endangered on October 13, 1970 
(35 FR 16047), and was included in the Maui-Molokai Forest Birds 
Recovery Plan (USFWS 1984, pp. 18-20) and the Revised Recovery Plan for 
Hawaiian Forest Birds (USFWS 2006, pp. 2-121- 2-123). At the time of 
listing, the Molokai creeper was considered extremely rare and faced 
threats from habitat loss, avian disease, and predation by introduced 
mammals. Three 5-year status reviews have been completed; the 2009 
(initiated on July 6, 2005; see 70 FR 38972) and 2015 (initiated on 
March 6, 2012; see 77 FR 13248) reviews did not

[[Page 54315]]

recommend a change in status, though there was some information 
indicating the species was already extinct (USFWS 2009, p. 11; USFWS 
2015, p. 8). The 5-year status review completed in 2018 (initiated on 
February 12, 2016; see 81 FR 7571) recommended delisting due to 
extinction based in part on continued lack of detections and 
consideration of extinction probability (USFWS 2018, p. 9).
    The Molokai creeper was known only from Molokai in the Hawaiian 
Islands. Only fragmentary information is available about the life 
history of the species from the writings of early naturalists (Perkins 
1903, pp. 413-417; Pekelo 1963, p. 64; USFWS 2006, p. 2-122). This 
species was an insectivore that gleaned vegetation and bark in wet ohia 
(Metrosideros polymorpha) forests and was known almost solely from 
boggy areas of Molokai (Pekelo 1963, p. 64), although there is one 
record in 1907 of the species from lower elevation forest of leeward 
east Molokai (USFWS 2006, pp. 2-121).
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    Adult males were mostly scarlet in various shades, while adult 
females were brown with scarlet washes and markings, and juvenile males 
ranged from brown to scarlet with many gradations. The bill was short 
and straight. Its calls were described as chip or chirping notes 
similar to other creeper calls (USFWS 2006, pp. 2-122). Its closest 
relatives are the Maui creeper (Paroreomyza montana) and the Oahu 
creeper (P. maculata). The species' coloration and bill shape were 
distinctive, and Molokai creeper was identified visually with 
confidence.
Survey Effort
    Molokai creeper was common in 1907, but by the 1930s, they were 
considered in danger of extinction (Scott et al. 1986, p. 148). The 
species was last detected in 1963, on the west rim of Pelekunu Valley 
(Pekelo 1963, p. 64). Surveys and searches have been unsuccessful in 
finding the Molokai creeper since the last sighting, including VCP 
surveys on the Olokui Plateau in 1980 and 1988, and the RBS of the 
Kamakou-Pelekunu Plateau in 1995 (Reynolds and Snetsinger 2001, p. 
141). Following up on a purported sighting in 2005 of a Molokai thrush 
(Myadestes lanaiensis rutha), a survey was conducted over 2 to 3 days 
in Puu Alii Natural Area Reserve (Puu Alii NAR), the last place the 
Molokai creeper was sighted in the 1960s (Pekelo 1963, p. 64; USFWS 
2006, pp. 2-29). Using playback recordings for Molokai thrush, 
searchers covered the reserve area fairly well, but no Molokai creepers 
or Molokai thrush were detected (Vetter 2018, pers. comm.).
    No Molokai creepers were detected during VCP surveys beginning in 
the late 1970s to the most recent Hawaiian forest bird survey on 
Molokai in 2010 (Scott et al. 1986, p. 37; Camp 2015, pers. comm.). On 
Molokai, VCP surveys are 8-minute point counts conducted at stations 
separated by a distance of 492 to 656 feet (150 to 200 meters) along 
transect lines 1 to 2 miles (1.6 to 3.2 kilometers) apart (Scott et al. 
1986, pp. 34-40). It was estimated that 215,427 8-minute point counts 
would be needed to determine with 95 percent confidence the absence of 
Molokai creeper on Maui (Scott et al. 2008, p. 7). In 2008, only 131 
VCP counts had been conducted on Molokai in areas where Molokai creeper 
could still potentially exist. For the Molokai creeper, nearly 1,650 
times more VCP counts than conducted up to 2008 would be needed to 
confirm the species' extinction with 95 percent confidence. Based on 
species detection probability, the RBS determined the likelihood of the 
Molokai creeper being extirpated from the Kamakou-Pelekunu plateau was 
greater than 95 percent. The RBS estimated the Molokai creeper to be 
extinct over the entirety of its range, but, because not all potential 
suitable habitat was searched, extinction probability was not 
determined (Reynolds and Snetsinger 2001, p. 141).
Time Since Last Detection
    The last reliable record (based on independent expert opinion and 
physical evidence) of Molokai creeper was from Pelekunu Valley in 1963 
(Pekelo 1963, p. 64). Using 1963 as the last reliable observation 
record for Molokai creeper, 1969 is estimated to be year of extinction 
of the Molokai creeper with 1985 as the upper 95 percent confidence 
bound (Elphick et al. 2010, p. 620).
III. Analysis
    The Molokai creeper faces similar threats to the other Maui bird 
species (see Analysis section for the Maui akepa, above). The last 
confirmed detection of the Molokai creeper was in 1963 (Pekelo 1963, p. 
64). Forest bird surveys in 1980, 1988, and 2010, and the RBS in 1994-
1996 (although not including the Olokui Plateau), failed to detect this 
species. A 2- to 3-day search by qualified personnel for the Molokai 
thrush in Puu Alii NAR in 2005, the last location where Molokai creeper 
was sighted, also failed to detect the Molokai creeper. The estimated 
year of extinction is 1969, with 1985 as the 95 percent confidence 
upper bound (Elphick et al. 2010, p. 620). It is highly likely that 
avian disease, thought to be the driver of range contraction and 
disappearance of many Hawaiian honeycreeper species, was present 
periodically throughout nearly all of the Molokai creeper's range over 
the last half-century.
IV. Conclusion
    At the time of listing in 1970, the Molokai creeper was considered 
to be facing threats from habitat loss, avian disease, and predation by 
introduced mammals. The best information now indicates that the Molokai 
creeper is extinct. The species appears to have been vulnerable to 
avian disease, as well as the effects of small population size. The 
latter likely limited the species' genetic variation and adaptive 
capacity, thereby increasing the vulnerability of the species to the 
environmental stressors of habitat degradation and predation by 
nonnative mammals. Since its last detection in 1963, qualified 
observers have conducted extensive searches for the Molokai creeper but 
have not detected the species. Available information indicates that the 
species was not able to persist in the face of environmental stressors, 
and we conclude that the best available scientific and commercial 
information indicates that the species is extinct.

Po`ouli (Melamprosops phaeosoma)

I. Background
    We listed the po`ouli (Melamprosops phaeosoma) as endangered on 
September 25, 1975 (40 FR 44149), and the species was included in the 
Maui-Molokai Forest Birds Recovery Plan (USFWS 1984, pp. 16-17), and 
the Revised Recovery Plan for Hawaiian Forest Birds (USFWS 2006, pp. 2-
144-2-154). At the time of listing, we considered the po`ouli to have 
very low abundance and to likely be threatened by habitat loss, avian 
disease, and predation by introduced mammals. Three 5-year status 
reviews have been completed; the 2010 (initiated on April 11, 2006; see 
71 FR 18346) and 2015 (initiated on March 6, 2012; see 77 FR 13248) 
reviews did not recommend a change in status, though there was some 
information indicating the species was already extinct (USFWS 2010, p. 
13; USFWS 2105, p. 8). The 5-year status review completed in 2018 
(initiated on February 12, 2016; see 81 FR 7571) recommended delisting 
due to extinction, based in part on continued lack of detections and 
consideration of

[[Page 54316]]

extinction probability (USFWS 2018, pp. 4-5, 10).
    The po`ouli was known only from the island of Maui in the Hawaiian 
Islands and was first discovered in 1973, in high-elevation rainforest 
on the east slope of Haleakala (USFWS 2006, p. 2-146). Fossil evidence 
shows that the po`ouli once inhabited drier forests at lower elevation 
on the leeward slope of Haleakala, indicating it once had a much 
broader geographic and habitat range (USFWS 2006, p. 2-147). Po`ouli 
were observed singly, in pairs, and in family groups consisting of both 
parents and a single offspring (Pratt et al. 1997, p. 1). Po`ouli 
foraged primarily on tree branches, making extensive use of the 
subcanopy and understory. They seemed to have preferred the native 
hydrangea (kanawao (Broussaisia arguta)), the native holly (kawau (Ilex 
anomala)), and ohia (Metrosideros polymorpha) (Pratt et al. 1997, p. 
4). Po`ouli gleaned from, probed, and excavated moss mats, lichen, and 
bark for small invertebrate prey. Egg-laying took place in March and 
April for two nests observed, and clutch size was probably two eggs 
(Kepler et al. 1996, pp. 620-638). The female alone incubated eggs and 
brooded chicks, but both parents fed the chicks. Throughout nesting, 
the male fed the female at or away from the nest. Po`ouli often 
associated with mixed species foraging flocks of other insectivorous 
honeycreepers. Po`ouli were unusually quiet. Males rarely sang and did 
so mostly as part of courtship prior to egg-laying. The maximum 
lifespan of this species is estimated to be 9 years (The Animal Aging 
and Longevity Database 2020, unpaginated).
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    The po`ouli was a medium-sized, 0.9 ounce (26 gram), stocky 
Hawaiian honeycreeper, easily recognized by its brown plumage and 
characteristic black mask framed by a gray crown and white cheek patch. 
However, po`ouli were unusually quiet. Although distinctive visually, 
because the species rarely vocalized, it was difficult to survey by 
audio detections.
Survey Effort
    The po`ouli was first discovered in 1973 (USFWS 2006, p. 2-146). 
Total population was estimated at 140 individuals, with a 95 percent 
confidence interval of plus or minus 280 individuals, during VCP 
surveys in 1980 (Scott et al. 1986, pp. 37, 183), but estimates of 
population size and density were likely inaccurate and considered 
imprecise due to the species' low density and cryptic behavior (USFWS 
2006, p. 2-147). In 1994, after nearly 2 years without a sighting, the 
continued existence and successful breeding of five to six po`ouli in 
the Kuhiwa drainage of Hanawi Natural Area Reserve (Hanawi NAR) was 
confirmed (Reynolds and Snetsinger 2001, p. 141). Thorough surveys of 
the historical range between 1997 and 2000, the Maui Forest Bird 
Recovery Program (MFBRP) located only three birds, all in separate 
territories in Hanawi NAR. These three po`ouli were color-banded in 
1996 and 1997, and subsequently observed (see below), but no other 
individuals have been observed since then (Baker 2001, p. 144; USFWS 
2006, pp. 2-147-2-148). The MFBRP searched Kipahulu Valley on northern 
Haleakala from 1997 to 2000, for a total of 320 hours, but failed to 
detect po`ouli. These searches were hampered by bad weather, however, 
and playback was not used (Vetter 2018, pers. comm.).
Time Since Last Detection
    In 2002, what was thought to be the only female po`ouli of the 
three in Hanawi NAR was captured and released into one of the male's 
territories, but she returned to her home range the following day 
(USFWS 2006, p. 2-151). In 2004, an effort was initiated to capture the 
three remaining po`ouli to breed them in captivity. One individual was 
captured and successfully maintained in captivity for 78 days, but died 
on November 26, 2004, before a potential mate could be obtained. The 
remaining two birds were last seen in December 2003 and January 2004 
(USFWS 2006, pp. 2-153-2-154). While working on Maui parrotbill 
(Pseudonestor xanthophrys) recovery from 2006 to 2011, the MFBRP spent 
extensive time in the area of the last po`ouli sightings. No po`ouli 
were seen or heard. The MFBRP project coordinator concluded that if 
po`ouli were present, they would have been detected (Mounce 2018, pers. 
comm.).
    Using 2004 as the last reliable observation record for po`ouli, 
2005 is estimated to be the year of extinction, with 2008 as the upper 
95 percent confidence bound on that estimate (Elphick et al. 2010, p. 
620).
III. Analysis
    The Po'ouli faced similar threats to other Maui occurring bird 
species (see the Analysis section for the Maui akepa, above). The last 
confirmed sighting of po`ouli was in 2004 from Hanawi NAR (USFWS 2006, 
p. 2-154). Extensive field presence by qualified individuals from 2006 
to 2011 in Hanawi NAR, where po`ouli was last observed, failed to 
detect this species, as did searches of Kipahulu Valley near Hanawi NAR 
from 1997 to 1999 (USFWS 2006, p. 2-94). Using 2004 as the last 
reliable observation record for po`ouli, the estimated year the species 
went extinct is 2005, with 2008 the upper 95 percent confidence bound 
on that estimate (Elphick et al. 2010, p. 620).
IV. Conclusion
    At the time of its listing in 1975, we considered po`ouli to have 
very low population abundance, and to face threats from habitat loss, 
avian disease, and predation by introduced mammals. The best available 
information now indicates that the po`ouli is extinct. Although the 
po`ouli was last detected as recently as early 2004, the species 
appears to have been vulnerable to the effects of small population size 
since it was first discovered in 1973. The small population size likely 
limited its genetic variation, disease resistance, and adaptive 
capacity over time, thereby increasing the vulnerability of the species 
to the environmental stressors of habitat degradation and predation by 
nonnative mammals. Experienced staff with MFBRP conducted extensive 
recovery work in po`ouli habitat between 2006 and 2011 and had no 
detections of the species. Available information indicates that the 
species was not able to persist in the face of environmental stressors, 
and we conclude that the species is extinct.

Fishes

San Marcos Gambusia (Gambusia georgei)

I. Background
    We listed the San Marcos gambusia (Gambusia georgei), a small fish, 
as endangered throughout all of its range on July 14, 1980 (45 FR 
47355). We concurrently designated approximately 0.5 miles of the San 
Marcos River as critical habitat for the species (45 FR 47355, July 14, 
1980, p. 47364). The San Marcos gambusia was endemic to the San Marcos 
River in San Marcos, Texas. The San Marcos gambusia has historically 
only been found in a section of the upper San Marcos River 
approximately from Rio Vista Dam to a point near the U.S. Geological 
Survey gaging station immediately downstream from Thompson's Island. 
Only a limited number of species of Gambusia are native to the United 
States; of this subset, the San Marcos gambusia had one of the most 
restricted ranges.
    We listed the species as endangered due to decline in population 
size, low

[[Page 54317]]

population numbers, and possibility of lowered water tables, pollution, 
bottom plowing (a farming method that brings subsoil to the top and 
buries the previous top layer), and cutting of vegetation (43 FR 30316, 
July 14, 1978, p. 30317). We identified groundwater depletion, reduced 
spring flows, contamination, habitat impacts resulting from severe 
drought conditions, and cumulative effects of human activities as 
threats to the species (45 FR 47355, July 14, 1980, p. 47361). At the 
time of listing, this species was extremely rare.
    There has also been evidence of hybridization between G. georgei 
and G. affinis (western mosquitofish) in the wild. Hybridization 
between G. georgei and G. affinis continued for many years without 
documented transfer of genes between the species that would have 
resulted in the establishment of a new species (Hubbs and Peden 1969, 
p. 357). Based on collections in the 1920s, a study in the late 1960s, 
surmised that limited hybridization with G. affinis did not seem to 
have reduced the specific integrity of either species. However, as 
fewer G. georgei individuals existed in the wild and therefore 
encountered each other, the chances of hybridization with the much more 
common G. affinis increased.
    All currently available scientific data and field survey data 
indicate that this species has been extinct in the wild for over 35 
years. The last known sighting in the wild was in 1983, and past 
hybridization in the wild between G. georgei and G. affinis failed to 
result in establishment of a hybridized species that would facilitate 
the transfer of genes from one species to the other. Also, captive 
breeding attempts of G. georgei failed. In 1985, the last captive 
female San Marcos gambusia died. Because no males remained, we 
concluded captive breeding efforts, and no individuals remain alive in 
captivity today.
    On March 20, 2008, we published a notice in the Federal Register 
(73 FR 14995) that we were initiating a 5-year review of the species. 
We did not receive any comments or new information, and the 5-year 
review was not completed at that time. On May 31, 2018, we published a 
notice in the Federal Register (83 FR 25034) initiating another 5-year 
review of the species. The review relied on available information, 
including survey results, fish collection records, peer-reviewed 
literature, various agency records, and correspondences with leading 
Gambusia species experts in Texas. That 5-year review recommended 
delisting the San Marcos gambusia due to extinction.
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    Historically, the San Marcos gambusia had small populations, and 
the pattern of abundance strongly suggests a decrease beginning prior 
to the mid-1970s. Historical records indicate that San Marcos gambusia 
was likely collected from the headwaters of the San Marcos River (Hubbs 
and Peden 1969, p. 28). The highest number of San Marcos gambusia ever 
collected was 119 in 1968. Because this species preferred sections of 
slow-moving waters and had a limited historical range of a small 
section of the San Marcos River, potential detection was not expected 
to be difficult.
Survey Effort
    In 1976, we contracted a status survey to improve our understanding 
of the species and its habitat needs. We facilitated bringing 
individuals into captivity for breeding and study. Many researchers 
have been involved and have devoted considerable effort to attempts to 
locate and preserve populations. Intensive collections during 1978 and 
1979 yielded only 18 San Marcos gambusia from 20,199 Gambusia total, 
which means San Marcos gambusia amounted to only 0.09 percent of those 
collections (Edwards et al. 1980, p. 20). Captive populations were 
established at the University of Texas at Austin in 1979, and fish from 
that captive population were used to establish a captive population at 
our Dexter National Fish Hatchery in 1980. Both captive populations 
later became contaminated with another Gambusia species. The fish 
hybridized, and the pure stocks were lost.
    Following the failed attempt at maintaining captive populations at 
Dexter National Fish Hatchery and the subsequent listing of the species 
in 1980, we contracted for research to examine known localities and 
collect fish to establish captive refugia. Collections made in 1981 and 
1982 within the range of San Marcos gambusia indicated a slight 
decrease in relative abundance of this species (0.06 percent of all 
Gambusia). From 1981 to 1984, efforts were made to relocate populations 
and reestablish a culture of individuals for captive refugia. Too few 
pure San Marcos gambusia and hybrids were found to establish a culture, 
although attempts were made with the few fish available (Edwards et al. 
1980, p. 24). In the mid-1980s, staff from the San Marcos National Fish 
Hatchery and Technology Center also searched unsuccessfully for the 
species in attempts to locate individuals to bring into captivity.
    Intensive searches for San Marcos gambusia were conducted in May, 
July, and September of 1990, but were unsuccessful in locating any pure 
San Marcos gambusia. The searches consisted of more than 180 people-
hours of effort over the course of 3 separate days and covered the area 
from the headwaters at Spring Lake to the San Marcos wastewater 
treatment plant outfall. Over 15,450 Gambusia were identified during 
the searches. One individual collected during the search was visually 
identified as a possible backcross of G. georgei and G. affinis 
(Service 1990 permit report). This individual was an immature fish with 
plain coloration. Additional sampling near the Interstate Highway 35 
type locality has occurred at approximately yearly intervals since 
1990, and no San Marcos gambusia have been found. No San Marcos 
gambusia were found in the 32,811 Gambusia collected in the upper San 
Marcos River by the Service from 1994 to 1996 (Edwards 1999, pp. 6-13).
Time Since Last Detection
    Academic researchers, Texas Parks and Wildlife Department 
scientists, and the Service have continued to search for the San Marcos 
gambusia during all collection and research with fishes on the San 
Marcos River. San Marcos gambusia have not been found in the wild since 
1983, even with intensive searches, including the ones conducted in 
May, July, and September of 1990, covering the species' known range and 
designated critical habitat. Since 1996, all attempts to locate and 
collect San Marcos gambusia have failed (Edwards 1999, p. 3; Edwards et 
al. 2002, p. 358; Hendrickson and Cohen 2015; Bio-West 2016, p. 43; 
Bonner 2018, pers. comm.). More recent surveys and analyses of fish 
species already consider the San Marcos gambusia extinct (Edwards et 
al. 2002; Hubbs et al. 2008). Additionally, hybridized individuals have 
not been documented since 1990.
III. Analysis
    Although the population of San Marcos gambusia was historically 
small, it also had one of the most restricted ranges of Gambusia 
species. San Marcos gambusia have not been found in the wild since 
1983, even with intensive searches, including the ones conducted in 
May, July, and September of 1990, covering the species' known range and 
designated critical habitat. No San Marcos gambusia were found in the 
32,811 Gambusia collected in the upper San Marcos River by the Service 
from 1994 to 1996 (Edwards 1999, pp. 6-13).

[[Page 54318]]

Additional sampling near the Interstate Highway 35 type locality has 
occurred at approximately yearly intervals since 1990. Since 1996, all 
attempts to survey and collect San Marcos gambusia failed to find them 
(Edwards 1999, p. 3; Edwards et al. 2002, p. 358; Hendrickson and Cohen 
2015; Bio-West 2016, p. 43; Bonner 2018, pers. comm.). Additionally, no 
detections of hybridized San Marcos gambusia with G. affinis is further 
evidence that extinction has occurred.
    In addition to the San Marcos gambusia not being found in the wild, 
all attempts at captive breeding have failed. This is largely due to 
unsuccessful searches for the species in attempts to locate individuals 
to bring into captivity.
    Due to the narrow habitat preference and limited range of the San 
Marcos gambusia, and the exhaustive survey and collection efforts that 
have failed to detect the species, we conclude there is a very low 
possibility of an individual or population remaining extant but 
undetected. Therefore, the decrease in San Marcos gambusia abundance, 
and the lack of hybridized individuals in any recent samples, indicates 
that the species is extinct.
IV. Conclusion
    The San Marcos gambusia was federally listed as endangered in 1980. 
At the time of listing, this species was rare. The last known 
collections of San Marcos gambusia from the wild were in 1981 (Edwards 
2018, pers. comm.), and the last known sighting in the wild occurred in 
1983. In 1985, after unsuccessful breeding attempts with Gambusia 
affinis from the upper San Marcos River, the last captive female San 
Marcos gambusia died. All available information and field survey data 
support a determination that the San Marcos gambusia has been extinct 
in the wild for more than 35 years. We have reviewed the best 
scientific and commercial data available to conclude that the species 
is extinct.

Scioto Madtom (Noturus trautmani)

I. Background
    The Scioto madtom (Noturus trautmani) was listed as endangered on 
September 25, 1975 (40 FR 44149) due to the pollution and siltation of 
its habitat and the proposal to construct two impoundments within its 
range. Scioto madtom was included in 5-year reviews initiated on 
February 27, 1981 (46 FR 14652), July 22, 1985 (50 FR 29901), and on 
November 6, 1991 (56 FR 56882). These reviews resulted in no change in 
the Scioto madtom's listing classification of endangered. Two 
additional 5-year reviews were initiated in 2009 (74 FR 11600; March 
18, 2009) and 2014 (79 FR 38560; July 8, 2014). The recommendations 
from both of these reviews were to delist the species due to extinction 
(Service 2009, p. 7; Service 2014, p. 6).
    The Scioto madtom was a small, nocturnal species of catfish in the 
family Ictaluridae. The Scioto madtom has been found only in a small 
section of Big Darby Creek, a major tributary to the Scioto River, and 
was believed to be endemic to the Scioto River basin in central Ohio 
(40 FR 44149, September 25, 1975; Service 1985, p. 10; Service 1988, p. 
1).
    The species was first collected in 1943 (Trautman 1981, p. 504), 
and was first described as a species, Noturus trautmani, in 1969 
(Taylor 1969, pp. 156-160). Only 18 individuals of the Scioto madtom 
were ever collected. All were found along one stretch of Big Darby 
Creek, and all but one were found within the same riffle known as 
Trautman's riffle. The riffle habitat was comprised of glacial cobble, 
gravel, sand, and silt substrate, with some large boulders (Trautman 
1981, p. 505) with moderate current and high-quality water free of 
suspended sediments.
    The Scioto madtom was an omnivorous bottom feeder that ate a wide 
variety of plant and animal life, which it found with its sensory 
barbels hanging down in front of its mouth. Little is known of its 
reproductive habits, although it likely spawned in summer and migrated 
downstream in the fall (Trautman 1981, p. 505).
    The exact cause of the Scioto madtom's decline is unknown, but was 
likely due to modification of its habitat from siltation, suspended 
industrial effluents, and agricultural runoff (40 FR 44149, September 
25, 1975; Service 1988, p. 2). At the time of listing, two dams were 
proposed for Big Darby Creek, although ultimately they were never 
constructed. It should also be noted that the northern madtom (Noturus 
stigmosus) was first observed in Big Darby Creek in 1957, the same year 
the last Scioto madtom was collected (Service 1982, p. 3; Kibbey 2009, 
pers. comm.). Both species likely feed on small invertebrates and 
shelter in openings in and around rocks and boulders. Given the 
apparent small population size and highly restricted range of the 
Scioto madtom in the 1940s and 1950s, it is possible that the species 
was unable to successfully compete with the northern madtom for the 
same food and shelter resources (Kibbey 2009, pers. comm.).
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    The Scioto madtom looked similar to other madtom species but could 
be distinguished by meristic and morphometric characters, such as the 
number of pectoral and anal rays. The species, like other madtom 
species, was relatively cryptic as they hid during the daylight hours 
under rocks or in vegetation and emerged after dark to forage along the 
bottom of the stream. Despite these detection challenges, many surveys 
by experienced biologists have been undertaken to try to locate extant 
populations of Scioto madtom.
Survey Effort
    No Scioto madtoms have been observed since 1957, despite intensive 
fish surveys throughout Big Darby Creek in 1976-1977 (Service 1977, p. 
15), 1981-1985 (Service 1982, p. 1; Service 1985, p. 1), 2014-2015 
(OEPA 2018, p. 48), and 2001-2019 (Kibbey 2009, pers. comm.; Zimmerman 
2014, 2020, pers. comm.).
    The fish surveys conducted in Big Darby Creek in 1976-1977 and 
1981-1985 specifically targeted the Scioto madtom. The 1976-1977 survey 
found 41 madtoms of 3 species and 34 species of fish in riffles at and 
near the Scioto madtom type locality (Service 1977, pp. 13-15). The 
1981-1985 survey occurred throughout Big Darby Creek and found a total 
of 2,417 madtoms of 5 species (Service 1985, pp. 1, 5, 19-23). Twenty-
two percent (542 individuals) of the total madtoms were riffle madtoms 
of the subgenus Rabida, which also includes the Scioto madtom (Service 
1985, p. 1). None of the species identified were the Scioto madtom.
    The 2014-2015 fish surveys occurred throughout the Big Darby Creek 
watershed as part of the Ohio Environmental Protection Agency's 
(OEPA's) water quality monitoring program. A total of 96,471 fish 
representing 85 different species and 6 hybrids, were collected at 93 
sampling locations throughout the Big Darby Creek study area during the 
2014 sampling season. Fish surveys were conducted at numerous sites in 
Big Darby Creek between 2001 and 2019, using a variety of survey 
techniques, including seining, boat electrofishing, backpack 
electrofishing, and dip netting (Zimmerman 2020, pers. comm.). Another 
survey was also conducted annually in the Big Darby Creek from 1970 to 
2005 (Cavender 1999, pers. comm.; Kibbey 2016, pers. comm.).
    These surveys also included extensive searches for populations of 
Scioto

[[Page 54319]]

madtoms outside of the type locality in Big Darby Creek (Kibbey 2016, 
pers. comm.). In addition to fish surveys in the Big Darby Creek 
watershed, the OEPA has conducted a number of fish studies throughout 
the Upper, Middle, and Lower Scioto River watershed as part of the 
agency's Statewide Water Quality Monitoring Program (OEPA 1993a, 1993b, 
1999, 2002, 2004, 2006, 2008, 2012, 2019, entire). These surveys have 
never detected a Scioto madtom.
Time Since Last Detection
    No collections of the Scioto madtom have been made since 1957. 
Given that the extensive fish surveys conducted since 1970 within the 
species' historical location, as well as along the entire length of Big 
Darby Creek and in the greater Scioto River watershed, have recorded 
three other species of madtom but not the Scioto madtom, it is highly 
unlikely that the Scioto madtom has persisted without detection.
Other Considerations Applicable to the Species' Status
    The habitat that once supported the Scioto madtom has been 
drastically altered, primarily via strong episodic flooding. Although 
periodic flooding has historically been a part of Big Darby Creek's 
hydrological regime, many of the original riffles where Scioto madtoms 
were collected from just downstream of the U.S. Route 104 Bridge to 
approximately one-half mile upstream have been washed out to the point 
where they are nearly gone (Kibbey 2009, pers. comm.). Furthermore, 
pollution sources throughout the Scioto River watershed, including row 
crop agriculture, development, and urban runoff, have reduced the water 
quality and suitability of habitat for madtoms (OEPA 2012, pp. 1-2).
III. Analysis
    There has been no evidence of the continued existence of the Scioto 
madtom since 1957. Surveys for the species were conducted annually 
between 1970 and 2005, at the only known location for the species. 
Additional surveys in the Big Darby Creek watershed have never found 
other locations of Scioto madtom. After decades of survey work with no 
individuals being detected, it is extremely unlikely that the species 
is extant. Further, available habitat for the species in the only 
location where it has been documented is now much reduced, which 
supports the conclusion that the species is likely extinct.
IV. Conclusion
    We conclude that the Scioto madtom is extinct and, therefore, 
should be delisted. This conclusion is based on a lack of detections 
during numerous surveys conducted for the species and significant 
alteration of habitat at its known historical location.

Mussels

Flat Pigtoe (Pleurobema marshalli)

I. Background
    The flat pigtoe (formerly known as Marshall's pearly mussel), 
Pleurobema marshalli, was listed as endangered on April 7, 1987 (52 FR 
11162) primarily due to habitat alteration from a free-flowing riverine 
system to an impounded system. The recovery plan (``Recovery Plan for 
Five Tombigbee River Mussels'') was completed on November 14, 1989. A 
supplemental recovery plan (``Mobile River Basin Aquatic Ecosystem 
Recovery Plan'') was issued on November 17, 2000. This plan did not 
replace the existing recovery plan; rather, it was intended to provide 
additional habitat protection and species husbandry recovery tasks. The 
species' recovery priority number (RPN) is 5, indicating a high degree 
of threat and low recovery potential. A 5-year review was announced on 
November 6, 1991 (56 FR 56882); no changes were proposed for the status 
of this mussel in that review. Two additional 5-year reviews were 
completed in 2009 (initiated on September 8, 2006; see 71 FR 53127) and 
2015 (initiated on March 25, 2014; see 79 FR 16366); both recommended 
delisting the flat pigtoe due to extinction. The Service solicited peer 
review from six experts for both 5-year reviews from State, Federal, 
university, and museum biologists with known expertise and interest in 
Mobile River Basin mussels (USFWS 2009, pp. 23-24; USFWS 2015, pp. 15-
16); we received responses from three of the peer reviewers, and they 
concurred with the content and conclusion that the species is presumed 
extinct.
    The flat pigtoe was described in 1927, from specimens collected in 
the Tombigbee River (USFWS 1989, p. 2). The shell of the flat pigtoe 
had pustules or welts on the postventral surface, and the adults were 
subovate in shape and approximately 2.4 inches long and 2 inches wide 
(USFWS 1989, p. 2). Freshwater mussels of the Mobile River Basin, such 
as the flat pigtoe, are most often found in clean, fast-flowing water 
in stable sand, gravel, and cobble gravel substrates that are free of 
silt (USFWS 2000, p. 81). They are typically found buried in the 
substrate in shoals and runs (USFWS 2000, p. 81). This type of habitat 
has been nearly eliminated within the historical range of the species 
because of the construction of the Tennessee-Tombigbee Waterway in 
1984, which created a dredged, straightened navigation channel and a 
series of impoundments that inundated nearly all riverine mussel 
habitat (USFWS 1989, p. 1).
    The flat pigtoe was historically known from the Tombigbee River 
from just above Tibbee Creek near Columbus, Mississippi, downstream to 
Epes, Alabama (USFWS 1989, p. 3). Surveys in historical habitat over 
the past three decades have failed to locate the species, and all 
historical habitat is impounded or modified by channelization and 
impoundments (USFWS 2015, p. 5). No live or freshly dead shells have 
been observed since the species was listed in 1987 (USFWS 2009, p. 4; 
USFWS 2015, p. 5).
    The Tombigbee River freshwater mussel fauna once consisted of more 
than 40 species (USFWS 1989, p. 1). Construction of the Tennessee-
Tombigbee Waterway adversely impacted some of the species (including 
flat pigtoe), as evidenced by surveys conducted by the Service, the 
Tennessee Valley Authority (TVA), the Mobile District Corps of 
Engineers, and others (USFWS 1989, p. 1). The construction of the 
Tennessee-Tombigbee Waterway was completed in 1984, and drastically 
modified the upper Tombigbee River from a riverine to a largely 
impounded ecosystem from Town Creek near Amory, Mississippi, downstream 
to the Demopolis Lock and Dam (USFWS 1989, p. 1). Construction of the 
Waterway adversely impacted mussels and eliminated mussel habitat by 
physical destruction during dredging, increasing sedimentation, 
reducing water flow, and suffocating juveniles with sediment (USFWS 
1989, p. 6). The only remaining habitat after the Waterway was 
constructed was in several bendways, resulting from channel cuts. These 
bendways have all experienced reduced flows and increased sediment 
accumulation, some with several feet of sediment buildup. Thus, no 
remaining mussel habitat exists (USFWS 1989, p. 6; USFWS 2015, p. 8). 
The species is presumed extinct by species experts (USFWS 2015, p. 8).
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    Detection of rare, cryptic, benthic-dwelling animals like 
freshwater mussels is challenging and can be

[[Page 54320]]

affected by a variety of factors, including:
     Size of the mussel (smaller mussels, including juvenile 
mussels, can be more difficult to find in complex substrates than 
larger mussels, and survey efforts must be thorough enough to try to 
detect smaller mussels);
     Behavior of the mussel (some are found subsurface, some at 
the surface, and some above the surface, and position can vary 
seasonally (some are more visible during the reproductive phase when 
they need to come into contact with host fish; therefore, surveys 
likely need to be conducted during different times of the year to 
improve detection));
     Substrate composition (it can be easier to see/feel 
mussels in sand and clay than in gravel or cobble; therefore, surveys 
need to include all substrate types because mussels can fall off host 
fish into a variety of substrates);
     Size of river (larger rivers usually have more expansive 
habitat areas to search and are sometimes deep, requiring specialized 
survey techniques such as self-contained underwater breathing apparatus 
(SCUBA));
     Flow conditions (visibility can be affected in very fast-
flowing, very shallow, or turbid conditions; therefore, surveys need to 
use tactile or excavation methods, or delay until turbidity conditions 
improve);
     Surveyor experience (finding mussels requires a well-
developed search image, knowledge of instream habitat dynamics, and 
ability to identify and distinguish species); and
     Survey methodology and effort (excavation and sifting of 
stream bottom can detect more mussels than visual or tactile surveys).
    All of these challenges are taken into account when developing 
survey protocols for any species of freshwater mussel, including the 
flat pigtoe. The flat pigtoe was medium-sized (but juveniles were very 
small) and most often found buried in sand, gravel, or cobble in fast-
flowing runs. However, mussels can be found in suboptimal conditions, 
depending on where they dropped off of the host fish. Therefore, all of 
the above-mentioned considerations need to be accounted for when trying 
to detect this mussel species. Despite detection challenges, many well-
planned, comprehensive surveys by experienced State and Federal 
biologists have not been able to locate extant populations of flat 
pigtoe in the Tombigbee River (USFWS 2000, p. 81; USFWS 2015, p. 5).
Survey Effort
    Prior to listing, freshly dead shells of flat pigtoe were collected 
in 1980, from the Tombigbee River, Lowndes County, Mississippi (USFWS 
2009, pp. 4-5), and a 1984 survey of the Gainesville Bendway of 
Tombigbee River also found shells of the flat pigtoe (USFWS 1989, p. 
4). After listing in 1987, surveys in 1988 and 1990 only found 
weathered, relict shells of the flat pigtoe below Heflin Dam, thus 
casting doubt on the continued existence of the species in the 
Gainesville Bendway (USFWS 1989, p. 4; USFWS 2009, p. 5). Over the past 
three decades, surveys between 1990-2001, and in 2002, 2003, 2009, 
2011, and 2015, of potential habitat throughout the historical range, 
including intensive surveys of the Gainesville Bendway, where adequate 
habitat and flows may still occur below the Gainesville Dam on the 
Tombigbee River in Alabama, have failed to find any live or dead flat 
pigtoes (USFWS 2000, p. 81).
Time Since Last Detection
    The flat pigtoe has not been collected alive since completion of 
the Tennessee-Tombigbee Waterway in 1984 (USFWS 2000, p. 81; USFWS 
2015, p. 5). Mussel surveys within the Tombigbee River drainage during 
1984-2015 failed to document the presence of the flat pigtoe (USFWS 
2015, p. 8).
Other Considerations Applicable to the Species' Status
    Habitat modification is the major cause of decline of the flat 
pigtoe (USFWS 2000, p. 81). Construction of the Tennessee-Tombigbee 
Waterway for navigation adversely impacted mussels and their habitat by 
physical destruction during dredging, increasing sedimentation, 
reducing water flow, and suffocating juveniles with sediment (USFWS 
1989, p. 6). Other threats include channel improvements such as 
clearing and snagging, as well as sand and gravel mining, diversion of 
flood flows, and water removal for municipal use. These activities 
impact mussels by altering the river substrate, increasing 
sedimentation, changing water flows, and killing individuals via 
dredging and snagging (USFWS 1989, pp. 6-7). Runoff from fertilizers 
and pesticides results in algal blooms and excessive growth of other 
aquatic vegetation, resulting in eutrophication and death of mussels 
due to lack of oxygen (USFWS 1989, p. 7). The cumulative impacts of 
habitat degradation due to these factors likely led to flat pigtoe 
populations becoming scattered and isolated over time. Low population 
levels increased the difficulty of successful reproduction (USFWS 1989, 
p. 7). When individuals become scattered, the opportunity for egg 
fertilization is diminished. Coupled with habitat changes that result 
in reduced host fish interactions, the spiral of failed reproduction 
leads to local extirpation and eventual extinction of the species 
(USFWS 1989, p. 7).
III. Analysis
    There has been no evidence of the continued existence of the flat 
pigtoe for more than three decades. Mussel surveys within the Tombigbee 
River drainage from 1984-2015 have failed to document the presence of 
the species (USFWS 2015, p. 8). All known historical habitat has been 
altered or degraded by impoundments, and the species is presumed 
extinct by most authorities.
IV. Conclusion
    We conclude that the flat pigtoe is extinct and, therefore, should 
be delisted. This conclusion is based on significant alteration of all 
known historical habitat and lack of detections during numerous surveys 
conducted throughout the species' range.

Southern Acornshell (Epioblasma othcaloogensis)

I. Background
    The southern acornshell (Epioblasma othcaloogensis) was listed as 
endangered on March 17, 1993 (58 FR 14330), primarily due to habitat 
modification, sedimentation, and water quality degradation. The 
recovery plan (``Mobile River Basin Aquatic Ecosystem Recovery Plan'') 
was completed on November 17, 2000. Critical habitat was initially 
determined to be not prudent (56 FR 58339, November 19, 1991, p. 58346) 
and later not determinable (58 FR 14330, March 17, 1993, p. 14338), but 
in 2001, in response to a legal challenge to the ``not determinable'' 
finding, the U.S. District Court for the Eastern District of Tennessee 
issued an order requiring the Service to propose and finalize critical 
habitat for 11 Mobile River Basin-listed mussels, including the 
southern acornshell. We subsequently published a final critical habitat 
rule on July 1, 2004 (69 FR 40084). Two 5-year reviews were completed 
in 2008 (initiated on June 14, 2005; see 70 FR 34492) and 2018 
(initiated on September 23, 2014; see 79 FR 56821), both recommending 
delisting the southern acornshell due to extinction. We solicited peer 
review from eight experts for both 5-year reviews from State, Federal, 
university, nongovernmental, and museum

[[Page 54321]]

biologists with known expertise and interest in Mobile River Basin 
mussels (Service 2008, pp. 36-37; Service 2018, p. 15); we received 
responses from five of the peer reviewers, who all concurred with the 
content and conclusion that the species is presumed extinct.
    The southern acornshell was described in 1857 from Othcalooga Creek 
in Gordon County, Georgia (58 FR 14330, March 17, 1993, p. 14331). 
Adult southern acornshells were round to oval in shape and 
approximately 1.2 inches in length (Service 2000, p. 57). Epioblasma 
othcaloogensis was included as a synonymy of E. penita and was 
considered to be an ectomorph of the latter (58 FR 14330, March 17, 
1993, p. 14331). Subsequent research classified the southern acornshell 
as distinct, belonging in a different subgenus; the species is 
distinguished from the upland combshell (E. metastriata) and the 
southern combshell (E. penita) by its smaller size, round outline, a 
poorly developed sulcus, and its smooth, shiny, yellow periostracum (58 
FR 14330, March 17, 1993, p. 14331). The Service recognizes Unio 
othcaloogensis (Lea) and Unio modicellus (Lea) as synonyms of 
Epioblasma othcaloogensis.
    The southern acornshell was historically found in shoals in small 
rivers to small streams in the Coosa and Cahaba river systems (Service 
2000, p. 57). As with many of the freshwater mussels in the Mobile 
River Basin, it was found in stable sand, gravel, cobble substrate in 
moderate to swift currents. The species had a sexual reproduction 
strategy and require a host fish to complete the life cycle. 
Historically, the species occurred in upper Coosa River tributaries and 
the Cahaba River in Alabama, Georgia, and Tennessee (Service 2000, p. 
57). In the upper Coosa River system, the southern acornshell occurred 
in the Conasauga River, Cowan's Creek, and Othcalooga Creek (58 FR 
14330, March 17, 1993, p. 14331). At the time of listing in 1993, the 
species was estimated to persist in low numbers in streams in the upper 
Coosa River drainage in Alabama and Georgia, and possibly in the Cahaba 
River (58 FR 14330, March 17, 1993, p. 14331; Service 2018, p. 6). The 
southern acornshell was last collected in 1973, from the Conasauga 
River in Georgia and from Little Canoe Creek, near the Etowah and St. 
Clair County line, Alabama. It has not been collected from the Cahaba 
River since the 1930s (Service 2018, p. 5).
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    Detection of rare, cryptic, benthic-dwelling animals like 
freshwater mussels is challenging, and can be affected by a variety of 
factors. Please refer to the Species Detectability section for the flat 
pigtoe above for the descriptions of these factors. The southern 
acornshell was small-sized (with very small juveniles) and most often 
found buried in sand, gravel, or cobble in fast flowing runs. However, 
mussels can be found in sub-optimal conditions, depending on where they 
dropped off of the host fish. Therefore, all of the detection 
considerations need to be accounted for when trying to detect this 
mussel species. Despite detection challenges, many well-planned, 
comprehensive surveys by experienced State and Federal biologists have 
not been able to locate extant populations of southern acornshell 
(Service 2000, p. 57; Service 2008, p. 20; Service 2018, p. 7).
Survey Effort
    Prior to listing, southern acornshell was observed during surveys 
in the upper Coosa River drainage in Alabama and Georgia in 1966-1968 
and in 1971-1973, by Hurd (58 FR 14330, March 17, 1993, p. 14331). 
Records of the species in the Cahaba River are from surveys at Lily 
Shoals in Bibb County, Alabama, in 1938, and from Buck Creek (Cahaba 
River tributary), Shelby County, Alabama, in the early 1900s (58 FR 
14330, March 17, 1993, p. 14331). Both the 2008 and 2018 5-year reviews 
reference multiple surveys by experienced Federal, State, and private 
biologists--17 survey reports from 1993-2006 and 6 survey reports from 
2008-2017--and despite these repeated surveys of historical habitat in 
both the Coosa and Cahaba River drainages, no living animals or fresh 
or weathered shells of the southern acornshell have been located 
(Service 2008, p. 19; Service 2018, p. 6).
Time Since Last Detection
    The most recent records for the southern acornshell were from 
tributaries of the Coosa River in 1966-1968 and 1974, and the Cahaba 
River in 1938 (58 FR 14330, March 17, 1993, p. 14331; Service 2008, p. 
19; Service 2018, p. 5). No living populations of the southern 
acornshell have been located since the 1970s (Service 2000, p. 57; 
Service 2008, p. 20; Service 2018, p. 7).
Other Considerations Applicable to the Species' Status
    Habitat modification was the major cause of decline of the southern 
acornshell (Service 2000, p. 57). Other threats included channel 
improvements such as clearing and snagging, as well as sand and gravel 
mining, diversion of flood flows, and water removal for municipal use; 
these activities impacted mussels by alteration of the river substrate, 
increasing sedimentation, alteration of water flows, and direct 
mortality from dredging and snagging (Service 2000, p. 6-13). Runoff 
from fertilizers and pesticides results in algal blooms and excessive 
growth of other aquatic vegetation, resulting in eutrophication and 
death of mussels due to lack of oxygen (Service 2000, p. 13). The 
cumulative impacts of habitat degradation likely lead to the southern 
acornshell populations becoming scattered and isolated over time. Low 
population levels mean increased difficulty for successful reproduction 
(Service 2000, p. 14). When individuals become scattered, the 
opportunity for a female southern acornshell to successfully fertilize 
eggs is diminished, and the spiral of failed reproduction leads to 
local extirpation and eventual extinction of the species (Service 2000, 
p. 14).
III. Analysis
    There has been no evidence of the continued existence of the 
southern acornshell for over five decades; the last known specimens 
were collected in the early 1970s. When listed in 1993, it was thought 
that the southern acornshell was likely to persist in low numbers in 
the upper Coosa River drainage and, possibly, in the Cahaba River. 
Numerous mussel surveys have been completed within these areas, as well 
as other areas within the historical range of the species since the 
listing, with no success. Although other federally listed mussels have 
been found by mussel experts during these surveys, no live or freshly 
dead specimens of the southern acornshell have been found (Service 
2018, p. 7). The species is presumed extinct.
IV. Conclusion
    We conclude that the southern acornshell is extinct and, therefore, 
should be delisted. This conclusion is based on significant alteration 
of known historical habitat and lack of detections during numerous 
surveys conducted throughout the species' range.

[[Page 54322]]

Stirrupshell (Quadrula stapes)

I. Background
    The stirrupshell (Quadrula stapes) was listed as endangered on 
April 7, 1987 (52 FR 11162), primarily due to habitat alteration from a 
free-flowing riverine system to an impounded system. The recovery plan 
(``Recovery Plan for Five Tombigbee River Mussels'') was completed on 
November 14, 1989. A supplemental recovery plan (``Mobile River Basin 
Aquatic Ecosystem Recovery Plan'') was completed on November 17, 2000. 
This plan did not replace the existing recovery plan; rather, it was 
intended to provide additional habitat protection and species husbandry 
recovery tasks. A 5-year review was announced on November 6, 1991 (56 
FR 56882); no changes were proposed for the status of the stirrupshell 
in that review. Two additional 5-year reviews were completed in 2009 
(initiated on September 8, 2006; see 71 FR 53127) and 2015 (initiated 
on March 25, 2014; see 79 FR 16366); both recommended delisting the 
stirrupshell due to extinction. We solicited peer review from six 
experts for both 5-year reviews from State, Federal, university, and 
museum biologists with known expertise and interest in Mobile River 
Basin mussels (Service 2009, pp. 23-24; Service 2015, pp. 15-16); we 
received responses from three of the peer reviewers, and they concurred 
with the content and conclusion that the species is presumed extinct.
    The stirrupshell was described as Unio stapes in 1831, from the 
Alabama River (Stansbery 1981, entire). Other synonyms are Margarita 
(Unio) stapes in 1836, Margaron (Unio) stapes in 1852, Quadrula stapes 
in 1900, and Orthonymus stapes in 1969 (Service 1989, pp. 2-3). Adult 
stirrupshells were quadrate in shape and reached a size of 
approximately 2 inches long and 2 inches wide. The stirrupshell 
differed from other closely related species by the presence of a sharp 
posterior ridge and truncated narrow rounded point posteriorly on its 
shell, and it had a tubercled posterior surface (Service 1989, p. 3; 
Service 2000, p. 85). Freshwater mussels of the Mobile River Basin, 
such as the stirrupshell, are most often found in clean, fast-flowing 
water in stable sand, gravel, and cobble gravel substrates that are 
free of silt (Service 2000, p. 85). They are typically found buried in 
the substrate in runs (Service 2000, p. 85). This type of habitat has 
been nearly eliminated in the Tombigbee River because of the 
construction of the Tennessee-Tombigbee Waterway, which created a 
dredged, straightened navigation channel and series of impoundments 
that inundated much of the riverine mussel habitat (Service 1989, p. 
1).
    The stirrupshell was historically found in the Tombigbee River from 
Columbus, Mississippi, downstream to Epes, Alabama; the Sipsey River, a 
tributary to the Tombigbee River in Alabama; the Black Warrior River in 
Alabama; and the Alabama River (Service 1989, p. 3). Surveys in 
historical habitat over the past three decades have failed to locate 
the species, as all historical habitat is impounded or modified by 
channelization and impoundments (Tombigbee and Alabama Rivers) or 
impacted by sediment and nonpoint pollution (Sipsey and Black Warrior 
Rivers) (Service 1989, p. 6; Service 2000, p. 85; Service 2015, p. 5). 
No live or freshly dead shells have been observed since the species was 
listed in 1987 (Service 2009, p. 6; Service 2015, p. 7). A freshly dead 
shell was last collected from the lower Sipsey River in 1986 (Service 
2000, p. 85).
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    Detection of rare, cryptic, benthic-dwelling animals like 
freshwater mussels is challenging, and can be affected by a variety of 
factors. Please refer to the Species Detectability section for the flat 
pigtoe above for the descriptions of these factors. The stirrupshell 
was medium-sized (with very small juveniles) and most often found 
buried in sand, gravel, or cobble in fast flowing runs. However, 
mussels can be found in sub-optimal conditions, depending on where they 
dropped off of the host fish. Therefore, all of the detection 
considerations need to be accounted for when trying to detect this 
mussel species. Despite detection challenges, many well-planned, 
comprehensive surveys by experienced State and Federal biologists have 
not been able to locate extant populations of stirrupshell (Service 
1989, pp. 3-4; Service 2000, p. 85; Service 2015, pp. 7-8).
Survey Effort
    Prior to listing in 1987, stirrupshell was collected in 1978, from 
the Sipsey River, and a 1984 and 1986 survey of the Sipsey River found 
freshly dead shells; a 1984 survey of the Gainesville Bendway of 
Tombigbee River found freshly dead shells of the stirrupshell (Service 
1989, p. 4; Service 2000, p. 85). After listing, surveys in 1988 and 
1990 only found weathered, relict shells of the stirrupshell from the 
Tombigbee River at the Gainesville Bendway and below Heflin Dam, which 
cast doubt on the continued existence of the species in the mainstem 
Tombigbee River (Service 1989, p. 4; Service 2009, p. 6). Over the past 
three decades, repeated surveys (circa 1988, 1998, 2001, 2002, 2003, 
2006, 2011) of unimpounded habitat in the Sipsey and Tombigbee Rivers, 
including intensive surveys of the Gainesville Bendway, have failed to 
find any evidence of stirrupshell (Service 2009, p. 6; Service 2015, p. 
7). The stirrupshell was also known from the Alabama River; however, 
over 92 hours of dive bottom time were expended searching appropriate 
habitats for imperiled mussel species between 1997-2007 without 
encountering the species (Service 2009, p. 6), and a survey of the 
Alabama River in 2011 also did not find stirrupshell (Service 2015, p. 
5). Surveys of the Black Warrior River in 1993 and from 2009-2012 (16 
sites) focused on finding federally listed and State conservation 
concern priority mussel species but did not find any stirrupshells 
(Miller 1994, pp. 9, 42; McGregor et al. 2009, p. 1; McGregor et al. 
2013, p. 1).
Time Since Last Detection
    The stirrupshell has not been collected alive since the Sipsey 
River was surveyed in 1978 (Service 1989, p. 4); one freshly dead shell 
was last collected from the Sipsey River in 1986 (Service 2000, p. 85). 
In the Tombigbee River, the stirrupshell has not been collected alive 
since completion of the Tennessee-Tombigbee Waterway in 1984 (Service 
2015, p. 7). Mussel surveys within the Tombigbee River drainage during 
1984-2015 failed to document the presence of the stirrupshell (Service 
2015, p. 8). The stirrupshell has not been found alive in the Black 
Warrior River or the Alabama River since the early 1980s (Service 1989, 
p. 3).
Other Considerations Applicable to the Species' Status
    Because the stirrupshell occurred in similar habitat type and area 
as the flat pigtoe, it faced similar threats. Please refer to the 
discussion for the flat pigtoe for more information.
III. Analysis
    There has been no evidence of the continued existence of the 
stirrupshell for nearly four decades; the last live individual was 
observed in 1978 and the last freshly dead specimen was from 1986. 
Mussel surveys within the Tombigbee River drainage (including the 
Sipsey and Black Warrior

[[Page 54323]]

tributaries) from 1984-2015, and the Alabama River from 1997-2007 and 
in 2011, have failed to document the presence of the species (Service 
2015, pp. 5, 8). All known historical habitat has been altered or 
degraded by impoundments and nonpoint source pollution, and the species 
is presumed extinct by most authorities.
IV. Conclusion
    We conclude that the stirrupshell is extinct and, therefore, should 
be delisted. This conclusion is based on significant alteration of all 
known historical habitat and lack of detections during numerous surveys 
conducted throughout the species' range.

Upland Combshell (Epioblasma metastriata)

I. Background
    The upland combshell, Epioblasma metastriata, was listed as 
endangered on March 17, 1993 (58 FR 14330), primarily due to habitat 
modification, sedimentation, and water quality degradation. The 
recovery plan (``Mobile River Basin Aquatic Ecosystem Recovery Plan'') 
was completed on November 17, 2000. Critical habitat was initially 
determined to be not prudent (56 FR 58339, November 19, 1991, p. 58346) 
and later not determinable (58 FR 14330, March 17, 1993, p. 14338), but 
in 2001, in response to a legal challenge to the ``not determinable'' 
finding, the U.S. District Court for the Eastern District of Tennessee 
issued an order requiring the Service to propose and finalize critical 
habitat for 11 Mobile River Basin-listed mussels, including the upland 
combshell. We subsequently published a final critical habitat rule on 
July 1, 2004 (69 FR 40084). Two 5-year reviews were completed in 2008 
(initiated on June 14, 2005; see 70 FR 34492) and 2018 (initiated on 
September 23, 2014; see 79 FR 56821), both recommending delisting the 
upland combshell due to extinction. We solicited peer review from eight 
experts for both 5-year reviews from State, Federal, university, 
nongovernmental, and museum biologists with known expertise and 
interest in Mobile River Basin mussels (Service 2008, pp. 36-37; 
Service 2018, p. 15); we received responses from five of the peer 
reviewers, who concurred with our conclusion that the species is 
presumed extinct.
    The upland combshell was described in 1838, from the Mulberry Fork 
of the Black Warrior River near Blount Springs, Alabama (58 FR 14330, 
March 17, 1993, p. 14331). Adult upland combshells were rhomboidal to 
quadrate in shape and were approximately 2.4 inches in length (58 FR 
14330, March 17, 1993, pp. 14330-14331). The upland combshell was 
considered to be a variation of the southern combshell (= penitent 
mussel, Epioblasma penita), and they were considered synonyms of each 
other (58 FR 14330, March 17, 1993, p. 14331). However, subsequent 
research identified morphological differences between the two, and both 
species were considered to be valid taxa; the upland combshell was 
distinguished from the southern combshell by the diagonally straight or 
gently rounded posterior margin of the latter, which terminated at the 
post-ventral extreme of the shell (58 FR 14330, March 17, 1993, p. 
14331). We recognize Unio metastriatus and Unio compactus as synonyms 
of Epioblasma metastriata (58 FR 14330, March 17, 1993, p. 14331).
    The upland combshell was historically found in shoals in rivers and 
large streams in the Black Warrior, Cahaba, and Coosa River systems 
above the Fall Line in Alabama, Georgia, and Tennessee (Service 2000, 
p. 61). As with many of the freshwater mussels in the Mobile River 
Basin, it was found in stable sand, gravel, and cobble in moderate to 
swift currents. The historical range included the Black Warrior River 
and tributaries (Mulberry Fork and Valley Creek); Cahaba River and 
tributaries (Little Cahaba River and Buck Creek); and the Coosa River 
and tributaries (Choccolocco Creek and Etowah, Conasauga, and Chatooga 
Rivers) (58 FR 14330, March 17, 1993, p. 14331). At the time of listing 
in 1993, the species was estimated to be restricted to the Conasauga 
River in Georgia, and possibly portions of the upper Black Warrior and 
Cahaba River drainages (58 FR 14330, March 17, 1993, p. 14331; Service 
2008, p. 19). The upland combshell was last collected in the Black 
Warrior River drainage in the early 1900s; in the Coosa River drainage 
in 1986, from the Conasauga River near the Georgia/Tennessee State 
line; and the Cahaba River drainage in the early 1970s (58 FR 14330, 
March 17, 1993, p. 14331; Service 2000, p. 61; Service 2018, p. 5).
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    Detection of rare, cryptic, benthic-dwelling animals like 
freshwater mussels is challenging, and can be affected by a variety of 
factors. Please refer to the Species Detectability section for the flat 
pigtoe above for the descriptions of these factors. The Upland 
combshell was small-sized (with very small juveniles) and most often 
found buried in sand, gravel, or cobble in fast flowing runs. However, 
mussels can be found in sub-optimal conditions, depending on where they 
dropped off of the host fish. Therefore, all of the detection 
considerations need to be accounted for when trying to detect this 
mussel species. Despite detection challenges, many well-planned, 
comprehensive surveys by experienced State and Federal biologists have 
not been able to locate extant populations of upland combshell (Service 
2008, p. 19; Service 2018, p. 5)
Survey Effort
    Prior to listing in 1993, upland combshell was observed during 
surveys in the Black Warrior River drainage in the early 1900s; 
repeated surveys in this drainage in 1974, 1980-1982, 1985, and 1990 
did not encounter the species (58 FR 14330, March 17, 1993, p. 14331). 
The upland combshell was observed in the Cahaba River drainage in 1938 
and in 1973, but a 1990 survey failed to find the species in the Cahaba 
River drainage (58 FR 14330, March 17, 1993, p. 14331). The species was 
observed in the upper Coosa River drainage in Alabama and Georgia in 
1966-1968, but not during 1971-1973 surveys; a single specimen was 
collected in 1988 from the Conasauga River (58 FR 14330, March 17, 
1993, p. 14331). Both the 2008 and 2018 5-year reviews reference 
multiple surveys by experienced Federal, State, and private 
biologists--18 survey reports from 1993-2006 and 10 survey reports from 
2008-2017--and despite these repeated surveys of historical habitat in 
the Black Warrior, Cahaba, and Coosa River drainages, no living animals 
or fresh or weathered shells of the upland combshell have been located 
(Service 2008, p. 19; Service 2018, p. 5).
Time Since Last Detection
    The most recent records for the upland combshell are many decades 
old: From tributaries of the Black Warrior in early 1900s, from the 
Cahaba River drainage in the early 1970s, and from the Coosa River 
drainage in the mid-1980s (58 FR 14330, March 17, 1993, p. 14331; 
Service 2008, p. 19; Service 2018, p. 5). No living populations of the 
upland combshell have been located since the mid-1980s (Service 2000, 
p. 61; Service 2008, p. 20; Service 2018, p. 7).
Other Considerations Applicable to the Species' Status
    Because the upland combshell occurred in similar habitat type and 
area

[[Page 54324]]

as the southern acornshell, it faced similar threats. Please refer to 
the discussion for the southern acornshell for more information on any 
other overarching consideration.
III. Analysis
    There has been no evidence of the continued existence of the upland 
combshell for over three decades; the last known specimens were 
collected in the late-1980s. When listed, it was thought that the 
upland combshell was likely restricted to the Conasauga River in 
Georgia, and possibly portions of the upper Black Warrior and Cahaba 
River drainages. Numerous mussel surveys have been completed within 
these areas, as well as other areas within the historical range of the 
species since the late-1980s, with no success. Although other federally 
listed mussels have been found by mussel experts during these surveys, 
no live or freshly dead specimens of the upland combshell have been 
found (Service 2018, p. 7). The species is presumed extinct.
IV. Conclusion
    We conclude that the upland combshell is extinct and, therefore, 
should be delisted. This conclusion is based on significant alteration 
of known historical habitat and lack of detections during numerous 
surveys conducted throughout the species' range.

Green Blossom (Epioblasma torulosa gubernaculum)

I. Background
    The green blossom (pearly mussel), Epioblasma torulosa 
gubernaculum, was listed as endangered on June 14, 1976 (41 FR 24062), 
and the final recovery plan was issued on July 9, 1984. At the time of 
listing, the single greatest factor contributing to the species' 
decline was the alteration and destruction of stream habitat due to 
impoundments. Two 5-year reviews were completed in 2007 (initiated on 
September 20, 2005; see 70 FR 55157) and 2017 (initiated on March 25, 
2014; see 79 FR 16366); both reviews recommended delisting due to 
extinction. For the 2017 5-year review, the Service solicited peer 
review from eight peer reviewers including Federal and State biologists 
with known expertise and interest in blossom pearly mussels (the green 
blossom was one of four species assessed in this 5-year review). All 
eight peer reviewers indicated there was no new information on the 
species, or that the species was presumed extirpated or extinct from 
their respective State(s) (USFWS 2017, pp. 8-9).
    The green blossom was described in 1865, with no type locality 
given for the species. However, all historical records indicate the 
species was restricted to the upper headwater tributary streams of the 
Tennessee River above Knoxville (USFWS 1983, pp. 1-2). The recovery 
plan described the green blossom as a medium-sized mussel with a 
lifespan up to 50 years. The shell outline was irregularly ovate, 
elliptical, or obovate. The green blossom was a sexually dimorphic, 
medium-sized species. Females were generally larger than the males and 
possessed a large, flattened, rounded swelling or expansion that 
extends from the middle of the base to the upper part of the posterior 
end. A comprehensive description of shell anatomy is provided in our 5-
year review and supporting documents (Parmalee and Bogan 1998, pp. 104-
107).
    The green blossom was always extremely rare and never had a wide 
distribution (USFWS 1984, p. 9). Freshwater mussels found within the 
Cumberland rivers and tributary streams, such as the green blossom, are 
most often observed in clean, fast-flowing water in substrates that 
contain relatively firm rubble, gravel, and sand substrates swept free 
from siltation (USFWS 1984, p. 5). They are typically found buried in 
substrate in shallow riffle and shoal areas. This type of habitat has 
been nearly eliminated by impoundment of the Tennessee and Cumberland 
Rivers and their headwater tributary streams (USFWS 1984, p. 9).
    The genus Epioblasma as a whole has suffered extensively because 
members of this genus are riverine, typically found only in streams 
that are shallow with sandy-gravel substrate and rapid currents 
(Stansbery 1972, pp. 45-46). Eight species of Epioblasma were presumed 
extinct at the time of the recovery plan, primarily due to 
impoundments, siltation, and pollution (USFWS 1984, p. 6).
    Stream impoundment affects species composition by eliminating those 
species not capable of adapting to reduced flows and altered 
temperatures. Tributary dams typically have storage impoundments with 
cold water discharges and sufficient storage volume to cause the stream 
below the dam to differ significantly from pre-impoundment conditions. 
These hypolimnial discharges result in altered temperature regimes, 
extreme water level fluctuations, reduced turbidity, seasonal oxygen 
deficits, and high concentrations of certain heavy metals (TVA 1980, 
entire).
    Siltation within the range of the green blossom, resulting from 
strip mining, coal washing, dredging, farming, and road construction, 
also likely severely affected the species. Since most freshwater 
mussels are riverine species that require clean, flowing water over 
stable, silt-free rubble, gravel, or sand shoals, smothering caused by 
siltation can be detrimental. The recovery plan indicated that 
siltation associated with poor agricultural practices and deforestation 
was probably the most significant factor impacting mussel communities 
(Fuller 1977, as cited in USFWS 1984, p. 12). The recovery plan also 
documented numerous coal operations within the range of the green 
blossom that have caused increased silt runoff, including in the Clinch 
River, where the last live specimen was collected in 1982 (USFWS 1984, 
pp. 12-13). Pollution, primarily from wood pulp, paper mills, and other 
industries, has also severely impacted many streams within the 
historical range of the species.
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    Detection of rare, cryptic, benthic-dwelling animals like 
freshwater mussels is challenging, and can be affected by a variety of 
factors. Please refer to the Species Detectability section for the flat 
pigtoe above for the descriptions of these factors. The green blossom 
was a medium-sized mussel most often found buried in substrate in 
shallow riffle and shoal areas. However, mussels can be found in sub-
optimal conditions, depending on where they dropped off of the host 
fish.
Survey Effort
    As of 1984, freshwater mussel surveys by numerous individuals had 
failed to document any living populations of green blossom in any 
Tennessee River tributary other than the Clinch River. The recovery 
plan cites several freshwater mussel surveys (which took place between 
1972 and 2005) of the Powell River; North, South, and Middle Forks of 
the Holston River; Big Moccasin Creek; Copper Creek; Nolichucky River; 
and French Broad River, all of which failed to find living or freshly 
dead green blossom specimens (USFWS 1984, p. 5). Annual surveys 
continue to be conducted in the Clinch River since 1972. Biologists 
conducting those surveys have not reported live or freshly dead 
individuals of the green blossom (Ahlstedt et al. 2016, entire; 
Ahlstedt et al. 2017, entire; Jones et al. 2014, entire; Jones et al. 
2018, entire).

[[Page 54325]]

Time Since Last Detection
    The last known record for the green blossom was a live individual 
collected in 1982, in the Clinch River at Pendleton Island, Virginia.
III. Analysis
    Habitat within the historical range of the green blossom has been 
significantly altered by water impoundments, siltation, and pollution, 
including at Pendleton Island on the Clinch River, the site of the last 
known occurrence of the species (Jones et al. 2018, pp. 36-56). The 
last known collection of the species was 38 years ago, and numerous 
surveys have been completed within the known range of the species over 
these 38 years. Although other federally listed mussels have been found 
by these experts during these surveys, no live or freshly dead 
specimens of the green blossom have been found (Ahlstedt et al. 2016, 
pp. 1-18; Ahlstedt et al. 2017, pp. 213-225). Mussel experts conclude 
that the species is likely to be extinct.
IV. Conclusion
    We conclude the green blossom is extinct and, therefore, should be 
delisted. This conclusion is based on lack of detections during surveys 
and searches conducted throughout the species' range since the green 
blossom was last observed in 1982, and the amount of significant 
habitat alteration that has occurred within the range of the species, 
rendering most of the species' historical habitat unlikely to support 
the species.

Tubercled Blossom (Epioblasma torulosa torulosa)

I. Background
    The tubercled blossom (pearly mussel), Epioblasma torulosa 
torulosa, was listed as endangered on June 14, 1976 (41 FR 24062), and 
the final recovery plan was completed on January 25, 1985. At the time 
of listing, the greatest factor contributing to the species' decline 
was the alteration and destruction of stream habitat due to 
impoundments. Two 5-year reviews were completed in 1991 (initiated on 
November 6, 1991; see 56 FR 56882) and 2011 (initiated on September 20, 
2005; see 70 FR 55157); both reviews recommended the species maintain 
its endangered status, although the 2011 review did conclude the 
species was likely extinct. The most recent 5-year review was completed 
in 2017 (initiated on March 25, 2014; see 79 FR 16366), indicated that 
the species was presumed extinct, and recommended delisting. The 
Service solicited peer review from three peer reviewers for the 2017 5-
year review from Federal and State biologists with known expertise and 
interest in blossom pearly mussels (the tubercled blossom was one of 
four species assessed in this 5-year review). All three peer reviewers 
indicated there was no new information on the species, all populations 
of the species were extirpated from their respective States, and the 
species was presumed extinct.
    The tubercled blossom was described as Amblema torulosa from the 
Ohio and Kentucky Rivers (Rafinesque 1820; referenced in USFWS 1985, p. 
2). All records for this species indicate it was widespread in the 
larger rivers of the eastern United States and southern Ontario, Canada 
(USFWS 1985, p. 2). Records for this species included the Ohio, 
Kanawha, Scioto, Kentucky, Cumberland, Tennessee, Nolichucky, Elk, and 
Duck Rivers (USFWS 1985, pp. 3-6). Historical museum records gathered 
subsequently add the Muskingum, Olentangy, Salt, Green, Barren, Wabash, 
White, East Fork White, and Hiwassee Rivers to its range (Service 2011, 
p. 5). The total historical range includes the States of Alabama, 
Illinois, Indiana, Kentucky, Ohio, Tennessee, and West Virginia. This 
species was abundant in archaeological sites along the Tennessee River 
in extreme northwestern Alabama, making it likely that the species also 
occurred in adjacent northeastern Mississippi where the Tennessee River 
borders that State (Service 2011, p. 5).
    The tubercled blossom was medium-sized, reaching about 3.6 inches 
(9.1 centimeters) in shell length, and could live as long as 50 years 
or more. The shell was irregularly egg-shaped or elliptical, slightly 
sculptured, and corrugated with distinct growth lines. The outer 
surface was smooth and shiny; was tawny, yellowish-green, or straw-
colored; and usually had numerous green rays (Parmalee and Bogan 1980, 
pp. 22-23).
    The genus Epioblasma as a whole has suffered extensively because 
members of this genus are characteristic riffle or shoal species, 
typically found only in streams that are shallow with sandy-gravel 
substrate and rapid currents (Parmalee and Bogan 1980, pp. 22-23). 
Eight species of Epioblasma were presumed extinct at the time of the 
1985 recovery plan. The elimination of these species has been 
attributed to impoundments, barge canals, and other flow alteration 
structures that have eliminated riffle and shoal areas (USFWS 1985, p. 
1).
    The single greatest factor contributing to the decline of the 
tubercled blossom is the alteration and destruction of stream habitat 
due to impoundments for flood control, navigation, hydroelectric power 
production, and recreation. Siltation is another factor that has 
severely affected the tubercled blossom. Increased silt transport into 
waterways due to strip mining, coal washing, dredging, farming, 
logging, and road construction increased turbidity and consequently 
reduced the depth of light penetration and created a blanketing effect 
on the substrate. The 1985 recovery plan documented numerous coal 
operations within the range of the tubercled blossom that were causing 
increased silt runoff. A third factor is the impact caused by various 
pollutants. An increasing number of streams throughout the blossom's 
range receive municipal, agricultural, and industrial waste discharges.
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    Detection of rare, cryptic, benthic-dwelling animals like 
freshwater mussels is challenging, and can be affected by a variety of 
factors. Please refer to the Species Detectability section for the flat 
pigtoe above for the descriptions of these factors. The tubercled 
blossom was a large-river species most often found inhabiting parts of 
those rivers that are shallow with sandy-gravel substrate and rapid 
currents. However, mussels can be found in sub-optimal conditions, 
depending on where they dropped off of the host fish.
Survey Effort
    All three rivers where the species was last located have been 
extensively sampled in the intervening years without further evidence 
of this species' occurrence, including Kanawha River, Nolichucky River, 
and Green River (Service 2011, p. 5).
    Based on this body of survey information in large rivers in the 
Ohio River system, investigators have been considering this species as 
possibly extinct since the mid-1970s. Probably the best reach of 
potential habitat remaining may be in the lowermost 50 miles of the 
free-flowing portion of the Ohio River, in Illinois and Kentucky. This 
reach is one of the last remnants of large-river habitat remaining in 
the entire historical range of the tubercled blossom. In our 2011 5-
year review for the tubercled blossom, we hypothesized that this mussel 
might be found in this stretch of the Ohio River. Unfortunately, mussel 
experts have not reported any new collections of the species (USFWS 
2017, p. 8). Additionally, State biologists have conducted extensive

[[Page 54326]]

surveys within the Kanawha Falls area of the Kanawha River since 2005, 
and have found no evidence that the tubercled blossom still occurs 
there (USFWS 2017, p. 4). This species is presumed extirpated.
Time Since Last Detection
    The last individuals were collected live or freshly dead in 1969, 
in the Kanawha River, West Virginia, below Kanawha Falls; in 1968, in 
the Nolichucky River, Tennessee; and in 1963, in the Green River, 
Kentucky.
III. Analysis
    The tubercled blossom has not been seen since 1969, despite 
extensive survey work in nearly all of the rivers of historical 
occurrence, prompting many investigators to consider this species as 
possibly extinct. According to the last two 5-year reviews, experts 
indicate that the species is presumed extinct throughout its range.
IV. Conclusion
    We conclude the tubercled blossom is extinct and, therefore, should 
be delisted. This conclusion is based on the lack of detections during 
surveys and searches conducted throughout the species' range since the 
tubercled blossom was last sighted in 1969, and the significant habitat 
alteration that has occurred within the range of the species, rendering 
most of the species' habitat unable to support the life-history needs 
of the species.

Turgid Blossom (Epioblasma turgidula)

I. Background
    The turgid blossom (pearly mussel), Epioblasma turgidula, was 
listed as endangered on June 14, 1976 (41 FR 24062), and the final 
recovery plan was completed on January 25, 1985 (USFWS 1985). At the 
time of listing, the single greatest factor contributing to the 
species' decline was the alteration and destruction of stream habitat 
due to impoundments. Two 5-year reviews were completed in 2007 
(initiated on September 20, 2005; see 70 FR 55157) and 2017 (initiated 
on August 30, 2016; see 81 FR 59650); both reviews recommended 
delisting due to extinction. The Service solicited peer review from 
eight peer reviewers for the 2017 5-year review from Federal and State 
biologists with known expertise and interest in blossom pearly mussels 
(the turgid blossom was one of four species assessed in this 5-year 
review). All eight peer reviewers indicated there was no new 
information on the species, all populations of the species were 
extirpated from their respective States, and the species was presumed 
extinct.
    The turgid blossom was described (Lea 1858; referenced in USFWS 
1985, p. 2) as Unio turgidulus from the Cumberland River, Tennessee, 
and the Tennessee River, Florence, Alabama. According to the recovery 
plan, this species was historically relatively widespread with a 
disjunct distribution occurring in both the Cumberlandian and Ozarkian 
Regions (USFWS 1985, p. 7). It has been reported from the Tennessee 
River and tributary streams including Shoal and Bear Creeks, and Elk, 
Duck, Holston, Clinch, and Emory Rivers (Ortmann 1918, 1924, 1925; 
Stanberry 1964, 1970, 1971, 1976a; Johnson 1978, as cited in USFWS 
2017, entire). Additional records are reported from the Cumberland 
River (Ortmann 1918; Clench and van der Schalie 1944; Johnson 1978, as 
cited in USFWS 2017, entire) and from the Ozark Mountain Region, 
including Spring Creek, and Black and White Rivers (Simpson 1914; 
Johnson 1978, as cited in USFWS 2017, entire).
    The turgid blossom was a medium-river, Cumberlandian-type mussel 
that was also reported from the Ozarks. These mussels could live as 
long as 50 years or more. The species was strongly dimorphic; males and 
females differed in shape and structure. This species seldom exceeded 
1.6 inches (4.1 centimeters) in shell length. Shells of the male tended 
to be more elliptical or oval, while females tended to be more rounded. 
Valves were inequilateral, solid, and slightly inflated. The outer 
shell was shiny yellowish-green with numerous fine green rays over the 
entire surface. The shell surface was marked by irregular growth lines 
that are especially strong on females. The inner shell surface was 
bluish-white (Parmalee and Bogan 1980, pp. 22-23).
    The genus Epioblasma as a whole has suffered extensively because 
members of this genus are characteristic riffle or shoal species, 
typically found only in streams that are shallow with sandy-gravel 
substrate and rapid currents (Parmalee and Bogan 1980, pp. 22-23). 
Eight species of Epioblasma were presumed extinct at the time of the 
1985 recovery plan. The elimination of these species has been 
attributed to impoundments, barge canals, and other flow alteration 
structures that have eliminated riffle and shoal areas (USFWS 1985, p. 
1). The last known population of the turgid blossom occurred in the 
Duck River and was collected in 1972, at Normandy (Ahlstedt 1980, pp. 
21-23). Field notes associated with this collection indicate that it 
was river-collected 100 yards above an old iron bridge. Water at the 
bridge one mile upstream was very muddy, presumably from dam 
construction above the site (Ahlstedt et al. 2017, entire). 
Additionally, surveys in the 1960s of the upper Cumberland Basin 
indicated an almost total elimination of the genus Epioblasma, 
presumably due to mine wastes (Neel and Allen 1964, as cited in USFWS 
1985, p. 10).
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    Detection of rare, cryptic, benthic-dwelling animals like 
freshwater mussels is challenging, and can be affected by a variety of 
factors. Please refer to the Species Detectability section for the flat 
pigtoe above for the descriptions of these factors. The turgid blossom 
was a small-sized mussel most often found buried in substrate in 
shallow riffle and shoal areas. However, mussels can be found in sub-
optimal conditions, depending on where they dropped off of the host 
fish.
Survey Effort
    This species has not been found in freshwater mussel surveys 
conducted on the Duck River since the time of the Normandy Dam 
construction (Ahlstedt 1980, pp. 21-23), nor has it been reported from 
any other stream or river system. The most recent 5-year review notes 
that the Tennessee Wildlife Resources Agency had completed or funded 
surveys (1972-2005) for blossom pearly mussels in the Cumberland, 
Tennessee, Clinch, Duck, Elk, Emory, Hiwassee, Little, and Powell 
Rivers, yet there were no recent records of turgid blossom (USFWS 2017, 
p. 4). Surveys in the Ozarks have not observed the species since the 
early 1900s (USFWS 1985, p. 7).
Time Since Last Detection
    The last known collection of the turgid blossom was a freshly dead 
specimen found in the Duck River, Tennessee, in 1972 by a biologist 
with the TVA. The species has not been seen in the Ozarks since the 
early 1900s (USFWS 1985, p. 7).
III. Analysis
    Habitat within the historical range of the turgid blossom has been 
significantly altered by water impoundments, siltation, and pollution. 
The last known collection of the species was more than 45 years ago. 
Mussel experts conclude that the species is likely to be extinct. 
Numerous surveys have been completed within the known range of the 
species over the years. Although other federally listed mussels have 
been found by experts during these

[[Page 54327]]

surveys, no live or freshly dead specimens of the turgid blossom have 
been found.
IV. Conclusion
    We conclude the turgid blossom is extinct and, therefore, should be 
delisted. This conclusion is based on the lack of detections during 
surveys and searches conducted throughout the species' range since the 
turgid blossom was last sighted in 1972, and the significant habitat 
alteration that occurred within the range of the species, rendering 
most of the species' habitat unlikely to support the species.

Yellow Blossom (Epioblasma florentina florentina)

I. Background
    The yellow blossom (pearly mussel), Epioblasma florentina 
florentina, was listed as endangered on June 14, 1976 (41 FR 24062), 
and the final recovery plan was completed on January 25, 1985. At the 
time of listing, the single greatest factor contributing to the 
species' decline was the alteration and destruction of stream habitat 
due to impoundments. Two 5-year reviews were completed in 2007 
(initiated on September 20, 2005; see 70 FR 55157) and 2017 (initiated 
on March 25, 2014; see 79 FR 16366); both reviews recommended delisting 
due to extinction. The Service solicited peer review from eight peer 
reviewers for the 2017 5-year review from Federal and State biologists 
with known expertise and interest in blossom pearly mussels (the yellow 
blossom was one of four species assessed in this 5-year review). All 
eight peer reviewers indicated there was no new information on the 
species, all populations of the species were extirpated from their 
respective States, and the species was presumed extinct.
    The yellow blossom was described (Lea 1857; referenced in USFWS 
1985, pp. 2-3) as Unio florentinus from the Tennessee River, Florence 
and Lauderdale Counties, Alabama, and the Cumberland River, Tennessee. 
According to the recovery plan, this species was a Cumberlandian-type 
mussel historically widespread in the Tennessee and Cumberland Rivers 
and tributaries to the Tennessee River. The yellow blossom was reported 
from Hurricane, Limestone, Bear, and Cypress Creeks, all tributary 
streams to the Tennessee River in northern Alabama (Ortmann 1925 p. 
362; Bogan and Parmalee 1983, p. 23). This species was also reported 
from larger tributary streams of the lower and upper Tennessee River, 
including the Flint, Elk, and Duck Rivers (Isom et al. 1973, p. 439; 
Bogan and Parmalee 1983, pp. 22-23) and the Holston, Clinch, and Little 
Tennessee Rivers (Ortmann 1918, pp. 614-616). Yellow blossoms 
apparently occurred throughout the Cumberland River (Wilson and Clark 
1914, p. 46; Ortmann 1918, p. 592; Neel and Allen 1964, p. 448).
    The yellow blossom seldom achieved more than 2.4 inches (6 
centimeters) in length. The slightly inflated valves were of unequal 
length, and the shell surface was marked by uneven growth lines. The 
shell was a shiny honey-yellow or tan with numerous green rays 
uniformly distributed over the surface. The inner shell surface was 
bluish-white (Bogan and Parmalee 1983, pp. 22-23).
    The genus Epioblasma as a whole has suffered extensively because 
members of this genus are characteristic riffle or shoal species, 
typically found only in streams that are shallow with sandy-gravel 
substrate and rapid currents (Bogan and Parmalee 1983, pp. 22-23). 
Eight species of Epioblasma were presumed extinct at the time of the 
1985 recovery plan. The elimination of these species has been 
attributed to impoundments, barge canals, and other flow alteration 
structures that have eliminated riffle and shoal areas (USFWS 1985, p. 
1).
    The single greatest factor contributing to the decline of the 
yellow blossom, not only in the Tennessee Valley but in other regions 
as well, is the alteration and destruction of stream habitat due to 
impoundments for flood control, navigation, hydroelectric power 
production, and recreation. Siltation is another factor that has 
severely affected the yellow blossom. Increased silt transport into 
waterways due to strip mining, coal washing, dredging, farming, 
logging, and road construction increased turbidity and consequently 
reduced light penetration, creating a blanketing effect on the 
substrate. The 1985 recovery plan documented numerous coal operations 
within the range of the yellow blossom. A third factor is the impact 
caused by various pollutants. An increasing number of streams 
throughout the mussel's range receive municipal, agricultural, and 
industrial waste discharges (USFWS 2017, p. 5).
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    Detection of rare, cryptic, benthic-dwelling animals like 
freshwater mussels is challenging, and can be affected by a variety of 
factors. Please refer to the Species Detectability section for the flat 
pigtoe above for the descriptions of these factors. The yellow blossom 
was a small-sized mussel most often found buried in substrate in 
shallow riffle and shoal areas. However, mussels can be found in sub-
optimal conditions, depending on where they dropped off of the host 
fish.
Survey Effort
    Since the last recorded collections in the mid-1960s, numerous 
mussel surveys (1872-2005) have been done by mussel biologists from the 
TVA, Virginia Tech, U.S. Geological Survey, and others in rivers 
historically containing the species. Biologists conducting those 
surveys have not reported live or freshly dead individuals of the 
yellow blossom.
Time Since Last Detection
    This species was last collected live from Citico Creek in 1957, and 
the Little Tennessee River in the 1966 (Bogan and Parmalee, 1983, p. 
23), and archeological shell specimens were collected from the 
Tennessee and Cumberland Rivers between 1976-1979 (Parmalee et al. 
1980, entire).
III. Analysis
    Habitat within the historical range of the yellow blossom has been 
significantly altered by water impoundments, siltation, and pollution. 
The last known collection of the species was over 50 years ago. Mussel 
experts conclude that the species is likely to be extinct. Numerous 
surveys have been completed within the known range of the species over 
the years. Although other federally listed mussels have been found by 
these experts during these surveys, no live or freshly dead specimens 
of the yellow blossom have been found.
IV. Conclusion
    We conclude the yellow blossom is extinct and, therefore, should be 
delisted. This conclusion is based on lack of detections during surveys 
conducted throughout the species' range since the yellow blossom was 
last sighted in the mid-1960s and on the significant habitat alteration 
that occurred within the range of the species, rendering most of the 
species' habitat unlikely to support the species.

Plants

Phyllostegia glabra var. lanaiensis

I. Background
    Phyllostegia glabra var. lanaiensis was listed as endangered on 
September 20, 1991 (56 FR 47686), and was included in the Lanai plant 
cluster recovery plan in 1995 (USFWS 1995).

[[Page 54328]]

At the time of listing, no wild individuals had been seen since 1914, 
although there was one questionable sighting from the 1980s that was 
later considered to be P. glabra var. glabra (USFWS 1995; 2012). 
Threats included habitat degradation and herbivory by feral ungulates, 
the establishment of ecosystem-altering invasive plant species, and the 
consequences of small population sizes (low numbers) (USFWS 1995). In 
2000, designation of critical habitat was considered not prudent for P. 
glabra var. lanaiensis because this plant had not been observed in the 
wild in over 20 years and no viable genetic material was available for 
recovery efforts (65 FR 82086; December 27, 2000). Two 5-year status 
reviews have been completed; the 2012 review (initiated on April 8, 
2010; see 75 FR 17947) recommended surveys within the historical range 
and within suitable habitat on Lanai, with no change in status. Despite 
repeated surveys of historical and suitable habitat by botanists since 
2006, P. glabra var. lanaiensis has not been found (Plant Extinction 
Prevention Program (PEPP) 2012; Oppenheimer 2019, in litt.). In 2012, 
PEPP reported that P. glabra var. lanaiensis was likely extinct. The 5-
year status review completed in 2019 (initiated on February 12, 2016; 
see 81 FR 7571) recommended delisting due to extinction.
    Historically, P. glabra var. lanaiensis was known from only two 
collections from Lanai, one from the ``mountains of Lanai,'' and the 
other from Kaiholena Gulch, where it was last collected in 1914 (USFWS 
1991, 1995, 2003; Wagner 1999; Hawaii Biodiversity and Mapping Program 
2010). A report of this species from the early 1980s in a gulch feeding 
into the back of Maunalei Valley probably was erroneous and likely P. 
glabra var. glabra (USFWS 1995, 2003; Wagner 1999, p. 269). Very little 
is known of the preferred habitat or associated species of P. glabra 
var. lanaiensis on the island of Lanai. It has been observed in lowland 
mesic to wet forest in gulch bottoms and sides, often in quite steep 
areas, in the same habitat as the endangered Cyanea macrostegia ssp. 
gibsonii (listed as C. gibsonii) (USFWS 1995).
    Phyllostegia glabra var. lanaiensis was a short-lived perennial 
herb. Flowering cycles, pollination vectors, seed dispersal agents, 
longevity, specific environmental requirements, and limiting factors of 
P. glabra var. lanaiensis remain unknown (USFWS 1995, 2003). P. glabra 
var. lanaiensis was described as a variety of P. glabra from specimens 
collected from Lanai by Ballieu, Munro, and Mann and Brigham. It 
differed from P. glabra var. glabra in its longer calyx (the collection 
of modified leaves that enclose the petals and other parts of a flower) 
(0.3 inches or 10-11 millimeters) and narrowly lanceolate leaves 
(Wagner et al. 1990, p. 816). No taxonomic changes have been made since 
the variety was described in 1934.
II. Information on Detectability, Survey Effort, and Time Since Last 
Detection
Species Detectability
    Phyllostegia glabra var. lanaiensis was a short-lived perennial 
herb. This taxon differed from the other variety by its longer calyces 
and narrowly lanceolate leaves, suggesting that flowers should be 
present in order to confirm identification. Most congeners tend to 
flower year-round, with peak flowering from April through June, 
indicating that it would be easier to detect and confirm the species 
during this time period.
Survey Effort
    The PEPP surveys and monitors rare plant species on Lanai; 
botanical surveys are conducted on a rotational basis, based on the 
needs for collections and monitoring. Opportunistic surveying is also 
conducted when botanists are within the known range and suitable 
habitat when other work brings them to that area. No observations of P. 
glabra var. lanaiensis have been reported since 1914. By 2012, PEPP 
determined that this variety was likely extirpated (PEPP 2012), with 
very little chance of rediscovery due to the restricted known range, 
thorough search effort, and extent of habitat degradation. However, 
botanists were still searching for this taxon on any surveys in or near 
its last known location and other suitable habitat, as recently as 
January 2019 (Oppenheimer 2019, in litt.).
Time Since Last Detection
    All P. glabra identified since 1914 have been determined to be P. 
glabra var. glabra, and, therefore, P. glabra var. lanaiensis has not 
been detected since 1914.
III. Analysis
    Threats to the species included habitat degradation and herbivory 
by feral ungulates, the establishment of ecosystem-altering invasive 
plant species, and the consequences of small population sizes. Despite 
repeated surveys of historical and suitable habitat by botanists from 
2006 through 2019, P. glabra var. lanaiensis has not been found since 
1914 (PEPP 2012; Oppenheimer 2019, in litt.). In 2012, PEPP reported 
that P. glabra var. lanaiensis was likely extinct. In 2019, the species 
was included on the list of possibly extinct Hawaiian vascular plant 
taxa (Wood et al. 2019).
IV. Conclusion
    At the time of listing in 1991, P. glabra var. lanaiensis had not 
been detected in over 75 years. Since its last detection in 1914, 
botanical surveys have not detected the species. Available information 
indicates that the species was not able to persist in the face of 
environmental stressors, and we conclude that the best available 
scientific and commercial information indicates that the species is 
extinct.

Required Determinations

Clarity of the Rule

    We are required by Executive Orders 12866 and 12988 and by the 
Presidential Memorandum of June 1, 1998, to write all rules in plain 
language. This means that each rule we publish must:

    (1) Be logically organized;
    (2) Use the active voice to address readers directly;
    (3) Use clear language rather than jargon;
    (4) Be divided into short sections and sentences; and
    (5) Use lists and tables wherever possible.

    If you feel that we have not met these requirements, send us 
comments by one of the methods listed in ADDRESSES. To better help us 
revise the rule, your comments should be as specific as possible. For 
example, you should tell us the names of the sections or paragraphs 
that are unclearly written, which sections or sentences are too long, 
the sections where you feel lists or tables would be useful, etc.

National Environmental Policy Act (42 U.S.C. 4321 et seq.)

    We have determined that environmental assessments and environmental 
impact statements, as defined under the authority of the National 
Environmental Policy Act (NEPA; 42 U.S.C. 4321 et seq.), need not be 
prepared in connection with regulations adopted pursuant to section 
4(a) of the Act. We published a notice outlining our reasons for this 
determination in the Federal Register on October 25, 1983 (48 FR 
49244). This position was upheld by the U.S. Court of Appeals for the 
Ninth Circuit (Douglas County v. Babbitt, 48 F.3d 1495 (9th Cir. 1995), 
cert. denied 516 U.S. 1042 (1996)).

Government-To-Government Relationship With Tribes

    In accordance with the President's memorandum of April 29, 1994

[[Page 54329]]

(Government-to-Government Relations with Native American Tribal 
Governments; 59 FR 22951), Executive Order 13175 (Consultation and 
Coordination with Indian Tribal Governments), and the Department of the 
Interior's manual at 512 DM 2, we readily acknowledge our 
responsibility to communicate meaningfully with recognized Federal 
Tribes on a government-to-government basis. In accordance with 
Secretarial Order 3206 of June 5, 1997 (American Indian Tribal Rights, 
Federal-Tribal Trust Responsibilities, and the Endangered Species Act), 
we readily acknowledge our responsibilities to work directly with 
Tribes in developing programs for healthy ecosystems, to acknowledge 
that Tribal lands are not subject to the same controls as Federal 
public lands, to remain sensitive to Indian culture, and to make 
information available to Tribes. The Seminole Tribe of Florida and the 
Miccousukee Tribe has expressed interest in the Bachman's warbler. We 
have reached out to these tribes by providing an advance notification 
prior to the publication of the proposed rule. We will continue to work 
with these and any other Tribal entities that expressed interest in 
these species during the development of a final rule to delist these 
species.

References Cited

    Lists of the references cited in in this document are available on 
the internet at http://www.regulations.gov in the dockets provided 
above under Public Comments and upon request from the appropriate 
person, as specified under FOR FURTHER INFORMATION CONTACT.

Authors

    The primary authors of this document are the staff members of the 
Branch of Delisting and Foreign Species, Ecological Services Program, 
as well as the staff of the Ecological Services Field Offices as 
specified under FOR FURTHER INFORMATION CONTACT.

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
recordkeeping requirements, Transportation.

Proposed Regulation Promulgation

    Accordingly, we hereby propose to amend part 17, subchapter B of 
chapter I, title 50 of the Code of Federal Regulations, as set forth 
below:

PART 17--ENDANGERED AND THREATENED WILDLIFE AND PLANTS

0
1. The authority citation for part 17 continues to read as follows:

    Authority:  16 U.S.C. 1361-1407; 1531-1544; and 4201-4245, 
unless otherwise noted.


Sec.  17.11  [Amended]

0
2. Amend Sec.  17.11(h), the List of Endangered and Threatened 
Wildlife:
0
a. Under MAMMALS, by removing the entry for ``Bat, little Mariana 
fruit'';
0
b. Under BIRDS, by removing the entries for ``Akepa, Maui'', ``Akialoa, 
Kauai'', ``Creeper, Molokai'', ``Nukupuu, Kauai'', ``Nukupuu'', Maui'', 
`` `O`o, Kauai (honeyeater)'', ``Po`ouli (honeycreeper)'', ``Thrush, 
large Kauai'', ``Warbler (wood), Bachman's'', ``White-eye, bridled'', 
and ``Woodpecker, ivory-billed'';
0
c. Under FISHES, by removing the entries for ``Gambusia, San Marcos'' 
and ``Madtom, Scioto''; and
0
d. Under CLAMS, by removing the entries for ``Acornshell, southern'' 
and ``Blossom, green''; both entries for ``Blossom, tubercled'', 
``Blossom, turgid'', and ``Blossom, yellow''; and the entries for 
``Combshell, upland'', ``Pigtoe, flat'', and ``Stirrupshell''.


Sec.  17.12  [Amended]

0
3. Amend Sec.  17.12(h), the List of Endangered and Threatened Plants, 
under FLOWERING PLANTS, by removing the entry for ``Phyllostegia glabra 
var. lanaiensis''.


Sec.  17.85  [Amended]

0
4. Amend Sec.  17.85(a) by:
0
a. In the heading, removing the word ``Seventeen'' and adding in its 
place the word ``Fourteen'';
0
b. In the table, removing the entries for ``tubercled blossom (pearly 
mussel)'', ``turgid blossom (pearly mussel)'', and ``yellow blossom 
(pearly mussel)'';
0
c. In paragraph (a)(1)(i), by removing the number ``17'' and adding in 
its place the number ``14'';
0
d. In paragraph (a)(1)(ii), by removing the number ``17'' and adding in 
its place the number ``14''; and
0
e. In paragraph (a)(2)(iii), by removing the number ``17'' and adding 
in its place the number ``14''.


Sec.  17.95  [Amended]

0
4. Amend Sec.  17.95 by:
0
a. In paragraph (e), removing the entry for ``San Marcos Gambusia 
(Gambusia georgei)''; and
0
b. In paragraph (f), the entry for, ``Eleven Mobile River Basin Mussel 
Species: Southern Acornshell (Epioblasma othcaloogensis), Ovate 
Clubshell (Pleurobema perovatum), Southern Clubshell (Pleurobema 
decisum), Upland Combshell (Epioblasma metastriata), Triangular 
Kidneyshell (Ptychobranchus greenii), Alabama Moccasinshell (Medionidus 
acutissimus), Coosa Moccasinshell (Medionidus parvulus), Orange-nacre 
Mucket (Lampsilis perovalis), Dark Pigtoe (Pleurobema furvum), Southern 
Pigtoe (Pleurobema georgianum), and Fine-lined Pocketbook (Lampsilis 
altilis)'', revising the entry's heading, the first sentence of the 
introductory text of paragraph (f)(1), the introductory text of 
paragraph (f)(2)(i), the table at paragraph (f)(2)(ii), the 
introductory text of paragraph (f)(2)(xiv), paragraph (f)(2)(xiv)(B), 
the introductory text of paragraph (f)(2)(xv), paragraph (f)(2)(xv)(B), 
the introductory text of paragraph (f)(2)(xx), paragraph (f)(2)(xx)(B), 
the introductory text of paragraph (f)(2)(xxi), paragraph 
(f)(2)(xxi)(B), the introductory text of paragraph (f)(2)(xxiii), 
paragraph (f)(2)(xxiii)(B), the introductory text of paragraph 
(f)(2)(xxvi), paragraph (f)(2)(xxvi)(B), the introductory text of 
paragraph (f)(2)(xxvii), paragraph (f)(2)(xxvii)(B), the introductory 
text of paragraph (f)(2)(xxviii), and paragraph (f)(2)(xxviii)(B) to 
read as follows:


Sec.  17.95   Critical habitat--fish and wildlife.

* * * * *
    (f) Clams and Snails.
* * * * *
    Nine Mobile River Basin Mussel Species: Ovate clubshell (Pleurobema 
perovatum), southern clubshell (Pleurobema decisum), triangular 
kidneyshell (Ptychobranchus greenii), Alabama moccasinshell (Medionidus 
acutissimus), Coosa moccasinshell (Medionidus parvulus), orange-nacre 
mucket (Lampsilis perovalis), dark pigtoe (Pleurobema furvum), southern 
pigtoe (Pleurobema georgianum), and fine-lined pocketbook (Lampsilis 
altilis)
    (1) The primary constituent elements essential for the conservation 
of the ovate clubshell (Pleurobema perovatum), southern clubshell 
(Pleurobema decisum), triangular kidneyshell (Ptychobranchus greenii), 
Alabama moccasinshell (Medionidus acutissimus), Coosa moccasinshell 
(Medionidus parvulus), orange-nacre mucket (Lampsilis perovalis), dark 
pigtoe (Pleurobema furvum), southern pigtoe (Pleurobema georgianum), 
and fine-lined pocketbook (Lampsilis altilis) are those habitat 
components that support feeding, sheltering, reproduction, and physical 
features for maintaining the natural processes that support these 
habitat components. * * *
    (2) * * *
    (i) Index map. The index map showing critical habitat units in the 
States of Mississippi, Alabama, Georgia, and Tennessee for the nine 
Mobile River Basin mussel species follows:

[[Page 54330]]

    (ii) * * *

----------------------------------------------------------------------------------------------------------------
                 Species                             Critical habitat units                     States
----------------------------------------------------------------------------------------------------------------
Ovate clubshell (Pleurobema perovatum)...  Units 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,   AL, GA, MS, TN.
                                            12, 13, 17, 18, 19, 21, 24, 25, 26.
Southern clubshell (Pleurobema decisum)..  Units 1, 2, 3, 4, 5, 6, 7, 8, 9, 13, 14,   AL, GA, MS, TN.
                                            15, 17, 18, 19, 21, 24, 25, 26.
Triangular kidneyshell (Ptychobranchus     Units 10, 11, 12, 13, 18, 19, 20, 21, 22,  AL, GA, TN.
 greenii).                                  23, 24, 25, 26.
Alabama moccasinshell (Medionidus          Units 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,   AL, GA, MS, TN.
 acutissimus).                              12, 13, 15, 25, 26.
Coosa moccasinshell (Medionidus parvulus)  Units 18, 19, 20, 21, 22, 23, 24, 25, 26.  AL, GA, TN.
Orange-nacre mucket (Lampsilis perovalis)  Units 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,   AL, MS.
                                            12, 13, 14, 15.
Dark pigtoe (Pleurobema furvum)..........  Units 10, 11, 12.........................  AL.
Southern pigtoe (Pleurobema georgianum)..  Units 18, 19, 20, 21, 22, 23, 24, 25, 26.  AL, GA, TN.
Fine-lined pocketbook (Lampsilis altilis)  Units 13, 16, 17, 18, 19, 20, 21, 22, 23,  AL, GA, TN.
                                            24, 25, 26.
----------------------------------------------------------------------------------------------------------------

* * * * *
    (xiv) Unit 12. Locust Fork and Little Warrior Rivers, Jefferson, 
Blount Counties, Alabama. This is a critical habitat unit for the ovate 
clubshell, triangular kidneyshell, Alabama moccasinshell, orange-nacre 
mucket, and dark pigtoe.
* * * * *
    (B) Map of Unit 12 follows:
BILLING CODE 4333-15-P

[[Page 54331]]

[GRAPHIC] [TIFF OMITTED] TP30SE21.004

    (xv) Unit 13. Cahaba River and Little Cahaba River, Jefferson, 
Shelby, Bibb Counties, Alabama. This is a critical habitat unit for the 
ovate clubshell, southern clubshell, triangular kidneyshell, Alabama 
moccasinshell, orange-nacre mucket, and fine-lined pocketbook.
* * * * *
    (B) Map of Unit 13 follows:

[[Page 54332]]

[GRAPHIC] [TIFF OMITTED] TP30SE21.005

* * * * *
    (xx) Unit 18. Coosa River (Old River Channel) and Terrapin Creek, 
Cherokee, Calhoun, Cleburne Counties, Alabama. This is a critical 
habitat unit for the ovate clubshell, southern clubshell, triangular 
kidneyshell, Coosa moccasinshell, southern pigtoe, and fine-lined 
pocketbook.
* * * * *
    (B) Map of Unit 18 follows:

[[Page 54333]]

[GRAPHIC] [TIFF OMITTED] TP30SE21.006

    (xxi) Unit 19. Hatchet Creek, Coosa, Clay Counties, Alabama. This 
is a critical habitat unit for the ovate clubshell, southern clubshell, 
triangular kidneyshell, Coosa moccasinshell, southern pigtoe, and fine-
lined pocketbook.
* * * * *
    (B) Map of Unit 19 follows:

[[Page 54334]]

[GRAPHIC] [TIFF OMITTED] TP30SE21.007

* * * * *
    (xxiii) Unit 21. Kelly Creek and Shoal Creek, Shelby, St. Clair 
Counties, Alabama. This is a critical habitat unit for the ovate 
clubshell, southern clubshell, triangular kidneyshell, Coosa 
moccasinshell, southern pigtoe, and fine-lined pocketbook.
* * * * *
    (B) Map of Unit 21 follows:

[[Page 54335]]

[GRAPHIC] [TIFF OMITTED] TP30SE21.008

* * * * *
    (xxvi) Unit 24. Big Canoe Creek, St. Clair County, Alabama. This is 
a critical habitat unit for the ovate clubshell, southern clubshell, 
triangular kidneyshell, Coosa moccasinshell, southern pigtoe, and fine-
lined pocketbook.
* * * * *
    (B) Map of Unit 24 follows:

[[Page 54336]]

[GRAPHIC] [TIFF OMITTED] TP30SE21.009

    (xxvii) Unit 25. Oostanaula, Coosawattee, and Conasauga Rivers, and 
Holly Creek, Floyd, Gordon, Whitfield, Murray Counties, Georgia; 
Bradley, Polk Counties, Tennessee. This is a critical habitat unit for 
the ovate clubshell, southern clubshell, triangular kidneyshell, 
Alabama moccasinshell, Coosa moccasinshell, southern pigtoe, and fine-
lined pocketbook.
* * * * *
    (B) Map of Unit 25 follows:

[[Page 54337]]

[GRAPHIC] [TIFF OMITTED] TP30SE21.010

    (xxviii) Unit 26. Lower Coosa River, Elmore County, Alabama. This 
is a critical habitat unit for the ovate clubshell, southern clubshell, 
triangular kidneyshell, Alabama moccasinshell, Coosa moccasinshell, 
southern pigtoe, and fine-lined pocketbook.
* * * * *
    (B) Map of Unit 26 follows:

[[Page 54338]]

[GRAPHIC] [TIFF OMITTED] TP30SE21.011

* * * * *

Martha Williams,
Principal Deputy Director, Exercising the Delegated Authority of the 
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2021-21219 Filed 9-29-21; 8:45 am]
BILLING CODE 4333-15-C