[Federal Register Volume 88, Number 199 (Tuesday, October 17, 2023)]
[Rules and Regulations]
[Pages 71644-71682]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-22377]



[[Page 71643]]

Vol. 88

Tuesday,

No. 199

October 17, 2023

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 21 Species 
From the List of Endangered and Threatened Wildlife; Final Rule

Federal Register / Vol. 88, No. 199 / Tuesday, October 17, 2023 / 
Rules and Regulations

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[FF08E22000 FXES111309FEDR 234]
RIN 1018-BC98


Endangered and Threatened Wildlife and Plants; Removal of 21 
Species From the List of Endangered and Threatened Wildlife

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service or USFWS), are 
removing 21 species from the Federal List of Endangered and Threatened 
Wildlife due to extinction. This action 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).

DATES: This rule is effective November 16, 2023.

ADDRESSES: The proposed rule and this final rule, the comments we 
received on the proposed rule, and supporting documents are available 
at https://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 [revaps]o[revaps]o (honeyeater).....           FWS-R1-ES-2020-0104
Large Kauai thrush (kam[revaps]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[revaps]ouli (honeycreeper).............           FWS-R1-ES-2020-0104
Bridled white-eye.........................           FWS-R1-ES-2020-0104
Little Mariana fruit bat..................           FWS-R1-ES-2020-0104
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
Bachman's warbler.........................           FWS-R4-ES-2020-0110
------------------------------------------------------------------------


FOR FURTHER INFORMATION CONTACT: 

------------------------------------------------------------------------
                Species                        Contact information
------------------------------------------------------------------------
Bridled white-eye, Kauai akialoa, Kauai  Earl Campbell, Field
 nukupuu, Kauai [revaps]o[revaps]o        Supervisor, Pacific Islands
 (honeyeater), large Kauai thrush         Fish and Wildlife Office, 300
 (kama), little Mariana fruit bat, Maui   Ala Moana Boulevard, Suite 3-
 akepa, Maui nukupuu, Molokai creeper     122, Honolulu HI 96850,
 (kakawahie), and po[revaps]ouli          Telephone: 808-792-9400.
 (honeycreeper).
Bachman's warbler......................  Thomas McCoy, Field Supervisor,
                                          South Carolina Field Office,
                                          176 Croghan Spur, Charleston,
                                          SC 29407, Telephone: 843-300-
                                          0431.
Flat pigtoe, southern acornshell,        James Austin, Deputy Field
 stirrupshell, and upland combshell.      Supervisor, Mississippi Field
                                          Office, 6578 Dogwood View
                                          Parkway, Suite A, Jackson, MS
                                          39213, Telephone: 601-321-
                                          1129.
Green blossom (pearly mussel),           Daniel Elbert, Field
 tubercled blossom (pearly mussel),       Supervisor, Tennessee Field
 turgid blossom (pearly mussel), and      Office, Interior Region 2--
 yellow blossom (pearly mussel).          South Atlantic-Gulf
                                          (Tennessee), 446 Neal Street,
                                          Cookeville, TN 38506,
                                          Telephone: 931-528-6481.
San Marcos gambusia....................  Karen Myers, Field Supervisor,
                                          Austin Ecological Services
                                          Field Office, 1505 Ferguson
                                          Lane, Austin, TX 78754,
                                          Telephone: 512-490-0057.
Scioto madtom..........................  Patrice Ashfield, Field
                                          Supervisor, Ohio Ecological
                                          Services Field Office, 4625
                                          Morse Road, Suite 104,
                                          Columbus, OH 43230, Telephone:
                                          614-416-8993.
------------------------------------------------------------------------

    Individuals in the United States who are deaf, deafblind, hard of 
hearing, or have a speech disability may dial 711 (TTY, TDD, or 
TeleBraille) to access telecommunications relay services. Individuals 
outside the United States should use the relay services offered within 
their country to make international calls to the point-of-contact in 
the United States.

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,

[[Page 71645]]

removing species from, or reclassifying species on the Federal Lists of 
Endangered and Threatened Wildlife and Plants 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 21 species in this final rule are currently listed as endangered or 
threatened; we are delisting them due to extinction. We can only delist 
a species by issuing a rule to do so.
    What this document does. We are removing 21 species from the List 
of Endangered and Threatened Wildlife (List) due to extinction.
    While our September 30, 2021, proposed rule (86 FR 54298) proposed 
to delist 23 species, this rule makes final the delisting of only 21 of 
those. Elsewhere in this issue of the Federal Register, we withdraw our 
proposed delisting of Phyllostegia glabra var. lanaiensis, which was 
part of our September 30, 2021, proposed rule.
    The basis for our action. We have determined that the 21 species 
that are the subjects of this rule should be removed from the List 
because the best available information indicates that they are extinct.
    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) and our 
August 22, 2016, Director's Memorandum ``Peer Review Process,'' we 
sought the expert opinion of 28 appropriate and independent specialists 
for 13 species in this rule. We requested those experts review the 
scientific data and interpretations for each species or group of 
species for which the associated 5-year review had not been peer 
reviewed prior to publication of the proposed rule (86 FR 54298; 
September 30, 2021). For the eight southeastern mussel species, the 5-
year reviews were peer reviewed prior to the publication of the 
proposed rule. In certain cases, species were grouped together for peer 
review based on similarities in biology or geographic occurrences. We 
sent copies of the 5-year species status reviews to the peer reviewers 
immediately following the proposed rule's publication in the Federal 
Register. The purpose of such review is to ensure that our decisions 
are based on scientifically sound data, assumptions, and analysis. We 
received feedback from 16 of the 28 peer reviewers contacted. We have 
incorporated the results of these reviews, as appropriate, into the 
appropriate assessment forms and this final rule. Additionally, we have 
provided our responses to peer review feedback below, under Summary of 
Comments and Recommendations.

Summary of Changes From the Proposed Rule

    In preparing this final rule, we reviewed and fully considered all 
applicable comments we received during the comment period from the peer 
reviewers and the public on the proposed rule to delist 23 species due 
to extinction. In this final rule, we are delisting 21 species due to 
extinction.
    Due to new surveys conducted, we are withdrawing our proposed rule 
to remove Phyllostegia glabra var. lanaiensis from the List of 
Endangered and Threatened Plants; the document withdrawing the proposed 
delisting of P. glabra var. lanaiensis is published elsewhere in this 
issue of the Federal Register.
    On July 7, 2022, we published in the Federal Register (87 FR 40477) 
a 6-month extension of the final determination on whether to delist the 
ivory-billed woodpecker (Campephilus principalis). That document also 
reopened the public comment period on the proposed delisting of the 
ivory-billed woodpecker. We extended the final determination on the 
proposed delisting of this species due to substantial disagreement 
among scientists knowledgeable about the species regarding the 
sufficiency or accuracy of the available data relevant to the 
determination. In a separate, future publication, we will either 
finalize the delisting of the ivory-billed woodpecker due to extinction 
or withdraw the proposed delisting of this species and retain the 
species' status as an endangered species.
    Lastly, in the proposed rule regulation Sec.  17.95 for the Eleven 
Mobile River Basin Mussel Species Critical Habitat designation, we had 
identified the orange-nacre mucket under the name Lampsilis perovalis. 
We have corrected this to the name the species was listed under, 
Hamiota perovalis.

Summary of Comments and Recommendations

    In the proposed rule published on September 30, 2021 (86 FR 54298), 
we requested that all interested parties submit written comments on the 
proposal by November 29, 2021. We also contacted appropriate State 
agencies, scientific experts and organizations, and other interested 
parties and invited them to comment on the proposal. A newspaper notice 
inviting the public to provide comments was published in USA Today on 
October 8, 2021. We received a request for a public hearing for the 
ivory-billed woodpecker on November 10, 2021. A newspaper notice 
inviting the public to provide comments at the public hearing was 
published in USA Today on January 11, 2022. A public hearing was 
conducted on January 26, 2022. All applicable substantive information 
we received during the comment period has been incorporated directly 
into this final determination and the appropriate species assessment 
forms or is addressed below.
    Of the public comments we received on the proposed rule, the 
majority concerned the ivory-billed woodpecker. We will address those 
comments in a separate, future publication. Of the public comments 
related to the other 22 species, two included substantive comments that 
are summarized below and incorporated into this final rule and the 
associated species assessment forms, as appropriate.

Peer Reviewer Comments

    In accordance with our 1994 peer review policy, we solicited expert 
opinion from knowledgeable individuals with scientific expertise that 
included familiarity with these species and their habitat, biological 
needs, and threats. As stated above, we sought peer review for species 
whose 5-year reviews had not been previously peer reviewed. We reviewed 
all comments received from peer reviewers for substantive issues and 
new information regarding these species. The reviewers made suggestions 
and comments that strengthened our analysis and improved this final 
rule.
    For the Bachman's warbler, we sent the 5-year reviews to a total of 
three peer reviewers. We received responses from all three reviewers. 
Peer reviewers provided additional information on the biological 
background information of the species. We have incorporated the 
information into both this rule and the supporting documents.
    For the Scioto madtom, we sent the 5-year review to a total of 
three peer reviewers. We received responses from all three reviewers. 
Peer reviewers provided clarification on the results of prior surveys 
that were conducted. We have incorporated the information into this 
rule and the supporting documents.
    For the San Marcos gambusia, we sought the expert opinions of three 
specialists with expertise in biology, habitat, and threats to the 
species, and we received responses from all three experts. Two peer 
reviewers confirmed that San Marcos gambusia should be delisted due to 
extinction, and the third peer reviewer had minor editorial

[[Page 71646]]

comments that were incorporated, where appropriate, into this rule and 
the supporting documents. The peer reviewers did not provide any 
additional substantial information that would influence a change in our 
decision from the proposed rule.
    For the Hawaiian and Mariana Islands species, we sought the expert 
opinion of a total of 11 individuals with expertise in the biology, 
habitat, and threats to the species. Six reviewers provided comments 
and feedback. We have organized and addressed those comments below.
Little Mariana Fruit Bat
    (1) Comment: One peer reviewer noted that the related, larger-
bodied Mariana fruit bat (called fanihi in the Chamorro language) moves 
between Rota and Guam, stating that Rota has larger populations of the 
species compared to Guam, but that large groups of fanihi can be 
observed on Guam when Rota experiences storms. The reviewer wondered 
whether, similarly, the little Mariana fruit bat could be present on 
Rota and move between Rota and Guam.
    Response: We conclude that it is extremely unlikely that the little 
Mariana fruit bat has persisted undetected on Rota or Guam considering 
the tremendous amount of effort that has gone into monitoring the 
fanihi on those islands.
    (2) Comment: One peer reviewer asked how environmental threats such 
as typhoons might impact little Mariana fruit bat populations and 
hypothesized that if the little Mariana fruit bat and the fanihi were 
to have roosted together, the fanihi may have contributed to the 
decline of the little Mariana fruit bat by outcompeting for resources 
following typhoon or other similar environmental events.
    Response: We noted possible vulnerabilities of the little Mariana 
fruit bat to typhoons and other environmental factors under ``Threats 
Evaluation'' in the species' 5-year review (USFWS 2019, p. 4). If the 
little Mariana fruit bat exhibited traits similar to that of other 
Pteropus spp., including low fecundity, it would have been susceptible 
to most large-scale disturbances to its habitat, particularly typhoons. 
However, too little is known about the little Mariana fruit bat's 
biology for us to speculate about the outcome of possible competition 
with the fanihi for resources following events such as typhoons.
    (3) Comment: One peer reviewer asked about the potential for using 
genetics to determine whether the bats present on Guam and Rota 
represent a single species and whether the little Mariana fruit bat is 
truly extinct on both islands.
    Response: As noted in our 5-year review for the little Mariana 
fruit bat, genetic analysis of skin samples of Pteropus spp. concluded 
that the species was genetically distinct (Almeida et al. 2014, 
entire). We would welcome any new genetic information about the fanihi 
or the little Mariana fruit bat should it become available, but in the 
absence of this information, we conclude that the best available 
information indicates that the little Mariana fruit bat is extinct.
Hawaiian Islands Bird Species
    (4) Comment: One peer reviewer mentioned that the referenced 
searches for po[revaps]ouli in K[imacr]pahulu Valley (1997-1999) relied 
primarily on existing trails from which it is not possible to 
adequately survey the entire area of rainforest habitat where 
po[revaps]ouli could still potentially persist. The reviewer further 
stated that K[imacr]pahulu Valley (and much of the east Maui 
rainforest) has many steep gulches and frequently dense and 
impenetrable vegetation and stream beds, and the area is very difficult 
to cover adequately on foot, adding further difficultly to survey 
efforts.
    Response: Specific searches to locate Maui's rarest forest birds 
were undertaken in 1967 and 1981 in K[imacr]pahulu Valley, and variable 
circular-plot (VCP) counts were conducted in 1980, 1992, and 1996 along 
Hawaii Forest Bird Survey (HFBS) transects in rainforests of Maui's 
east region (Reynolds and Snetsinger 2001, p. 139). Variable circular 
plot (VCP) studies are surveys conducted at pre-established stations 
along transects. A 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, the VCP studies 
estimate the number of birds in a surveyed area, along with a 
confidence interval for the estimate. Despite these searches, the 
po[revaps]ouli has never been found in K[imacr]pahulu Valley and is 
known historically only from the Hanawi Natural Area Reserve (NAR) of 
northeast Maui (Scott et al. 1986, p. 183), where it was most recently 
observed in 2003 and 2004 (USFWS 2006, pp. 2-153-2-154). Collectively, 
the weight of evidence indicates that the po[revaps]ouli is extinct.
    (5) Comment: One peer reviewer indicated that po[revaps]ouli is 
extremely cryptic and moves quietly through the understory and canopy. 
This species could easily be missed by inexperienced observers not 
familiar with the bird's behavior and is even easy to miss for 
experienced observers searching in known occupied habitat.
    Response: After the continued existence of five to six 
po[revaps]ouli was confirmed in 1994-1995 in the K[umacr]hiwa drainage 
of Hanawi NAR, thorough surveys of the species' historical range were 
conducted from 1995 to 1997, with 81 sightings of five individual 
po[revaps]ouli (Baker et al. 2001, p. 144). In 1997, only three 
individual birds were found in three separate territories, and one 
individual was color-banded in 1997. The po[revaps]ouli was last 
observed in 2003 and 2004 (USFWS 2006, pp. 2-153-2-154) and despite 
extensive time in the area from 2006 to 20011, no other birds have been 
located since these surveys. Using 2004 as the last reliable 
observation record for po[revaps]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). It is extremely unlikely 
that the po[revaps]ouli has persisted undetected considering extensive 
search efforts to document presence of the species on Maui.
    (6) Comment: One peer reviewer indicated that extensive searches 
for birds on the island of Maui were not conducted at elevations where 
higher presence of avian disease is expected, based on the assumption 
that rare bird species would not persist because of the threat of avian 
malaria.
    Response: The Rare Bird Search (RBS) on east Maui was conducted at 
elevations as low as 3,280 feet (1,000 meters), which is well within 
the zone of higher prevalence of avian malaria (Reynolds and Snetsinger 
2001, p. 134). We have added this information to the species accounts 
of the Maui forest birds in this final rule.
    (7) Comment: One peer reviewer indicated that the traditional VCP 
survey methods are not effective for detecting rarer, patchily 
distributed birds and particularly ineffective for a species like the 
po[revaps]ouli, which vocalizes infrequently and sounds similar to both 
Maui parrotbill (Pseudonestor xanthophrys) and Maui creeper 
(Paroreomyza montana). The reviewer further stated that confirmation of 
po[revaps]ouli is primarily visual, which can be quite challenging 
given its dark coloration, the dense vegetation it inhabits, and the 
frequently inclement rainy/misty survey conditions.
    Response: The VCP survey method does have limited effectiveness for 
detection of po[revaps]ouli. Because of this, we relied strongly on 
information from other sources including RBS and field studies 
conducted in Hanawi NAR in

[[Page 71647]]

the area of the only known historical population of po[revaps]ouli. 
Collectively, the weight of evidence indicates that the po[revaps]ouli 
is extinct.
    (8) Comment: One peer reviewer asked that we better define what is 
meant by ``extensive presence'' and ``qualified observers'' in 
reference to personnel conducting forest bird research in the field.
    Response: While working on Maui parrotbill (also called kiwikiu) 
recovery from 2006 to 2011, personnel with the Maui Forest Bird 
Recovery Project (MFBRP) spent thousands of person hours (i.e., 
extensive presence) in the area of the last po[revaps]ouli sightings. 
These personnel (i.e., qualified observers) who conducted this field 
work were highly trained to be able to detect all species of Hawaiian 
forest birds by sight and sound.
    (9) Comment: One peer reviewer recommended exploring some of the 
newer survey design methods and analyses (e.g., occupancy estimation) 
for rare species and to further develop and optimize sampling protocols 
for rarer bird species like po[revaps]ouli, Maui akepa, and Maui 
nukupuu.
    Response: Exploring possible application of different survey design 
methods and analyses and further developing and optimizing sampling 
protocols for rarer bird species will be taken into consideration for 
future survey and sampling efforts. However, we determined that the 
methods we used to determine absence of rare species are robust, and we 
have high confidence in our conclusion that the Hawaiian forest birds 
that are addressed in this rule are extinct.
    (10) Comment: One peer reviewer indicated that the three types of 
surveys/searches used to detect po[revaps]ouli each have their own 
inherent strengths and weaknesses. The commenter stated that although 
the protocols for two of the surveys/searches (VCP and RBS) are 
described, protocols and analytical techniques for additional surveys 
conducted within Hanawi NAR and elsewhere on east Maui are not 
described.
    Response: The third type of survey/search is best described as the 
long-term presence of qualified personnel doing field work in an area 
where rare species could still persist. While working on Maui 
parrotbill (kiwikiu) recovery from 2006 to 2011, personnel with the 
MFBRP spent thousands of person hours in the area of the last 
po[revaps]ouli sightings. Much of this consisted of active searches for 
kiwikiu, observations of this species when it was detected, and other 
types of conservation work in the area. Personnel who conducted field 
work were highly trained to be able to detect all species of Hawaiian 
forest birds by sight and sound. After thousands of hours of working in 
the Hanawi NAR in areas where po[revaps]ouli, Maui akepa, and Maui 
nukupuu were last detected, and no detections of these species 
occurred, MFBRP was strongly confident that po[revaps]ouli, Maui akepa, 
and Maui nukupuu are no longer present (Mounce 2021, pers. comm.).

Public Comments

Flat Pigtoe, Stirrupshell, Southern Acornshell, Upland Combshell
    (11) Comment: One commenter indicated that we prematurely concluded 
that the mussel species are extinct, stating that the species could 
possibly be found in places that have not yet been surveyed. The 
commenter asked that we study the species longer before they are 
declared extinct and removed from the List.
    Response: We deemed each of the species (flat pigtoe, stirrupshell, 
southern acornshell, and upland combshell) extinct based on significant 
alteration of all known historical habitat and lack of detections 
during numerous surveys conducted throughout each species' range.
    For the flat pigtoe, 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. 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). Lack of finding the 
flat pigtoe despite extensive survey efforts in many habitats indicate 
that the species is extinct.
    For the stirrupshell, 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). The stirrupshell has not 
been found alive in the Black Warrior River or the Alabama River since 
the early 1980s (Service 1989, p. 3). 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). Lack of 
finding the stirrupshell despite extensive survey efforts in many 
habitats indicate that the species is extinct.
    For the southern acornshell, 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). 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). 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 at 14331, March 17, 1993; 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). 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). Lack of finding the southern acornshell 
despite extensive survey efforts in many

[[Page 71648]]

habitats indicate that the species is extinct.
    For the upland combshell, the species 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 at 14331, March 17, 1993; Service 2000, p. 61; Service 2018, p. 
5). 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). 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 at 14331, March 17, 
1993; 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). Lack of finding 
the upland combshell despite extensive survey efforts in many habitats 
indicate that the species is extinct.

Background

    Section 4(c) of the Act (16 U.S.C. 1531 et seq.) requires the 
Secretary of the Interior to publish and maintain lists of endangered 
and threatened species. This includes delisting species that are 
extinct based on the best scientific and commercial data available. The 
Service can decide to delist a species due to extinction 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.
    Congress made clear that an integral part of the statutory 
framework is for the Service to make delisting decisions when 
appropriate and to revise the Lists of Endangered and Threatened 
Wildlife and Plants accordingly. For example, section 4(c)(1) of the 
Act requires the revision of the Lists of Endangered and Threatened 
Wildlife and Plants to reflect recent determinations, designations, and 
revisions. Similarly, section 4(c)(2) requires review of those Lists at 
least every 5 years; determination(s), based on those reviews, whether 
any species should be delisted or reclassified; and, if so, the 
application of the same standards and procedures as for listings under 
sections 4(a) and 4(b) of the Act. 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 determining 
whether a species is an endangered species or a threatened species.
    In 2019, jointly with the National Marine Fisheries Service, the 
Service issued a final rule that revised the regulations in 50 CFR part 
424 regarding how we add, remove, and reclassify endangered and 
threatened species and the criteria for designating listed species' 
critical habitat (84 FR 45020; August 27, 2019).
    Under the Act, we must review the status of all listed species at 
least once every 5 years. We must delist a species if we determine, on 
the basis of the best available scientific and commercial data, that 
the species is neither a threatened species nor an endangered species. 
Our regulations at 50 CFR 424.11(e) identify three reasons why we might 
determine that a listed species is neither an endangered species nor a 
threatened species: (1) The species is extinct; (2) the species does 
not meet the definition of an endangered species or a threatened 
species; or (3) the listed entity does not meet the statutory 
definition of a species.
    In this final 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 https://www.regulations.gov under the 
appropriate docket number (see table under ADDRESSES, above). The 
following information summarizes the analyses for each of the species 
delisted by this rule.

Summary of Biological Status and Threats

Mammals

Little Mariana Fruit Bat (Pteropus Tokudae)
I. Background
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On August 27, 1984, we listed the little Mariana fruit bat as 
endangered (49 FR 33881). The most recent 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) (USFWS 2019, entire). This recommendation was based on an 
assessment of all available

[[Page 71649]]

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.
    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 
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).
    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 indicated 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 millimeters (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 Mariana 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 possible 
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 (Utzurrum et al. 2003, p. 54).
Survey Effort
    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). In the final rule listing the little 
Mariana fruit bat as endangered (49 FR 33881; August 27, 1984), we 
noted that the species was on the verge of extinction 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, Mariana fruit bat numbers on Guam decreased and 
fatalities of immature bats increased, hypothesized to be a result of 
predation by the brown tree snake (Wiles et al. 1995, pp. 33-34, 39-
42). With bat abundance continuing to decline in the 2000s, 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

[[Page 71650]]

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 bat species (Savidge 1987, entire; Wiles 1987, pp. 155-
156). To date, there is only one documented instance of the brown tree 
snake preying upon 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
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On March 11, 1967, we listed the Bachman's warbler as endangered under 
the Endangered Species Preservation Act of 1966 (32 FR 4001), 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 
(American Ornithologists' Union (AOU) 1983, pp. 601-602). The species 
was found in the southeastern portions of the United States from the 
south Atlantic and Gulf Coastal Plains. 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).
    Migratory habitat preferences appear to have differed from winter 
and breeding habitat preferences in that the bird used or tolerated a 
wider range of conditions and vegetative associations during migration. 
Bachman's warbler typically nested in low, wet, forested areas 
containing variable amounts of water, but usually with some permanent 
water. Nests were typically found in shrubs low to the ground from late 
March through June, and average known clutch size was 4.2 (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 was likely 7 years, which is the documented lifespan of the two 
species most closely related to Bachman's warbler, blue-winged warbler 
(V. cyanoptera) and golden-winged warbler (V. chrysoptera) (Gill et al. 
2020 and Confer et al. 2020, respectively).
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. 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 fast series of buzzy 
``zeeps'' usually ending with a short, downward whistled note given by 
both sexes (Hamel 2020, Sounds and Vocal Behavior). This species may 
have been difficult to differentiate by 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 four 
recordings exist, all from the 1950s (two cited in Hamel 2018, p. 32, 
and all four in Cornell Lab of Ornithology, Macaulay Library), to guide 
ornithologists on distinguishing it by sound.

[[Page 71651]]

    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 (see 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 the Bachman's warbler. Much of 
the search period for ivory-billed woodpecker is during the winter, and 
the searches usually continued until the end of April, when the 
Bachman's warbler would be expected in its breeding range. Because the 
Bachman's warbler was a very early migrant, many knowledgeable 
searchers looking for ivory-billed woodpeckers would have had 
opportunities to encounter this warbler as early as February across the 
southeastern United States, yet no putative encounters were reported. 
Given that Bachman's warbler habitat overlaps with ivory-billed 
woodpecker habitat, the probability that the 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 the Bachman's warbler because of its high interest among 
birders (Service 2015, p. 5). Despite these efforts, the Bachman's 
warbler has not been observed in the United States in more than three 
decades. With a likely maximum lifespan of 7 years, the time period 
through which this species has not been seen constitutes at least 7 
generations, and the time period since its last confirmed breeding 
constitutes more than 10 generations.
    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 (Geothlypis trichas) (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 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

[[Page 71652]]

have resulted in large losses of the birds (Hamel 2018, p. 19). The 
dramatic reduction in encounter frequency, beginning in the late 1930s 
following the string of hurricanes in Cuba, never reversed, strongly 
suggesting that these storms, combined with accumulated habitat loss in 
breeding grounds, diminished viability of the Bachman's warbler as it 
approached extinction.
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
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On August 27, 1984, we listed the bridled white-eye (Nossa in the 
Chamorro language) as endangered (49 FR 33881). 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), citing disease and predation by nonnative 
predators, including the brown tree snake, as the likely factors 
contributing to its rarity (49 FR 33881, August 27, 1984, p. 49 FR 
33884). The most recent 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 
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; Stophlet 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 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 was 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 2000, pp. 
14-15), the detectability of the related Rota bridled white-eye 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
    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;

[[Page 71653]]

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.
Time Since Last Detection
    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.). 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 
17 of Guam's 22 (77 percent) native bird species, including all of the 
native forest bird species (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. Observed bird species 
declines of greater than or equal to 90 percent occurred rapidly, 
averaging 8.9 years from invasion by the snake. Additionally, birds 
that nested and roosted in locations where the brown tree snake was 
uncommon had a greater likelihood of coexisting with the snake. Bird 
species with large clutch sizes and large body sizes also exhibited 
longer persistence, although large body size delayed but did not 
prevent extirpation. Measuring a mere 0.33 ounces (9.3 grams), the 
bridled white-eye was relatively small, and its nests occurred 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.
Kauai Akialoa (Akialoa Stejnegeri)
I. Background
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On March 11, 1967, we listed the Kauai akialoa (listed as Hemignathus 
stejnegeri), a Hawaiian honeycreeper, as endangered (32 FR 4001). This 
bird was included in the Kauai Forest Birds Recovery Plan (USFWS 1983, 
p. 1), 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). 
The most recent 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, as discussed 
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).
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). Please 
refer to the ``Summary of Comments and Recommendations'' for a 
description of the VCP method. 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 issue, the 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.

[[Page 71654]]

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 
akikiki (or Kauai creeper) (Oreomystis bairdi). HFBSs were conducted in 
1981, 1989, 1994, 2000, 2005, 2007, 2008, 2012, and 2018 (Paxton et al. 
2016, entire; Paxton et al. 2020, entire). The Kauai Forest Bird 
Recovery Project (KFBRP) conducted occupancy surveys for the small 
Kauai thrush in Kokee State Park, Hono O NaPali NAR, 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 akikiki 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 of 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
    The Kauai akialoa has not been seen since the 1960s, 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.). 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, the mosquito Culex quinquefasciatus (Atkinson and 
Lapointe 2009a, pp. 237-238, 245-246).
    We relied on a recently developed analytic tool that uses 
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).
    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. Surveys and searches have been unsuccessful in detecting 
Kauai akialoa (refer to ``Survey Effort'' discussion, above).
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
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On March 11, 1967, we listed the Kauai nukupuu as endangered (32 FR 
4001). This bird was included in the Kauai Forest Birds Recovery Plan 
(USFWS 1983, p. 1), as well as the Revised Recovery Plan for Hawaiian 
Forest Birds (USFWS 2006, p. viii). 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). The latest 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, as discussed below (USFWS 2019, pp. 4-5, 10).
    The historical record provides little information on the life 
history of Kauai

[[Page 71655]]

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 H. wilsoni), a honeycreeper from the island of Hawaii. 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. 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 
was 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, akekee, and akikiki. HFBSs were conducted in 1981, 1989, 1994, 
2000, 2005, 2007, 2008, 2012, and 2018 (Paxton et al. 2016, entire; 
Paxton et al. 2020, entire). During the HFBSs 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 of 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 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.
IV. 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 [revaps]o[revaps]o (Moho Braccatus)
I. Background
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On March 11, 1967, we listed the Kauai [revaps]o[revaps]o (Moho 
braccatus) as endangered (32 FR 4001). This bird was included in the 
Kauai Forest Birds Recovery Plan (USFWS 1983, p. 1), as well as the 
Revised Recovery Plan for Hawaiian Forest Birds (USFWS 2006, p. viii). 
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 
[revaps]o[revaps]o was a vocal response to a recorded vocalization 
played by a field biologist on April 28, 1987, in the locality of 
Halepaakai Stream. The latest 5-year status review completed in 2019 
recommended delisting due to extinction based on consideration of new 
information about the biological status of the species, as discussed 
below (USFWS 2019, pp. 5, 10).
    The Kauai [revaps]o[revaps]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 [revaps]o[revaps]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 (Metrosideros polymorpha) 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 
[revaps]o[revaps]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

[[Page 71656]]

Kauai [revaps]o[revaps]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 [revaps]o[revaps]o cannot be 
reconstructed. The comprehensive surveys of Hawaiian forest birds are 
described above under ``Survey Effort'' for the Kauai akialoa. Several 
recent surveys and searches, including the VCP and RBS, have been 
unsuccessful in detecting Kauai [revaps]o[revaps]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 [revaps]o[revaps]o. 
None were detected, and it was concluded the Kauai [revaps]o[revaps]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 [revaps]o[revaps]o searching for the 
small Kauai thrush, akekee, and akikiki. HFBSs were conducted in 1981, 
1989, 1994, 2000, 2005, 2007, 2008, 2012, and 2018 (Paxton et al. 2016, 
entire; Paxton et al. 2020, entire). During the HFBSs in 2012 and 2018, 
occupancy surveys and nest searches did not yield any new detections of 
Kauai [revaps]o[revaps]o. The KFBRP conducted mist-netting in various 
locations within the historical range for Kauai [revaps]o[revaps]o from 
2006 through 2009 and 2011 through 2018, and no Kauai 
[revaps]o[revaps]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 
[revaps]o[revaps]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 
[revaps]o[revaps]o, are highly susceptible to introduced avian disease, 
particularly avian malaria. 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, the mosquito Culex quinquefasciatus (Atkinson and Lapointe 
2009a, pp. 237-238, 245-246). Because they occur at similar altitudes 
and face similar threats, please refer to ``III. Analysis'' for the 
Kauai akialoa, above, for more information.
IV. Conclusion
    At the time of listing in 1967, the Kauai [revaps]o[revaps]o faced 
threats from effects of low population numbers, habitat loss, avian 
disease, and predation by introduced mammals. The best available 
information now indicates that the Kauai [revaps]o[revaps]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
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On October 13, 1970, we listed the large Kauai thrush (kama[revaps]o in 
the Hawaiian language) as endangered (35 FR 16047). This bird was 
included in the Kauai Forest Birds Recovery Plan (USFWS 1983, p. 1), as 
well as the Revised Recovery Plan for Hawaiian Forest Birds (USFWS 
2006, p. viii). 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. The latest 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, as discussed 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) (USFWS 2006, p. 2-19). 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 
indicate 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; Scott et al. 
1986, entire; 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, akekee, and akikiki. HFBSs were conducted in 1981, 1989, 
1994, 2000, 2005, 2007, 2008, 2012, and 2018 (Paxton et al. 2016, 
entire; Paxton et al. 2020, entire). During the HFBS in 2012 and 2018, 
occupancy surveys and nest

[[Page 71657]]

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 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
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On October 13, 1970, we listed the Maui akepa (originally listed as 
Loxops ochraceus) as endangered (35 FR 16047). This bird 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. The 
latest 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 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 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 rainforest) 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 centuries 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 0. 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, given the density of VCP survey stations, it is estimated that 
5,865 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, pp. 6-8). 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 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 (Reynolds and Snetsinger 2001, p. 140).
    Qualified observers spent extensive time searching for Maui akepa, 
po[revaps]ouli (Melamprosops phaeosoma), and Maui nukupuu in the 1990s. 
Between September 1995 and October 1996,

[[Page 71658]]

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[revaps]ouli and 
Maui nukupuu were heard, and would play either Maui parrotbill or 
akiapolaau calls and songs to attract the bird for identification. Six 
po[revaps]ouli were found, but no Maui akepa were detected (Baker 2001, 
p. 147). The 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 most recent 
survey in 2017 across much of east and west Maui did not find Maui 
akepa (Judge et al. 2019, entire). The MFBRP project coordinator 
concluded that if Maui akepa were present, they would have been 
detected (Mounce 2018, pers. comm.).
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, 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 (L. c. 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 are more accessible 
to rats. High densities of both black and Polynesian rats (R. 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
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On October 13, 1970, we listed the Maui nukupuu (originally listed as 
Hemignathus affinis) as endangered (35 FR 16047). This bird 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 on Hawaii Island. 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

[[Page 71659]]

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 (Haemorhous mexicanus) but was lower in pitch. Both 
the song and the ``kee-wit'' call resembled those of Maui parrotbill, 
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. 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, given the 
density of VCP survey stations, it was estimated that 1,357 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, pp. 6-8). 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 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[revaps]ouli, and Maui akepa 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 
``Survey Effort'' for the Maui akepa, above, for the method used in 
this survey. The 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 the 1996 detection 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 most 
recent survey in 2017 across much of east and west Maui did not find 
Maui nukupuu (Judge et al. 2019, entire). 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'' for Kauai akialoa, above). However, 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 ``III. Analysis'' 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 they 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

[[Page 71660]]

scientific and commercial data indicate that the species is extinct.
Molokai Creeper (Paroreomyza Flammea)
I. Background
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On October 13, 1970, we listed the Molokai creeper 
(k[amacr]k[amacr]wahie in the Hawaiian language) as endangered (35 FR 
16047). This bird 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. The latest 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 
forests and was known almost solely from boggy areas of Molokai (Pekelo 
1963, p. 64.
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, p. 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 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, given the density of VCP survey stations, it was estimated 
that 215,427 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. Additional 
VCP surveys were conducted on Molokai in 2010 and 2021, but no Molokai 
creepers were detected (Camp 2015, pers. comm., p. 2; Berry 2021, pers. 
comm., p. 1). 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 faced similar threats to the other Maui bird 
species (see ``III. Analysis'' 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[revaps]ouli (Melamprosops Phaeosoma)
I. Background
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On September 25, 1975, we listed the po[revaps]ouli (Melamprosops 
phaeosoma) as endangered (40 FR 44149), and the species was included in 
the Maui-

[[Page 71661]]

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[revaps]ouli to 
have very low abundance and likely to be threatened by habitat loss, 
avian disease, and predation by introduced mammals. The latest 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. 4-5, 10).
    The po[revaps]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[revaps]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[revaps]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[revaps]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 (Pratt et 
al. 1997, p. 4). Po[revaps]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[revaps]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[revaps]ouli were unusually quiet. Although distinctive 
visually, because the species rarely vocalized, it was difficult to 
survey by audio detections.
Survey Effort
    The po[revaps]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[revaps]ouli in the Kuhiwa drainage of Hanawi NAR was confirmed 
(Reynolds and Snetsinger 2001, p. 141). Thorough surveys of the 
historical range between 1997 and 2000, the MFBRP located only three 
birds, all in separate territories in Hanawi NAR. These three 
po[revaps]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[revaps]ouli. These searches 
were hampered by bad weather, however, and playback was not used 
(Vetter 2018, pers. comm.). The most recent survey in 2017 across much 
of east and west Maui did not find po[revaps]ouli (Judge et al. 2019, 
entire).
Time Since Last Detection
    In 2002, what was thought to be the only female po[revaps]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[revaps]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 recovery from 2006 to 2011, the MFBRP spent extensive time 
in the area of the last po[revaps]ouli sightings. No po[revaps]ouli 
were seen or heard. The MFBRP project coordinator concluded that if 
po[revaps]ouli were present, they would have been detected (Mounce 
2018, pers. comm.).
    Using 2004 as the last reliable observation record for 
po[revaps]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[revaps]ouli faced threats similar to other bird species 
occurring on Maui (see ``III. Analysis'' for the Maui akepa, above). 
The last confirmed sighting of po[revaps]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[revaps]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[revaps]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[revaps]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[revaps]ouli is extinct. 
Although the po[revaps]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[revaps]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
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On July 14, 1980, we listed the San Marcos gambusia, a small fish, as 
endangered (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

[[Page 71662]]

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 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). 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 (43 FR 30316; July 14, 1978). 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.
    On May 31, 2018, we initiated a 5-year review of the species (83 FR 
25034). 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, unpaginated; 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, p. 358; Hubbs et al. 2008, p. 3). 
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. 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

[[Page 71663]]

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 the early 
1980s (Edwards 1999, p. 2; Edwards 2002, p. 358), and the last known 
sighting in the wild occurred in 1983. In 1985, after unsuccessful 
breeding attempts with G. 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
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On September 25, 1975, we listed the Scioto madtom (Noturus trautmani) 
as endangered (40 FR 44149), due to the pollution and siltation of its 
habitat and the proposal to construct two impoundments within its 
range. Two 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 the 2009 and 2014 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 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 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 (N. 
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.). 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 characteristics such as the number of pectoral and 
anal rays (Taylor 1969, p. 156). 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 (Tetzloff 2003, p. 1). Despite these detection 
challenges, many surveys by experienced biologists have been undertaken 
to try to locate extant populations of Scioto madtom (USFWS 1977, 
entire; USFWS 1982, entire; USFWS 1985, entire; USFWS 1997, entire; 
Kibbey 2009, pers. comm.).
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 
(Ohio Environmental Protection Agency (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 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

[[Page 71664]]

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
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On April 7, 1987, we listed the flat pigtoe (formerly known as 
Marshall's mussel), as endangered, primarily due to habitat alteration 
from a free-flowing riverine system to an impounded system (52 FR 
11162). Two 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 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).
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, including:
    <bullet> 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);
    <bullet> 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]);
    <bullet> 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);
    <bullet> 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]);
    <bullet> 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);
    <bullet> Surveyor experience (finding mussels requires a well-
developed search image, knowledge of instream habitat dynamics, and 
ability to identify and distinguish species); and
    <bullet> 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 been carried out, and those surveys 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

[[Page 71665]]

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
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On March 17, 1993, we listed the southern acornshell as endangered, 
primarily due to habitat modification, sedimentation, and water-quality 
degradation (58 FR 14330). We designated critical habitat 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 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 extinct.
    The southern acornshell was described in 1857 from Othcalooga Creek 
in Gordon County, Georgia (58 FR 14330 at 14331, March 17, 1993). 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 synonym of E. penita and was considered to be an 
ectomorph of the latter (58 FR 14330 at 14331, March 17, 1993). The 
Service recognizes Unio othcaloogensis (Lea) and U. 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 required 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 at 14331, March 17, 1993). 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 at 14331, March 17, 1993; 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 ``Species Detectability'' 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 been carried out, and 
those surveys 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 at 14331, March 17, 1993). 
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 at 14331, March 17, 1993). 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

[[Page 71666]]

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 at 14331, March 17, 1993; 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, pp. 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 led to 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 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.
Stirrupshell (Quadrula Stapes)
I. Background
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On April 7, 1987, we listed the stirrupshell as endangered, primarily 
due to habitat alteration from a free-flowing riverine system to an 
impounded system (52 FR 11162). Two 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 
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 ``Species Detectability'' 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 been carried out, and 
those surveys 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 Gainsesville Bendway of 
Tombigbee River found

[[Page 71667]]

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 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
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On March 17, 1993, we listed the upland combshell as endangered, 
primarily due to habitat modification, sedimentation, and water-quality 
degradation (58 FR 14330). We designated critical habitat 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 
extinct.
    The upland combshell was described in 1838, from the Mulberry Fork 
of the Black Warrior River near Blount Springs, Alabama (58 FR 14330 at 
14331, March 17, 1993). Adult upland combshells were rhomboidal to 
quadrate in shape and were approximately 2.4 inches in length (58 FR 
14330-14331, March 17, 1993).
    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 at 14331, March 17, 1993). 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 at 14331, March 17, 1993; 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 at 
14331, March 17, 1993; 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 ``Species Detectability'' 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 been carried out, and 
those surveys 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 at 14331, March 17, 1993). 
The upland combshell was observed in the Cahaba River drainage in 1938 
and

[[Page 71668]]

in 1973, but a 1990 survey failed to find the species in the Cahaba 
River drainage (58 FR 14330 at 14331, March 17, 1993). 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 at 14331, March 
17, 1993). 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 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 at 14331, March 17, 1993; 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 as the southern acornshell, it faced similar threats. Please refer 
to the discussion of the southern acornshell, above, 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 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
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On June 14, 1976, we listed the green blossom as endangered (41 FR 
24062). 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. 
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 1984, pp. 1-2). 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 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 (Tennessee 
Valley Authority (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. 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 ``Species Detectability'' 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.

[[Page 71669]]

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).
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 41 years ago, and numerous 
surveys have been completed within the known range of the species over 
these 41 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 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
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On June 14, 1976, we listed the tubercled blossom as endangered (41 FR 
24062). At the time of listing, the greatest factor contributing to the 
species' decline was the alteration and destruction of stream habitat 
due to impoundments. The most recent 5-year review, completed in 2017 
(initiated on March 25, 2014; see 79 FR 16366), indicated that the 
species was 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. 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 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 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. A third factor is the impact caused by various 
pollutants. An increasing number of streams throughout the tubercled 
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 ``Species Detectability'' 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. 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

[[Page 71670]]

of the species (USFWS 2017, p. 8). Additionally, State biologists have 
conducted extensive 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 extinct.
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
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the species background and 
legal history. Here, we will briefly summarize the species background. 
On June 14, 1976, we listed the turgid blossom as endangered (41 FR 
24062). 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. It has been reported from 
the Tennessee River and tributary streams, including Shoal and Bear 
Creeks, and Elk, Duck, Holston, Clinch, and Emory Rivers (USFWS 2017, 
p. 4). Additional records are reported from the Cumberland River (USFWS 
2017, p. 4) and from the Ozark Mountain Region, including Spring Creek, 
and Black and White Rivers (USFWS 2017, p. 6).
    The turgid blossom was a medium-river, Cumberlandian-type mussel 
that was also reported from the Ozarks. These mussels could live 50 
years or more. 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 et al. 1980, pp. 93-105). 
Eight species of Epioblasma were 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 ``Species Detectability'' 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 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
    Please refer to our proposed rule, published on September 30, 2021 
(86 FR 54298), for a thorough review of the

[[Page 71671]]

species background and legal history. Here, we will briefly summarize 
the species background. On June 14, 1976, listed the yellow blossom as 
endangered (41 FR 24062). 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. 
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 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. 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 ``Species Detectability'' 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 and 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.

Required Determinations

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

    We do not need to prepare environmental analyses pursuant to the 
National Environmental Policy Act (NEPA; 42 U.S.C. 4321 et seq.) 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). Further, 
NEPA analyses are not applicable for the removal of any associated 
rules (e.g., critical habitat) as the removal of those rules are 
required with the delisting of a species.

Government-to-Government Relationship With Tribes

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

[[Page 71672]]

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 have 
expressed interest in the Bachman's warbler. We reached out to these 
Tribes by providing an advance notification prior to the publication of 
the September 30, 2021, proposed rule (86 FR 54298). We received no 
comments from any Tribes during the public comment period on the 
proposed rule.

References Cited

    Lists of the references cited in in this document are available on 
the internet at https://www.regulations.gov in the dockets provided 
above under ADDRESSES 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, Plants, 
Reporting and recordkeeping requirements, Transportation, Wildlife.

Regulation Promulgation

    Accordingly, we hereby 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 in paragraph (h), the List of Endangered and 
Threatened Wildlife, by:
0
a. Under MAMMALS, removing the entry for ``Bat, little Mariana fruit'';
0
b. Under BIRDS, removing the entries for ``Akepa, Maui'', ``Akialoa, 
Kauai'', ``Creeper, Molokai'', ``Nukupuu, Kauai'', ``Nukupuu, Maui'', 
``[revaps]O[revaps]o, Kauai (honeyeater)'', ``Po[revaps]ouli 
(honeycreeper)'', ``Thrush, large Kauai'', ``Warbler (wood), 
Bachman's'', and ``White-eye, bridled'';
0
c. Under FISHES, removing the entries for ``Gambusia, San Marcos'' and 
``Madtom, Scioto''; and
0
d. Under CLAMS, 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.  17.85  [Amended]

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

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), in 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), orangenacre 
mucket (Hamiota perovalis), dark pigtoe (Pleurobema furvum), southern 
pigtoe (Pleurobema georgianum), and finelined pocketbook (Hamiota 
altilis)'', revising the entry's heading, the first sentence of 
paragraph (1) introductory text, the introductory text of paragraph 
(2)(i), the table in paragraph (2)(ii), the introductory text of 
paragraph (2)(xiv), paragraph (2)(xiv)(B), the introductory text of 
paragraph (2)(xv), paragraph (2)(xv)(B), the introductory text of 
paragraph (2)(xx), paragraph (2)(xx)(B), the introductory text of 
paragraph (2)(xxi), paragraph (2)(xxi)(B), the introductory text of 
paragraph (2)(xxiii), paragraph (2)(xxiii)(B), the introductory text of 
paragraph (2)(xxvi), paragraph (2)(xxvi)(B), the introductory text of 
paragraph (2)(xxvii), paragraph (2)(xxvii)(B), the introductory text of 
paragraph (2)(xxviii), and paragraph (2)(xxviii)(B).
    The revisions 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 (Hamiota Perovalis), Dark Pigtoe (Pleurobema Furvum), Southern 
Pigtoe (Pleurobema Georgianum), and Fine-Lined Pocketbook (Hamiota 
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 (Hamiota perovalis), dark 
pigtoe (Pleurobema furvum), southern pigtoe (Pleurobema georgianum), 
and fine-lined pocketbook (Hamiota 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:
* * * * *
    (ii) * * *

                       Table 1 to Nine Mobile River Basin Mussel Species Paragraph (2)(ii)
----------------------------------------------------------------------------------------------------------------
                 Species                       Critical habitat units                      States
----------------------------------------------------------------------------------------------------------------
Ovate clubshell (Pleurobema perovatum)..  Units 1, 2, 3, 4, 5, 6, 7, 8, 9,  AL, GA, MS, TN.
                                           10, 11, 12, 13, 17, 18, 19, 21,
                                           24, 25, 26.

[[Page 71673]]

 
Southern clubshell (Pleurobema decisum).  Units 1, 2, 3, 4, 5, 6, 7, 8, 9,  AL, GA, MS, TN.
                                           13, 14, 15, 17, 18, 19, 21, 24,
                                           25, 26.
Triangular kidneyshell (Ptychobranchus    Units 10, 11, 12, 13, 18, 19,     AL, GA, TN.
 greenii).                                 20, 21, 22, 23, 24, 25, 26.
Alabama moccasinshell (Medionidus         Units 1, 2, 3, 4, 5, 6, 7, 8, 9,  AL, GA, MS, TN.
 acutissimus).                             10, 11, 12, 13, 15, 25, 26.
Coosa moccasinshell (Medionidus           Units 18, 19, 20, 21, 22, 23,     AL, GA, TN.
 parvulus).                                24, 25, 26.
Orange-nacre mucket (Hamiota perovalis).  Units 1, 2, 3, 4, 5, 6, 7, 8, 9,  AL, MS.
                                           10, 11, 12, 13, 14, 15.
Dark pigtoe (Pleurobema furvum).........  Units 10, 11, 12................  AL.
Southern pigtoe (Pleurobema georgianum).  Units 18, 19, 20, 21, 22, 23,     AL, GA, TN.
                                           24, 25, 26.
Fine-lined pocketbook (Hamiota altilis).  Units 13, 16, 17, 18, 19, 20,     AL, GA, TN.
                                           21, 22, 23, 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 71674]]

Figure 14 to Nine Mobile River Basin Mussel Species Paragraph 
(2)(xiv)(B)

Unit 12: Ovate Clubshell, Triangular Kidneyshell, Alabama 
Moccasinshell, Orange-Nacre Mucket, Dark Pigtoe
[GRAPHIC] [TIFF OMITTED] TR17OC23.000

    (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.
* * * * *

[[Page 71675]]

    (B) Map of Unit 13 follows:

Figure 15 to Nine Mobile River Basin Mussel Species Paragraph 
(2)(xv)(B)

Unit 13: Ovate Clubshell, Southern Clubshell, Triangular Kidneyshell, 
Alabama Moccasinshell, Orange-Nacre Mucket, Fine-Lined Pocketbook
[GRAPHIC] [TIFF OMITTED] TR17OC23.001

* * * * *
    (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

[[Page 71676]]

moccasinshell, southern pigtoe, and fine-lined pocketbook.
* * * * *
    (B) Map of Unit 18 follows:

Figure 20 to Nine Mobile River Basin Mussel Species Paragraph 
(2)(xx)(B)

Unit 18: Ovate Clubshell, Southern Clubshell, Triangular Kidneyshell, 
Coosa Moccasinshell, Southern Pigtoe, Fine-Lined Pocketbook
[GRAPHIC] [TIFF OMITTED] TR17OC23.002

    (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.
* * * * *

[[Page 71677]]

    (B) Map of Unit 19 follows:

Figure 21 to Nine Mobile River Basin Mussel Species Paragraph 
(2)(xxi)(B)

Unit 19: Ovate Clubshell, Southern Clubshell, Triangular Kidneyshell, 
Coosa Moccasinshell, Southern Pigtoe, Fine-Lined Pocketbook
[GRAPHIC] [TIFF OMITTED] TR17OC23.003

* * * * *
    (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 71678]]

Figure 23 to Nine Mobile River Basin Mussel Species Paragraph 
(2)(xxiii)(B)

Unit 21: Ovate Clubshell, Southern Clubshell, Triangular Kidneyshell, 
Coosa Moccasinshell, Southern Pigtoe, Fine-Lined Pocketbook
[GRAPHIC] [TIFF OMITTED] TR17OC23.004

* * * * *
    (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.
* * * * *

[[Page 71679]]

    (B) Map of Unit 24 follows:

Figure 26 to Nine Mobile River Basin Mussel Species Paragraph 
(2)(xxvi)(B)

Unit 24: Ovate Clubshell, Southern Clubshell, Triangular Kidneyshell, 
Coosa Moccasinshell, Southern Pigtoe, Fine-Lined Pocketbook
[GRAPHIC] [TIFF OMITTED] TR17OC23.005

    (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,

[[Page 71680]]

Coosa moccasinshell, southern pigtoe, and fine-lined pocketbook.
* * * * *
    (B) Map of Unit 25 follows:

Figure 27 to Nine Mobile River Basin Mussel Species Paragraph 
(2)(xxvii)(B)

Unit 25: Ovate Clubshell, Southern Clubshell, Triangular Kidneyshell, 
Alabama Moccasinshell, Coosa Moccasinshell, Southern Pigtoe, Fine-Lined 
Pocketbook
[GRAPHIC] [TIFF OMITTED] TR17OC23.006

    (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,

[[Page 71681]]

Coosa moccasinshell, southern pigtoe, and fine-lined pocketbook.
* * * * *
    (B) Map of Unit 26 follows:

Figure 28 to Nine Mobile River Basin Mussel Species Paragraph 
(2)(xxviii)(B)

Unit 26: Ovate Clubshell, Southern Clubshell, Triangular Kidneyshell, 
Alabama Moccasinshell, Coosa Moccasinshell, Southern Pigtoe, Fine-Lined 
Pocketbook
[GRAPHIC] [TIFF OMITTED] TR17OC23.007


[[Page 71682]]


* * * * *

Martha Williams,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2023-22377 Filed 10-16-23; 8:45 am]
BILLING CODE 4333-15-C