71644 Federal Register / Vol. 88, No. 199 / Tuesday, October 17, 2023 / Rules and Regulations 

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. 

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 1o1o (honeyeater) ............................................................................................................................................. FWS–R1–ES–2020–0104 

Large Kauai thrush (kam1a) ....................................................................................................................................... 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 

Po1ouli (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 nukupuu, Kauai 1o1o 

(honeyeater), large Kauai thrush (kama), little Mariana fruit bat, Maui 

akepa, Maui nukupuu, Molokai creeper (kakawahie), and po1ouli 

(honeycreeper).

Earl Campbell, Field Supervisor, Pacific Islands Fish and Wildlife Office, 300 Ala Moana Boulevard, Suite 3–122, Honolulu HI 96850, 

Telephone: 808–792–9400. 

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, stirrupshell, and upland combshell ...... James Austin, Deputy Field Supervisor, Mississippi Field Office, 6578 

Dogwood View Parkway, Suite A, Jackson, MS 39213, Telephone: 

601–321–1129. 

Green blossom (pearly mussel), tubercled blossom (pearly mussel), 

turgid blossom (pearly mussel), and yellow blossom (pearly mussel).

Daniel Elbert, Field Supervisor, Tennessee Field Office, Interior Region 

2—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-ofcontact 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, 


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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 ivorybilled 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 

§ 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 


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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 po1ouli in Kı ̄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 po1ouli could 

still potentially persist. The reviewer 

further stated that Kı ̄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 

Kı ̄pahulu Valley, and variable circularplot (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 

po1ouli has never been found in 

Kı ̄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 po1ouli is 

extinct. 

(5) Comment: One peer reviewer 

indicated that po1ouli 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 po1ouli was 

confirmed in 1994–1995 in the Ku ̄hiwa 

drainage of Hanawi NAR, thorough 

surveys of the species’ historical range 

were conducted from 1995 to 1997, with 

81 sightings of five individual po1ouli 

(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 po1ouli 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 po1ouli, 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 po1ouli 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 po1ouli, which vocalizes 

infrequently and sounds similar to both 

Maui parrotbill (Pseudonestor 

xanthophrys) and Maui creeper 

(Paroreomyza montana). The reviewer 

further stated that confirmation of 

po1ouli 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 po1ouli. Because of this, we 

relied strongly on information from 

other sources including RBS and field 

studies conducted in Hanawi NAR in 


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the area of the only known historical 

population of po1ouli. Collectively, the 

weight of evidence indicates that the 

po1ouli 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 po1ouli 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 po1ouli, 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 po1ouli 

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 po1ouli 

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 po1ouli, 

Maui akepa, and Maui nukupuu were 

last detected, and no detections of these 

species occurred, MFBRP was strongly 

confident that po1ouli, 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 TennesseeTombigbee 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 


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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 


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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 


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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. 


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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 


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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 whiteeye 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 whiteeyes 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; 


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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 whiteeye 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 olivegreen; 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. 


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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 Soule ́ 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 


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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 mistnetting 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 1o1o (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 1o1o (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 1o1o 

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 1o1o 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 1o1o 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 1o1o. 

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 


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Kauai 1o1o 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 1o1o 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 1o1o 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 1o1o. 

None were detected, and it was 

concluded the Kauai 1o1o 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 1o1o 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 1o1o. The KFBRP 

conducted mist-netting in various 

locations within the historical range for 

Kauai 1o1o from 2006 through 2009 and 

2011 through 2018, and no Kauai 1o1o 

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 1o1o 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 1o1o, 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 1o1o 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 1o1o 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 

(kama1o 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 


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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, po1ouli 

(Melamprosops phaeosoma), and Maui 

nukupuu in the 1990s. Between 

September 1995 and October 1996, 


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1,730 acres (700 hectares) in Hanawi 

NAR were searched during 318 persondays (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 po1ouli and 

Maui nukupuu were heard, and would 

play either Maui parrotbill or 

akiapolaau calls and songs to attract the 

bird for identification. Six po1ouli 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 MauiMolokai 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 mediumsized (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 


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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, 

po1ouli, 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 personsearch 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 


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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 

(ka ̄ka ̄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. 

Po1ouli (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 po1ouli 

(Melamprosops phaeosoma) as 

endangered (40 FR 44149), and the 

species was included in the MauiVerDate Sep<11>2014 18:15 Oct 16, 2023 Jkt 262001 PO 00000 Frm 00018 Fmt 4701 Sfmt 4700 E:\FR\FM\17OCR2.SGM 17OCR2

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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 po1ouli 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 po1ouli 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 

po1ouli 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). Po1ouli 

were observed singly, in pairs, and in 

family groups consisting of both parents 

and a single offspring (Pratt et al. 1997, 

p. 1). Po1ouli 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). Po1ouli 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 po1ouli 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, po1ouli were 

unusually quiet. Although distinctive 

visually, because the species rarely 

vocalized, it was difficult to survey by 

audio detections. 

Survey Effort 

The po1ouli 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 po1ouli 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 

po1ouli 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 po1ouli. 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 po1ouli (Judge et al. 2019, 

entire). 

Time Since Last Detection 

In 2002, what was thought to be the 

only female po1ouli 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 po1ouli 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 

po1ouli sightings. No po1ouli were seen 

or heard. The MFBRP project 

coordinator concluded that if po1ouli 

were present, they would have been 

detected (Mounce 2018, pers. comm.). 

Using 2004 as the last reliable 

observation record for po1ouli, 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 po1ouli faced threats similar to 

other bird species occurring on Maui 

(see ‘‘III. Analysis’’ for the Maui akepa, 

above). The last confirmed sighting of 

po1ouli 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 

po1ouli 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 po1ouli, 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 po1ouli 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 po1ouli is extinct. 

Although the po1ouli 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 po1ouli 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 


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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 mid1970s. 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 peoplehours 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 


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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 highquality 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). Twentytwo 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 


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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, benthicdwelling animals like freshwater 

mussels is challenging and can be 

affected by a variety of factors, 

including: 

• Size of the mussel (smaller mussels, 

including juvenile mussels, can be more 

difficult to find in complex substrates 

than larger mussels, and survey efforts 

must be thorough enough to try to detect 

smaller mussels); 

• Behavior of the mussel (some are 

found subsurface, some at the surface, 

and some above the surface, and 

position can vary seasonally [some are 

more visible during the reproductive 

phase when they need to come into 

contact with host fish; therefore, surveys 

likely need to be conducted during 

different times of the year to improve 

detection]); 

• Substrate composition (it can be 

easier to see/feel mussels in sand and 

clay than in gravel or cobble; therefore, 

surveys need to include all substrate 

types because mussels can fall off host 

fish into a variety of substrates); 

• Size of river (larger rivers usually 

have more expansive habitat areas to 

search and are sometimes deep, 

requiring specialized survey techniques 

such as self-contained underwater 

breathing apparatus [SCUBA]); 

• Flow conditions (visibility can be 

affected in very fast-flowing, very 

shallow, or turbid conditions; therefore, 

surveys need to use tactile or excavation 

methods, or delay until turbidity 

conditions improve); 

• Surveyor experience (finding 

mussels requires a well-developed 

search image, knowledge of instream 

habitat dynamics, and ability to identify 

and distinguish species); and 

• Survey methodology and effort 

(excavation and sifting of stream bottom 

can detect more mussels than visual or 

tactile surveys). 

All of these challenges are taken into 

account when developing survey 

protocols for any species of freshwater 

mussel, including the flat pigtoe. The 

flat pigtoe was medium-sized (but 

juveniles were very small) and most 

often found buried in sand, gravel, or 

cobble in fast-flowing runs. However, 

mussels can be found in suboptimal 

conditions, depending on where they 

dropped off of the host fish. Therefore, 

all of the above-mentioned 

considerations need to be accounted for 

when trying to detect this mussel 

species. Despite detection challenges, 

many well-planned, comprehensive 

surveys by experienced State and 

Federal biologists have 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 


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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 TennesseeTombigbee 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 waterquality 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, benthicdwelling 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 


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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 TennesseeTombigbee 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, benthicdwelling 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 


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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 waterquality 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, benthicdwelling 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 suboptimal 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 


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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, fastflowing 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 preimpoundment conditions. These 

hypolimnial discharges result in altered 

temperature regimes, extreme waterlevel 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, benthicdwelling 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. 


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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 mediumsized, 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 sandygravel 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, benthicdwelling 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 freeflowing 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 


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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 mediumriver, 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, benthicdwelling 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 


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


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71672 Federal Register / Vol. 88, No. 199 / Tuesday, October 17, 2023 / Rules and Regulations 

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 

■ 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. 

§ 17.11 [Amended] 

■ 2. Amend § 17.11 in paragraph (h), the 

List of Endangered and Threatened 

Wildlife, by: 

■ a. Under MAMMALS, removing the 

entry for ‘‘Bat, little Mariana fruit’’; 

■ b. Under BIRDS, removing the entries 

for ‘‘Akepa, Maui’’, ‘‘Akialoa, Kauai’’, 

‘‘Creeper, Molokai’’, ‘‘Nukupuu, Kauai’’, 

‘‘Nukupuu, Maui’’, ‘‘1O1o, Kauai 

(honeyeater)’’, ‘‘Po1ouli (honeycreeper)’’, 

‘‘Thrush, large Kauai’’, ‘‘Warbler 

(wood), Bachman’s’’, and ‘‘White-eye, 

bridled’’; 

■ c. Under FISHES, removing the 

entries for ‘‘Gambusia, San Marcos’’ and 

‘‘Madtom, Scioto’’; and 

■ 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’’. 

§ 17.85 [Amended] 

■ 3. Amend § 17.85 by: 

■ a. In paragraph (a) introductory text: 

■ i. In the heading, removing the word 

‘‘Seventeen’’ and adding in its place the 

word ‘‘Fourteen’’; and 

■ ii. In the table, removing the entries 

for ‘‘tubercled blossom (pearlymussel)’’, 

‘‘turgid blossom (pearlymussel)’’, and 

‘‘yellow blossom (pearlymussel)’’; 

■ b. In paragraph (a)(1)(i), removing the 

number ‘‘17’’ and adding in its place the 

number ‘‘14’’; 

■ c. In paragraph (a)(1)(ii), removing the 

number ‘‘17’’ and adding in its place the 

number ‘‘14’’; and 

■ d. In paragraph (a)(2)(iii), by removing 

the number ‘‘17’’ and adding in its place 

the number ‘‘14’’. 

■ 4. Amend § 17.95 by: 

■ a. In paragraph (e), removing the entry 

for ‘‘San Marcos Gambusia (Gambusia 

georgei)’’; and 

■ 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: 

§ 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 FineLined 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 finelined 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, 10, 11, 12, 13, 17, 18, 19, 21, 

24, 25, 26.

AL, GA, MS, TN. 


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Federal Register / Vol. 88, No. 199 / Tuesday, October 17, 2023 / Rules and Regulations 71673 

TABLE 1 TO NINE MOBILE RIVER BASIN MUSSEL SPECIES PARAGRAPH (2)(ii)—Continued 

Species Critical habitat units States 

Southern clubshell (Pleurobema decisum) ............................. Units 1, 2, 3, 4, 5, 6, 7, 8, 9, 13, 14, 15, 17, 18, 19, 21, 24, 

25, 26.

AL, GA, MS, TN. 

Triangular kidneyshell (Ptychobranchus greenii) .................... Units 10, 11, 12, 13, 18, 19, 20, 21, 22, 23, 24, 25, 26 ....... AL, GA, TN. 

Alabama moccasinshell (Medionidus acutissimus) ................ Units 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 25, 26 ...... AL, GA, MS, TN. 

Coosa moccasinshell (Medionidus parvulus) ......................... Units 18, 19, 20, 21, 22, 23, 24, 25, 26 ................................ AL, GA, TN. 

Orange-nacre mucket (Hamiota perovalis) ............................. Units 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 ............. AL, MS. 

Dark pigtoe (Pleurobema furvum) ........................................... Units 10, 11, 12 ..................................................................... AL. 

Southern pigtoe (Pleurobema georgianum) ............................ Units 18, 19, 20, 21, 22, 23, 24, 25, 26 ................................ AL, GA, TN. 

Fine-lined pocketbook (Hamiota altilis) ................................... Units 13, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26 ............. AL, GA, TN. 

* * * * * 

(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 


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71674 Federal Register / Vol. 88, No. 199 / Tuesday, October 17, 2023 / Rules and Regulations 

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 

(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. 

* * * * * 


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LOCUITFORt< 

PmPD .. nd Crlical.Hllllat Roads 

RiHR 

CountJU..s 

Blount 

l.OOUST,FO 

O 2 4 6 8 1 O 12 Miles 

- - - - - - (j) 

0 10000 20000 Meters 
Federal Register / Vol. 88, No. 199 / Tuesday, October 17, 2023 / Rules and Regulations 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 

* * * * * 

(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 


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Shelby 

Bibb 

0 5 10 15 20 Miles 

- - (i) 

O 9000 18000 27000 Meter, 
71676 Federal Register / Vol. 88, No. 199 / Tuesday, October 17, 2023 / Rules and Regulations 

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 

(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. 

* * * * * 


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Etowah 

'Calhoun 

/J,,l.Aoposed Oiticel Hl!lblet 

~Roads 

'•'Y.,RN"ers. 

~lines 

Powerllnes 

Cherokee 

0 2 4 6 8 10 Miles 

-- -- - (1) 

0 9000 18000 Meters 
Federal Register / Vol. 88, No. 199 / Tuesday, October 17, 2023 / Rules and Regulations 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 

* * * * * 

(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: 


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Talladega 

Coosa 

~:Clilical Habitat 0 2 4' 6 MlleS 

~Unes (1) 

0 6000 12000 --rs 
71678 Federal Register / Vol. 88, No. 199 / Tuesday, October 17, 2023 / Rules and Regulations 

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 

* * * * * (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. 

* * * * * 


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St. Clair 

IKEu. v CREEK =J==--,,.-

Shelby 

~Qftical Habitat 

~= D countyunes 

0 1 2 3 4 ... 

(1) - - - -

o 2000 4000 6000 Meters 
Federal Register / Vol. 88, No. 199 / Tuesday, October 17, 2023 / Rules and Regulations 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 

(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, 


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Blount Etowah 

FALL 

st Clair 

Jefferson 

61!!~ Critkel Hebitat 

~= CJ County Lines 

O 3 6 9 12 Miles 

- - - -

0 8000 16000 Meters 
71680 Federal Register / Vol. 88, No. 199 / Tuesday, October 17, 2023 / Rules and Regulations 

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, FineLined Pocketbook 

(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, 


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TENNESSEE 

.GEORGIA 

00$TANAULAR 

.I ... .' . opose,d.. . • Crltlcaf Habitat . Ro8dJ .... Rivers 

. ~Lines 

~RIVER 

O 5 10 15 20 Miles 

- - - o 10000 20000 30000· Meter:s 
Federal Register / Vol. 88, No. 199 / Tuesday, October 17, 2023 / Rules and Regulations 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, FineLined Pocketbook 


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Elmore 

0 1 2 3 4 Miles 

- - - -

0 2000 4000 
71682 Federal Register / Vol. 88, No. 199 / Tuesday, October 17, 2023 / Rules and Regulations 

* * * * * 

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 


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