[Federal Register Volume 87, Number 133 (Wednesday, July 13, 2022)]
[Proposed Rules]
[Pages 41641-41655]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-14961]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R4-ES-2021-0162; FF09E22000 FXES1113090FEDR 223]
RIN 1018-BF54


Endangered and Threatened Wildlife and Plants; Removal of the 
Puerto Rican Boa From the Federal List of Endangered and Threatened 
Wildlife

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to 
remove the Puerto Rican boa (Chilabothrus inornatus, but listed as 
Epicrates inornatus), an endemic snake from Puerto Rico, from the 
Federal List of Endangered and Threatened Wildlife (List). This 
determination is based on the best available scientific and commercial 
data, which indicate that the species has recovered and the threats to 
the species have been eliminated or reduced to the point that the 
species no longer meets the definition of an endangered species or 
threatened species under the Endangered Species Act of 1973, as amended 
(Act). If this proposal is finalized, the Puerto Rican boa will be 
removed from the List and the prohibitions and conservation measures 
provided by the Act, particularly through sections 7 and 9, would no 
longer apply to the species.

DATES: We will accept comments received or postmarked on or before 
September 12, 2022. Comments submitted electronically using the Federal 
eRulemaking Portal (see ADDRESSES, below) must be received by 11:59 
p.m. Eastern Time on the closing date. We must receive requests for 
public hearings, in writing, at the address shown in FOR FURTHER 
INFORMATION CONTACT by August 29, 2022.

ADDRESSES: Written comments: You may submit comments by one of the 
following methods:
    (1) Electronically: Go to the Federal eRulemaking Portal: https://www.regulations.gov. In the Search box, enter FWS-R4-ES-2021-0162, 
which is the docket number for this rulemaking. Then, click on the 
Search button. On the resulting page, in the Search panel on the left 
side of the screen, under the Document Type heading, check the Proposed 
Rule box to locate this document. You may submit a comment by clicking 
on ``Comment.''
    (2) By hard copy: Submit by U.S. mail to: Public Comments 
Processing, Attn: FWS-R4-ES-2021-0162, U.S. Fish and Wildlife Service, 
MS: PRB/3W, 5275 Leesburg Pike, Falls Church, VA 22041-3803.
    We request that you send comments only by the methods described 
above. We will post all comments on https://www.regulations.gov. This 
generally means that we will post any personal information you provide 
us (see Information Requested, below, for more information).
    Availability of supporting materials: This proposed rule and 
supporting documents, including the species status assessment (SSA) 
report and references cited, the 5-year review, the Recovery Plan, and 
draft post-delisting monitoring plan are available at https://www.regulations.gov under Docket No. FWS-R4-ES-2021-0162 and at the 
Caribbean Ecological Services Field Office website at https://www.fws.gov/southeast/caribbean/.

FOR FURTHER INFORMATION CONTACT: Edwin Mu[ntilde]iz, Field Supervisor, 
U.S. Fish and Wildlife Service, Caribbean Ecological Services Field 
Office, P.O. Box 491, Boquer[oacute]n, PR 00622; email: 
<a href="/cdn-cgi/l/email-protection#96d5f7e4fff4f4f3f7f8c9f3e5d6f0e1e5b8f1f9e0"><span class="__cf_email__" data-cfemail="7033110219121215111e2f1503301607035e171f06">[email protected]</span></a>; telephone: (787) 405-3641.
    Individuals in the United States who are deaf, deafblind, hard of 
hearing, or have a speech disability may dial 711 (TTY, TDD, or 
TeleBraille) to access telecommunications relay services. Individuals 
outside the United States should use the relay services offered within 
their country to make international calls to the point-of-contact in 
the United States.

SUPPLEMENTARY INFORMATION:

Executive Summary

    Why we need to publish a rule. Under the Act, a species warrants 
protection through listing if it is endangered or threatened. 
Conversely, a species may be removed from the List if the Act's 
protections are determined to be no longer required because the species 
is extinct, the species does not meet the definition of an endangered 
or a threatened species (because of, for example, recovery), or the 
listed entity does not meet the statutory definition of a species. We 
are proposing to remove the Puerto Rican boa from the List due to 
recovery. Removing a species from the List can be completed only by 
issuing a rule.
    What this document does. This rule proposes to delist the Puerto 
Rican boa based on its recovery.

[[Page 41642]]

    The basis for our action. Under the Act, we may determine that a 
species is an endangered species or a threatened species based on the 
five factors described in section 4(a)(1) of the Act: The present or 
threatened destruction, modification, or curtailment of its habitat or 
range (Factor A); overutilization for commercial, recreational, 
scientific or educational purposes (Factor B); disease or predation 
(Factor C); the inadequacy of existing regulatory mechanisms (Factor 
D); and other natural or humanmade factors affecting its continued 
existence (Factor E). We must consider the same factors in removing a 
species from the List (delisting).
    Under the Act and our implementing regulations at 50 CFR 424.11, we 
may delist a species if the best available scientific and commercial 
data indicate that: (1) The species is extinct; (2) the species does 
not meet the definition of an endangered species or a threatened 
species when considering the five factors listed above; or (3) the 
listed entity does not meet the statutory definition of a species. 
Here, we have determined that the Puerto Rican boa should be proposed 
for delisting under the Act because, based on an analysis of the five 
listing factors, it has recovered and no longer meets the definition of 
an endangered species or a threatened species.

Information Requested

    We intend that any final action resulting from this proposed rule 
will be based on the best scientific and commercial data available and 
be as accurate and as effective as possible. Therefore, we request 
comments or information from other concerned governmental agencies, 
Native American Tribes, the scientific community, industry, or any 
other interested parties concerning this proposed rule.
    We particularly seek comments concerning:
    (1) Reasons we should or should not delist the Puerto Rican boa;
    (2) New information on the historical and current status, range, 
distribution, and population size of the Puerto Rican boa;
    (3) New information on the known and potential threats to the 
Puerto Rican boa, including development and habitat loss, nonnative 
snakes and other nonnative species, and diseases;
    (4) New information regarding the life history, ecology, and 
habitat use of the Puerto Rican boa;
    (5) The extent of protection and management that would be provided 
by the Commonwealth of Puerto Rico to the Puerto Rican boa as a 
delisted species; and
    (6) The draft post-delisting monitoring plan and the methods and 
approaches detailed in it.
    Please include sufficient information with your submission (such as 
scientific journal articles or other publications) to allow us to 
verify any scientific or commercial information you include.
    Please note that submissions merely stating support for or 
opposition to the action under consideration without providing 
supporting information, although noted, will not be considered in 
making a determination, as section 4(b)(1)(A) of the Act directs that 
determinations as to whether any species is an endangered or a 
threatened species must be made ``solely on the basis of the best 
scientific and commercial data available.''
    You may submit your comments and materials concerning this proposed 
rule by one of the methods listed in ADDRESSES. We request that you 
send comments only by the methods described in ADDRESSES.
    If you submit information via https://www.regulations.gov, your 
entire submission--including any personal identifying information--will 
be posted on the website. If your submission is made via a hardcopy 
that includes personal identifying information, you may request at the 
top of your document that we withhold this information from public 
review. However, we cannot guarantee that we will be able to do so. We 
will post all hardcopy submissions on https://www.regulations.gov.
    Comments and materials we receive, as well as supporting 
documentation we used in preparing this proposed rule, will be 
available for public inspection on https://www.regulations.gov.
    Because we will consider all comments and information we receive 
during the comment period, our final determination may differ from this 
proposal. Based on the new information we receive (and any comments on 
that new information), we may conclude that the species should remain 
listed as endangered, or we may conclude that the species should be 
reclassified as threatened.

Public Hearing

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

Supporting Documents

    A species status assessment (SSA) team prepared an SSA report for 
the Puerto Rican boa. The SSA team was composed of Service biologists, 
in consultation with other species experts. The SSA report represents a 
compilation of the best scientific and commercial data available 
concerning the status of the species, including the impacts of past, 
present, and future factors (both negative and beneficial) affecting 
the species. The SSA report and other materials relating to this 
proposal can be found at https://www.regulations.gov under Docket No. 
FWS-R4-ES-2021-0162, and at the Caribbean Ecological Services Field 
Office website at https://www.fws.gov/southeast/caribbean/.
    In accordance with our July 1, 1994, peer review policy (59 FR 
34270; July 1, 1994), our August 22, 2016, Director's Memo on the Peer 
Review Process, and the Office of Management and Budget's December 16, 
2004, Final Information Quality Bulletin for Peer Review (revised June 
2012), we solicited independent scientific reviews of the information 
contained in the Puerto Rican boa SSA report. We sent the SSA report to 
nine independent peer reviewers and received eight responses. The SSA 
report was also submitted to our Federal, Commonwealth, and Tribal 
partners for scientific review. We received review from seven partners. 
In preparing this proposed rule, we incorporated the results of these 
reviews, as appropriate, into the final SSA report, which is the 
foundation for this proposed rule.

Previous Federal Actions

    The Puerto Rican boa (as Epicrates inornatus) was originally listed 
as an endangered species on October 13, 1970 (35 FR 16047), under the 
Endangered Species Conservation Act of 1969, and remained listed with 
the passage of the Act in 1973. A recovery plan for the Puerto Rican 
boa was completed on March 27, 1986 (Service 1986, 21 pp.), and 
modified on September 27, 2019 (Service 2019, 9 pp.). In 1991, we 
initiated a 5-year review for the Puerto

[[Page 41643]]

Rican boa (56 FR 56882; November 6, 1991), but we did not formally 
complete that review. We completed a 5-year status review for the 
Puerto Rican boa on September 16, 2011 (Service 2011, 26 pp.) and did 
not recommend to reclassify or delist the Puerto Rican boa due to 
remaining threats and lack of population data (Service 2011, pp. 16-
17).
    On August 22, 2016, we announced that we were initiating a 5-year 
review for the Puerto Rican boa and 13 other Caribbean species, and we 
requested new information that could have a bearing on the status of 
the Puerto Rican boa (81 FR 56692). We completed an SSA in 2021 
(Service 2021, 66 pp.) to inform the most recent Puerto Rican boa 5-
year review. This proposed rule also serves as our 5-year review of the 
species.
    For additional details on previous Federal actions, including 
recovery actions, go to https://www.fws.gov/program/endangered-species 
and search for the species' profile.

Background

    A thorough review of the taxonomy, life history, and ecology of the 
Puerto Rican boa is presented in the SSA report, version 1.1 (Service 
2021, 66 pp.), which is available at https://www.regulations.gov under 
Docket No. FWS-R4-ES-2021-0162 and is summarized in this proposed rule.
    The Puerto Rican boa is a large, semi-arboreal, nocturnal, 
nonvenomous snake endemic to Puerto Rico with the largest recorded 
sizes around 2 meters (m) (6.6 feet (ft)) in length (Reagan 1984, p. 
121; Wiley 2003, p. 192). Dorsal coloration of the Puerto Rican boa is 
variable and has been described from tan to reddish brown to very dark 
brown, with several dark bars or spots along its body; juveniles may 
have a reddish color (Rivero 1998, p. 432).
    The Puerto Rican boa uses both ambush and active foraging modes, 
eating smaller prey when young and mostly rats as they get larger 
(Rivero 1998, p. 432; Wiley 2003, p. 190; Henderson and Powell 2009, p. 
349). In general, prey items include rats, mice, bats, lizards, birds 
(including domestic fowl), and frogs, but even land crabs and insect 
fragments have been found in stomach contents (Rodr[iacute]guez and 
Reagan 1984, p. 219; Rodr[iacute]guez-Dur[aacute]n 1996, entire; Rivero 
1998, p. 432; Wiley 2003, p. 190; Henderson and Powell 2009, p. 349; 
Puente-Rol[oacute]n 2012, p. 54).
    Although the Puerto Rican boa is considered widely distributed, it 
is not uniformly abundant across the island and has a reported 
elevation range from sea level to 1,050 m (3,445 ft) (Henderson and 
Powell 2009, p. 349). Earlier occurrence records for the Puerto Rican 
boa described its wide distribution, with the species occurring in 
protected, rural, and developed areas (P[eacute]rez-Rivera and 
V[eacute]lez, Jr. 1978, p. 71). Later descriptions of Puerto Rican boa 
distribution increased the occurrence records for the species' wide 
distribution (Bird-Pic[oacute] 1994, p. 33; Rivero 1998, p. 433; Wiley 
2003, p. 190). The Puerto Rican boa has been reported in all of the 
municipalities on the main island of Puerto Rico (Puente-Rol[oacute]n 
2018, pers. comm.; Service 2021, p. 14).
    The Puerto Rican boa is considered a habitat generalist (Reynolds 
et al. 2016, p. 1883) and tolerates a wide variety of habitat types 
(terrestrial and arboreal) (Tolson and Henderson 1993, p. 45; Joglar 
2005, p. 143; Henderson and Powell 2009, p. 349). Cave systems and 
their surrounding forests are identified as particularly important for 
the Puerto Rican boa because of the ecological resources available 
(i.e., prey, shelter, thermal gradients, and mating opportunities) 
(Puente-Rol[oacute]n and Bird-Pic[oacute] 2004, pp. 349-350).
    In general, Puerto Rican boas have smaller home ranges when 
associated with more productive habitats (e.g., concentrated food 
resources) like cave ecosystems (Puente-Rol[oacute]n and Bird-
Pic[oacute] 2004, p. 349; Wunderle et al. 2004, p. 567). In areas where 
food resources are more dispersed or in lower densities, the Puerto 
Rican boa needs larger home ranges (Puente-Rol[oacute]n and Bird-
Pic[oacute] 2004, p. 349; Wunderle et al. 2004, p. 567). However, in 
urban karst landscapes, such as Fort Buchanan, Puerto Rican boas tend 
to have intermediate home range sizes that might be due to the scarcity 
and fragmentation of suitable habitat and the presence of artificial 
barriers like roads (Mulero-Oliveras 2019, p. 33).
    Although the actual life span of Puerto Rican boas in the wild is 
unknown, they may live between 20 and 30 years (Rivero 1998, p. 433; 
Henderson and Powell 2009, p. 349). The specific time for a Puerto 
Rican boa to reach sexual maturity is also unknown, but reproductive 
females that are older than 17 years of age have been found (Tolson 
1991, p. 100).
    Courtship and mating of the Puerto Rican boa is seasonal, and 
reproduction appears to be mostly biennial in the wild (Huff 1978, p. 
96; Tolson and Henderson 1993, p. 45; Tolson 1994, p. 355). Although 
there can be some temporal variability in the Puerto Rican boa's 
reproductive activity, courtship usually starts in February and March, 
and mating for most Puerto Rican boas is reported to occur at the 
beginning of the wet season, from late April to May (Tolson and 
Henderson 1993, p. 45; Tolson 1994, p. 355; Puente-Rol[oacute]n 2012, 
p. 85). Puerto Rican boas are born after a gestation period of 
approximately 5 to 6 months (Huff 1978, p. 97; Rivero 1998, p. 433; 
Puente-Rol[oacute]n 2012, p. 85). Thus, the reproductive cycle of the 
Puerto Rican boa is synchronized with the seasonal patterns of 
precipitation and temperature in Puerto Rico (Huff 1978, p. 96; Tolson 
and Henderson 1993, p. 45; Puente-Rol[oacute]n 2012, p. 85).
    The Puerto Rican boa was considered relatively rare by the 1900s 
(Stejneger 1904, p. 691) and is probably less abundant now than it was 
in Pre-Columbian times, when Puerto Rico had extensive forest cover 
(Reagan 1984, p. 119). However, the Puerto Rican boa is more abundant 
today than at the time of listing in 1970 (Service 2011, entire). This 
increase is probably in part due to the increase in forested areas in 
Puerto Rico (Lugo and Helmer 2004, p. 145; Kennaway and Helmer 2007, p. 
356; Par[eacute]s-Ramos et al. 2008, p. 1). In general, the species is 
more abundant in the karst region of northern Puerto Rico and less 
abundant in the dry southern region of the island (Rivero 1998, p. 
433).

Recovery Criteria

    Section 4(f) of the Act directs us to develop and implement 
recovery plans for the conservation and survival of endangered and 
threatened species unless we determine that such a plan will not 
promote the conservation of the species. Under section 4(f)(1)(B)(ii), 
recovery plans must, to the maximum extent practicable, include 
objective, measurable criteria which, when met, would result in a 
determination, in accordance with the provisions of section 4 of the 
Act, that the species be removed from the List.
    Recovery plans provide a roadmap for us and our partners on methods 
of enhancing conservation and minimizing threats to listed species, as 
well as measurable criteria against which to evaluate progress towards 
recovery and assess the species' likely future condition. However, they 
are not regulatory documents and do not substitute for the 
determinations and promulgation of regulations required under section 
4(a)(1) of the Act. A decision to revise the status of a species, or to 
delist a species, is ultimately based on an analysis of the best 
scientific and commercial data available to determine whether a species 
is no longer an endangered species or a threatened species, regardless 
of whether that information differs from the recovery plan.

[[Page 41644]]

    There are many paths to accomplishing recovery of a species, and 
recovery may be achieved without all criteria in a recovery plan being 
fully met. For example, one or more criteria may be exceeded while 
other criteria may not yet be accomplished. In that instance, we may 
determine that the threats are minimized sufficiently and that the 
species is robust enough that it no longer meets the definition of an 
endangered species or a threatened species. In other cases, we may 
discover new recovery opportunities after having finalized the recovery 
plan. Parties seeking to conserve the species may use these 
opportunities instead of methods identified in the recovery plan. 
Likewise, we may learn new information about the species after we 
finalize the recovery plan. The new information may change the extent 
to which existing criteria are appropriate for identifying recovery of 
the species. The recovery of a species is a dynamic process requiring 
adaptive management that may, or may not, follow all of the guidance 
provided in a recovery plan.
    The Puerto Rican Boa Recovery Plan (recovery plan), issued by the 
Service on March 27, 1986 (Service 1986, entire), did not contain 
measurable criteria. On September 27, 2019, the Service issued an 
amendment to the recovery plan (Service 2019, 9 pp.) that includes 
delisting criteria. The following discussion provides an assessment of 
the delisting criteria as they relate to evaluating the status of this 
species.

Delisting Criterion 1

    Delisting Criterion 1 reads: ``At least three Puerto Rican boa 
populations (moist limestone (i.e., moist karst), wet limestone (i.e., 
wet karst), and montane forest regions) occupy at least 50 percent of 
the species' suitable habitat, and populations are distributed island-
wide.'' The intent of this criterion is to maintain the species' 
viability (resiliency, representation, redundancy) in at least 50 
percent of suitable habitat throughout its range. Although this 
criterion specifies having ``at least three Puerto Rican boa 
populations,'' we now consider there to be one contiguous, 
interbreeding, island-wide population and evaluate this criterion as 
such (see ``Current Resiliency,'' below). The current abundance 
estimate of between 37,903 and 189,515 boas and the density estimates 
of 1.2 boas per ha (2.5 ac) to 5.6 boas per ha (2.5 ac) (see ``Current 
Resiliency,'' below) were used to evaluate this criterion.
    For the purposes of evaluating this criterion, we also considered 
both natural and developed habitat as described in the SSA report 
(Service 2021, p. 36), which combined three land use types with the 
predicted suitable habitat of the species (see ``Current Resiliency,'' 
below). Natural and developed areas include not only karst and forest 
habitat types, but also a broader island-wide diversity of habitats per 
the species' predicted habitat model (Gould et al. 2008, p. 50; Service 
2021, pp. 36-37). Habitat classifications occur within a diversity of 
currently occupied areas ranging from urban and densely populated 
landscapes to sparsely populated and rural landscapes (Gould et al. 
2008, p. 50).
    The current resilience evaluation used the Puerto Rico Gap Analysis 
Project (PRGAP) predicted habitat model (379,029 ha or 936,601 ac), of 
which 57 percent falls within natural habitat as described (see 
``Current Resiliency,'' below). Natural habitats that occur within 
public and private protected lands are the most important areas for 
maintaining the species' current and future viability. Examples of such 
areas include the El Yunque National Forest, Commonwealth Forests 
within the northern and southern karst areas, Mata de Pl[aacute]tano 
and El Tallonal Nature Reserves, and Puerto Rico Conservation Trust 
lands. Areas in the northern and southern karst regions are 
particularly important for the Puerto Rican boa and provide some of the 
best habitat currently occupied by the species. The Puerto Rican boa 
also currently occupies suitable habitat within certain developed 
landscapes that provide conservation benefits as well (e.g., Fort 
Buchanan, Julio Enrique Monagas State Park, and Las Cabezas de San 
Juan).
    Ultimately, the Puerto Rican boa is considered a habitat generalist 
and occurs within a variety of landscapes (Reynolds et al. 2016, p. 
1883). Using the minimum population estimate of more than 37,000 boas 
island-wide, and confirmed occurrence records for the species, we 
consider the Puerto Rican boa to be well represented within suitable 
habitats across its range and conclude that the intent of this 
criterion has been met.

Delisting Criterion 2

    Delisting Criterion 2 reads: ``Populations show a stable or 
increasing population trend, evidenced by natural recruitment and 
multiple age classes.''
    Multiple age classes of Puerto Rican boas have been documented 
indicating natural recruitment within the population (Mulero-Oliveras 
2022, pers. comm.). We do not have population trend data for the Puerto 
Rican boa, however, the best available information indicates that the 
species is relatively abundant and has a broad distribution across a 
variety of natural and developed habitats as explained in Delisting 
Criterion 1. The species is both more abundant and widely distributed 
today than at the time of listing. The apparent increase in population 
abundance is largely attributed to the increase in forested areas in 
Puerto Rico (Lugo and Helmer 2004, p. 145; Kennaway and Helmer 2007, p. 
356; Par[eacute]s-Ramos et al. 2008, p. 1), and the designation of 
protected areas within habitats that Puerto Rican boas occupy (Castro-
Prieto et al. 2019, p. 54). Based on this information, we consider this 
criterion to be met.

Delisting Criterion 3

    Delisting Criterion 3 reads: ``Threat reduction and management 
activities have been implemented to a degree that the species will 
remain viable for the foreseeable future.''
    One of the main threats to Puerto Rican boas is habitat loss, 
degradation, and fragmentation. These threats can also exacerbate other 
threats, such as road kill and increased conflicts with humans and 
nonnative animals such as cats, as well as the need for management 
(e.g., translocations). Thus, the occurrence of Puerto Rican boas 
within areas designated for conservation is the most important positive 
influence towards the species' persistence and viability.
    Puerto Rican boas occur within several protected areas (Service 
2019, pp. 5-6; Service 2021, pp. 23-24). In particular, the northern 
karst region, which is preferred habitat for the Puerto Rican boa, 
consists of numerous protected areas, private lands, and Federal lands 
where Puerto Rican boas are known to occur. A detailed description of 
protected lands within Puerto Rico is provided in ``Development and 
Habitat Protection,'' below.
    The Puerto Rican boa is protected under Commonwealth laws, 
including Law No. 241-1999 (Nueva Ley de Vida Silvestre de Puerto Rico 
(New Wildlife Law of Puerto Rico)) and Regulation 6766 or Reglamento 
para Regir el Manejo de las Especies Vulnerables y en Peligro de 
Extinci[oacute]n en el Estado Libre Asociado de Puerto Rico (Regulation 
6766: To govern the management of threatened and endangered species in 
the Commonwealth of Puerto Rico). The purpose of Law No. 241-1999 is to 
protect, conserve, and enhance both native and migratory wildlife 
species; declare property of Puerto Rico all wildlife species within 
its jurisdiction; and regulate permits, hunting activities, and exotic 
species, among other

[[Page 41645]]

activities. Law No. 241-1999 also prohibits the modification of natural 
habitat without a mitigation plan approved by the Puerto Rico 
Department of Natural and Environmental Resources (DNR).
    Various other laws have also been approved by the Commonwealth of 
Puerto Rico that will continue to provide protection to the Puerto 
Rican boa and its habitat. Law No. 292-1999, Ley para la 
Protecci[oacute]n y Conservaci[oacute]n de la Fisiograf[iacute]a 
C[aacute]rsica de Puerto Rico (Puerto Rico Karst Physiographic 
Protection and Conservation Law), was approved in 1999 to protect karst 
areas as one of the most valuable natural resources of the island. This 
law indirectly protects the Puerto Rican boa and all other species that 
occur in the karst and provides for stricter land regulations to 
prohibit development within the Karst Restricted Zone (Castro-Prieto et 
al. 2019, p. 59). In addition, the Puerto Rico Conservation Trust has 
acquired lands for conservation within the northern and the southern 
karst regions of Puerto Rico, in areas where Puerto Rican boas have 
been confirmed (Service 2019, pp. 5-6).
    The northern and the southern karst regions of Puerto Rico harbor 
the majority of cave formations on the island, which are essential 
habitat for this species. The cave populations of Puerto Rican boas are 
genetically diverse and represent excellent targets for conservation 
and for maintaining the species' genetic diversity (see ``Current 
Representation,'' below). Therefore, the conservation and protection 
efforts, and the corresponding reduction of the threats in lands where 
these formations are located, help to maintain sufficient resiliency of 
this species, promote its dispersion and recolonization of unoccupied 
habitats (representation), and improve its potential to adapt to 
natural and anthropogenic changes (redundancy).
    As explained below in ``Translocations,'' the translocation of 
Puerto Rican boas has been implemented with varying degrees of success 
to avoid and minimize potential detrimental effects on the species from 
development and other human-boa conflicts. Because the species will 
continue to be protected by the DNR, pursuant to the laws and 
regulations discussed above, the Puerto Rican boa translocation 
strategies as a conservation management activity are expected to 
continue.
    Based on our review of current local laws, regulations, and 
protected lands that have provided protection for the species, have 
helped to reduce the impact of threats, and will continue to provide 
benefits to the species into the foreseeable future, we conclude that 
the status of the Puerto Rican boa is improved throughout its range as 
a result of these protections, and that this criterion has been met.

Regulatory and Analytical Framework

Regulatory 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''. The Act defines an ``endangered species'' as a species that 
is in danger of extinction throughout all or a significant portion of 
its range, and a ``threatened species'' as a species that is likely to 
become an endangered species within the foreseeable future throughout 
all or a significant portion of its range. The Act requires that we 
determine whether any species is an ``endangered species'' or a 
``threatened species'' because of any of the following factors:
    (A) The present or threatened destruction, modification, or 
curtailment of its habitat or range;
    (B) Overutilization for commercial, recreational, scientific, or 
educational purposes;
    (C) Disease or predation;
    (D) The inadequacy of existing regulatory mechanisms; or
    (E) Other natural or manmade factors affecting its continued 
existence.
    These factors represent broad categories of natural or human-caused 
actions or conditions that could have an effect on a species' continued 
existence. In evaluating these actions and conditions, we look for 
those that may have a negative effect on individuals of the species, as 
well as other actions or conditions that may ameliorate any negative 
effects or may have positive effects. We consider these same five 
factors in delisting a species (50 CFR 424.11(c) and (e)).
    We use the term ``threat'' to refer in general to actions or 
conditions that are known to or are reasonably likely to negatively 
affect individuals of a species. The term ``threat'' includes actions 
or conditions that have a direct impact on individuals (direct 
impacts), as well as those that affect individuals through alteration 
of their habitat or required resources (stressors). The term ``threat'' 
may encompass--either together or separately--the source of the action 
or condition or the action or condition itself.
    However, the mere identification of any threat(s) does not 
necessarily mean that the species meets the statutory definition of an 
``endangered species'' or a ``threatened species.'' In determining 
whether a species meets either definition, we must evaluate all 
identified threats by considering the species' expected response and 
the effects of the threats--in light of those actions and conditions 
that will ameliorate the threats--on an individual, population, and 
species level. We evaluate each threat and its expected effects on the 
species, then analyze the cumulative effect of all of the threats on 
the species as a whole. We also consider the cumulative effect of the 
threats in light of those actions and conditions that will have 
positive effects on the species--such as any existing regulatory 
mechanisms or conservation efforts. The Secretary determines whether 
the species meets the definition of an ``endangered species'' or a 
``threatened species'' only after conducting this cumulative analysis 
and describing the expected effect on the species now and in the 
foreseeable future.
    The Act does not define the term ``foreseeable future,'' which 
appears in the statutory definition of ``threatened species.'' Our 
implementing regulations at 50 CFR 424.11(d) set forth a framework for 
evaluating the foreseeable future on a case-by-case basis. The term 
foreseeable future extends only so far into the future as we can 
reasonably determine that both the future threats and the species' 
responses to those threats are likely. In other words, the foreseeable 
future is the period of time in which we can make reliable predictions. 
``Reliable'' does not mean ``certain''; it means sufficient to provide 
a reasonable degree of confidence in the prediction. Thus, a prediction 
is reliable if it is reasonable to depend on it when making decisions.
    It is not always possible or necessary to define foreseeable future 
as a particular number of years. Analysis of the foreseeable future 
uses the best scientific and commercial data available and should 
consider the timeframes applicable to the relevant threats and to the 
species' likely responses to those threats in view of its life-history 
characteristics. Data that are typically relevant to assessing the 
species' biological response include species-specific factors such as 
lifespan, reproductive rates or productivity, certain behaviors, and 
other demographic factors.

Analytical Framework

    The SSA report documents the results of our comprehensive 
biological review of the best scientific and commercial

[[Page 41646]]

data regarding the status of the species, including an assessment of 
the potential threats to the species. The SSA report does not represent 
our decision on whether the species should be proposed for removal from 
the List (``delisted''). However, it does provide the scientific basis 
that informs our regulatory decisions, which involve the further 
application of standards within the Act and its implementing 
regulations and policies. The following is a summary of the key results 
and conclusions from the SSA report; the full SSA report can be found 
at Docket No. FWS-R4-ES-2021-0162 on https://www.regulations.gov and on 
the Caribbean Ecological Services Field Office website at https://www.fws.gov/southeast/caribbean/.
    To assess the Puerto Rican boa's viability, we used the three 
conservation biology principles of resiliency, redundancy, and 
representation (Shaffer and Stein 2000, pp. 306-310). Briefly, 
resiliency supports the ability of the species to withstand 
environmental and demographic stochasticity (e.g., wet or dry, warm or 
cold years), redundancy supports the ability of the species to 
withstand catastrophic events (e.g., droughts, large pollution events), 
and representation supports the ability of the species to adapt over 
time to long-term changes in the environment (e.g., climate changes). 
In general, the more resilient and redundant a species is and the more 
representation it has, the more likely it is to sustain populations 
over time, even under changing environmental conditions. Using these 
principles, we identified the species' ecological requirements for 
survival and reproduction at the individual, population, and species 
levels, and described the beneficial and risk factors influencing the 
species' viability.
    The SSA process can be categorized into three sequential stages. 
During the first stage, we evaluated individual species' life-history 
needs. The next stage involved an assessment of the historical and 
current condition of the species' demographics and habitat 
characteristics, including an explanation of how the species arrived at 
its current condition. The final stage of the SSA involved making 
predictions about the species' responses to positive and negative 
environmental and anthropogenic influences. Throughout all of these 
stages, we used the best available information to characterize 
viability as the ability of a species to sustain populations in the 
wild over time. We use this information to inform our regulatory 
decision.

Summary of Biological Status and Threats

    In this discussion, we review the biological condition of the 
Puerto Rican boa and its resources, and the threats that influence the 
species' current and future condition, in order to assess the species' 
overall viability and the risks to that viability.

Influences on Viability

Development and Habitat Protection
    The Puerto Rican boa occurs on both private and public land. Puerto 
Rican boas that occur outside of protected habitat may be more 
vulnerable to deforestation and land impacts associated with 
commercial, industrial, highway, and urban development. In Puerto Rico, 
human activity has been described as ``intense, pervasive, and 
fragments natural habitat'' (Lugo and Helmer 2004, p. 156). Although 
forest areas have increased in Puerto Rico, unprotected forests are 
vulnerable to urban development, particularly those near or within 
urban centers (Kennaway and Helmer 2007, p. 376). Urban growth in 
Puerto Rico increased at a rate of 16 percent between 2000 to 2010 
(Castro-Prieto et al. 2017, p. 476). In 2007, about 5.2 percent of the 
island was protected (Kennaway and Helmer 2007, p. 357); this increased 
to 8 percent by September 2015 (Castro-Prieto et al. 2017, p. 474). By 
December 2016, 159 terrestrial protected areas occurred in Puerto Rico, 
representing 16.1 percent of the island. However, this increase largely 
reflected a more inclusive definition of ``protected area,'' extending 
that to the Restricted Zone within the Karst Special Planning Zone 
(Castro-Prieto et al. 2019, p. 54). As of December 2018, approximately 
16.4 percent of terrestrial protected areas were classified as areas 
for conservation (Castro-Pietro et al. 2019, pp. 57-59).
    Consequences of human development on Puerto Rican boa habitat 
include habitat loss and fragmentation as land is deforested for 
development (e.g., commercial, industrial, and highway development, and 
urbanization) and areas of suitable habitat are increasingly isolated 
from each other. Direct impacts on Puerto Rican boas may include 
harassment, harm, and mortality due to trampling with construction and 
vegetation clearing machinery, road kills, predation by domesticated 
and feral cats associated with human populations, competition with 
other nonnative species (i.e., Boa constrictor), and persecution by the 
public and poachers (Service 2011, pp. 12-16). As Puerto Rican boa 
habitat is modified and developed, it increases human-boa conflicts, 
thus exacerbating these direct impacts and also increasing the need to 
translocate Puerto Rican boas (Service 2021, pp. 26-28). These factors 
have the potential to impact population resiliency by affecting the 
species' breeding and reproductive success and by limiting connectivity 
among suitable habitats.
    In 1999, the Commonwealth of Puerto Rico approved Law No. 241-1999 
(title 12 of the Laws of Puerto Rico Annotated (L.P.R.A.), section 
107), known as Nueva Ley de Vida Silvestre de Puerto Rico (New Wildlife 
Law of Puerto Rico); presently, the Puerto Rican boa is legally 
protected under this law. The purpose of this law is to protect, 
conserve, and enhance native and migratory wildlife species; declare as 
property of Puerto Rico all wildlife species within its jurisdiction; 
and regulate permits, hunting activities, and exotic species, among 
other activities. This law also has provisions to protect habitat for 
all wildlife species, including plants and animals. In 2004, the DNR 
approved Regulation 6766 or Reglamento para Regir el Manejo de las 
Especies Vulnerables y en Peligro de Extinci[oacute]n en el Estado 
Libre Asociado de Puerto Rico (Regulation 6766: To govern the 
management of threatened and endangered species in the Commonwealth of 
Puerto Rico). Law No. 241-1999 prohibits the modification of natural 
habitat (including Puerto Rican boa habitat) without a mitigation plan 
approved by the DNR (Service 2011, p. 15).
    The DNR has developed similar conservation measures as provided in 
section 7 of the Act to avoid and minimize potential effects of 
development projects on the Puerto Rican boa, conservation measures are 
implemented with varying degrees of success and oversight (Service 
2021, pp. 26-28). Because the Puerto Rican boa is a cryptic species, 
not all boas are likely to be detected during survey efforts, thus 
making it challenging to avoid or detect take of the species.
    The Puerto Rican boa occurs within several protected areas, 
including El Yunque National Forest, the largest reserve in Puerto 
Rico. The Puerto Rican boa is also presumed to occur in all 
Commonwealth forests managed by the DNR (Rivera 2019, pers. comm.), and 
has been reliably confirmed to occur within the R[iacute]o Abajo, 
Guajataca, Camabalache, Vega, and Maricao forests (Service 2021, 
Appendix B). The species has also been confirmed in the Gu[aacute]nica 
Commonwealth Dry Forest; however, the species is extremely rare there 
(Canals 2019, pers. comm.), with a single record from 1974 (Wiley 2003, 
p.

[[Page 41647]]

190) and limited fossil evidence (Pregill 1981, p. 50). This rarity is 
consistent with the general description that the species is less 
abundant in the dry southern region of the island (Rivero 1998, p. 
433).
    Within the karst region of Puerto Rico, the Karst Restricted Zone 
(Zone) has strict land regulations (Ort[iacute]z-Maldonado et al. 2019, 
entire; Service 2021, Appendix B). This Zone represents 7.2 percent of 
the total area of Puerto Rico, includes both public and private lands, 
and was designated for conservation purposes by prohibiting land 
exploitation of any type (Castro-Prieto et al. 2019, p. 59). The Puerto 
Rico Conservation Trust, through its unit Para La Naturaleza, also 
manages numerous protected natural areas throughout Puerto Rico where 
the Puerto Rican boa has been confirmed as well: El Convento Caves, 
Cabezas de San Juan, R[iacute]o Jacaboa, R[iacute]o Encantado, 
R[iacute]o Maricao, Hacienda La Esperanza, and Cordillera Sabana Alta 
(Ort[iacute]z-Maldonado et al. 2019, entire; Service 2021, Appendix B). 
Other protected areas that are important for the Puerto Rican boa are 
Julio Enrique Monagas State Park, Mata de Pl[aacute]tano Nature 
Reserve, and El Tallonal Private Reserve (managed by the 
nongovernmental organization, Citizens of the Karst) (Ort[iacute]z-
Maldonado et al. 2019, entire; Service 2021, Appendix B). Fort 
Buchanan, managed by the Department of Defense, is important for the 
Puerto Rican boa and has an Integrated Management Resource Management 
Plan with an endangered species management plan to protect federally 
listed species in coordination with the Service and the DNR.
    Since 2001, the Service's habitat restoration programs (i.e., 
Partners for Fish and Wildlife, and coastal programs) have been 
actively restoring private lands previously impacted by agricultural 
activities to provide suitable habitat for the Puerto Rican boa and 
other species within these regions.
    The occurrence of Puerto Rican boas within areas designated for 
conservation is the most important positive influence towards the 
species' persistence and viability. However, even within these 
protected areas, Puerto Rican boas are still vulnerable to certain 
risks like roadkill, intentional killings, and predation by cats, 
especially along the edges of forests close to human settlements. A 
number of studies have documented roadkill of Puerto Rican boas both 
within and outside El Yunque National Forest (Reagan 1984, p. 125; 
Wiley 2003, p. 189), with records as far back as the 1970s (Wiley 2003, 
pp. 191-192). Puerto Rican boa deaths associated with roads and 
development continue to occur today, with documentation through both 
social media and project consultation reports (Zegarra 2019, pers. 
comm.).
    In summary, since its listing in 1970, there has been an island-
wide increase in forested areas, directly benefiting the Puerto Rican 
boa by increasing available habitat. Beginning in the 1990s, numerous 
Federal and Commonwealth laws have been implemented that provide 
habitat protections in areas where Puerto Rican boas occur. 
Additionally, restoration of private and public lands that were 
historically impacted by deforestation, agricultural conversions, and 
other human development activities have also benefitted the species. 
These habitat protection and conservation measures have contributed to 
the current, relatively high, island-wide abundance of Puerto Rican 
boas.
Nonnative Species
    Another risk to the Puerto Rican boa is the presence of nonnative 
mammalian predators, namely cats (Felis catus) and mongoose (Herpestes 
auropunctatus). Neonate and juvenile life stages are thought to be the 
most vulnerable to nonnative predators, and cats are thought to have 
the greatest effect since they hunt both by day and night. Puerto Rico 
has a pervasive and unmanaged feral cat population associated with 
human settlements, even occurring within protected areas like El Yunque 
National Forest (Engeman et al. 2006, p. 95) and Cambalache State 
Forest (Rodr[iacute]guez-Vel[aacute]zquez et al. 2019, entire). Cats on 
islands affect native vertebrates, including reptiles such as the 
Jamaican boa (Chilabothrus subflavus; Medina et al. 2011, Appendix S1), 
Virgin Islands tree boa (C. granti), and Mona boa (C. monensis) (Tolson 
1996, p. 409). However, there are no specific data to accurately assess 
the level of impact of feral cats on the Puerto Rican boa population.
    The mongoose does not appear to have seriously impacted the Puerto 
Rican boa population (Rivero 1998, p. 432). Although a mongoose might 
occasionally eat a neonate or juvenile Puerto Rican boa, studies of 
mongoose food habits in Puerto Rico and throughout the Caribbean have 
not documented any such predation (Pimentel 1955, entire; Henderson 
1992, entire). Remains of a dead Puerto Rican boa were found with tooth 
impressions consistent with mongoose, but scavenging rather than 
predation was suggested (Wiley 2003, p. 193).
    There is now a well-known and reproductively established population 
of Boa constrictor in Puerto Rico that likely originated near 
Mayag[uuml]ez around the 1990s from a genetic lineage common to zoo and 
breeding collections (Reynolds et al. 2013, entire). This relatively 
recent invasion of a large snake is an emerging concern for the Puerto 
Rican boa. As with cats, the Boa constrictor has been established on 
Puerto Rico for several decades, but there is insufficient information 
to rigorously assess or measure the risks that this nonnative snake is 
having on the Puerto Rican boa population. Although the specific risks 
of this species on the Puerto Rican boa is uncertain, potential risks 
from this nonnative snake may include competition for food resources, 
displacement, and vectors for pathogens or parasites (Reed and Rodda 
2009, entire). Nonnative snake species also cause public confusion 
between which species are in need of conservation (native snakes) and 
which are not (nonnative snakes). There are also several recent 
sightings in Puerto Rico of the larger Reticulated python (Malayopython 
reticulatus), but this invasion is apparently more recent and more 
restricted than the Boa constrictor.
    Overall, nonnative species, especially predators such as cats and 
mongoose, may have an impact on individual Puerto Rican boas (e.g., 
killing or harming individuals), but the Puerto Rican boa is currently 
considered to have a wider distribution that when listed and there is 
no information currently available to suggest that nonnative species 
are having a significant effect on the overall population status of the 
Puerto Rican boa.
Translocations
    For many years, the translocation of Puerto Rican boas out of 
developed areas has been used as a management strategy to minimize 
conflicts with the public and minimize potential effects of development 
projects that disturb and modify Puerto Rican boa habitat. 
Translocations move Puerto Rican boas from areas of human-boa conflict 
into areas where these conflicts are potentially reduced (e.g., 
suitable protected Puerto Rican boa habitat away from humans). Although 
this strategy has been used for a long time, translocations have been 
poorly documented. Critical information on how many Puerto Rican boas 
were moved, their size classes, when and how they were moved, and where 
they were relocated is largely unavailable, and there is no information 
on the condition or the survival of these animals. In addition, Puerto 
Rican boas

[[Page 41648]]

are sometimes moved to a holding facility (Puente-Rol[oacute]n et al. 
2013, p. 8). This has raised concerns about the impact that these 
practices might have on wild Puerto Rican boa populations, both in 
numbers being removed and the potential spread of infectious diseases 
(see Disease section below).
    Despite poorly documented Puerto Rican boa translocation practices, 
research has shown that translocations can work when conducted 
correctly (Puente-Rol[oacute]n 2012, p. 116; Puente-Rol[oacute]n et al. 
2013, p. 7; Mulero-Oliveras 2019, p. 69). For example, Fort Buchanan 
personnel maintain a record of Puerto Rican boa sightings and 
translocations in their facility. They developed a protocol to capture 
and translocate Puerto Rican boas that are found inside or around 
structures (houses and buildings) and construction sites. Captured 
Puerto Rican boas are translocated to forested areas previously 
identified as boa habitat within Fort Buchanan. Although some Puerto 
Rican boas tend to travel back to their original capture site, most 
boas remain within the new transfer area. Thus, translocation 
strategies that consider the type and amount of habitat at release 
sites and the distance to the initial capture location are most 
successful (Puente-Rol[oacute]n 2012, p. 116; Mulero-Oliveras 2019, p. 
69). Fort Buchanan's management, research, and education efforts are 
examples of the positive influence of conservation on Puerto Rican 
boas. The U.S. Forest Service staff at El Yunque National Forest also 
successfully translocated live Puerto Rican boas within the forest 
(Ilse 2020, pers. comm.).
    Translocations can be an effective management tool for minimizing 
conflict with the public and for protecting Puerto Rican boas from 
development and other activities.
Poaching and Intentional Killings
    The hunting of Puerto Rican boas to extract their fat due to the 
alleged medicinal properties of the snake ``oil'' has been reported 
since the 1930s (Grant 1933, p. 225; Rivero 1998, p. 433) and was 
identified as a factor contributing to the species' decline 
(P[eacute]rez-Rivera and V[eacute]lez, Jr. 1978, p. 70). The practice 
of hunting Puerto Rican boas for their fat continued through the early 
2000s (Reagan 1984, p. 119; Joglar 2005, pp. 162-163). In addition, one 
report of snake meat being used for human consumption occurred in the 
1990s (Bird-Pic[oacute] 1994, p. 35), and there are reports of Puerto 
Rican boas collected to be kept as pets (Joglar 2005, p. 146). Based on 
the best available information, the practice of hunting or capturing 
Puerto Rican boas may still occur, but probably on a limited basis as 
outreach and education efforts have increased.
    Killing of Puerto Rican boas out of fear, religious prejudice, or 
ignorance may occur. However, most, if not all, of the available 
information on these killings is anecdotal, and there are no data to 
determine the level of impact this is having on the Puerto Rican boa 
population (Puente-Rol[oacute]n and Bird-Pic[oacute] 2004, p. 343; 
Mulero-Oliveras 2019, p. 6). In addition, development and habitat 
destruction may also exacerbate killing of Puerto Rican boas as it may 
increase human-boa interactions, especially in close proximity to prime 
Puerto Rican boa habitat. Even within protected habitat in El Yunque 
National Forest, one Puerto Rican boa was recently found on a trail 
with its head chopped off (Ilse 2020, pers. comm.). Although both 
Federal and local laws and regulations currently prohibit the killing 
of Puerto Rican boas and commercial use of Puerto Rican boas, most of 
these cases are thought to go unreported (Service 2021, p. 28).

Hurricanes and Post-hurricane Restoration Actions

    While there is scarce information on the potential direct effects 
of hurricanes on the Puerto Rican boa, some inferences can be drawn 
from the effects of recent hurricanes. After Hurricane Georges in 
September 1998, some Puerto Rican boas at El Yunque National Forest 
increased their movements and changed their habitat use, suggesting 
Puerto Rican boas responded as expected to hurricane alterations in 
forest cover and prey distribution (Wunderle et al. 2004, p. 555). 
Additionally, hurricane damage (i.e., loss of leaves, vines, and 
branches) may limit the arboreal use and movements of Puerto Rican boas 
(Wunderle et al. 2004, p. 569). Depending on the hurricane category and 
damages caused, we can expect that some Puerto Rican boas, including 
adult and juvenile individuals, may die due to injury from falling 
debris or other unknown sources. For example, the category 4 Hurricane 
Mar[iacute]a in September 2017 caused more than 40,000 landslides in at 
least 75 percent of Puerto Rico's 78 municipalities (Bessette-Kirton et 
al. 2019, p. 4). Such landslides may have caused the death of Puerto 
Rican boas in some areas.
    Puerto Rican boa casualties have also been documented during post-
hurricane restoration actions. Infrastructure restoration (e.g., 
clearing or opening new rights-of-way) and debris collection and 
disposal after Hurricane Maria was anticipated to cause some impacts to 
the Puerto Rican boa in the form of death or injury. Projects with a 
Federal nexus were evaluated through an emergency consultation under 
section 7 of the Act. Although the emergency consultation process 
included Puerto Rican boa conservation measures, at least four Puerto 
Rican boas were killed at least nine captured and relocated during 
post-hurricane debris management activities. Because Puerto Rican boas 
are difficult to detect, we suspect that more Puerto Rican boas may 
have been killed during these activities. Moreover, since the emergency 
consultation only covered projects with a Federal nexus, it is likely 
that an unknown number of other hurricane-related restoration projects 
without Federal involvement could have negatively impacted the species.
    Despite direct impacts from past and more recent hurricanes, and 
post-hurricane debris management on the species' habitat, the Puerto 
Rican boa continues to be reported throughout its range. Thus, 
individual Puerto Rican boas are likely impacted by hurricanes and 
post-hurricane restoration activities, but overall, based on the best 
information available, this threat does not appear to have population-
level effects.
Disease
    Initially observed in 2006, ophidiomycosis (formerly known as snake 
fungal disease and likely caused by the fungal pathogen Ophidiomyces 
ophiodiicola) was considered an emerging disease documented in both 
wild and captive snakes throughout most of the eastern United States by 
2015 (Lorch et al. 2016, p. 2; Allender et al. 2019, p. 7). However, 
ophidiomycosis is now considered a widespread, previously unrecognized 
endemic disease (Allender et al. 2019, p. 6; Davy et al. 2021, entire). 
Ophidiomycosis can cause lethal infections, but multiple factors may 
determine impacts of ophidiomycosis on snake populations (Lorch et al. 
2016, pp. 2, 6; Davy et al. 2021, p.2). Signs of ophidiomycosis include 
crusted, ulcerated, and discolored scales; nodules under the skin; and 
a swollen or disfigured face, leading to emaciation and death (Thompson 
et al. 2018, p. 1; McKenzie et al. 2019, p. 142). Secondary effects 
from the disease may include starvation, poor body condition, and 
bacterial infection, possibly leading to mortality (Lorch et al. 2016, 
pp. 4-5; McKenzie et al. 2019, p. 142). Behavioral changes in infected 
individuals may include abnormal or excessive molting, decrease in 
activity, frequency in ecdysis (shedding of skin),

[[Page 41649]]

and abnormal behaviors such as anorexia and basking in open and 
conspicuous areas which can increase the risk of mortality (Lorch et 
al. 2016, pp. 4-5; Thompson et al. 2018, p. 2).
    In 2018, ophidiomycosis was first confirmed in Puerto Rican boas 
within Fort Buchanan (Allender et al. 2019, p. 20). Out of seven live 
Puerto Rican boas sampled, one showed clinical signs (dermal lesions) 
of ophidiomycosis and had a positive DNA test. Samples from three other 
Puerto Rican boas from Fort Buchanan showed clinical signs but had 
negative test results.
    This disease may be underreported in populations where it affects 
snakes infrequently or in species that develop less severe symptoms 
(Thompson et al. 2018, p. 1), which may be the case for the Puerto 
Rican boa. Preliminary results from an ongoing study show additional 
positive results for at least 11 Puerto Rican boas, mostly sampled in 
caves (Mulero-Oliveras 2021, pers. comm.). There are also positive 
results for other native and nonnative snake species being sampled 
(i.e., Chilabothrus granti, Borikenophis portoricensis, Boa 
constrictor, Malayopython reticulatus).
    Currently, there have been no reported fatalities of Puerto Rican 
boas associated with ophidiomycosis. We do not have sufficient 
information on the potential future spread of ophidiomycosis to 
reliably model this threat for forecasting future conditions for the 
Puerto Rican boa. However, based on the best available information, 
ophidiomycosis does not appear to have population-level effects on the 
Puerto Rican boa population, and given the lack of evidence for 
population level effects in other snake populations (Davy et al. 2021, 
p. 8), we do not consider this disease to be a primary threat to this 
species.
Climate Change
    The Intergovernmental Panel on Climate Change (IPCC) concluded that 
warming of the climate system is unequivocal (IPCC 2014, p. 2). 
Projections for future precipitation trends are less certain than those 
for temperature, but suggest that overall annual precipitation will 
decrease, and that tropical storms will occur less frequently, but with 
more force (more category 4 and 5 hurricanes) than historical averages 
(Knutson et al. 2010, entire; Carter et al. 2014, entire). These 
predictions are consistent with the predicted scenario of a gradual 
trend towards a drier and hotter climate for Puerto Rico (Khalyani et 
al. 2016, entire; Bhardwaj et al. 2018, entire).
    The Puerto Rican boa's reproductive cycle is synchronized with 
seasonal patterns of precipitation and temperature (Huff 1978, p. 96; 
Tolson and Henderson 1993, p. 45; Puente-Rol[oacute]n 2012, p. 85), and 
climate variations may affect availability of prey such as rats 
(Puente-Rol[oacute]n 2012, p. 89). Thus, climate change may alter 
certain critical aspects of the biology of the Puerto Rican boa, 
potentially shifting the reproductive activity of adults and reducing 
fitness. Puerto Rican boa habitat is also expected to change with the 
predicted shifts in life zones, as rain, wet, and moist zones gradually 
become drier (Khalyani et al. 2016, p. 265). This shift would 
potentially reduce the amount of available suitable habitat for the 
Puerto Rican boa. In general, all habitats are susceptible to one or 
more climate change stressors, such as sea level rise, increased 
severity of storms (i.e., hurricanes), increased droughts, and higher 
temperatures (Puerto Rico Climate Change Council (PRCCC) Working Group 
2 2013, pp. 157-168).
    Species that are dependent on specialized habitat types, limited in 
distribution, or at the extreme periphery of their range are most 
susceptible to the impacts of climate change (Byers and Norris 2011, p. 
22). However, none of these conditions applies to the Puerto Rican boa, 
which is a habitat generalist (Reynolds et al. 2016, p. 1883) and has 
an island-wide distribution. However, several potential mechanisms for 
climate change impacts have been suggested, including increased 
physiological stress on the Puerto Rican boa and exacerbation of the 
species' response to pathogenic infections (PRCCC Working Group 2 2013, 
p. 162). Climate change may also affect the species' dispersal 
behavior, increase its feeding frequency, reduce the availability of 
prey, and increase water loss, further affecting the survival of the 
Puerto Rican boa (PRCCC Working Group 2 2013, p. 162). Lastly, although 
sea level rise is not specifically mentioned as a potential threat to 
the Puerto Rican boa (PRCCC Working Group 2 2013, p. 164), we expect 
sea level rise to reduce available coastal habitat. Sea level rise 
projections for Puerto Rico are between 0.4 m (1.3 ft) and 1.0 m (3.2 
ft) by the year 2100 (PRCCC Working Group 2 2013, p. 67) and could 
reduce or degrade habitat within coastal mangrove forests. However, 
because the Puerto Rican boa is a habitat generalist, we do not expect 
the potential loss of coastal habitat to sea level rise, to have 
population-level effects.
    In summary, climate change may cause changes in some of the Puerto 
Rican boa's life-history strategies (e.g., timing of reproduction), or 
it may impact habitats that Puerto Rican boas use (e.g., coastal 
habitats), but overall, because the Puerto Rican boa is a habitat 
generalist, and based on the best information currently available, we 
do not anticipate that climate change will have population-level 
effects on the species in the foreseeable future.

Current Condition

    A more recent study within the urban landscape of Fort Buchanan 
documented a total of 50 live and 9 dead Puerto Rican boas from 2013 to 
2017 (Mulero-Oliveras 2019, p. 23). Thirty-eight of the live 
individuals were used for the per person-hour estimate of the Puerto 
Rican boa population in Fort Buchanan, resulting in a general 
population density of 1.2 boas per ha (2.5 ac), as well as 3.8 boas per 
ha (2.5 ac) within one karst forest fragment, considered a Puerto Rican 
boa hot spot within Fort Buchanan (Mulero-Oliveras 2019, p. 24).
Current Resiliency
    Based on the available information, including input from species 
experts, we determined there is one island-wide Puerto Rican boa 
population (Service 2021, pp. 34-35). This population may function as 
several interbreeding groups, which are concentrated within certain 
habitat patches or landscapes that may or may not interact at different 
levels via natural or human-facilitated dispersal. The Puerto Rican boa 
is characterized as a homogenous population with relatively high 
genetic diversity (Puente-Rol[oacute]n et al. 2013, entire; Service 
2021, pp. 34-35). For the Puerto Rican boa to maintain its viability, 
its population must be able to withstand stochastic events 
(demographic, environmental, and anthropogenic). To maintain resiliency 
to stochastic events, this species needs an adequate number of 
individuals (abundance) from all life stages (breeding adults, 
juveniles, and hatchlings).
    Prior to Puerto Rico's historical deforestation, the Puerto Rican 
boa probably occurred in almost all habitats below 500 m (1,640 ft) 
elevation (Puente-Rol[oacute]n et al. 2013, p. 7). Based on current 
abundance estimates, it was recently suggested that the Puerto Rican 
boa ``is widely considered to have recovered from the near-complete 
deforestation of the island of Puerto Rico in the early 20th century'' 
(Reynolds and Henderson 2018, p. 13). This assessment suggests that the 
Puerto Rican boa population is able to withstand certain levels of 
natural and

[[Page 41650]]

anthropogenic disturbances through long periods of time. Puerto Rican 
boa populations can persist in urban fragmented landscapes in low 
densities, but not without certain costs (e.g., smaller home range 
sizes, lower abundance, and greater exposure to threats) (Mulero-
Oliveras 2019, pp. 58-59).
    We assessed the population's resiliency by using the available 
density estimates of 1.2 boas per ha (2.5 ac) to 5.6 boas per ha (2.5 
ac) in combination with the species' PRGAP predicted habitat model to 
calculate a rough estimate of the Puerto Rican boa's population size 
(Gould et al. 2008, pp. 49-50; Service 2021, pp. 14-15, Appendix A-2). 
The PRGAP predicted an estimated 414,379 ha (1,023,952 ac) of Puerto 
Rican boa habitat, that is, 46.3 percent of the island from sea level 
to 1,000 m (3,281 ft) (Gould et al. 2008, p. 50; Service 2021, pp. 14-
15, Appendix A-2). We used this as our baseline model to assess the 
variability of the current quality of habitats available for the Puerto 
Rican boa across the island. Because there are no clear records of 
Puerto Rican boas above 700 m (2,297 ft), we refined the PRGAP model to 
consider only areas below 700 m (2,297 ft) as predicted suitable 
habitat, resulting in an estimated 379,029 ha (936,601 ac) of predicted 
Puerto Rican boa habitat.
    Based on the analysis in the SSA, population abundance ranges from 
37,903 to 189,515 boas (i.e., 0.1 boas per ha (2.5 ac) and 0.5 boa per 
ha (2.5 ac), as multiplied by 379,029 ha (936,601 ac) of Puerto Rican 
boa suitable habitat for the entire island) (Service 2021, p.37). 
Because Puerto Rican boas occur in higher densities in some areas, 
37,903 can be viewed as the lower bound of the current population 
estimate for Puerto Rican boas in Puerto Rico.
    Using the lower bound population estimate combined with the 
species' known high adult survival rate (greater than 90 percent), we 
consider the Puerto Rican boa population to have a medium to high level 
of resiliency (Service 2021, pp. 37-38). That is, the Puerto Rican boa 
population has a medium to high ability to withstand stochastic events 
(demographic, environmental, and anthropogenic). We also assume that 
the most resilient interbreeding groups occur where suitable habitat 
and resources are least fragmented, occur the farthest from human 
settlements, and occur where nonnative predators are few or absent, 
which are reasonable assumptions given our understanding of the ecology 
of the species.
Current Redundancy
    High redundancy reduces the species' extinction risk in the event a 
portion of the species' range is negatively affected by a natural or 
anthropogenic catastrophic disturbance. For the Puerto Rican boa to 
withstand catastrophic events such as hurricanes, it needs to maintain 
sufficient resiliency across its range. Thus, we used the geographic 
distribution from the PRGAP predicted potential habitat model to assess 
redundancy. The exact historical distribution of the Puerto Rican boa 
is unknown, but its present, seemingly fragmented, distribution 
suggests that it occupied more areas than its current range. The 
current range likely reflects localized extirpations due to habitat 
degradation and human persecution.
    The Puerto Rican boa has a wide distribution across Puerto Rico, 
and the presence of suitable habitat throughout its range reduces the 
risk that any large portion of the species' range will be negatively 
affected by a single catastrophic or anthropogenic event at any one 
time, except for hurricanes, which can have island-wide effects. Given 
the amount of suitable habitat available for the Puerto Rican boa 
(Service 2021, p. 37), the species appears to be well-buffered against 
the effects of catastrophic events. Catastrophic events that could 
affect Puerto Rican boa habitat include, but are not limited to, 
hurricanes and the emergence of new threats, like snake fungal diseases 
(see Influences on Viability, above). During Hurricane Maria in 2017, 
the entire range of the Puerto Rican boa was subject to hurricane force 
winds (greater than 64 knots (74 miles per hour)) as the mostly 
Category 4 hurricane passed over the Puerto Rico mainland. Despite 
direct impacts from past and more recent hurricanes, and post-hurricane 
debris management of the species' habitat, the Puerto Rican boa 
continues to be reported throughout its range (Service 2021, Appendix 
C). Thus, we do not consider hurricanes to be a threat to the species.
    In summary, the current redundancy for the Puerto Rican boa is 
characterized by one island-wide population with a medium to high level 
of resiliency across most of the species' historical range, although 
the current distribution is likely fragmented due to habitat 
degradation.
Current Representation
    Representation describes the ability of a species to adapt to 
changing environmental conditions over time and is characterized by the 
genetic structure of the species and the environmental diversity within 
and among populations (Service 2016, p. 10). The more representation, 
or diversity, a species has, the more it is capable of adapting to 
changes (natural or anthropogenic) in its environment. Thus, to 
evaluate representation for the Puerto Rican boa, we used the available 
species-specific genetic information. In addition, we considered the 
ecological variability of habitats used by the Puerto Rican boa.
    Genetic assessments of the Puerto Rican boa demonstrate a 
relatively high level of genetic diversity. Based on 86 samples from 15 
municipalities in Puerto Rico, three clear haplogroups and no distinct 
phylogeographic structure across the island were identified, indicating 
a relatively high level of genetic diversity within the areas sampled 
and an overall high haplotype diversity (Puente-Rol[oacute]n et al. 
2013, p. 7). Although Puerto Rican boas inhabiting caves are not 
genetically different from Puerto Rican boas that occur in other 
habitats, they harbor multiple genetic lineages and represent a large 
proportion of the genetic diversity of Puerto Rican boas (Puente-
Rol[oacute]n et al. 2013, p. 5; Reynolds and Puente-Rol[oacute]n 2014, 
p. 1). Additionally, genetic analyses from at least one location in the 
north (municipality of Dorado) are indicative of reduced gene flow and 
genetic drift, potentially due to habitat fragmentation or isolation 
that is affecting the species' ability to naturally disperse (Puente-
Rol[oacute]n et al. 2013, p. 6).
    The available genetic studies have not indicated that critical 
genetic differences currently exist across the range of the Puerto 
Rican boa (Puente-Rol[oacute]n et al. 2013, entire). In addition, there 
is no evidence that any genetic abnormalities have emerged or that 
overall fitness of the Puerto Rican boa population has decreased. The 
best available science indicates that the Puerto Rican boa population 
seems well represented with relatively high genetic diversity.
Current Condition Summary
    The Puerto Rican boa population exhibits medium to high resiliency 
and has an estimated island-wide current population of approximately 
37,903 to 189,515 boas, with density estimates that range from 1.2 boas 
per ha (2.5 ac) to 5.6 boas per ha (2.5 ac). Given the amount of 
predicted habitat and the medium to high resiliency across its range, 
the Puerto Rican boa population appears to have adequate redundancy and 
seems well buffered against catastrophic events. We determined the 
Puerto Rican boa is well represented, with an overall high level of 
genetic

[[Page 41651]]

diversity over relatively broad and diverse geographic areas.

Projected Future Status

    To assess the future viability of the Puerto Rican boa, we used a 
demographic matrix model and projected the overall population response 
to four different habitat change scenarios 30 years into the future 
(2050). We predicted resilience at 30 years into the future (year 2050) 
considering input from species experts and the information available to 
reasonably predict development changes in threats, and the species' 
response to these changes. This timeframe reflects more than one 
generation of Puerto Rican boas, which may live more than 20 years 
(Rivero 1998, p. 433; Henderson and Powell 2009, p. 349).
    These four scenarios provide a range of viability predictions for 
the species and are intended to represent Puerto Rican boa population 
response to the key threats of habitat loss, habitat fragmentation, and 
human interactions. These habitat and human-associated influences can 
be related to increased development, conversion of natural areas to 
urban areas for residential and commercial development, and road 
construction and expansion. Human-caused habitat loss can also be 
related to other threats such as increased human-boa conflicts, 
intentional killings, and predation by cats. We do not explicitly 
include in our scenarios the impacts of hurricanes, diseases, or 
climate change on Puerto Rican boas or their habitat. Information 
available for these threats is lacking or the response of Puerto Rican 
boas to these threats is unknown.
    To project Puerto Rican boa population size into the future based 
on different amounts of development, we used a stage-based Lefkovitch 
matrix model (Caswell 2001, pp. 56-109; Tucker et al. 2020, p. 2; 
Service 2021, pp. 43-45). This model allows us to account for stage-
specific differences in survival and reproductive output into the 
future. We considered four life stages based on size: young (less than 
60 cm (2 ft)), juveniles (60-90 cm (2-3 ft)), subadults (90-110 cm (3-
3.6 ft)), and adults (greater than 110 cm (3.6 ft)). We elicited the 
probabilities of annual survival, growth to the next size class, and 
fecundity (average number of offspring per individual) for each size 
class from the Puerto Rican boa expert team or drew values from the 
available literature (Tucker et al. 2020, p. 3; Service 2021, pp. 19, 
43-45). Personal information, unpublished data, and inference from 
captive zoo populations was used by the expert team to determine 
productivity and survival rates. For more details on the model, please 
see Tucker et al. (2020, entire) and the SSA report (Service 2021, pp. 
43-49).
    We considered future scenarios that included changes in land cover 
such that developed areas would encroach upon natural areas, resulting 
in both an increased proximity of development to natural areas and loss 
of overall Puerto Rican boa habitat. With these scenarios, we also 
sought to indirectly capture key threats due to habitat loss and 
increased conflicts with humans and cats. Some Puerto Rican boa 
populations can coexist with development when suitable habitat and prey 
are available within a managed urbanized matrix like Fort Buchanan, but 
not in a purely developed landscape (Mulero-Oliveras 2019, p. 35).
    The four future scenarios were based on an analysis of past rates 
of urbanization in proximity to protected natural areas in Puerto Rico, 
which found that urban growth increased at a rate of 16 percent over a 
decade (years 2000-2010) (Castro-Prieto et al. 2017, p. 476). One of 
the scenarios includes projected the status quo urbanization rate, 
while the other three scenarios include different changes in 
urbanization rate (described below). Urbanization rate was defined as 
the rate at which both overall suitable Puerto Rican boa habitat 
declined and the rate at which the percent of available habitat that 
fell within developed areas increased (Service 2021, pp. 49-50). By 
simulating simultaneous habitat loss and land cover change, these 
scenarios represent the most intense impacts of urbanization on Puerto 
Rican boa populations.
    The four potential future scenarios are described as follows: no 
further urbanization (0 percent), reduced urbanization (8 percent), 
status quo urbanization (16 percent), and increased urbanization (24 
percent) (see table 1, below; Tucker et al. 2020, entire). Under the 
``best-case'' scenario of no future urban growth, the proportion of 
Puerto Rican boa habitat in natural and urban areas would remain the 
same as current condition (estimated at 43 percent), and the total 
amount of habitat would remain constant (see table 1, below). Under the 
``reduced urbanization'' scenario, we assumed an 8 percent increase in 
urbanization per decade, with both the proportion of Puerto Rican boa 
habitat falling in an urban matrix increasing by 8 percent every 10 
years and the total Puerto Rican boa habitat area decreasing by 8 
percent every 10 years (see table 1, below). The third ``status quo'' 
scenario assumes the rate of urbanization continues at 16 percent per 
decade, and the total amount of available Puerto Rican boa habitat 
would likewise decrease by 16 percent every 10 years (see table 1, 
below). The fourth, ``worst-case'' scenario assumes that the rate of 
urbanization would increase to a rate of 24 percent per decade (see 
table 1, below), with all the associated impacts to Puerto Rican boa 
habitat realized. To implement all scenarios in the model, we 
calculated the expected rate of development per year and used this to 
calculate the predicted total Puerto Rican boa habitat availability and 
proportion in urban areas. This assumes that development occurs 
gradually each year and is based on analysis conducted by Castro-Prieto 
et al. (2017, entire).

   Table 1--Total Puerto Rican Boa Habitat Area and Proportion of Habitat Falling Within an Urban Area in 30 Years Under Four Potential Rates of Urban
                                                                        Growth *
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    Total habitat      Developed      Total natural    Total developed
                                                   Urban growth   area in 30 years   habitat in 30    habitat in 30     habitat in 30     Total habitat
                    Scenario                        per decade       in hectares         years          years in          years in        area lost in
                                                     (percent)         (acres)         (percent)    hectares (acres)  hectares (acres)  hectares (acres)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1. No further urbanization......................               0           379,029              43           215,046           163,983                 0
                                                                         (936,601)                         (531,390)         (405,210)
2. Reduced urbanization.........................               8           300,269              54           138,124           162,145            78,760
                                                                         (741,980)                         (341,311)         (400,669)         (194,620)
3. Status quo...................................              16           237,427              68            75,977           161,450           141,602
                                                                         (586,694)                         (187,743)         (398,951)         (349,906)

[[Page 41652]]

 
4. Increased urbanization.......................              24           187,377              86            25,233           162,144           191,652
                                                                         (463,018)                          (62,352)         (400,666)         (473,582)
--------------------------------------------------------------------------------------------------------------------------------------------------------
* The total habitat available in a given year (hab) is found by hab = hab-1 - r * hab-1 and the percent developed habitat (dev) is given by dev = dev-1
  + r * dev-1, where r is the yearly rate of urbanization (Table data from Tucker et al. 2020, entire).

    We used a stochastic simulation model to assess the future 
condition of Puerto Rican boas under different rates of urbanization 
(Tucker et al. 2020, pp. 5-6; Service 2021, pp. 51-52). We projected 
each population for 30 years, starting in the stable stage distribution 
(calculated from the average demographic matrix). For more details on 
the projected population model, please see Tucker et al. (2020, entire) 
and the SSA report (Service 2021, pp. 51-55, Appendix F).
    Quasi-extinction risk was used as a measure for future resilience 
under the different scenarios. Many population viability analyses use a 
quasi-extinction threshold to assess extinction risk. The quasi-
extinction threshold is the population size below which either the 
population cannot recover because it enters an ``extinction vortex'' 
(Gilpin and Soul[eacute] 1986, pp. 19-34), or the plausible management 
alternatives would drastically change (e.g., switching from habitat 
management to captive breeding). Selecting an appropriate quasi-
extinction threshold for a specific population is often challenging due 
to uncertainties about both how demographic feedbacks and management 
actions influence realized population dynamics. Therefore, we assessed 
quasi-extinction risk at four thresholds, chosen to demonstrate the 
sensitivity of the results to quasi-extinction threshold levels: total 
population size of 50, 500, 1,000, or 5,000 (Service 2021, p. 53, 
Appendix E). For each scenario, we calculated the probability of the 
population falling below these thresholds as the proportion of 
replicates in which this occurred.
    Our projection model indicated that the Puerto Rican boa population 
is most likely to decline over a 30-year period under all scenarios 
except the zero percent urbanization scenario (see table 2, below). 
However, in all scenarios, the rates of decline are low; even under the 
worst-case scenario, the population growth rate was 0.98. Quasi-
extinction probability within 30 years was 0 for all scenarios for 
thresholds less than 1,000. Under the worst-case scenario and a 
population threshold of 5,000, the quasi-extinction probability was 
only 0.015 (see table 2, below) (Tucker et al. 2020, pp. 6-9; Service 
2021, pp. 55-56). These low probabilities of quasi-extinction indicate 
that the species is resilient to the future development even in the 
worst-case scenario.

                      Table 2--The Probabilities of Quasi-Extinction, Population Growth, and Population Decline for Each Scenario *
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                         Quasi-extinction probability                                         Average
                                                            Urban    ------------------------------------ Probability of  Probability of    population
                        Scenario                          growth per                                        population      population      growth rate
                                                            decade       50      500     1,000    5,000    stability or       decline       (95 percent
                                                          (percent)                                           growth                        quantiles)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1. No further urbanization.............................            0        0        0        0    0.005           0.502           0.499             1.0
                                                                                                                                           (0.933, 1.06)
2. Reduced urbanization................................            8        0        0        0    0.006           0.435           0.565           0.994
                                                                                                                                           (0.927, 1.06)
3. Status quo..........................................           16        0        0        0    0.011           0.357           0.643           0.987
                                                                                                                                           (0.921, 1.05)
4. Increased urbanization..............................           24        0        0        0    0.015           0.285           0.715            0.98
                                                                                                                                           (0.916, 1.04)
--------------------------------------------------------------------------------------------------------------------------------------------------------
* The probability of population growth and decline are the proportion of replicates in which the average population growth rate ([lambda]) was greater
  than 1.0 or less than 1.0, respectively. Average population growth rate is presented as the median, and 95 percent quantiles are included in
  parentheses. (Table from Tucker et al. 2020, p. 8).

Summary of Future Condition Analysis
    We characterized resiliency, redundancy, and representation in the 
future based on interpretation of the current condition versus the 
population projection results and predicted quasi-extinction 
probabilities. Based on the results under the status quo scenario, we 
expect resiliency to be slightly lower (medium) than the current 
condition (high to medium) in the foreseeable future (year 2050), 
especially if we consider all factors that may influence resilience 
(e.g., development and protection). Possible changes to resiliency are 
expected to be related to parameters such as habitat quality and 
quantity, and both of those are expected to deteriorate with time, more 
so at the edges and outside of protected habitat. We do not expect 
changes to redundancy and representation since the single Puerto Rican 
boa population would likely continue to occur across its range.
    Quasi-extinction probabilities were low for all scenarios. The 
large initial population size (roughly estimated at 37,903 to 189,515 
individuals) likely buffers the Puerto Rican boa population from 
falling below the quasi-extinction thresholds, and if current 
population size is lower than our projected minimum of 37,903, quasi-
extinction probability may be greater (Tucker et al. 2020, p. 7). 
However, as stated above under ``Current Resiliency,'' this minimum 
population size estimate is likely an underestimate given the 
assumptions used to derive it.

[[Page 41653]]

    We conclude it is reasonable to assume that the status quo scenario 
(16 percent rate of urbanization per decade) will continue, regardless 
of growth or decline in the overall human population, as residential 
construction in natural areas is expected to continue (Castro-Prieto et 
al. 2017, p. 474). Although the status quo scenario was more likely to 
result in population declines (64.3 percent) than in population 
stability or growth (35.7 percent), the projections also demonstrate 
that the decline under this scenario would be slight, with a very low 
probability of abundance reaching 5,000 individuals or fewer (see table 
2, above) (Service 2021, p. 55; Tucker et al. 2020, p.8). Because 
population size is not expected to decline substantially into the 
foreseeable future, neither is the viability of the species as a whole 
within a 30-year timeframe.
    With a continued increase in the urban landscape representing 
status quo growth, we may expect the Puerto Rican boa's density and 
distribution to slowly decline. This may be exacerbated by other 
influences on viability, such as exposure to cats, intentional 
killings, and road kill. Habitat fragmentation may also increase, and 
this may reduce gene flow locally within highly urbanized areas. 
Furthermore, lands around protected areas in Puerto Rico are vulnerable 
to development (Castro-Prieto et al. 2017, p. 478). This is reflected 
in the higher probability of declines, even under the reduced 
urbanization scenario (8 percent per decade) (see table 2, above), 
although the magnitude of these declines is slight.
    Collectively, these results emphasize the import role that habitat 
protection is playing in the current and future status of the Puerto 
Rican boa. Caves contain some of the most important habitats for the 
Puerto Rican boa (Puente-Rol[oacute]n et al. 2013, entire) and are 
broadly covered under the Karst Conservation Zone (PRPB and DNER 2014, 
p. 1; Service 2021, p. 40), as described above under ``Development and 
Habitat Protection,'' and Delisting Criterion 3.
    There are some unique urban and highly modified landscapes like 
Fort Buchanan where the Puerto Rican boa has been found at moderate 
densities (between 1.2 and 3.8 boas per ha) or more than 30 years 
(P[eacute]rez and V[eacute]lez, Jr. 1978, p. 71), which represents 
lower densities than in less modified landscapes (Mulero-Oliveras 2019, 
p. 24). The Fort Buchanan population is an example of how the species 
has responded to threats to its viability. Maintaining remnant forest 
fragments within the Fort Buchanan area has proved vital for the Puerto 
Rican boa's conservation, but it has also benefited from management 
efforts from the Fort Buchanan staff and cooperators.
    Based on all of the above information, we anticipate the Puerto 
Rican boa population to largely maintain current numbers with small 
declines occurring as habitat degradation and fragmentation increase 
and development encroaches into suitable areas. The current condition 
of the Puerto Rican boa population is encouraging, particularly when 
compared to the available information when the species was listed.
    We note that, by using the SSA framework to guide our analysis of 
the scientific information documented in the SSA report, we have not 
only analyzed individual effects on the species, but we have also 
analyzed their potential cumulative effects. We incorporate the 
cumulative effects into our SSA analysis when we characterize the 
current and future condition of the species. To assess the current and 
future condition of the species, we undertake an iterative analysis 
that encompasses and incorporates the threats individually and then 
accumulates and evaluates the effects of all the factors that may be 
influencing the species, including threats and conservation efforts. 
Because the SSA framework considers not just the presence of the 
factors, but to what degree they collectively influence risk to the 
entire species, our assessment integrates the cumulative effects of the 
factors and replaces a standalone cumulative effects analysis.

Determination of the Puerto Rican Boa's Status

    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 meets the definition of an endangered species or a 
threatened species. The Act defines an ``endangered species'' as a 
species that is in danger of extinction throughout all or a significant 
portion of its range, and a ``threatened species'' as a species that is 
likely to become an endangered species within the foreseeable future 
throughout all or a significant portion of its range. For a more 
detailed discussion on the factors considered when determining whether 
a species meets the definition of an endangered species or a threatened 
species and our analysis on how we determine the foreseeable future in 
making these decisions, please see Regulatory and Analytical Framework, 
above.

Status Throughout All of the Puerto Rican Boa's Range

    In 1970, the Puerto Rican boa was listed as endangered under the 
Endangered Species Conservation Act of 1969, due to apparent declines 
in both population size and distribution associated with the widespread 
deforestation of Puerto Rico in the 1800s (35 FR 16047, October 13, 
1970; Service 1986, p. 7). After evaluating threats to the species and 
assessing the cumulative effects of the threats under the Act's section 
4(a)(1) factors, we find that, while the present or threatened 
destruction, modification, or curtailment of its habitat (Factor A) 
remains the primary stressor for the species, the species is not 
currently at risk of extinction now throughout all of its range. The 
species has demonstrated resiliency and the ability to recover from 
human and natural disturbances, including catastrophic events such as 
hurricanes. Additionally, the Puerto Rican boa has increased in 
abundance since the time of listing, and conservation efforts continue 
to benefit the species, particularly in protected areas where Puerto 
Rican boas occur. Therefore, we expect the species' relatively medium 
to high population resiliency to continue to ameliorate this threat in 
the foreseeable future.
    The Puerto Rican boa has shown an ability to adapt to changing 
environmental conditions caused by both human (e.g., development) and 
natural disturbances (e.g., hurricanes). Past, current, and expanding 
urban development will continue to impact the Puerto Rican boa; 
however, the projected population declines will be slight and well 
above levels that would be at risk of extinction. When suitable habitat 
and resources are present, the Puerto Rican boa has demonstrated a 
medium to high level of resiliency (with a current estimated population 
abundance between 37,903 and 189,515 boas, and an island-wide density 
estimate of 1.2 boas per ha (2.5 ac) to 5.6 boas per ha (2.5 ac)) in 
its current ability to maintain viability in spite of these threats. 
The species' representation is ensured by its relatively high genetic 
diversity and its continued occurrence within varied habitat types, as 
well as its relatively high abundance and broad distribution throughout 
its island-wide range (redundancy). Ongoing efforts to preserve optimal 
habitats, notably caves in the northern karst region where the highest 
genetic diversity exists, are highly beneficial to Puerto Rican boa 
conservation.
    At the time of listing, the Puerto Rican boa's population size was 
unknown, but

[[Page 41654]]

the species was considered to be rare. Now, we estimate that between 
37,903 and 189,515 Puerto Rican boas may occur island-wide. Although 
this estimate is considered a rough population estimate, the best 
available information indicates that the Puerto Rican boa is likely 
more abundant today than at the time of listing. Given the demonstrated 
resilience of the Puerto Rican boa to historical habitat loss and 
fragmentation, the present threat of development (Factor A) and the 
newer threats of nonnative species and disease do not put the species 
at risk of extinction now. Hurricanes (Factor E) have the potential to 
negatively impact the Puerto Rican boa directly through mortality and 
habitat destruction, and indirectly through post-hurricane restoration 
activities. However, even after recent severe hurricanes (e.g., 
Hurricane Maria in 2017), the species demonstrated the ability to 
recover from these natural disturbances. Therefore, we find that 
habitat loss, nonnative species, disease and hurricanes are not 
currently having population-level impacts on the species.
    To more closely examine the future threat posed by habitat loss and 
habitat fragmentation, we projected four different development (or 
urbanization) scenarios 30 years into the future (2050). The model 
estimated a very low probability of significant decline within 30 years 
and a less than 2 percent probability of reaching quasi-extinction 
(5,000 individuals or fewer) under all four scenarios of future 
urbanization (Service 2021, p. 55). Because population size is 
projected to only decrease slightly in the foreseeable future, the 
species is not likely to become an endangered species within the next 
30 years. Therefore, after assessing the best available data, we 
conclude that the Puerto Rican boa is not in danger of extinction now 
(i.e., does not meet the Act's definition of an ``endangered species'') 
nor is it likely to become so within the foreseeable future (i.e., does 
not meet the Act's definition of a ``threatened species'') throughout 
all of its range.

Status Throughout a Significant Portion of Its Range

    Under the Act and its implementing regulations, a species may 
warrant listing if it is in danger of extinction or likely to become so 
in the foreseeable future throughout all or a significant portion of 
its range. Having determined that the Puerto Rican boa is not in danger 
of extinction or likely to become so in the foreseeable future 
throughout all of its range, we now consider whether it may be in 
danger of extinction or likely to become so in the foreseeable future 
in a significant portion of its range--that is, whether there is any 
portion of the species' range for which it is true that both (1) the 
portion is significant; and (2) the species is in danger of extinction 
now or likely to become so in the foreseeable future in that portion. 
Depending on the case, it might be more efficient for us to address 
either the ``significance'' question or the ``status'' question first. 
We can choose to address either question first. Regardless of which 
question we address first, if we reach a negative answer with respect 
to the first question that we address, we do not need to evaluate the 
other question for that portion of the species' range.
    In undertaking this analysis for the Puerto Rican boa, we choose to 
address the status question first--we consider information pertaining 
to the geographic distribution of both the species and the threats that 
the species faces to identify any portions of the range where the 
species is endangered or threatened. We considered whether any of the 
threats acting on the Puerto Rican boa are geographically concentrated 
in any portion of the species' range at a biologically meaningful 
scale.
    The primary threats to the species include development and habitat 
loss, nonnative predators, and public attitudes towards snakes. The 
Puerto Rican boa functions as a single, contiguous population and 
occurs island-wide. Puerto Rican boas occur on both privately and 
publicly owned land, and impacts from human development and habitat 
loss are prevalent throughout the species' range. Introduced predators, 
especially feral cats, occur rangewide. Similarly, the intentional 
killing of Puerto Rican boas can occur anywhere throughout the range 
when humans encounter boas. While Puerto Rican boas that live in 
proximity to developed areas are more susceptible to intentional 
killings, public fear towards snakes is a threat that can impact Puerto 
Rican boas throughout their range. Therefore, we conclude that none of 
these threats are concentrated in any particular portion of the 
species' range so as to affect the representation, redundancy, or 
resiliency of the species.
    We found no concentration of threats in any portion of the Puerto 
Rican boa's range at a biologically meaningful scale. Therefore, no 
portion of the species' range can provide a basis for determining that 
the species is in danger of extinction now or likely to become so in 
the foreseeable future throughout a significant portion of its range, 
and we find the species is not in danger of extinction now or likely to 
become so in the foreseeable future in any significant portion of its 
range. This does not conflict with the courts' holdings in Desert 
Survivors v. U.S. Department of the Interior, 321 F. Supp. 3d 1011, 
1070-74 (N.D. Cal. 2018) and Center for Biological Diversity v. Jewell, 
248 F. Supp. 3d 946, 959 (D. Ariz. 2017).

Determination of Status

    Our review of the best available information indicates that the 
Puerto Rican boa does not meet the definition of an endangered species 
or a threatened species in accordance with sections 3(6) and 3(20) of 
the Act. Therefore, we propose to remove this species from the Federal 
List of Endangered and Threatened Wildlife.

Effects of This Proposed Rule

    This proposal, if made final, would revise 50 CFR 17.11(h) to 
remove the Puerto Rican boa from the Federal List of Endangered and 
Threatened Wildlife. The prohibitions and conservation measures 
provided by the Act, particularly through sections 7 and 9, would no 
longer apply to this species. Federal agencies would no longer be 
required to consult with the Service under section 7 of the Act in the 
event that activities they authorize, fund, or carry out may affect the 
Puerto Rican boa. There is no critical habitat designated for this 
species.

Post-Delisting Monitoring

    Section 4(g)(1) of the Act requires us, in cooperation with the 
States, to implement a monitoring program for not less than 5 years for 
all species that have been delisted due to recovery. Post-delisting 
monitoring (PDM) refers to activities undertaken to verify that a 
species delisted due to recovery remains secure from the risk of 
extinction after the protections of the Act no longer apply. The 
primary goal of PDM is to monitor the species to ensure that its status 
does not deteriorate, and if a decline is detected, to take measures to 
halt the decline so that proposing it as endangered or threatened is 
not again needed. If at any time during the monitoring period data 
indicate that protective status under the Act should be reinstated, we 
can initiate listing procedures, including, if appropriate, emergency 
listing.
    We are proposing to delist the Puerto Rican boa based on our 
analysis in the SSA report, expert opinions, and as conservation and 
recovery actions taken. Since delisting would be, in part, due to 
conservation actions taken by partners, we have prepared a draft post-
delisting monitoring (PDM) plan for the Puerto Rican boa. The draft PDM 
plan

[[Page 41655]]

discusses the current status of the taxon and describes the methods 
proposed for monitoring if we delist the taxon. The draft PDM plan: (1) 
Summarizes the status of the Puerto Rican boa at the time of proposed 
delisting; (2) describes frequency and duration of monitoring; (3) 
discusses monitoring methods and potential sampling regimes; (4) 
defines what potential triggers will be evaluated to address the need 
for additional monitoring; (5) outlines reporting requirements and 
procedures; (6) proposes a schedule for implementing the PDM plan; and 
(7) defines responsibilities. It is our intent to work with our 
partners towards maintaining the recovered status of the Puerto Rican 
boa. We appreciate any information on what should be included in post-
delisting monitoring strategies for this species (see Information 
Requested, above).

Required Determinations

Clarity of the Rule

    We are required by Executive Orders 12866 and 12988 and by the 
Presidential Memorandum of June 1, 1998, to write all rules in plain 
language. This means that each rule we publish must:
    (1) Be logically organized;
    (2) Use the active voice to address readers directly;
    (3) Use clear language rather than jargon;
    (4) Be divided into short sections and sentences; and
    (5) Use lists and tables wherever possible.
    If you feel that we have not met these requirements, send us 
comments by one of the methods listed in ADDRESSES. To better help us 
revise the rule, your comments should be as specific as possible. For 
example, you should tell us the numbers of the sections or paragraphs 
that are unclearly written, which sections or sentences are too long, 
the sections where you feel lists or tables would be useful, etc.

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

    We have determined that environmental assessments and environmental 
impact statements, as defined under the authority of the National 
Environmental Policy Act (NEPA; 42 U.S.C. 4321 et seq.), need not be 
prepared in connection with determining a species' listing status under 
the Endangered Species Act. We published a notice outlining our reasons 
for this determination in the Federal Register on October 25, 1983 (48 
FR 49244).

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 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. We have determined that there are no 
Tribal interests affected by this proposal.

References Cited

    A complete list of references cited in this rulemaking is available 
on the internet at https://www.regulations.gov and upon request from 
the Caribbean Ecological Services Field Office (see FOR FURTHER 
INFORMATION CONTACT).

Authors

    The primary authors of this proposed rule are the staff members of 
the Fish and Wildlife Service's Species Assessment Team and the 
Caribbean Ecological Services Field Office.

List of Subjects in 50 CFR Part 17

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

Proposed Regulation Promulgation

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

PART 17--ENDANGERED AND THREATENED WILDLIFE AND PLANTS

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

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


Sec.  17.11  [Amended]

0
2. Amend Sec.  17.11, in paragraph (h), by removing the entry for 
``Boa, Puerto Rican'' under REPTILES in the List of Endangered and 
Threatened Wildlife.

Martha Williams,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2022-14961 Filed 7-12-22; 8:45 am]
BILLING CODE 4333-15-P


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