Federal Register / Vol. 87, No. 133 / Wednesday, July 13, 2022 / Proposed Rules 41641 

The EPA encourages electronic 

submittals, but if you are unable to 

submit electronically or need other 

assistance, please contact Robin 

Billings, the contact listed in the FOR

FURTHER INFORMATION CONTACT section. 

Please also contact Robin Billings if you 

need assistance in a language other than 

English or if you are a person with 

disabilities who needs a reasonable 

accommodation at no cost to you. 

All documents in the docket are listed 

in the www.regulations.gov index. 

Publicly available docket materials are 

available electronically in 

www.regulations.gov. For alternative 

access to docket materials, please 

contact Robin Billings, the contact listed 

in the FOR FURTHER INFORMATION

CONTACT section. 

FOR FURTHER INFORMATION CONTACT: 

Robin Billings; RCRA Programs and 

Cleanup Branch; Land, Chemicals and 

Redevelopment Division; U.S. 

Environmental Protection Agency; 

Atlanta Federal Center, 61 Forsyth 

Street SW, Atlanta, Georgia 30303–8960; 

telephone number: (404) 562–8515; fax 

number: (404) 562–9964; email address: 

billings.robin@epa.gov. 

SUPPLEMENTARY INFORMATION: This 

document proposes to take action on 

Tennessee’s changes to its hazardous 

waste management program under the 

Resource Conservation and Recovery 

Act (RCRA), as amended. We have 

published a direct final rule authorizing 

these changes in the ‘‘Rules and 

Regulations’’ section of this Federal 

Register because we view this as a 

noncontroversial action and anticipate 

no adverse comment. We have 

explained our reasons for this action in 

the preamble to the direct final rule. 

If we receive no adverse comment, we 

will not take further action on this 

proposed rule. If we receive an adverse 

comment, we will withdraw the direct 

final rule and it will not take effect. We 

would then address all public 

comments in a subsequent final rule and 

base any further decision on the 

authorization of the State program 

changes after considering all comments 

received during the comment period. 

We do not intend to institute a second 

comment period on this action. Any 

parties interested in commenting must 

do so at this time. For further 

information, please see the information 

provided in the ADDRESSES section of 

this document. 

Dated: June 28, 2022. 

Daniel Blackman, 

Regional Administrator, Region 4. 

[FR Doc. 2022–14517 Filed 7–12–22; 8:45 am] 

BILLING CODE 6560–50–P 

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. 

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 Mun ̃iz, Field Supervisor, U.S. 

Fish and Wildlife Service, Caribbean 

Ecological Services Field Office, P.O. 

Box 491, Boquero ́n, PR 00622; email: 

Caribbean_es@fws.gov; 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-ofcontact 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. 


jspears on DSK121TN23PROD with PROPOSALS1
41642 Federal Register / Vol. 87, No. 133 / Wednesday, July 13, 2022 / Proposed Rules 

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 

§ 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 


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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, semiarboreal, 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 (Rodrı ́guez and 

Reagan 1984, p. 219; Rodrı ́guez-Dura ́n 

1996, entire; Rivero 1998, p. 432; Wiley 

2003, p. 190; Henderson and Powell 

2009, p. 349; Puente-Rolo ́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 

(Pe ́rez-Rivera and Ve ́lez, Jr. 1978, p. 71). 

Later descriptions of Puerto Rican boa 

distribution increased the occurrence 

records for the species’ wide 

distribution (Bird-Pico ́ 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-Rolo ́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-Rolo ́n and BirdPico ́ 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-Rolo ́n and Bird-Pico ́

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-Rolo ́n and Bird-Pico ́

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-Rolo ́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-Rolo ́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-Rolo ́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 PreColumbian 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; 

Pare ́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. 


jspears on DSK121TN23PROD with PROPOSALS1
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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 islandwide.’’ 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 Pla ́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; 

Pare ́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 Extincio ́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 


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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 Proteccio ́n y Conservacio ́n 

de la Fisiografı ́a Ca ́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 speciesspecific 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 


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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 longterm 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 (CastroPrieto 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 

Extincio ́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 Rı ́o Abajo, Guajataca, 

Camabalache, Vega, and Maricao forests 

(Service 2021, Appendix B). The species 

has also been confirmed in the Gua ́nica 

Commonwealth Dry Forest; however, 

the species is extremely rare there 

(Canals 2019, pers. comm.), with a 

single record from 1974 (Wiley 2003, p. 


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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 (Ortı ́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, Rı ́o Jacaboa, Rı ́o Encantado, 

Rı ́o Maricao, Hacienda La Esperanza, 

and Cordillera Sabana Alta (Ortı ́zMaldonado 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 Pla ́tano Nature 

Reserve, and El Tallonal Private Reserve 

(managed by the nongovernmental 

organization, Citizens of the Karst) 

(Ortı ́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 

(Rodrı ́guez-Vela ́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 Mayagu ̈ 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 


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are sometimes moved to a holding 

facility (Puente-Rolo ́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-Rolo ́n 2012, p. 116; PuenteRolo ́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-Rolo ́n 2012, p. 116; MuleroOliveras 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 (Pe ́rez-Rivera and 

Ve ́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-Pico ́ 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-Rolo ́n and Bird-Pico ́

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 

Marı ́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 posthurricane 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), 


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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; PuenteRolo ́n 2012, p. 85), and climate 

variations may affect availability of prey 

such as rats (Puente-Rolo ́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-Rolo ́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-Rolo ́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 


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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-Rolo ́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 (PuenteRolo ́n et al. 2013, p. 5; Reynolds and 

Puente-Rolo ́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-Rolo ́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 (PuenteRolo ́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 


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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. Humancaused 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 * 

Scenario 

Urban growth 

per decade 

(percent) 

Total habitat 

area in 

30 years in 

hectares 

(acres) 

Developed 

habitat in 

30 years 

(percent) 

Total natural 

habitat in 

30 years in 

hectares 

(acres) 

Total 

developed 

habitat in 

30 years in 

hectares 

(acres) 

Total habitat 

area lost in 

hectares 

(acres) 

1. No further urbanization ......................................... 0 379,029 

(936,601) 

43 215,046 

(531,390) 

163,983 

(405,210) 

0 

2. Reduced urbanization ........................................... 8 300,269 

(741,980) 

54 138,124 

(341,311) 

162,145 

(400,669) 

78,760 

(194,620) 

3. Status quo ............................................................. 16 237,427 

(586,694) 

68 75,977 

(187,743) 

161,450 

(398,951) 

141,602 

(349,906) 


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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 *—Continued 

Scenario 

Urban growth 

per decade 

(percent) 

Total habitat 

area in 

30 years in 

hectares 

(acres) 

Developed 

habitat in 

30 years 

(percent) 

Total natural 

habitat in 

30 years in 

hectares 

(acres) 

Total 

developed 

habitat in 

30 years in 

hectares 

(acres) 

Total habitat 

area lost in 

hectares 

(acres) 

4. Increased urbanization .......................................... 24 187,377 

(463,018) 

86 25,233 

(62,352) 

162,144 

(400,666) 

191,652 

(473,582) 

* The total habitat available in a given year (habt) is found by habt = habt¥1 ¥ r * habt¥1 and the percent developed habitat (devt) is given by devt = devt¥1 + r * 

devt¥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 Soule ́ 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 quasiextinction 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 quasiextinction 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 * 

Scenario 

Urban 

growth 

per decade 

(percent) 

Quasi-extinction probability Probability 

of population 

stability 

or growth 

Probability 

of population 

decline 

Average 

population 

growth rate 

(95 percent 

quantiles) 

50 500 1,000 5,000 

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 (λ) 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 quasiextinction 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. 


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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 (CastroPrieto 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-Rolo ́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 (Pe ́rez and Ve ́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 


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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. Postdelisting 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 postdelisting monitoring (PDM) plan for the 

Puerto Rican boa. The draft PDM plan 


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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 postdelisting 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 

■ 1. The authority citation for part 17 

continues to read as follows: 

Authority: 16 U.S.C. 1361–1407; 1531– 

1544; and 4201–4245, unless otherwise 

noted. 

§ 17.11 [Amended] 

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