11750 Federal Register / Vol. 89, No. 32 / Thursday, February 15, 2024 / Rules and Regulations 

DEPARTMENT OF THE INTERIOR 

Fish and Wildlife Service 

50 CFR Part 17 

[Docket No. FWS–R6–ES–2021–0134; 

FF09E21000 FXES1111090FEDR 245] 

RIN 1018–BE98 

Endangered and Threatened Wildlife 

and Plants; Threatened Species Status 

With Section 4(d) Rule for the 

Silverspot Butterfly 

AGENCY: Fish and Wildlife Service, 

Interior. 

ACTION: Final rule. 

SUMMARY: We, the U.S. Fish and 

Wildlife Service (Service), determine 

threatened species status under the 

Endangered Species Act of 1973 (Act), 

as amended, for a subspecies of butterfly 

(Speyeria nokomis nokomis), a 

silverspot butterfly from Colorado, New 

Mexico, and Utah. We also finalize a 

rule issued under the authority of 

section 4(d) of the Act that provides 

measures that are necessary and 

advisable to provide for the 

conservation of this subspecies. We 

have determined that the designation of 

critical habitat is not prudent. 

DATES: This rule is effective March 18, 

2024. 

ADDRESSES: This final rule is available 

on the internet at https://

www.regulations.gov at Docket No. 

FWS–R6–ES–2021–0134. Comments 

and materials we received, as well as 

supporting documentation we used in 

preparing this rule, are available for 

public inspection at https://

www.regulations.gov at Docket No. 

FWS–R6–ES–2021–0134. 

FOR FURTHER INFORMATION CONTACT: 

Nathan Darnall, Western Colorado 

Supervisor, U.S. Fish and Wildlife 

Service, Colorado Ecological Services 

Field Office, 445 West Gunnison 

Avenue, Grand Junction, CO 81501; 

telephone 970–628–7181. 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 listing if it 

meets the definition of an endangered 

species (in danger of extinction 

throughout all or a significant portion of 

its range) or a threatened species (likely 

to become endangered within the 

foreseeable future throughout all or a 

significant portion of its range). If we 

determine that a species warrants 

listing, we must list the species 

promptly and designate the species’ 

critical habitat to the maximum extent 

prudent and determinable. We have 

determined that the silverspot butterfly 

meets the Act’s definition of a 

threatened species; therefore, we are 

listing it as such. Listing a species as an 

endangered or threatened species can be 

completed only by issuing a rule 

through the Administrative Procedure 

Act rulemaking process (5 U.S.C. 551 et 

seq.). We have determined that the 

designation of critical habitat is not 

prudent due to the threat of collection. 

What this document does. This rule 

finalizes the listing of the silverspot 

butterfly as a threatened species with a 

rule issued under the authority of 

section 4(d) of the Act (a ‘‘4(d) rule’’). 

The basis for our action. Under the 

Act, we may determine that a species is 

an endangered or threatened species 

because of any of five 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. We 

have determined that the silverspot 

butterfly is threatened due to the 

individual and cumulative effects of 

habitat loss and fragmentation (Factor 

A), incompatible livestock grazing 

(Factor A), human-caused hydrologic 

alteration (Factor A), genetic isolation 

(Factor E), and climate change (Factor 

E). 

Section 4(a)(3) of the Act requires the 

Secretary of the Interior (Secretary), to 

the maximum extent prudent and 

determinable, to designate critical 

habitat concurrent with listing. We have 

determined that designating critical 

habitat is not prudent for the silverspot 

butterfly at this time, for the reasons 

discussed below in section III. Critical 

Habitat. 

Previous Federal Actions 

Please refer to the May 4, 2022, 

proposed rule (87 FR 26319) to list the 

silverspot butterfly for a detailed 

description of previous Federal actions 

concerning this subspecies. 

Peer Review 

A species status assessment (SSA) 

team prepared an SSA report for the 

silverspot butterfly (hereafter, 

silverspot). 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 subspecies, including 

the impacts of past, present, and future 

factors (both negative and beneficial) 

affecting the subspecies. 

In accordance with our joint policy on 

peer review published in the Federal 

Register on July 1, 1994 (59 FR 34270), 

and our August 22, 2016, memorandum 

updating and clarifying the role of peer 

review of listing actions under the Act, 

we solicited independent scientific 

review of the information contained in 

the silverspot SSA report. We sent the 

SSA report to four appropriate and 

independent peer reviewers and 

received four responses. Results of this 

structured peer review process can be 

found at https://www.regulations.gov at 

Docket No. FWS–R6–ES–2021–0134. 

We incorporated the results of these 

reviews, as appropriate, into the SSA 

report, which is the foundation for the 

May 4, 2022, proposed rule and this 

final rule. A summary of the peer review 

comments and our responses can be 

found in the ‘‘Summary of Public 

Comments and Recommendations’’ 

below. 

Summary of Changes From the 

Proposed Rule 

After consideration of the comments 

we received during the public comment 

period on the May 4, 2022, proposed 

rule (87 FR 26319), we made changes to 

this final rule. In addition to minor 

editorial changes, we updated 

information in this final rule and the 

SSA report (Service 2023, entire) based 

on comments and additional 

information provided, as follows: 

First, we incorporated new survey 

information from 2021 and 2022 for six 

populations (Garfield, Mesa/Grand, 

Montrose/San Juan, Ouray, San Miguel/ 

Mora, and Taos) into the SSA report and 

our evaluation of current and future 

condition in this final rule. Recent 

surveys for these populations provided 

updated information on the number of 

colonies and habitat acreage. There are 

now 21 known silverspot colonies 

grouped into 10 populations, an 

increase from the 19 colonies reported 

in the May 4, 2022, proposed rule (the 

number of silverspot populations has 

not changed). There are now known to 

be approximately 714 habitat acres (289 


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hectares (ha)) within the 10 populations, 

a slight increase from the 710.5 acres 

(287.5 ha) reported in the May 4, 2022, 

proposed rule. This information 

resulted in changes to resiliency scores 

identified in tables 1 and 2 of the May 

4, 2022, proposed rule, and the current 

and future resiliency condition 

categories for three (Garfield, Mesa/ 

Grand, and San Miguel/Mora) of the six 

populations with new survey 

information (see Service 2023, pp. 8, 

39–48). These changes include both 

increases and decreases in current and 

future resiliency scores, depending on 

the population (see tables 1 and 2, 

below). This information improves our 

understanding of the silverspot’s status. 

Second, we incorporated into the SSA 

report a change to the categories that we 

used to evaluate the current status of 

silverspot populations (extant, likely 

extant, intermittent, unknown, likely 

extirpated, extirpated) as shown in the 

resiliency tables (see Service 2023, pp. 

8, 40–47). We no longer consider there 

to be a relevant distinction between the 

‘‘intermittent’’ and ‘‘unknown’’ status 

categories given the similar levels of 

uncertainty ascribed to their status. 

Therefore, we merged the two categories 

into the ‘‘unknown’’ category, and, as a 

result, we changed the status of the 

Garfield and LaPlata populations from 

intermittent to unknown. This change 

simplifies and better delineates the 

status categories for the subspecies and 

does not affect the scoring of current 

and future condition. 

Third, we updated the range map in 

the SSA report and removed higher 

elevation areas. Now, the range map 

only identifies areas within the 

elevation range of the silverspot (Service 

2023, pp. 16, 18). 

Finally, we made the following 

changes to the preamble discussion and/ 

or regulatory text of the 4(d) rule: 

(1) We added an exception for 

maintenance and operation of existing 

utility infrastructure within existing 

rights-of-way (for more information, see 

‘‘Provisions of the 4(d) Rule’’ below); 

and 

(2) We made editorial corrections to 

the wording of certain exceptions in the 

regulatory text of the 4(d) rule to 

increase clarity and to better align the 

language with existing regulations and 

law. These corrections include revisions 

such as specifying that a machine 

blade’s height be measured from ‘‘above 

the ground’’ and that certain excepted 

activities can occur ‘‘year-round.’’ These 

editorial corrections do not alter the 

original meaning of these exceptions. 

Summary of Public Comments and 

Recommendations 

In the proposed rule published on 

May 4, 2022 (87 FR 26319), we 

requested that all interested parties 

submit written comments on the 

proposal by July 5, 2022. We also 

contacted appropriate Federal and State 

agencies, Tribes, scientific experts and 

organizations, and other interested 

parties and invited them to comment on 

the proposal. On May 3, 2022, we 

published a press release on our website 

inviting the public to comment. On May 

4, 2022, a newspaper notice inviting 

general public comment was also 

published in the Grand Junction Daily 

Sentinel. We did not receive any 

requests for a public hearing. All 

substantive information we received 

during the comment period has either 

been incorporated directly into this final 

determination, has been used to clarify 

the information in the SSA report, or is 

addressed below. 

Peer Reviewer Comments 

As discussed in ‘‘Peer Review’’ above, 

we received comments from four peer 

reviewers on the draft SSA report. We 

reviewed all comments we received 

from the peer reviewers for substantive 

issues and new information regarding 

the contents of the SSA report. Peer 

reviewer comments are addressed in the 

following summary. As discussed 

above, because we conducted this peer 

review prior to the publication of our 

proposed rule, we had already 

incorporated all applicable peer review 

comments into version 1.0 of the SSA 

report, which was the foundation for the 

proposed rule and this final rule. The 

four peer reviewers provided additional 

information, clarifications, and 

recommendations that we have either 

incorporated into the SSA report or 

address below. We received a few 

comments on recovery efforts for the 

silverspot. We note these for future 

reference in recovery planning but do 

not respond here because they are 

outside the scope of this rulemaking. 

(1) Comment: One reviewer 

recommended including more 

discussion in the SSA report about the 

results of a recent genetic study (Cong 

et al. 2019, entire) regarding the timing 

of introgression (also known as 

introgressive hybridization, the transfer 

of genetic material between species 

following hybridization by repeated 

backcrossing of an interspecific hybrid 

with one of its parent species) between 

the silverspot and other species or 

subspecies, and how populations 

became introgressed. The reviewer also 

recommended that we evaluate 

introgression as a future threat to the 

silverspot if this would result in the loss 

of the subspecies’ conservation value. 

Our response: We did not add more 

discussion on this topic to the SSA 

report because the document already 

has a summary of the genetic variation 

and introgression results from the recent 

genetic study referenced by the reviewer 

(Cong et al. 2019, entire). In the SSA 

report, we refer to introgression as 

hybridization that resulted in hybrid 

segregates or intermediate hybrids with 

various levels of genetic mixing between 

Speyeria nokomis nokomis, S. n. 

apacheana, and S. n. nitocris (Service 

2023, pp. 13–14). We also stated that 

various levels of hybridization occurred 

historically between the silverspot and 

other subspecies, but that hybridization 

declined under warmer, drier climate 

conditions since the last ice age as the 

subspecies became isolated from each 

other. There is evidence of isolation 

between the silverspot and the other 

subspecies or hybrids that has persisted 

for centuries (over the last few hundred 

years or longer). We also identify 

genetic isolation as a threat to the 

silverspot based on the distances 

between known populations (see 

Factors Influencing Subspecies 

Viability, below). Given the low 

likelihood of current or future 

hybridization, we do not consider 

hybridization to be a threat to the 

silverspot. 

(2) Comment: One reviewer stated 

their concern with the current 

distribution description in the SSA 

report and the treatment of known sites 

as somewhat fixed in both space and 

time. The reviewer felt that the presence 

of undiscovered colonies within each 

population could have important 

consequences for colony persistence by 

augmenting known populations both 

demographically and genetically, 

thereby increasing resilience. The 

reviewer noted there is documentation 

of this in one Great Basin Speyeria n. 

apacheana colony (Britten et al. 2003, 

entire). The reviewer suggested that 

some discussion of this possibility and 

a description of systematic efforts that 

have been made to find additional 

colonies within the subspecies’ range 

(as shown on the SSA report’s range 

map) should be included. 

Our response: We acknowledge that 

species can shift their ranges over space 

and time. The range map in the SSA 

report (Service 2023, p. 18) is based on 

the best available information at the 

time it was created, and we will update 

the SSA report and range map as new 

information becomes available for the 

subspecies. We also characterize the 

importance of colonies for population 


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persistence, demographics, and genetics 

in the SSA report (Service 2023, pp. 17, 

23–26, 35–36). The demographic and 

genetic benefits of connectivity between 

known colonies would apply to 

undiscovered colonies, and we added 

this statement to the SSA report (Service 

2023, p. 35). We are not able to disclose 

details or results of systematic survey 

efforts and colony locations due to the 

threat of collection; however, we have 

surveyed, and will continue to survey, 

historical locations and potential habitat 

to determine the presence or absence of 

the silverspot. 

(3) Comment: One reviewer agreed 

with the definition of the silverspot’s 

occupied habitat, the individual site 

descriptions presented in the SSA 

report, and how current and past habitat 

patches have changed through time. 

However, the reviewer noted that the 

SSA report does not include 

implications of the long-term dynamics 

of habitat quality and dispersion. The 

reviewer thought a more in-depth 

analysis of the dynamic nature of the 

butterfly’s habitat and population 

fluctuations would be helpful to the 

long-term persistence of the subspecies 

even if it is based on educated opinion. 

The reviewer stated that there is enough 

information to at least speculate on the 

potential for the silverspot to follow its 

habitat, or find newly formed habitat, as 

climate change and other perturbations 

alter the current distribution of its 

habitat. The reviewer wondered if there 

are places within the current 

distribution where butterfly colonies 

could move upslope as the current 

habitat becomes unsuitable due to 

warming. A second reviewer stated that 

climate change could cause small 

elevation shifts in silverspot colonies. 

Our response: Currently, we do not 

have sufficient information to make a 

reliable or well-informed projection of 

the silverspot’s ability to find newly 

formed habitat or occupy higher 

elevation habitat if climate change or 

habitat loss and fragmentation alter its 

current distribution. We lack detailed 

information on the locations of bog 

violet populations across the range and 

in higher elevations. One species expert 

stated that the silverspot was not likely 

to move upslope in a warmer/drier 

climate unless habitat is continuous and 

the bog violet already occurs there (Ellis 

2020b, pers. comm.; Service 2023, p. 

50). We will develop a recovery plan 

and recovery actions for the silverspot 

to improve our understanding of the 

silverspot and perhaps its ability to 

occupy higher elevation habitats. 

(4) Comment: One reviewer 

recommended referring to a silverspot 

population as a metapopulation because 

colonies connected by demographic and 

genetic exchange are better described as 

metapopulations. 

Our response: We use the term 

metapopulation when discussing 

silverspot populations with more than 

one colony. However, in the SSA report, 

we continue to use the term population 

in general, because there are also many 

single colony silverspot populations, 

and it is a standard term we use to 

describe the groupings of silverspots we 

used in our analysis of resiliency and 

viability. 

(5) Comment: One reviewer supported 

the subspecies delineation presented in 

the recent genetic study (Cong et al. 

2019, entire) and the SSA report. 

However, the reviewer noted that while 

the genetic study uses strong methods, 

it has not been peer-reviewed and lacks 

some details about methods and 

analyses. The reviewer recommended a 

discussion in the SSA report about the 

level of confidence in the results and 

why we identify 10 major populations 

for the genus, Speyeria. Their 

interpretation of the results was that a 

delineation of 13 populations was better 

supported than the 10 populations we 

state in the SSA report. 

Our response: We report the results 

and conclusions of the draft genetic 

study (Cong et al. 2019, entire) in the 

SSA report because the draft genetic 

study provides the best available 

information on the genetics of the 

silverspot and the other Speyeria 

nokomis subspecies. We are confident 

in the results of the draft study because 

of the researchers’ genetic expertise 

despite the fact that the study has not 

been peer-reviewed. We will update the 

SSA report as needed to reflect major 

changes, if any, once the genetic study 

is published. 

(6) Comment: One reviewer stated 

that the SSA report does not include 

published reports of Speyeria nokomis 

apacheana to their full potential. The 

reviewer noted that the ecology and life 

history of S. n. nokomis and S. n. 

apacheana are similar and suggested 

that S. n. apacheana should serve as a 

good surrogate for S. n. nokomis where 

data are lacking. The reviewer noted 

that two reports document gene flow 

among S. n. apacheana colonies that 

may mitigate the effects of genetic drift 

(the loss of alleles (version of a gene) or 

change in their frequency in a 

population) on colony genetic diversity 

(Britten et al. 1994, entire; Britten 2003, 

entire). The reviewer noted that S. n. 

apacheana also experiences high levels 

of colony turnover and routinely 

disperses about 4 kilometers (about 2.5 

miles) from natal (birth) sites based on 

years of mark/recapture studies at 

several locations in Nevada (Fleishman 

et al. 2002, entire). The reviewer noted 

that the SSA report concluded that 

about 10 miles is a good estimate of S. 

n. nokomis dispersal distance but 

questioned whether estimates of the 

silverspot’s viability would differ if 

shorter dispersal distances, closer to 

those of S. n. apacheana, were applied 

in the SSA report. 

Our response: In the SSA report, we 

evaluate connectivity between 

silverspot populations based on their 

estimated long-distance dispersal ability 

of 5 to 10 miles (Ellis 2020c, 2020d, 

2020e, pers. comm.) and the potential 

for longer term gene flow between 

colonies within a 20-mile distance 

based on the recent genetic study (Cong 

et al. 2019, entire). Taken together, these 

distances characterize the potential for 

gene flow and population connectivity 

over short-term and long-term 

timeframes and provide a more 

appropriate evaluation of gene flow than 

the annual dispersal distances for the 

silverspot and Speyeria nokomis 

apacheana. Therefore, we did not 

change the metrics we used to evaluate 

resiliency, although we note that the 

shorter, annual dispersal distances the 

reviewer mentions would receive the 

highest score for genetic connectivity in 

our analysis because those distances 

allow for a high level of genetic 

interchange and maintenance of a 

metapopulation structure. 

(7) Comment: One reviewer stated 

that collecting has never been shown to 

cause the extirpation of an insect 

population or species because it is a 

density-independent factor. 

Our response: The reviewer did not 

provide information to support their 

comment. Many of the silverspot 

populations are small and currently in 

low resiliency condition, and therefore 

could be easily extirpated if collection 

pressure increased. The best available 

information indicates that poaching of 

rare and imperiled taxa for profit does 

occur, even to the point of driving a 

species to extinction to increase the 

value of individual specimens (Kleiner 

1995, entire; Hoekwater 1997, entire; 

Courchamp et al. 2006, entire; O’Neill 

2007, entire; Stratton 2012, entire). 

(8) Comment: One reviewer stated 

that changes in water management are 

the most likely immediate threat to 

silverspot populations based on the 

decline of other S. nokomis subspecies’ 

colonies from the capping of springs 

and water diversions. 

Our response: We consider hydrologic 

alteration to be a major factor affecting 

the subspecies (see Factors Influencing 

Subspecies Viability, below). We 

recognize that water management can 


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result in the loss or alteration of 

silverspot habitat, and that extensive 

hydrologic alteration has occurred 

within the range of the silverspot for 

agricultural, commercial, and municipal 

purposes. The reviewer did not 

recommend any changes to our analysis, 

and we accounted for water 

management practices and hydrologic 

alteration of silverspot habitat in the 

habitat factor score for current and 

future condition (see Summary of 

Biological Status and Threats, below). 

(9) Comment: One reviewer stated 

that some colonies may require 

management, such as light grazing or 

mowing, to maintain habitat suitability. 

For example, the Speyeria nokomis 

apacheana population in Round Valley 

(Inyo County, California) has persisted 

at least over the past 70 years under a 

regime of light grazing. Conversely, the 

reviewer noted that heavy park-like 

mowing of the Mono County Park near 

Mono Lake, California, caused the 

extirpation of a small colony. 

Our response: We agree that light 

grazing or mowing in addition to other 

occasional disturbances, such as 

burning or non-catastrophic flooding, 

are needed to maintain suitable habitat 

conditions for the silverspot. We 

identify some of these practices as 

exceptions to the take prohibitions 

under the 4(d) rule (see ‘‘Provisions of 

the 4(d) rule’’ below). We intend to 

work with landowners or managers to 

provide occasional disturbance or even 

light annual disturbance that is 

compatible with conserving the 

silverspot and the bog violet. 

(10) Comment: A reviewer stated that 

the current common name for the 

species is Nokomis Fritillary according 

to the North American Butterfly 

Association (NABA) Common Names 

List, which is the recognized source for 

North American butterfly species. 

However, the reviewer noted that there 

is no recognized source for subspecies’ 

common names. 

Our response: We state that Nokomis 

Fritillary is the accepted common name 

for the species, Speyeria nokomis, in the 

SSA report (Service 2023, appendix C, 

p. 80). We refer to the subspecies that 

is the subject of this document, S. n. 

nokomis, as the silverspot to distinguish 

it from the other Nokomis Fritillary 

subspecies and to minimize public 

confusion once it is listed under the 

Act. Prior to the recent genetic study 

(Cong et al. 2019, entire), which 

clarified the range of the subspecies, we 

referred to the silverspot butterfly as the 

Great Basin silverspot butterfly, a 

common name that is no longer 

applicable (see 87 FR 26319, May 4, 

2022, p. 26322). We will report updates 

to its common name and taxonomy, if 

needed, in the SSA report and future 5- 

year status reviews to be consistent with 

the accepted taxonomic nomenclature. 

We note in the SSA report that the 

silverspot and other members of the 

Nokomis genus may be assigned to a 

different genus (Argynnis) soon (Service 

2023, p. 13). This change in genus 

would likely not affect the silverspot’s 

listing status under the Act. 

Comments From States 

(11) Comment: The Utah Public Lands 

Policy Coordination Office (PLPCO) of 

the Utah Governor’s Office stated that 

they advocate for silverspot 

conservation and are available to assist 

in the development of a conservation 

strategy for the subspecies. They 

expressed that the most effective 

conservation strategy is to coordinate 

with State agencies, local governments, 

and landowners because the silverspot 

is mostly on private lands. The PLPCO 

also supported our determination that 

the designation of critical habitat is not 

prudent for the silverspot. 

Our response: We welcome 

participation by the PLPCO and any 

stakeholder or landowner to provide 

conservation for the silverspot through 

the development of a conservation 

strategy or other means. We agree that 

State and local support will be critical 

to the recovery and successful 

management of the silverspot. 

(12) Comment: The PLPCO expressed 

that managed grazing, burning, mowing, 

and non-catastrophic flooding are 

necessary to remove harmful and 

invasive vegetation to benefit the 

silverspot and its host plants. They 

suggested that lack of grazing could lead 

to population extinction of the 

silverspot based on a published study 

from another endangered butterfly, the 

Quino checkerspot (Preston et al. 2012, 

entire). 

Our response: The SSA report 

(Service 2023, entire), proposed rule (87 

FR 26319; May 4, 2022), and this final 

rule state that managed grazing, 

burning, mowing, and non-catastrophic 

flooding can benefit the silverspot. 

Livestock grazing that is done in a 

manner consistent with local ecological 

conditions, including soil types, 

precipitation zones, vegetation 

composition, and drought conditions, to 

provide early seral or more open 

conditions for the bog violet can be 

compatible with the needs and 

conservation of the silverspot. For more 

information, see the discussions under 

‘‘Summary of Biological Status and 

Threats’’ and ‘‘Beneficial Factors’’ 

below. We also recognize that 

maintenance of sustainable grazing 

practices on private lands can aid in 

recovery of the silverspot by 

discouraging further conversion of the 

species’ habitat into habitat unsuitable 

to the species (i.e., due to development). 

We reviewed the Preston et al. 2012 

paper, and it does not state that lack of 

grazing resulted in the extinction or 

extirpation of the Quino checkerspot 

(Euphydryas editha quino), which is 

currently listed as endangered under the 

Act. However, the paper did reference 

another article (Weiss 1999, entire) 

related to beneficial grazing practices to 

suppress nonnative plants in butterfly 

populations. We have incorporated this 

article into the SSA report (Service 

2023, p. 38). 

(13) Comment: The New Mexico 

Department of Agriculture (NMDA) and 

others expressed concern that the range 

map of the silverspot in the SSA report 

(Service 2021, p. 12) is overly broad 

relative to the small amount of known, 

occupied habitat, and includes 

elevations much higher than the upper 

elevation for the butterfly. The NMDA 

recommended the use of range 

delineation methods from a published 

article (Burgman and Fox 2003, entire) 

to refine the subspecies’ range. Another 

commenter suggested the range map in 

the 2021 SSA report is an example of a 

flawed habitat model that could be 

corrected with a more detailed 

discussion of why the area is thought to 

be suitable, and the commenter 

provided a definition of wildlife habitat 

to improve how we define habitat in the 

proposed rule. Both commenters 

expressed the need for comprehensive 

surveys and improvements to the 

habitat model to better define suitable, 

occupied habitat, and the silverspot’s 

range, to reduce unnecessary regulatory 

burden. 

Our response: We have updated the 

range map in the SSA report and 

removed higher elevation areas to 

address the comment. Now, the range 

map in the SSA report identifies only 

areas within the known elevation range 

of the silverspot (Service 2023, p. 18). 

The range map provides an 

intentionally broad delineation of the 

current extent of the silverspot’s range 

to protect the exact locations of colonies 

and should not be used or considered as 

a habitat model for the subspecies. We 

acknowledge that most of the lands 

identified in the range map are not 

suitable habitat for the silverspot; the 

subspecies is a habitat specialist with 

very specific habitat needs. 

We do not have a habitat model for 

the silverspot; however, when this rule 

is effective (see DATES, above), we 

intend to develop one using the best 

available habitat information and 


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methods used by the Service, which are 

consistent with those recommended in 

the published paper recommended by 

the commenter (Burgman and Fox 2003, 

entire) (see Service 2019, entire). Once 

developed, the suitable habitat model 

will inform the need for surveys, and 

additional surveys would better 

delineate occupied habitat, suitable 

habitat, and the current range of the 

subspecies. 

(14) Comment: The NMDA and others 

requested time to implement proactive 

conservation and education in 

cooperation with private landowners, 

Federal land managers, and lessees prior 

to a final listing determination for the 

silverspot. They state that there are 

beneficial management practices for the 

silverspot that have yet to be 

implemented. 

Our response: The commenters are 

correct that beneficial management 

practices have not been implemented 

for the silverspot, and we welcome 

participation by States, counties, 

landowners, or other stakeholders to 

implement conservation and recovery 

efforts for the subspecies. Under the 

Act, we must list a species or subspecies 

if it meets the definition of an 

endangered species or a threatened 

species. Moreover, our policy for the 

evaluation of conservation efforts when 

making listing decisions (PECE policy; 

68 FR 15100, March 28, 2003) identifies 

criteria we use in determining whether 

formalized conservation efforts that 

have yet to be implemented or to show 

effectiveness contribute to making 

listing a species as endangered or 

threatened unnecessary. The PECE 

policy applies to conservation efforts 

identified in conservation agreements, 

conservation plans, management plans, 

or similar documents developed by 

Federal agencies, State and local 

governments, Tribal governments, 

businesses, organizations, and 

individuals. For the silverspot, there 

were no formalized conservation efforts 

that had yet to be implemented prior to 

this final rule for us to consider under 

the PECE policy. 

(15) Comment: The NMDA expressed 

that the 4(d) rule should ensure that 

private landowners and public land 

managers will not be exposed to risk of 

take of the silverspot for their normal 

agricultural activities in wet meadows 

that do not contain the silverspot within 

its range. They recommend the 4(d) rule 

clarify that take of the silverspot from 

habitat modification only applies to 

areas where the silverspot is found 

(known colonies) and requested that we 

modify the specific take prohibition in 

the 4(d) rule to reflect that. 

Our response: Under 50 CFR 17.31(c), 

for a species listed as a threatened 

species, the species-specific 4(d) rule 

will contain all the applicable 

prohibitions and exceptions. On the 

effective date of this rule (see DATES

above), the protections of the Act 

provided for in the 4(d) rule for the 

silverspot will apply to the subspecies 

wherever it is found. We acknowledge 

that there is uncertainty about the extent 

of suitable habitat within the 

silverspot’s range, and thus it would be 

premature to except take prohibitions 

for actions in suitable habitats where 

occupancy is unknown until adequate 

surveys for the butterfly are conducted. 

In the 4(d) rule, we provide exceptions 

for take for common agricultural 

practices in wet meadow habitats (see 

‘‘Provisions of the 4(d) Rule’’ below). 

Additionally, if anyone has concerns 

about specific agricultural practices in 

wet meadow habitats that are not 

identified as exceptions in the 4(d) rule, 

we welcome those discussions and will 

provide information (see FOR FURTHER

INFORMATION CONTACT above). Therefore, 

we have not made any changes to the 

4(d) rule in response to this comment. 

(16) Comment: The NMDA and others 

recommended developing an outreach 

strategy and materials for private 

landowners and local entities to provide 

them information on the listing of the 

silverspot, the subspecies’ 4(d) rule, and 

beneficial conservation actions for the 

subspecies (such as protecting bog 

violets and planting beneficial nectar 

plants). 

Our response: As part of our outreach 

efforts, we intend to contact landowners 

of known occupied habitat and discuss 

the silverspot’s listing and 4(d) rule, as 

well as beneficial conservation actions 

for the subspecies. We welcome the 

assistance of the commenters, State and 

Federal agencies, Tribes, 

nongovernmental organizations, and 

other interested parties with outreach 

and implementation of conservation and 

recovery actions. 

Public Comments 

(17) Comment: One commenter 

expressed opposition to listing the 

silverspot under the Act because the 

reasons for population declines are 

lacking and several of the factors 

influencing viability in the SSA report 

are either not detectable or are 

unknown. Without an understanding of 

what is causing the presumed 

population decline, the commenter 

thought it will be nearly impossible to 

develop a viable recovery plan. 

Our response: We summarize the 

threats to the silverspot in this final rule 

(see ‘‘Summary of Biological Status and 

Threats’’ below). While we acknowledge 

that there are gaps in our understanding 

of the subspecies, listing under the Act 

will confer protections to the silverspot 

from several of the identified threats to 

help arrest and reverse its decline. 

When this rule is effective (see DATES

above), actions authorized, funded, or 

carried out by Federal agencies that may 

affect the subspecies will require 

consultations under section 7 of the Act 

in all occupied areas. Prohibitions 

against take under section 9 of the Act 

will further protect the silverspot from 

human-caused mortality such as 

continued habitat loss. 

The Act requires us to develop 

recovery plans for all listed species, 

unless such a plan will not promote the 

conservation of the species. Recovery 

plans must, to the maximum extent 

practicable, contain objective, 

measurable criteria that, when met, 

would lead to ‘‘delisting,’’ that is, 

removal of the species from the Lists of 

Endangered and Threatened Wildlife 

and Plants. These recovery plans are 

created following a final determination 

to list a species as endangered or 

threatened. Recovery plans are nonbinding documents intended to 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. Recovery criteria and 

objectives are developed based on the 

information known at that time, and 

much is learned about a species 

between the time the recovery plan is 

developed and the time it is determined 

to no longer meet the Act’s definition of 

endangered or threatened. 

(18) Comment: One commenter stated 

that utility corridors maintain or create 

open, early successional areas that 

support the silverspot’s needs, and 

requested that the proposed exception 

for maintenance of other existing 

structures in the 4(d) rule apply to many 

common electric company operation, 

maintenance, and modernization 

(OMM) activities that are essentially 

maintenance of other existing 

structures. The commenter felt that the 

additional requirement in the 4(d) rule 

for those activities to be kept within the 

confines of already disturbed ground 

was unclear and, depending on how it 

is interpreted and applied in practice, 

could significantly limit many OMM 

activities. For example, transmission 

lines often span long distances of 

relatively undisturbed vegetation 

between the support towers or poles. 

However, electric companies regularly 

need to conduct OMM activities along 

transmission line rights-of-way (ROWs) 


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in the space between towers or poles. 

The commenter requested the scope of 

this exception be clarified to include 

OMM activities along entire 

transmission line ROWs rather than 

limited to previously disturbed areas 

centered on support towers or poles. 

Our response: Maintenance and 

operation activities and vegetation 

removal along existing transmission line 

and utility corridors are not major 

factors influencing the silverspot and 

are not known to negatively affect the 

subspecies (Service 2023, pp. 28–38). 

Therefore, in this final rule, we add to 

the silverspot’s 4(d) rule an exception to 

the take prohibitions for these activities 

if the activities are kept within the 

confines of existing ROWs. This does 

not remove the requirement for section 

7 consultation and appropriate 

permitting processes. Importantly, 

construction of new transmission lines 

and utility corridors is not an excepted 

activity under the 4(d) rule. 

(19) Comment: One commenter 

requested that we revise one aspect of 

the definition of ‘‘reasonable care’’ in 

the silverspot’s 4(d) rule. The 

commenter asked that instead of 

‘‘ensuring no introduction of’’ invasive 

plant species, we revise the 4(d) rule to 

read, ‘‘minimizing the potential to 

introduce’’ invasive plant species. 

Our response: We agree with the 

commenter that reasonable care to 

control for invasive plant species should 

be to minimize their potential 

introduction rather than ensure no 

introduction. We used language in the 

proposed 4(d) rule that was stricter than 

we intended, and because it is not 

feasible to ensure no introduction of 

invasive plant species, in this final rule, 

we clarify that statement in the 4(d) rule 

in accordance with the commenter’s 

suggestion. 

(20) Comment: One commenter 

requested listing the silverspot as 

endangered or alternatively 

strengthening the 4(d) rule. They also 

recommended designating critical 

habitat. Their reasons are explained in 

greater detail below: 

a. List as endangered: The commenter 

stated that the silverspot faces 

immediate extinction and climate 

change should be considered a major 

factor, rather than a minor factor, as it 

has significant impacts to the 

subspecies’ viability as defined in the 

SSA report. Most silverspot populations 

face very low or low resiliency 

conditions and possess little to no 

ability to respond to and recover from 

disturbances and the negative effects of 

climate change, such as earlier springs, 

rising temperatures, less snowpack, and 

soil-moisture drought. The commenter 

felt that the proposed rule provided no 

analysis or evidence that these very low 

resiliency populations are currently not 

at risk of extirpation. The commenter 

suggested that the imminent threat of 

losing half of the silverspot’s 

populations should make the subspecies 

in danger of extinction throughout a 

significant portion of its range, thus 

warranting an endangered listing. The 

commenter stated that the loss of these 

populations may occur in 5 years, not 

the 30 years identified as the foreseeable 

future. 

b. Strengthen the 4(d) rule: 

Alternatively, the commenter requested 

that we develop a more protective 4(d) 

rule that does not permit year-round 

grazing, because it is not scientifically 

supported and not enforceable. The 

commenter felt that the proposed 4(d) 

rule gave disproportionate weight to 

inconclusive possible benefits of grazing 

in need of further study over the more 

conclusive studies establishing grazing’s 

detrimental effects to the silverspot’s 

habitat. They recommend that the final 

4(d) rule should not allow summer 

grazing, to provide for adequate 

protection and enforcement. 

c. Designate critical habitat: The 

commenter requested that we designate 

critical habitat for the silverspot because 

the benefit of designation outweighs the 

threat of collection. As stated in the SSA 

report, collection is not thought to be a 

current stressor, and designation can be 

done without disclosing silverspot 

locations. The commenter stated that 

without credible information regarding 

actual collection risk, designating 

critical habitat is prudent and necessary 

to conserve the silverspot. 

Our response: Climate change is 

occurring, and there is strong scientific 

support for projections that warming 

will continue through the 21st century 

(see ‘‘Climate Change’’ under Factors 

Influencing Subspecies Viability, 

below). However, to date, there is only 

one small silverspot population 

(Archuleta) of the 10 total populations 

where prolonged drought combined 

with overgrazing is identified as a 

potential contributor to the population’s 

very low resiliency rank based on the 

best available information (Whiteman 

2022, pers. comm.; Service 2023, pp. 30, 

40–41, 57–60). The other nine 

populations currently appear to have an 

adequate water supply despite existing 

hydrologic alterations, recent droughts, 

and drier, current climate conditions 

(Bainbridge and Ireland 2022, pers. 

comm; Service 2023, p. 30). While 

current water availability is not a 

concern, we are concerned about future 

climate effects to the silverspot in 

combination with other threats, and we 

determined that the subspecies meets 

the Act’s definition of a threatened 

species. For additional explanation as to 

why the species does not meet the Act’s 

definition of an endangered species 

throughout all or a significant portion of 

its range, see ‘‘Summary of Biological 

Status and Threats and Determination of 

Silverspot’s Status’’ below. 

We find that the 4(d) rule exception 

for grazing is scientifically supported 

and enforceable. The exception for 

grazing is based on the best available 

scientific information that light summer 

grazing (30 percent or less utilization of 

forage) and moderate fall and spring 

grazing (40 to 50 percent utilization) 

appears to be compatible with the 

subspecies’ needs and habitat 

requirements (Arnold 1989, entire; 

Service 2023, pp. 33–34). In practice, 

little summer grazing occurs in 

silverspot habitat because many 

landowners move their cattle to higher 

elevations with more seasonal forage 

(Service 2023, p. 33). While livestock 

grazing under this exception may result 

in low levels of take, these grazing 

practices do not pose a threat to the 

silverspot’s continued existence and 

should help maintain suitable habitat 

conditions for the subspecies. 

Additionally, we consider the 

utilization rates for seasonal grazing to 

provide enforceable and objective 

grazing measurements. We find that the 

4(d) rule provides flexibility to our 

partners and satisfies the requirement in 

section 4(d) of the Act to issue 

regulations deemed necessary and 

advisable to provide for the 

conservation of the silverspot. When 

this rule is effective (see DATES above), 

we will work with private landowners, 

public land managers, Tribes, and 

grazing experts to maintain or improve 

silverspot habitat using seasonal grazing 

practices. 

Finally, the demand for butterflies is 

high by collectors in the illegal animal 

trade, and the best available information 

indicates that collection may have 

resulted in the extirpation of one 

silverspot colony (Scott 2023, pers. 

comm.; Service 2023, p. 31). We believe 

that the public has been largely unaware 

of the subspecies and that listing under 

the Act will raise public awareness and 

result in a greater demand from 

collectors. We determine in this final 

rule that the designation of critical 

habitat is not prudent in accordance 

with 50 CFR 424.12(a)(1), because the 

silverspot faces a threat of unauthorized 

collection and trade, and designation 

can reasonably be expected to increase 

the degree of this threat to the 

subspecies. We have determined that 

the publication of maps and 


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descriptions outlining the locations of 

the silverspot would further facilitate 

unauthorized collection and trade, as 

collectors would know the exact 

locations where silverspots occur (see 

section III. Critical Habitat below). 

For the reasons explained above, we 

are not making any changes to this final 

rule in response to this comment. 

(21) Comment: Some commenters 

opposed listing the silverspot and stated 

that the Act does not work for insects 

and other species that cannot accurately 

be identified. Commenters felt that the 

silverspot’s definition and description 

in the proposed rule was highly 

ambiguous and the SSA report 

identified almost every color as a 

characteristic of the subspecies. They 

are concerned about the ability to 

accurately count and distinguish the 

silverspot from other subspecies with 

ranges that overlap and from potential 

hybrids that may result from 

reproduction between the silverspot and 

other subspecies; they are also 

concerned about the environmental 

factors that may impact the silverspot’s 

characteristics. The commenters felt that 

the Service’s inability to clearly identify 

the silverspot will lead to public 

confusion, an erosion of public support, 

and the assumption that any butterfly or 

moth in the silverspot’s range would be 

treated as a listed species. The inability 

to accurately describe the species falls 

into the category of intrinsic uncertainty 

as defined by a published paper they 

provided and may not be resolvable 

(Freckleton 2020, entire). The 

commenters requested to know what 

has changed since our previous 

determinations that suggested the 

silverspot was not a listable entity. 

Our response: We understand the 

commenters’ questions and uncertainty 

regarding identification and taxonomy. 

We disagree with the comment that the 

subspecies is not well defined or 

described, or that there is intrinsic 

uncertainty regarding the taxonomy that 

cannot be resolved. A recent genetic 

study identified the silverspot as a 

distinct taxon, and we have delineated 

the subspecies’ range based on that 

report (Cong et al. 2019, entire) (see 

‘‘Background’’ under section I. Final 

Listing Determination below). The 

silverspot and its habitat can be 

identified accurately by experts or with 

training, in the field or with close-up 

photographs. There is always the 

potential for hybridization to occur at 

the margins of a species’ range or areas 

of overlapping ranges with other species 

or subspecies. However, there is a low 

likelihood of interbreeding to produce 

hybrid butterflies within the silverspot’s 

range (Service 2023, pp. 1–14). Any 

potential hybrids can be confirmed 

through additional genetic analysis, and 

we will address methods to count and 

estimate butterfly numbers during the 

recovery planning process. 

Our determination in 1996 that 

removed the designation of the 

silverspot as a category 2 candidate was 

not related to taxonomy; rather, we 

discontinued the practice of 

maintaining a list of species regarded as 

category 2 candidates (see 61 FR 7596, 

February 28, 1996; see also ‘‘Previous 

Federal Actions’’ in the May 4, 2022, 

proposed rule (87 FR 26319)). Category 

2 candidate species were taxa for which 

we lacked conclusive data on biological 

vulnerability and threats. By 2013, we 

had more information on the silverspot 

to evaluate its status and threats in 

response to a petition submitted to us by 

Wild Earth Guardians. 

(22) Comment: Commenters asked 

about the status of potential silverspot 

hybrids under the Act. 

Our response: We address hybrids on 

a case-by-case basis under the Act, and 

in this case, we did not propose to list 

hybrids of the silverspot because as we 

describe above in our response to 

Comment (1), there is a low likelihood 

of finding hybrid butterflies in the 

silverspot’s range in the future because 

the various subspecies of S. nokomis are 

isolated from one another. 

(23) Comment: Some commenters felt 

that the Service made an arbitrary 

decision when we determined that 

habitat fragmentation is a threat to the 

silverspot, while pesticide usage is not. 

The best available science for other 

insect species such as the monarch 

butterfly (Danaus plexippus) identifies 

pesticide use as a significant component 

of activities that cause habitat 

fragmentation (e.g., agriculture and 

haying). Commenters also stated that it 

was not clear whether we evaluated 

habitat fragmentation across the entire 

range or only in known, occupied 

habitat. 

Our response: The hypothesis that 

pesticides are a major threat to the 

silverspot presented in this comment 

appears to be based solely on the 

commenters’ evaluation of threats 

identified for other species. No methods 

or data are given or cited for pesticide 

use and effects on the silverspot or 

similar species in the arid western 

United States. Evidence in support of 

such a hypothesis would need to be 

provided for further consideration. We 

do not discuss pesticides in the May 4, 

2022, proposed rule or this final rule 

because our evaluation in the SSA 

report identified it as a minor factor 

influencing the current and future 

condition of the silverspot (Service 

2023, pp. 27–28, 32). The primary 

agricultural practices in the silverspot’s 

range are haying and grazing that 

generally use fewer pesticides than are 

used on croplands. However, we state in 

the SSA report that further research is 

needed on pesticide use and its effects 

on the subspecies. 

Based on the best available 

information, habitat loss and 

fragmentation are primary threats to the 

silverspot in occupied habitat and 

across the range (see Factors Influencing 

Subspecies Viability, below). Nearly all 

populations have been or are expected 

to be negatively affected by this threat, 

which has resulted in lower current and 

future population resiliency and 

connectivity. 

(24) Comment: Commenters expressed 

concern that there would be significant 

restrictions placed on recreation as a 

result of listing the silverspot, even 

though the proposed rule identifies 

recreation as a minimal threat to the 

silverspot. The commenters were 

familiar with listing decisions for other 

species (wolverine (Gulo gulo luscus) 

and Mexican spotted owl (Strix 

occidentalis lucida)) where the Service 

explicitly and clearly states that 

recreation is not a threat, but other 

agencies placed significant restrictions 

on recreation because of the potential 

for habitat fragmentation. 

Our response: The silverspot 

primarily occurs on private lands (18 of 

the 21 colonies), where recreation does 

not occur. Occupied habitat on public 

lands also currently appears to have 

minimal recreational use, and we are 

not aware of plans that may increase the 

level of future recreational use in these 

areas. However, recreation could pose a 

threat to the silverspot if trails or other 

recreational facilities are planned in the 

future within the butterfly’s habitat that 

may result in habitat loss or 

degradation, invasive plant 

establishment, changes to the water 

regime, or erosion. 

Section 7(a)(2) of the Act requires 

Federal agencies to ensure that activities 

they authorize, fund, or carry out are not 

likely to jeopardize the continued 

existence of any endangered or 

threatened species or destroy or 

adversely modify its critical habitat. 

When this rule is effective (see DATES

above), Federal agencies will be 

required to consult with us on the 

potential effects to the silverspot for all 

proposed projects, including recreation 

projects, that are subject to the 

requirements of section 7(a)(2) of the 

Act. For proposed projects without a 

Federal nexus, the proponent must 

ensure that the project will not result in 

take of the silverspot as set forth in the 


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4(d) rule. We will cooperate with 

Federal agencies, landowners, and 

project proponents to identify 

conservation measures that avoid or 

minimize effects and take of the 

silverspot during project planning. 

I. Final Listing Determination 

Background 

A thorough review of the taxonomy, 

life history, and ecology of the 

silverspot is presented in the SSA report 

(Service 2023, pp. 9–27), and is briefly 

summarized here. 

The silverspot is a relatively large 

butterfly with up to a 3-inch wingspan. 

Males typically have bright orange on 

the upper side of the wing, while 

females typically have cream or light 

yellow with brown or black. The 

underside of the wing of both sexes has 

silvery-white spots, giving the 

subspecies’ the common name of 

silverspot butterfly. 

Based on recent genetic analysis, 

there are 10 major populations of 

Speyeria nokomis comprised of five 

subspecies throughout the United States 

and Mexico (Cong et al. 2019, entire). 

We established a new, more precise 

range boundary for the subspecies that 

is the subject of this document, the 

silverspot (S. n. nokomis), in the SSA 

report based on the genetic analysis, 

which limits the distribution to eastcentral Utah through western and southcentral Colorado and into north-central 

New Mexico (Service 2023, p. 18). The 

new range delineation shows that the 

subspecies does not occur in the Great 

Basin and thus the former common 

name, Great Basin silverspot butterfly, is 

no longer valid. Consequently, we refer 

to the S. n. nokomis subspecies as 

‘‘silverspot’’ in this final rule. 

In the SSA report, we identified 10 

populations of silverspot in our 

analysis, consisting of the following: 

Archuleta, Conejos, Costilla, Garfield, 

La Plata, Mesa/Grand, Montrose/San 

Juan, and Ouray populations in 

Colorado and Utah; and the San Miguel/ 

Mora and Taos populations in New 

Mexico (Service 2023, figure 14 and 

table 4, pp. 39–47). Populations of 

silverspot occur between 5,200 feet (ft) 

(1,585 meters (m)) and 8,300 ft (2,530 

m). The butterfly requires moist habitats 

in mostly open meadows with a variety 

of herbaceous and woody vegetation. 

Eggs are laid on or near the bog violet 

(Viola nephrophylla/V. sororia var. 

affinis), which the larvae feed on 

exclusively. A variety of flowering 

plants provide adult nectar sources. The 

butterfly completes its entire life cycle 

in one year. 

Regulatory and Analytical Framework 

Regulatory Framework 

Section 4 of the Act (16 U.S.C. 1533) 

and the implementing regulations in 

title 50 of the Code of Federal 

Regulations set forth the procedures for 

determining whether a species is an 

endangered species or a threatened 

species, issuing protective regulations 

for threatened species, and designating 

critical habitat for endangered and 

threatened species. In 2019, jointly with 

the National Marine Fisheries Service, 

the Service issued a final rule that 

revised the regulations in 50 CFR part 

424 regarding how we add, remove, and 

reclassify endangered and threatened 

species and the criteria for designating 

listed species’ critical habitat (84 FR 

45020; August 27, 2019). On the same 

day, we issued a finalrule that revised 

50 CFR 17.31 and 17.71(84 FR 44753; 

hereinafter, ‘‘the 20194(d) rule’’) and 

ended the ‘‘blanket rule’’ option for 

application of section 9prohibitions to 

species newly listed as threatened after 

the effective date ofthose regulatory 

revisions (September 26, 2019). Blanket 

rules hadextended the majority of the 

protections (all of the prohibitions that 

apply to endangered species under 

section 9 and additional exceptions to 

the prohibitions) to threatened species, 

unless we issued an alternative rule 

under section 4(d) of the Act for a 

particular species (i.e., a species-specific 

4(d) rule).The blanket rule 

protectionscontinued to apply to 

threatened speciesthat were listed prior 

to September 26,2019, without an 

associated species-specificrule. Under 

the 2019 4(d) rule,the only way to apply 

protections to aspecies newly listed as 

threatened is forus to issue a speciesspecific rule settingout the protective 

regulations that areappropriate for that 

species. 

Our analysis for this decision applied 

our current regulations, portions of 

which were last revised in 2019. Given 

that we proposed further revisions to 

these regulations on June 22, 2023 (88 

FR 40742; 88 FR 40764), we have also 

undertaken an analysis of whether the 

decision would be different if we were 

to apply those proposed revisions. We 

concluded that the decision would have 

been the sameif we had applied the 

proposed 2023 regulations. The analyses 

under both the regulations currently in 

effect and the regulations after 

incorporating the June 22, 2023, 

proposed revisions are included in our 

decision file. 

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: 

• Factor A—The present or 

threatened destruction, modification, or 

curtailment of its habitat or range; 

• Factor B—Overutilization for 

commercial, recreational, scientific, or 

educational purposes; 

• Factor C—Disease or predation; 

• Factor D—The inadequacy of 

existing regulatory mechanisms; or 

• Factor 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 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 

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 


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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 the Service 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 the 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 

data regarding the status of the 

subspecies, including an assessment of 

the potential threats to the subspecies. 

The SSA report does not represent our 

decision on whether the subspecies 

should be listed as an endangered or 

threatened species under the Act. 

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. 

To assess the silverspot’s viability, we 

used the three conservation biology 

principles of resiliency, redundancy, 

and representation (Shaffer and Stein 

2000, pp. 306–310). Briefly, resiliency is 

the ability of a species to withstand 

environmental and demographic 

stochasticity (for example, wet or dry, 

warm or cold years); redundancy is the 

ability of a species to withstand 

catastrophic events (for example, 

droughts, large pollution events); and 

representation is the ability of a species 

to adapt to both near-term and long-term 

changes in its physical and biological 

environment (for example, climate 

conditions, pathogens). In general, 

species viability will increase with 

increases in resiliency, redundancy, and 

representation (Smith et al. 2018, p. 

306). Using these principles, we 

identified the silverspot’s ecological 

requirements for survival and 

reproduction at the individual, 

population, and subspecies levels, and 

described the beneficial and risk factors 

influencing the subspecies’ viability. 

The SSA process can be categorized 

into three sequential stages. During the 

first stage, we evaluated the individual 

subspecies’ life-history needs. The next 

stage involved an assessment of the 

historical and current condition of the 

subspecies’ demographics and habitat 

characteristics, including an 

explanation of how the subspecies 

arrived at its current condition. The 

final stage of the SSA report involved 

making predictions about the 

subspecies’ 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 (or in 

this case, subspecies, which is a listable 

entity under the Act) to sustain 

populations in the wild over time. We 

use this information to inform our 

regulatory decision. 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–R6–ES–2021–0134 on https:// 

www.regulations.gov. 

Summary of Biological Status and 

Threats 

In this discussion, we review the 

biological condition of the silverspot 

and its resources, and the threats that 

influence the subspecies’ current and 

future condition, to assess the 

subspecies’ overall viability and the 

risks to that viability. 

Individual Needs 

Individual silverspot needs include 

wet meadows supported by springs, 

seeps, streams, or irrigated areas that 

contain the bog violet host plant for eggs 

and larvae, and other herbaceous 

vegetation for cover and food resources. 

The butterflies may benefit from a light 

interspersion of willow or other shrubs 

for shade and for larval shelter. More 

dense willow and shrubs often surround 

open meadows where the silverspot 

occurs and, if the woody vegetation 

does not take over the meadows, the 

margins of denser stands can be 

beneficial for shade and shelter as well. 

Population Needs 

Populations need abundant 

individuals within habitat patches of 

adequate size and quality to maintain 

survival and reproduction. In general, 

the greater the suitable habitat acreage, 

and the greater the number of 

individuals within a population, the 

greater the resilience. Furthermore, 

colonies and populations need to be 

close enough to each other for 

individuals to breed with each other to 

maintain genetic diversity. The 

silverspot likely does not fly more than 

5–10 miles (mi) (8–16 kilometers (km)) 

and would likely have difficulty finding 

another colony beyond this distance 

(Ellis 2020c, 2020d, 2020e, pers. 

comms.). Additionally, the silverspot 

needs the bog violet to be of sufficient 

extent and density to support colonies 

and populations. We define colonies to 

mean areas of abundant violets that 

produce butterflies, as well as 

surrounding habitat with nectar plants. 

If there is narrow but contiguous nectar 

habitat up or down a drainage but 

without violets (or with only sparse 

violets), we consider those areas 

transitional corridors that are likely 

valuable for dispersal and genetic 

connectivity. 

The silverspot and other S. nokomis 

subspecies can move between colonies 

within a continuous or nearly 

continuous riparian zone (Arnold 1989, 

pp. 10, 14; Fleishman et al. 2002, p. 

708). For example, six colonies occurred 

along a 5-mile stretch in Unaweep 

Canyon that had likely genetic 

interchange (Ellis 1989, p. 3). However, 

these are considered separate colonies 

due to the natural or human-caused 

patchiness of bog violets up and down 

the canyon. In a mark-recapture study 

(Arnold 1989, pp. 10, 14, 21) in 

Unaweep Canyon, about 50 percent of 

the recaptured butterflies moved 

between two colonies separated by 

about 0.75 mi (1.2 km). Based on this 

work, the researcher inferred that the 

silverspot could easily move at least 1 

mile, and based on this, Ellis (1989, p. 

19) further inferred that there was 

exchange of individuals among all the 

Unaweep Canyon colonies every 1 to 5 

years. This information provided the 

basis for Ellis’ professional judgement 

that colonies or populations farther than 

5 to 10 mi (8 to 16 km) from each other 

are likely isolated (Ellis 2020c, 2020d, 

2020e, pers. comm.). 

Some silverspot populations are 

comprised of a single colony, while 


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others are comprised of multiple 

colonies that function as a 

metapopulation. Within a 

metapopulation, butterflies are close 

enough to move between colonies and 

to interbreed and can recolonize 

temporarily extirpated areas that may 

result from local, naturally occurring 

(stochastic) events. For instance, a flood 

may extirpate a colony, but if there are 

nearby colonies, the temporarily flooded 

area may return to suitable habitat 

conditions and be recolonized by the 

silverspot. 

Unfortunately, there is very little 

information on what an adequate-sized 

habitat patch is, especially if there is 

only a single colony in a population. A 

professional estimate for minimum 

patch size of colonies is 2 acres (ac) (0.8 

hectares (ha)) if the habitat has a reliable 

groundwater source and has high violet 

density and is 5 ac (2 ha) if violets are 

less dense due to natural or humancaused variability within a patch (Ellis 

2020e, pers. comm.). Although it is 

possible a single 2-ac or 5-ac patch of 

habitat could support the butterfly for a 

period of time, a more resilient 

metapopulation will likely contain at 

least three colonies of those patch sizes 

or greater. A three-colony 

metapopulation will have a better 

chance of survival by spreading the risk 

of extirpation if a natural event occurs 

at one or two of the colonies. Thus, the 

remaining one or two colonies can 

recolonize the extirpated sites assuming 

suitable habitat remains or reestablishes. 

Due to natural variability in soil and 

topographic conditions, we assume that 

most areas within the silverspot’s range 

are likely to have a lower density of 

violets, rather than dense violets 

(Service 2023, pp. 23–25). 

Consequently, under this assumption, a 

minimum amount of habitat for a 

sufficiently resilient population may be 

12 ac (5 ha), and this can be made up 

of multiple colonies if they are at least 

2 ac (0.8 ha) in size (Service 2023, p. 

25). The specific minimum threshold for 

single colonies to maintain viability is 

unknown, but the larger the acreage the 

greater the resiliency and higher 

likelihood of viability. 

There is also little information on the 

minimum number of silverspot 

individuals needed to sustain a colony. 

There have only been two demographic 

studies for the silverspot that occurred 

at the same locations 10 years apart: 

1979 and 1989 (Arnold 1989, entire). 

The 1989 study found a daily estimate 

of between 48 and 260 butterflies with 

two different models at the Unaweep 

Seep colony (Arnold 1989, pp. 6, 14). A 

combined population estimate at the 

Unaweep Seep colony and another 

upstream colony in Unaweep Canyon 

(which is considered two colonies due 

to intervening transitional habitat) 

resulted in a range of daily abundance 

from 594 to 2,689 butterflies. 

Quality of habitat may have as much 

weight in determining resiliency of a 

colony or population as does overall 

size of a habitat patch or number of 

individuals. Habitat quality could 

potentially be measured by density of 

violets. The Unaweep Seep study 

(Arnold 1989, p. 20) revealed that the 

larger colony with many individuals 

became extirpated, likely due to 

vegetative encroachment, while the 

upstream colony with more violets 

remained extant. Consequently, 

populations appear to have greater 

chance for survival when containing 

more violets. 

Based on observations of grazed and 

burned properties in Unaweep Canyon, 

occasional or well-managed grazing and 

burning likely benefit the violet by 

reducing willows, as well as reducing 

thatch buildup from grasses and sedges 

(Arnold 1989, p. 14; Ellis 1989, pp. 18, 

19). Consequently, natural factors or 

management activities that lead to early 

seral stages or at least more open 

conditions, where willow, grass, sedge, 

or other vegetation does not outcompete 

violets, is important to colonies and 

populations. 

Based on the scant evidence, the 

minimum number of individuals that 

are needed to sustain a silverspot colony 

or population is unknown, and even 

apparent natural but detrimental habitat 

factors, such as excessive growth of 

other plants, can cause extirpation of 

seemingly large colonies. Without 

additional study, it is not known what 

the minimum habitat size is to maintain 

viability, nor what density or abundance 

of bog violets or nectar plants is needed 

to sustain a colony or population, nor 

the maximum distance between 

colonies or populations that can be 

reached for genetic interchange to 

continue to occur on a regular basis. 

Furthermore, it is unknown if large 

single-colony populations can be 

sufficiently resilient without occasional 

genetic interchange from other 

populations. 

In summary, to be adequately 

resilient, silverspot populations need 

water to sustain violets for the larvae, as 

well as occasional or seasonal 

disturbance by grazing from native 

ungulates or domestic livestock, or 

burning, mowing, or non-catastrophic 

flooding, to occasionally remove 

vegetation that might otherwise crowd 

out the violets and other nectar plants 

for the adults. Furthermore, based on 

expert opinion and evidence, the most 

resilient populations need to be at least 

2 ac (0.8 ha) in size with dense violets 

or at least 5 ac (2 ha) in size with less 

dense violets (Ellis 2020e, pers. comm.), 

and need to have a few to several 

colonies within 0.75 to 5 mi (1.2 to 8 

km) of each other and likely be not more 

than 10 mi (16 km) from each other 

(Arnold 1989, pp. 10, 14; Ellis 1989, p. 

19; Ellis 2020c, 2020d, 2020e pers. 

comm.). 

Subspecies Needs 

To maintain viability, the silverspot 

needs to have a sufficient quality and 

quantity of habitat for adequately 

resilient populations, numerous 

populations to create redundancy in the 

event of catastrophic events, and broad 

enough genetic and ecological diversity 

to adapt to changing environmental 

conditions (representation). The 

subspecies will have a better chance of 

long-term viability if single-colony 

populations and even the 

metapopulations occasionally receive 

individuals from other populations such 

that genetic interchange occurs, better 

enabling them to adapt to 

environmental changes. 

Factors Influencing Subspecies Viability 

We reviewed the potential risk factors 

(i.e., threats, stressors) that could be 

affecting the silverspot now and in the 

future. In this final rule, we will discuss 

only those factors in detail that could 

meaningfully impact the status of the 

subspecies. Habitat loss and 

fragmentation, human-caused 

hydrologic alteration, livestock grazing, 

genetic isolation, exotic plant invasion, 

climate change, climate events, larval 

desiccation, and collecting are all 

factors that influence or could influence 

the subspecies’ viability. Those risks 

that are not known to have effects on 

silverspot populations, such as disease, 

predation, prescribed burning or 

wildfire, and pesticides, are not 

discussed here but are evaluated in the 

SSA report. 

Habitat Loss and Fragmentation 

Habitat loss from golf course and 

housing development caused the 

extirpation of two historical colonies 

north of Durango, Colorado (Selby 2007, 

entire; Ellis and Fisher 2020, pers. 

comm.). The remaining colony in the La 

Plata population has residential and 

commercial development across the 

street from it, and one of two drainages 

supplying water to it has relatively new 

housing and golf courses within 1.5 air 

miles (2.4 km), potentially degrading 

downstream silverspot habitat through 

hydrologic alteration. Housing 

development also appears to have been 


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a contributing factor in extirpation of 

the Beulah, New Mexico, colony (Scott 

and Fisher 2014, p. 3). In Colorado, it 

is possible that Rifle Gap Reservoir and 

Dam degraded and fragmented habitat, 

as one butterfly was sighted at a small 

wetland downstream of the dam and the 

reservoir flooded and fragmented 

habitat upstream. Additional habitat 

alteration upstream and downstream 

from a variety of factors (residential and 

commercial development, roads, and 

agricultural conversion of habitat) also 

has likely fragmented habitat. Many 

other colonies and populations have 

development around them that also 

either directly encroaches on the habitat 

or likely has caused degradation and 

fragmentation from homes, roads, 

hydrologic alteration, and habitat 

conversion. 

Agricultural habitat conversion can 

cause loss or fragmentation of habitat 

and typically involves mowing native 

meadows or growing exotic grasses for 

hay. Aerial imagery reveals that 

agricultural conversion has been 

extensive within the silverspot’s range. 

It has likely caused loss of unknown 

colonies over the last 150 years and has 

fragmented native habitat, reducing 

connectivity between colonies and 

populations. Annual haying may be less 

detrimental than haying two or three 

times a summer. One major population 

of Speyeria nokomis (Chuska 

Mountains) in Arizona and New Mexico 

has persisted for many years even 

though haying occurs there once a year 

typically in late August or September 

(Cong et al. 2019, entire; Smith 2019, 

pers. comm.). 

Despite the silverspot’s potential 

compatibility with annually mowing 

native hay fields, agricultural 

conversion to unsuitable crops or 

fragmentation of habitat in the 

silverspot’s range has been extensive. 

Furthermore, the impact of residential 

and commercial development, and other 

development like roads, continues to 

limit and/or degrade habitat in or 

adjacent to existing colonies and 

populations. Habitat loss and 

fragmentation, therefore, has 

meaningfully reduced the viability of 

the subspecies. 

Hydrologic Alteration 

Hydrologic alteration is also a factor 

influencing the subspecies’ viability. 

Hydrologic alteration can result from a 

variety of sources, including, but not 

limited to, diversions for agricultural 

and domestic use; erosion and stream 

channel incision caused by livestock 

grazing, mining, roads, or dredging and 

filling of wetlands; removal of beaver 

dams; manipulation of waterways that 

minimizes flooding and reduces natural 

meander features; and creation and 

operation of large human-made dams. 

For example, the only colony in the 

Costilla population has a diversion 

ditch running through it that likely 

reduced the size of colony. The ditch 

and other diversions have allowed for 

extensive agricultural development in 

the drainage that has altered native 

habitat and likely dropped the water 

table in much of the area. The Montrose 

County colony in the Montrose/San 

Juan population also has had livestock 

grazing and water diversions occur over 

the last 30 years, which have degraded 

the quality of the wet meadow areas and 

lowered the water table (Ireland 2018, 

pers. comm.). 

Many drainages in the Sacramento 

Mountains, where one historical 

silverspot colony may have occurred, 

succumbed to incision of streams 

around 1900, in turn lowering water 

tables and eliminating wet meadow 

habitat (Service 2023, p. 35). Incision of 

stream channels occurred due to erosion 

from deforestation, conversion to 

agricultural and grazing lands, mining, 

and so forth. Beavers were also 

eliminated around 1900 in the 

Sacramento Mountains (and other parts 

of the West), which also undoubtedly 

caused reduction of water tables and 

elimination of wet meadow habitat 

suitable for the silverspot and other 

wetland-dependent species. Hydrologic 

alteration that degrades riparian areas 

and lowers water tables from natural 

systems has occurred not only in the 

Costilla population, Montrose/San Juan 

population, and Sacramento Mountains, 

but extensively in the western United 

States, including much of the 

silverspot’s range. Hydrologic alteration 

continues to limit suitable habitat and is 

a major factor influencing the viability 

of the subspecies. 

Livestock Grazing 

Grazing is ongoing in suitable habitat 

for the subspecies and is a major factor 

influencing the subspecies’ viability. 

Livestock grazing may cause habitat loss 

and degradation if excessive, especially 

in the naturally scarce habitats of the 

silverspot (Hammond and McCorkle 

1983, p. 219) and depending on the 

timing and intensity. Year-round 

grazing or heavy summer grazing is 

typically incompatible with the 

silverspot because livestock graze on the 

violet leaves, nectar sources, and other 

vegetation necessary for the butterfly 

when the larvae and adults need them 

(Ellis 1999, p. 5). For example, an area 

adjacent to a colony in the Ouray 

population has underlying hydrology 

and soils beneficial for the silverspot, 

but the habitat is unsuitable due 

primarily to grazing and perhaps to a 

lesser extent occasional mowing for hay 

(Service 2023, figure 13, p. 34). 

Livestock grazing benefits and is 

compatible with silverspot conservation 

if managed appropriately. Winter 

grazing is beneficial to maintain the bog 

violet and suitable habitat conditions. 

Light or moderate summer grazing (up 

to 20 or 30 percent vegetative 

utilization) appears to be acceptable 

(Arnold 1989, p. 14), but total rest from 

grazing in the summer is preferred (Ellis 

2020g, pers. comm.). If one or more 

kinds of vegetation are too dense, they 

can prevent the bog violet from 

persisting and thus cause extirpation of 

the silverspot. This occurred in the 

Unaweep Seep colony in the Mesa/ 

Grand population, perhaps primarily 

because of spike rush (Eleocharis spp.) 

invasion of meadows but also seemingly 

because of grass, sedge, and willow 

invasion (Arnold 1989, pp. 9, 14; Ellis 

1999, pp. 3, 5, 6). It is unknown if this 

invasion would have occurred without 

grazing or if long-term grazing was the 

factor that shifted vegetation. Without 

occasional reduction or removal, 

herbaceous or woody vegetation could 

crowd out violets. Seasonal grazing or 

mowing and other occasional 

disturbances, such as burning or noncatastrophic flooding, are needed to 

maintain suitable habitat conditions for 

the silverspot. We identify some of these 

practices as exceptions to the take 

prohibitions under the 4(d) rule (see 

‘‘Provisions of the 4(d) rule’’ below). 

Genetic Isolation 

Population isolation can cause 

detrimental genetic and demographic 

effects and is a concern for the 

silverspot’s population resiliency as 

well as its redundancy and 

representation. Lower levels of genetic 

diversity can reduce the capacity of a 

population to respond to environmental 

change (representation) and may lead to 

reduced population fitness through 

reductions in individual longevity and 

fecundity (i.e., fewer offspring) and 

smaller population sizes (Darvill et al. 

2006, p. 608). Another silverspot 

subspecies, S. n. apacheana, has low 

genetic diversity, likely from genetic 

drift (loss of alleles (versions of a gene) 

or change in their frequency in a 

population) due to genetic isolation and 

small population size (Britten et al. 

1994, entire). Genetic exchange between 

and within populations can alleviate 

problems with genetic drift and 

augment populations demographically. 

In S. n. apacheana, routine dispersal 

distances up to 2.5 mi (3.9 km) were 

documented, and 26 percent of the 


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recaptured butterflies had emigrated 

from the initial patch of capture 

(Fleishman et al. 2002, p. 708). This 

migration appears to play an important 

role for S. n. apacheana populations 

both demographically and genetically 

(Britten et al. 2003, p. 232). 

Consequently, the ability or inability of 

individuals to migrate between colonies 

and populations is expected to also be 

of benefit or detriment, respectively, for 

the silverspot. 

Genetic isolation among silverspot 

populations indicates reduced 

population fitness and could be of 

concern in the future (Cong et al. 2019, 

p. 22). Based on the latest scientific 

evidence, genetic exchange does not 

appear to occur between colonies or 

populations that are at least 20 miles 

apart (Cong et al. 2019, entire). 

Currently, the distance between the two 

closest populations, which we know are 

genetically different and represent 

separate populations, is 24.5 air miles 

(39 km) (between the Taos and San 

Miguel/Mora populations in New 

Mexico). Consequently, and more 

specifically, the distance where 

silverspot populations may not 

interbreed and thus may not support 

each other genetically or 

demographically appears to be 

somewhere between 20 and 24.5 air 

miles (32 and 39 km). We used the 

minimum distance of 20 mi (32 km), 

based on findings of Cong et al. (2019, 

entire), in our analysis of genetic 

connectivity (see Current Condition, 

below). 

Reasons for isolation, specifically 

whether from natural fragmentation or 

human habitat alteration, are not 

currently known for all populations. It 

is also not known how long single 

colonies may have been isolated from 

each other. If an isolated colony has 

enough area of habitat to support large 

numbers of the butterfly, it may be 

resilient enough to survive without 

nearby colonies and thus maintain 

viability for a long time. However, many 

silverspot populations, whether singlecolony or multi-colony, have limited 

amounts of habitat. It is unknown 

specifically how long it will take for low 

genetic diversity to become a threat to 

the silverspot, but isolation of 

populations indicates that loss of 

genetic diversity could be a threat at 

some point, if loss of populations 

through lack of demographic support 

does not occur first, and both are cause 

for concern for the subspecies’ viability. 

Exotic Plant Invasion 

The Taos population has experienced 

some invasion by the exotic Siberian 

elm (Ulmus pumila). Because Siberian 

elm is widespread in the silverspot’s 

range, we expect its occurrence to 

increase if changes in climate reduce 

snowpack and water levels in the wet 

meadows of the Taos population or 

other populations. Similarly, the 

extirpated Unaweep Seep colony 

location was invaded by other exotic 

species, including Himalayan 

blackberry (Rubus armeniacus) and treeof-heaven (Ailanthus altissima). 

Although not known to occupy other 

colonies at present, these plant species 

could invade other colonies (Plank 

2020, pers. comm.). Other exotic woody 

or herbaceous species (such as Russian 

olive (Elaeagnus angustifolia), tamarisk 

(Tamarix spp.), or leafy spurge 

(Euphorbia esula)) can rapidly take over 

habitat and could eliminate bog violets 

and other native plants. However, there 

is currently little to no data on plants at 

the colonies (Ellis 1989, pp. 14–15). 

Some nonnative thistles, such as 

Canada thistle (Cirsium arvense), occur 

in or around colonies and can create 

monocultures that create poor overall 

habitat conditions for the silverspot and 

bog violet by replacing native species 

(Ellis 1989, p. 14; Selby 2007, p. 30). 

Land managers in the West sometimes 

control the spread of exotic thistles, but 

Canada thistle (as well as native thistles) 

provides a nectar source for the 

silverspot. Additionally, the adventive 

(exotic but not well-established) bull 

thistle (C. vulgare) and burdock 

(Arctium minus) can provide nectar 

sources (Ellis 1989, p. 14). Because the 

silverspot uses exotic thistles, aggressive 

control of them has been advised against 

(Fisher 2020e, pers. comm.). It does not 

appear that monocultures of Canada 

thistle or other exotic vegetation have 

replaced native vegetation beneficial for 

the silverspot at observed colonies 

(Ireland 2018, pers. comm.), but study of 

plant composition at all colonies is 

needed to determine levels of exotic 

plant presence. Exotic plant invasion is 

currently considered a minor factor 

because exotic species are not currently 

known to be significantly influencing 

the subspecies’ viability. 

Climate Events 

Climate events are defined in the SSA 

report as events that would happen 

within the range of normal variability 

(i.e., stochastic events). However, they 

may reduce the amount and quality of 

habitat and the number of butterflies. A 

record of other Speyeria in Utah 

indicates that too much rain can reduce 

the number of butterflies but may be 

beneficial to violets, which can support 

greater numbers of butterflies in 

following years (Myrup 2020b, pers. 

comm.). Similarly, floods may at least 

temporarily reduce the amount and 

quality of habitat and vegetation as well 

as butterfly numbers by inundating the 

area with water for long periods or by 

erosion. For instance, the Lake Fork 

River in northeast Utah flooded in the 

spring of 2019 and caused the reduction 

or extirpation of a related silverspot 

subspecies colony in the Uinta 

Mountains documented the year before 

(Ellis 2019, pers. comm.). However, the 

flood event was not outside the norm for 

past observed flood events in that 

drainage. This stochastic event provides 

an example of normal climate events 

that can cause reduction in numbers of 

individual butterflies or temporary 

extirpation of a colony but are not 

expected to cause permanent reduction 

or extirpation. Thus, climate events are 

not expected to reduce the subspecies’ 

viability in the long term and are 

considered a minor factor influencing 

the subspecies’ viability. 

Climate Change 

The climate within the silverspot’s 

range already appears to be changing 

because of increased greenhouse gas 

emissions, with earlier springs and 

warmer temperatures. Average 

temperatures in Colorado have 

increased by 2.5 °F (1.4 °C) in the last 50 

years (Lukas et al. 2014, p. 2). 

Snowpack, as measured by snow water 

equivalent, has mostly been below 

average in Colorado since 2000. The 

timing of snowmelt and peak runoff has 

also shifted 1 to 4 weeks earlier in the 

last 30 years in Colorado. Furthermore, 

the Palmer Drought Severity Index has 

shown an increasing trend in soilmoisture drought conditions due to 

below average precipitation since 2000 

and the warming trend (Lukas et al. 

2014, p. 2). More recent analysis using 

National Oceanic and Atmospheric 

Administration (NOAA) temperature 

data shows that, since 1895, the average 

temperature in much of the northern 

half of the silverspot’s range has 

increased by 3.6 °F (2 °C) or more, and 

it is reported that average annual flows 

in the Colorado River Basin have 

declined by 20 percent over the past 

century (Eilperin 2020, entire). 

However, tree ring and other 

paleoclimate data indicate that there 

were more severe and sustained 

droughts prior to recent climate data 

(since 1900) (Lukas et al. 2014, pp. 2, 3). 

The silverspot has survived through the 

more severe past droughts, and, despite 

noted changes in climate over the last 

36 years, climate has thus far not been 

a detectable factor in reduction of the 

subspecies’ viability. Consequently, at 

the present and for the current 

condition analysis in the SSA report, 


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climate change is considered a minor 

factor. However, climate may become a 

major factor; see additional discussion 

of climate change under Future 

Condition, below. 

Desiccation of Larvae 

Desiccation of overwintering larvae 

may be a stressor if soil moisture and air 

humidity are too low or if larvae cannot 

remain hydrated. Soil moisture and 

dead vegetation, along with some air 

flow, may provide suitable conditions 

that prevent desiccation (Fisher 2020b, 

2020f, pers. comm.). Hydration also 

appears to be needed prior to first instar 

larvae overwintering and is achievable if 

water for drinking is freely available and 

if soil or air moisture is sufficient for 

absorption (Myrup 2020a, pers. comm.; 

Stout 2020, entire). Snow cover may 

also provide some desiccation 

prevention and thermal cover, although 

it may not be a significant factor (Ellis 

2020a, 2020b, pers. comm.). Snow cover 

may be of benefit during extreme cold 

(Fisher 2020b, pers. comm.). In general, 

however, extreme cold in the 

silverspot’s range is preceded by snow; 

thus, extreme cold may kill some larvae 

but is likely not a major factor that 

reduces the subspecies’ viability. 

Collecting 

Collecting has occurred in silverspot 

colonies, and it is possible collecting in 

small colonies could negatively affect 

population resiliency (Ellis 1989, p. 15; 

Selby 2007, p. 31; Scott 2023, pers. 

comm.). We know of one colony that 

was extirpated, in part, from collection 

by multiple people (Scott 2023, pers. 

comm.). However, collecting is not 

currently thought to be a significant 

stressor for the silverspot because most 

colonies occur on private land, colony 

locations are largely unknown to the 

public, and current collecting pressure 

is not thought to be extensive (Ellis 

2020f, pers. comm.). In terms of the 

effect on the current condition of the 

subspecies, collecting is currently 

considered a minor factor and does not 

appear to be significantly reducing the 

subspecies’ viability. Efforts should be 

taken to keep it a minor factor, as losing 

even one of the remaining populations 

to collection could have a substantial 

impact on the subspecies’ redundancy 

and representation. We are concerned 

about the potentially detrimental effects 

to the subspecies’ viability from future 

collection if silverspot locations, 

especially the locations of smaller 

populations, are made public (see 

section III. Critical Habitat below). 

Current Condition 

We assessed current conditions of 

silverspot populations in relation to the 

ecological requirements of this 

subspecies. Measurements available that 

are consistent across populations are 

habitat patch size, number of colonies, 

and approximate distance between 

colonies within a population from 

which genetic connectivity can be 

estimated. Additionally, the presence 

and potential influence of the three 

major habitat factors affecting the 

subspecies (habitat loss and 

fragmentation, livestock grazing, and 

hydrologic alteration) were derived from 

aerial imagery and/or on-the-ground 

knowledge. Therefore, we used these 

metrics to characterize the current 

resiliency condition of populations (see 

the SSA report’s section 3.5 ‘‘Current 

Condition by Population’’ on how 

metric scores were derived; Service 

2023, pp. 39–40). 

Resiliency scores and categories were 

established based on the best available 

information and professional opinion of 

species experts. Habitat patch sizes are 

estimates based on expert opinion of 

individual colony bog violet areas and 

primary nectar plant areas using aerial 

imagery or field observations. 

Determination of the number and status 

of colonies within a population was 

primarily based on expert input and 

survey information. 

There are 10 silverspot populations 

comprised of 21 known colonies. Two 

populations, Archuleta and Garfield, 

were not included in the genetic 

analysis by Cong et al. (2019, entire) due 

to a lack of samples, but we consider 

them to be part of the silverspot 

subspecies due to their geographic 

proximity to confirmed populations. We 

designated the Archuleta and Garfield 

populations as separate populations 

because they are more than 20 air miles 

(32 km) away from other populations 

(41 and 80 mi (66 and 129 km), 

respectively) and it is likely populations 

more than 20 mi (32 km) apart are not 

genetically connected (Ellis 2020c, 

2020d, 2020e, pers. comm.; Grishin 

2020b, pers. comm.) 

Within the range of and among all 10 

populations, five previously known 

colonies have been extirpated; one was 

confirmed as extirpated from the Ouray 

population as recently as 2022 (Fisher 

2022b, pers. comm.). The other four 

extirpations occurred over the last 40 

years (since the late 1970s) (Scott and 

Fisher 2014, p. 3; Service 2023, pp. 18– 

19). Not including the extirpated 

colonies or stray sightings, and based on 

recent surveys or expert input, we 

evaluated the 21 known colonies that 

make up the 10 populations. There is 

some uncertainty whether all 21 

colonies are extant based on the lack of 

consistent and consecutive surveys over 

the last 5 years. We characterize their 

current status in the SSA report as 

extant, likely extant, unknown, likely 

extirpated, or extirpated (Service 2023, 

pp. 40, 47). 

Resiliency for each population was 

scored using metrics for population size 

(in acres), number of colonies within 

populations, connectivity within 

populations, and habitat condition. 

Resiliency scores are categorized as 

follows: 0 = predicted extirpation 

(future scenarios only); 1 = very low 

resiliency; 2 and 3 = low resiliency; 4 

to 6 = moderate resiliency; and 7 and 

above = high resiliency (see table 1, 

below). According to our current 

condition analysis in the SSA report, 

three populations have very low 

resiliency, three populations have low 

resiliency, two populations have 

moderate resiliency, and two 

populations have high resiliency (see 

table 1, below; Service 2023, pp. 46–49). 

TABLE 1—CURRENT CONDITION RESILIENCY RANKINGS FOR SILVERSPOT POPULATIONS

Population Size in ac 

(ha) 

Number of 

colonies 

Population 

resiliency 

score 

Archuleta ...................................................................................................................................... 11.9 (4.8) 1 1 

Conejos ........................................................................................................................................ 39.2 (15.9) 1 3 

Costilla ......................................................................................................................................... 4.3 (1.7) 1 1 

Garfield ........................................................................................................................................ 25.8 (10.4) 1 2 

La Plata ........................................................................................................................................ 5.2 (2.1) 1 1 

Mesa/Grand ................................................................................................................................. 45.6 (18.5) 6 9 

Montrose/San Juan ...................................................................................................................... 19.9 (8.1) 2 5 

Ouray ........................................................................................................................................... 38.6 (15.6) 2 5 


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TABLE 1—CURRENT CONDITION RESILIENCY RANKINGS FOR SILVERSPOT POPULATIONS—Continued 

Population Size in ac 

(ha) 

Number of 

colonies 

Population 

resiliency 

score 

San Miguel/Mora .......................................................................................................................... 1.5 (0.6) 2 3 

Taos ............................................................................................................................................. 522.2 (211.3) 4 11 

With 10 populations spread across 

284 air miles (457 km) north to south 

and 237 air miles (381 km) east to west, 

there appears to be adequate 

redundancy should catastrophic events 

occur that cause extirpation of one or a 

few populations. However, if 

catastrophic events cause extirpation of 

the populations with the highest 

resiliency (Mesa/Grand, Montrose/San 

Juan, Ouray, and Taos), it could be quite 

detrimental to the viability of the 

subspecies because the six remaining 

populations have very low or low 

resiliency. Due to the low resiliency of 

many populations, more populations 

with sufficient resiliency would 

contribute to the subspecies’ viability. 

Based on our evaluation of the 10 

populations, we consider the current 

condition of the subspecies’ redundancy 

to be moderate. 

The 10 silverspot populations 

represent the genetic and ecological 

variation (representation) currently 

known for this subspecies. Eight 

silverspot populations were identified 

based on genetic variation, which 

supports the ability of the subspecies to 

adapt over time to long-term changes in 

the environment (for example, climate 

change) (Cong et al. 2019, entire). 

However, 5 populations are comprised 

of a single colony, and all 10 

populations appear isolated from one 

another. Genetic drift, the change in 

allele frequency in a population, is a 

particular concern for the small, isolated 

populations, and could impact the 

subspecies’ adaptive capacity. In 

general, the bog violet and the silverspot 

occur in the same habitat across the 

range, but ecological representation 

adds to adaptive capacity because the 

silverspot occurs at different elevations 

and latitudes, such that overall, the 

silverspot has low to moderate 

representation. Future analysis of 

ecological settings at all colonies and 

populations is needed to improve our 

understanding of representation across 

the subspecies’ range. 

In summary, there are currently 21 

colonies representing the 10 

populations. In terms of resiliency, three 

populations are in very low condition, 

three in low condition, two in moderate 

condition, and two in high condition. 

Current redundancy is determined to be 

moderate, and representation is thought 

to be low to moderate. 

Future Condition 

In the SSA report, we forecast the 

resiliency of silverspot populations and 

the redundancy and representation of 

the subspecies over the next 

approximately 30 years (to the year 

2050) using a range of plausible future 

scenarios. This timeframe encompasses 

approximately 30 generations of the 

subspecies, and we can reasonably rely 

on the climate model projections and 

our projections of the subspecies’ 

response up to this point. Climate 

change impacts and human habitat 

impacts are likely to be the biggest 

drivers of changes to resiliency, 

redundancy, and representation for the 

silverspot. We evaluated four future 

scenarios that capture the range of 

plausible futures based on four climate 

models and future climate projections 

developed for southern Colorado and 

northern New Mexico (Rangwala 2020a, 

entire; 2020b, entire). Three of the four 

models use representative concentration 

pathway (RCP; a greenhouse gas 

concentration trajectory) 4.5, and the 

fourth uses RCP8.5. The RCP4.5 is 

considered a medium emissions 

trajectory, and the RCP8.5 is considered 

a high emissions trajectory. The higher 

the emissions, the greater chance the 

climate will change further from the 

1971–2000 baseline. Current policies are 

projected to take us slightly above the 

RCP4.5 emission trends by mid-century 

(Hausfather and Peters 2020, p. 260). 

The climate models are presented in the 

SSA report (Service 2023, tables 5–8, 

pp. 51–54). 

Using the four climate scenarios, we 

developed four future condition 

scenarios to evaluate the future viability 

of the silverspot. In simple terms, the 

four scenarios include: 

• Scenario 1: Warm Climate with 

Conservation Efforts; 

• Scenario 2: Hot and Dry Summers/ 

Very Wet Winters with Conservation 

Efforts; 

• Scenario 3: Very Hot and Very Dry 

Summers/Wet Winters with No 

Conservation Efforts; and 

• Scenario 4: Hot and Very Dry 

Summers/Dry Winters with No 

Conservation Efforts. 

Because Scenarios 1 and 2 included 

potential future conservation efforts, 

which are not certain to occur and are 

not formalized in any conservation 

agreements, we did not consider these 

scenarios when determining if the 

silverspot meets the Act’s definition of 

an endangered species or of a threatened 

species. However, Scenarios 1 and 2 

will inform our strategies for recovery of 

the subspecies. Therefore, our analysis 

in this final rule focuses on the future 

condition of the silverspot under 

Scenarios 3 and 4, as summarized 

below. Refer to the SSA report for full 

descriptions of the future scenarios 

(Service 2023, chapter 4, pp. 49–67). 

Scenario 3 

Scenario 3 is characterized by the 

following assumptions: 

• An increase in direct habitat loss 

due to development occurs, particularly 

in colonies close to existing housing 

development. 

• Habitat fragmentation due to 

agricultural conversion remains 

unchanged from the current condition. 

• Greater negative effects from 

summer grazing occur because of dry or 

drought conditions (an increase from 

current condition) that reduce nectar 

sources. 

• No efforts are made to maintain 

current hydrology, and, in combination 

with dry or drought conditions, the 

habitat areas of small colonies will dry 

up and become extirpated and larger 

colonies are reduced in size (a decrease 

in suitable habitat from the current 

condition). 

• All populations receive a negative 

habitat factor score due to climaterelated hydrologic alteration whether 

there is surrounding development or 

not. 

• No translocations of butterflies are 

implemented, and genetic diversity is 

low. 

• Climate emissions follow RCP8.5 (a 

high emissions scenario) with very hot 

and dry summers and wet winters. 

Scenario 4 

Scenario 4 is characterized by the 

following assumptions: 

• We include the same assumptions 

as Scenario 3 for habitat loss and 

fragmentation, summer grazing, 


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hydrology and climate-related 

hydrologic factors, and translocation 

(the first six bullets, above). 

• Climate emissions follow RCP4.5 (a 

medium emissions scenario) with hot 

and very dry summers and dry winters. 

Results of Scenarios 3 and 4 

Resiliency rankings for each 

population under Scenario 3 can be 

found in table 2, below, and in the SSA 

report (Service 2023, table 11, p. 64). 

Four of the previously ranked low or 

very low resiliency populations under 

current conditions are expected to 

become extirpated, three populations 

have a very low resiliency, two have 

low resiliency, and the Ouray 

population retains a moderate 

resiliency, surpassing the Mesa/Grand 

and Taos populations as the highestranking population. Extirpation of 

colonies will reduce resiliency and 

redundancy of populations and will also 

undoubtedly decrease representation 

relative to the current condition, 

causing a decline in subspecies’ 

viability. 

Resiliency rankings for each 

population under Scenario 4 can be 

found in table 2, below, and in the SSA 

report (Service 2023, table 12, p. 66). As 

in Scenario 3, we expect climate change 

will cause the extirpation of four 

populations, which have habitat areas 

smaller than 12 ac (5 ha). The size of 

habitat in the remaining populations is 

projected to decrease compared to the 

current condition. Compared to 

Scenario 3, habitat size is projected to 

be larger in the Colorado populations 

and smaller in the Taos population, but 

not enough to change the size scoring. 

With slightly less evaporative stress and 

slightly lower frequency of severe 

drought under Scenario 4 compared to 

Scenario 3, remaining populations may, 

in turn, be slightly more resilient in this 

scenario than in Scenario 3. However, 

using the resiliency scoring metrics in 

the SSA report, the minor differences in 

resiliency between the two scenarios are 

too small to result in different scores. 

Consequently, resiliency scorings are 

the same in both Scenarios 3 and 4, with 

four extirpated populations, three very 

low and two low resiliency populations, 

and only one moderately resilient 

population. Redundancy and 

representation are projected to be low, 

the same as in Scenario 3, and a 

decrease from the current condition. 

Summary of Current and Future 

Conditions 

A comparison of the resiliency of each 

population for the current condition and 

future scenarios is presented below in 

table 2, and table 3 presents a summary 

of redundancy and representation (see 

also Service 2023, table 13, p. 67). 

Currently, we have determined that 3 of 

the 10 silverspot populations are in a 

very low resiliency condition, 3 are in 

a low resiliency condition, 2 are in a 

moderate resiliency condition, and 2 of 

the largest populations are in a high 

resiliency condition. With 10 

populations spread across the 

subspecies’ range, there appears to be 

adequate redundancy should 

catastrophic events occur that cause the 

extirpation of one or a few populations, 

and we consider current redundancy to 

be moderate for the silverspot. It is 

likely there is sufficient representation 

and adaptability due to the genetic 

differences observed among 

populations. However, many of the 

populations are composed of a single 

colony, and all populations appear 

isolated genetically. In general, the bog 

violet and the silverspot occur in the 

same habitat across the subspecies’ 

range, but ecological representation 

adds to adaptive capacity through 

occurrences at different elevations and 

latitudes and provides a low-tomoderate subspecies representation 

currently. 

The effects of future climate changes 

coupled with the continuation of other 

stressors that alter hydrology and cause 

habitat loss and fragmentation are 

projected to increase over the next 30 

years in Scenarios 3 and 4, resulting in 

future conditions that cause resiliency, 

redundancy, and representation to 

decrease, and thus the subspecies’ 

viability is expected to decrease from 

the current condition. Resiliency 

rankings are the same for Scenarios 3 

and 4 with four extirpated populations, 

three very low and two low resiliency 

populations, and only one moderately 

resilient population. Redundancy and 

representation are both projected to be 

reduced from the current condition. 

TABLE 2—SUMMARY OF SILVERSPOT RESILIENCY FOR CURRENT CONDITION AND TWO FUTURE SCENARIOS

Population 

Resiliency 

Current 

condition 

Future 

scenario 3 

Future 

scenario 4 

Archuleta ...................................................................................................................................... 1 0 0 

Conejos ........................................................................................................................................ 3 2 2 

Costilla ......................................................................................................................................... 1 0 0 

Garfield ........................................................................................................................................ 2 1 1 

La Plata ........................................................................................................................................ 1 0 0 

Mesa/Grand ................................................................................................................................. 9 1 1 

Montrose/San Juan ...................................................................................................................... 5 1 1 

Ouray ........................................................................................................................................... 5 5 5 

San Miguel/Mora .......................................................................................................................... 3 0 0 

Taos ............................................................................................................................................. 11 3 3 

TABLE 3—SUMMARY OF SILVERSPOT REDUNDANCY AND REPRESENTATION FOR CURRENT CONDITION AND TWO FUTURE

SCENARIOS

Current condition Future scenario 3 Future scenario 4 

Redundancy ...................................................... Moderate ................................ Very Low ................................ Very Low. 

Representation .................................................. Low-Moderate ......................... Low ......................................... Low. 


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Cumulative Effects 

We note that, by using the SSA 

framework to guide our analysis of the 

scientific information documented in 

the SSA report, we have analyzed the 

cumulative effects of identified threats 

and conservation actions on the 

subspecies. To assess the current and 

future condition of the subspecies, we 

evaluate the effects of all the relevant 

factors that may be influencing the 

subspecies, including threats and 

conservation efforts. 

Habitat loss and fragmentation, 

human-caused hydrologic alteration, 

livestock grazing, genetic isolation, 

exotic plant invasion, climate change, 

climate events, larval desiccation, and 

collecting are all factors that influence 

or could influence the subspecies’ 

viability. These factors also have the 

potential to act cumulatively to impact 

silverspot viability and their cumulative 

impacts were considered in our 

characterization of the subspecies’ 

current and future condition in the SSA 

report. Because the SSA framework 

considers not just the presence of the 

factors, but to what degree they 

collectively influence risk to the entire 

subspecies, our assessment integrates 

the cumulative effects of factors and 

replaces a standalone cumulative effects 

analysis. 

Beneficial Factors 

Mowing or haying: Periodic mowing 

or haying, occasionally or once a year, 

appears to be beneficial to open the 

canopy for violets, to reduce a buildup 

of thatch from dead vegetation, and to 

keep woody vegetation from 

encroaching beyond what is suitable for 

the silverspot. Mowing or haying may 

approximate disturbance that would 

have occurred historically from native 

ungulate grazing or wildfire or both. 

Mowing in the early summer would 

allow for regrowth of vegetation and 

nectar plants suitable for the silverspot 

(Ellis 2020g, pers. comm.). Mowing once 

in the late summer or early fall could 

also potentially be compatible (Smith 

2019, pers. comm.), but has a higher risk 

of reducing vegetation and nectar plants 

for that year’s pupae and adults and 

possibly crushing pupae, eggs, and 

larvae. Occasional or annual mowing 

can, nonetheless, be beneficial to reduce 

competition from other plants if 

adequate nectar plants remain in the 

field or if there are enough within a 

short distance around the field to 

supply nectar to adult silverspots. 

Grazing: Winter and spring grazing 

(October to mid-April) can be beneficial 

to the silverspot (Arnold 1989, pp. 14– 

15). This is because removal of thatch 

from the dead vegetation limits 

competition in the spring for the violets. 

It also may approximate historical 

grazing patterns by native ungulates 

(deer and elk), which, in the winter, 

come down to lower valleys where there 

is less snow. Horses grazed an 

apparently healthy colony in the spring 

and summer (Arnold 1989, p. 14), so 

some light to moderate grazing in the 

spring or summer appears to be 

acceptable. In contrast, grazing when 

violets have emerged and are actively 

growing (spring and summer) may be 

detrimental if livestock readily consume 

or trample the violets and possibly eggs, 

larvae, and pupae. 

Burning: Burning of meadows to 

reduce dead vegetation and reduce 

woody vegetation to suitable levels for 

the silverspot can also be beneficial and 

can possibly increase violet density 

(Arnold 1989, p. 14; Ellis 1989, p. 14). 

Exotic plant invasion: Some exotic 

plants considered invasive or adventive 

may provide nectar sources that benefit 

the silverspot (Ellis 1989, p. 14; Fisher 

2020e, pers. comm.). However, 

especially with invasive plants, this 

may only be the case where native 

nectar plants have been substantially 

reduced or eliminated. 

Conservation efforts: The historical 

Unaweep Seep colony in the Mesa/ 

Grand population was designated as a 

State Natural Area in 1983 (Ellis 1999, 

p. 2). The Bureau of Land Management 

(BLM) also established a Research 

Natural Area around it in 1983 and 

designated it as an Area of Critical 

Environmental Concern (ACEC) through 

their 2015 Resource Management Plan 

(Ellis 1989, p. 1; BLM 2015, pp. 207– 

208). Some monitoring, at least for the 

bog violet, occurred through 1999, but 

sometime after 1989 or possibly 1999, 

the colony became extirpated (Ellis 

1999, entire). Habitat monitoring actions 

were recommended, but it is unclear 

whether any of them were ever 

implemented (Ellis 1999, pp. 8–9). 

Although the State of Colorado and the 

BLM implemented land conservation 

designations around the Unaweep Seep 

colony in the Mesa/Grand population, 

this colony has been extirpated for at 

least 20 years. Therefore, unless the bog 

violet and silverspot are translocated 

back to Unaweep Seep, the land 

designations do not benefit the 

silverspot. There are no other State 

regulatory mechanisms that benefit the 

silverspot in Colorado, New Mexico, or 

Utah. The Colorado State Wildlife 

Action Plan (SWAP) includes the 

silverspot, but there are no State statutes 

for management of the subspecies, so 

management would occur through 

cooperative efforts with other agencies 

or organizations. 

The BLM (Colorado), U.S. Forest 

Service (USFS) Region 2 (Colorado), and 

USFS Region 3 (New Mexico) have the 

silverspot on their sensitive species 

lists. The USFS Region 4 (Utah) does 

not, but no silverspots are currently 

known on USFS land in Utah. No 

silverspot colonies are currently known 

on USFS land in Colorado or New 

Mexico either, but the elevational range 

of the subspecies includes some lower 

elevation USFS land. The BLM does not 

have the silverspot on its sensitive 

species lists in either Utah or New 

Mexico. If species are on BLM sensitive 

species lists, the BLM works 

cooperatively with other Federal and 

State agencies and nongovernmental 

organizations to conserve these species 

and ensure that activities on BLM lands 

do not contribute to the need for their 

listing under the Act. Specific 

conservation objectives for BLM 

sensitive species are established in BLM 

land use plans. BLM’s Grand Junction 

Field Office manages the Unaweep Seep 

property and, in addition to ACEC 

designation, includes management of 

the area for the butterfly in their 2015 

Resource Management Plan (BLM 2015, 

pp. 207–208, appendix B, appendix H). 

The butterfly is not included in other 

BLM land use plans in any of the other 

BLM resource areas in Colorado, New 

Mexico, or Utah, because the butterfly 

was not known to occur on BLM land 

in areas other than Unaweep Seep until 

very recently (only one new colony has 

been identified on BLM lands). 

Only three silverspot colonies are 

known to occur on public land (Federal 

and State lands), but there is potentially 

part of a fourth colony (unconfirmed) on 

public land in the Ouray population. 

Additionally, there are unsurveyed bog 

violet patches on State and Federal 

lands in the Garfield, Mesa/Grand, and 

Montrose/San Juan populations. 

Consequently, at present, any regulatory 

mechanisms or conservation efforts on 

State, BLM, and USFS lands, although 

contributing to conservation of the 

silverspot, would have a low impact on 

the silverspot’s overall viability because 

most colonies and populations occur on 

private land. 

Determination of Silverspot’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 Act’s definition of an endangered 

species or a threatened species. The Act 

defines an ‘‘endangered species’’ as a 

species in danger of extinction 

throughout all or a significant portion of 


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its range, and a ‘‘threatened species’’ as 

a species 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 a 

species meets the definition of 

endangered species or 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. 

Status Throughout All of Its Range 

After evaluating threats to the species 

and assessing the cumulative effect of 

the threats under the Act’s section 

4(a)(1) factors, we found habitat loss and 

fragmentation (Factor A), incompatible 

livestock grazing (Factor A), humancaused hydrologic alteration (Factor A), 

and genetic isolation (Factor E) to be the 

main drivers of the silverspot’s current 

condition, with the addition of the 

effects of climate change (Factor E) 

influencing future condition. These 

stressors all contribute to loss of habitat 

quantity and quality for the silverspot 

and for the bog violet, the plant on 

which silverspot larvae exclusively 

feed. These threats can currently occur 

anywhere in the range of the silverspot, 

and the future effects of climate change 

are expected to be ubiquitous 

throughout the subspecies’ range. The 

existing regulatory mechanisms (Factor 

D) do not significantly affect the 

subspecies or ameliorate these stressors; 

thus, these stressors continue and are 

predicted to increase in prevalence in 

the future. 

Under the two future scenarios 

considered in this evaluation, we expect 

some populations to become extirpated 

and resiliency of the remaining 

populations to decrease. This would 

result in decreased redundancy and 

representation in the future compared to 

the current condition. 

We find that the silverspot is not 

currently in danger of extinction 

because the subspecies is still 

widespread with multiple populations 

of various sizes and levels of resiliency 

spread across its range, capturing 

known genetic and ecological variation. 

Therefore, the subspecies currently has 

sufficient redundancy and 

representation to withstand catastrophic 

events and maintain adaptability to 

changes. However, we expect that the 

stressors, individually and 

cumulatively, will reduce resiliency, 

redundancy, and representation within 

all parts of the range within the 

foreseeable future, in light of future 

climate change effects. Thus, after 

assessing the best available information, 

we conclude that the silverspot is not 

currently in danger of extinction but is 

likely to become in danger of extinction 

within the foreseeable future throughout 

all of its range. This finding is based on 

anticipated reductions in resiliency, 

redundancy, and representation in the 

future as a result of predicted loss and 

degradation of wet meadow habitat from 

the synergistic and cumulative 

interactions between climate change 

and other stressors. Climate change is 

predicted to increase temperatures and 

decrease water availability and 

snowpack necessary to maintain the wet 

meadows that the silverspot and bog 

violet need. This, coupled with the 

continuation of other stressors that alter 

hydrology and cause habitat loss and 

fragmentation, is expected to impact the 

future viability of this subspecies. We 

can reasonably determine that both the 

future threats and the subspecies’ 

responses to those threats are likely 

within a 30-year timeframe (i.e., the 

foreseeable future). Thus, after assessing 

the best available information, we 

determine that the silverspot is not 

currently in danger of extinction but is 

likely to become in danger of extinction 

within the foreseeable future throughout 

all of its range. 

Status Throughout a Significant Portion 

of Its Range 

Under the Act and our 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. The court in Center 

for Biological Diversity v. Everson, 435 

F. Supp. 3d 69 (D.D.C. 2020) (Everson), 

vacated the provision of the Final Policy 

on Interpretation of the Phrase 

‘‘Significant Portion of Its Range’’ in the 

Endangered Species Act’s Definitions of 

‘‘Endangered Species’’ and ‘‘Threatened 

Species’’ (Final Policy; 79 FR 37578, 

July 1, 2014) that provided if the 

Services determine that a species is 

threatened throughout all of its range, 

the Services will not analyze whether 

the species is endangered in a 

significant portion of its range. 

Therefore, we proceed to evaluating 

whether the species is endangered in a 

significant portion of its range—that is, 

whether there is any portion of the 

species’ range for which both (1) the 

portion is significant; and (2) the species 

is in danger of extinction in that 

portion. Depending on the case, it might 

be more efficient for us to address 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. 

Following the court’s holding in 

Everson, we now consider whether there 

are any significant portions of the 

species’ range where the species is in 

danger of extinction now (i.e., 

endangered). In undertaking this 

analysis for the silverspot, we choose to 

address the status question first—we 

consider information pertaining to the 

geographic distribution of both the 

subspecies and the threats that the 

subspecies faces to identify portions of 

the range where the subspecies may be 

endangered. 

We evaluated the range of the 

silverspot to determine if the species is 

in danger of extinction now in any 

portion of its range. The range of a 

species can theoretically be divided into 

portions in an infinite number of ways. 

We focused our analysis on portions of 

the subspecies’ range that may meet the 

definition of an endangered species. 

For the silverspot, we considered 

whether the threats or their effects on 

the subspecies are greater in any 

biologically meaningful portion of the 

subspecies’ range than in other portions 

such that the subspecies is in danger of 

extinction now in that portion. We 

examined the following threats: Habitat 

loss and fragmentation; livestock 

grazing; human-caused hydrologic 

alteration; genetic isolation; climate 

change; climate events; invasion by 

nonnative plants; larval desiccation; and 

collecting. These are all factors that 

influence or could influence the 

subspecies’ viability, including 

cumulative effects. All of these threats 

are similar in scope, scale, and 

distribution across the range of the 

subspecies. The spatial distribution of 

these threats is evenly distributed 

throughout the range and not 

concentrated in any particular area. 

However, there are several smaller 

populations distributed throughout the 

range that are currently in low 

resiliency condition and therefore could 

experience an elevated risk of extinction 

in the future (see tables 1 and 2, above). 

These smaller populations are not 

concentrated in their location, instead 

they are distributed across the range 

with more highly resilient populations 

interspersed between them. These 

smaller populations are not at risk of 

extinction currently due to the lack of 

imminent threats, as described in our 


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analysis above. Climate events are 

currently a minor factor and when 

considered with the other stressors are 

not expected to reduce the subspecies’ 

viability in the near term. The risk of 

extinction of the smaller populations 

increases in the foreseeable future when 

climate change becomes a major factor 

and when other major factors such as 

habitat loss and degradation are 

predicted to increase. Therefore, the 

smaller populations risk of extinction is 

influenced by the predicted increase in 

threats from habitat loss and 

degradation, climate change, and (to a 

lesser extent) the other stressors 

analyzed in this rule, and their future 

effects to the silverspot. 

We found no portion of the 

silverspot’s range where threats are 

impacting individuals differently from 

how they are affecting the subspecies 

elsewhere in its range, or where the 

biological condition of the subspecies 

differs from its condition elsewhere in 

its range such that the status of the 

subspecies in that portion differs from 

any other portion of the subspecies’ 

range. Therefore, no portion of the 

subspecies’ range provides a basis for 

determining that the subspecies is in 

danger of extinction in a significant 

portion of its range, and we determine 

that the subspecies is likely to become 

in danger of extinction within the 

foreseeable future throughout all 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), because, in reaching 

this conclusion, we did not apply the 

aspects of the Final Policy, including 

the definition of ‘‘significant’’ that those 

court decisions held to be invalid. 

Determination of Status 

Our review of the best scientific and 

commercial data available indicates that 

the silverspot meets the Act’s definition 

of a threatened species. Therefore, we 

are listing the silverspot as a threatened 

species in accordance with sections 

3(20) and 4(a)(1) of the Act. 

Available Conservation Measures 

Conservation measures provided to 

species listed as endangered or 

threatened species under the Act 

include recognition as a listed species, 

planning and implementation of 

recovery actions, requirements for 

Federal protection, and prohibitions 

against certain practices. Recognition 

through listing results in public 

awareness, and conservation by Federal, 

State, Tribal, and local agencies, private 

organizations, and individuals. The Act 

encourages cooperation with the States 

and other countries and calls for 

recovery actions to be carried out for 

listed species. The protection required 

by Federal agencies, including the 

Service, and the prohibitions against 

certain activities are discussed, in part, 

below. 

The primary purpose of the Act is the 

conservation of endangered and 

threatened species and the ecosystems 

upon which they depend. The ultimate 

goal of such conservation efforts is the 

recovery of these listed species, so that 

they no longer need the protective 

measures of the Act. Section 4(f) of the 

Act calls for the Service to develop and 

implement recovery plans for the 

conservation of endangered and 

threatened species. The goal of this 

process is to restore listed species to a 

point where they are secure, selfsustaining, and functioning components 

of their ecosystems. 

Recovery planning consists of 

preparing draft and final recovery plans, 

beginning with the development of a 

recovery outline and making it available 

to the public soon after a final listing 

determination. The recovery outline 

guides the immediate implementation of 

urgent recovery actions and describes 

the process to be used to develop a 

recovery plan. The recovery planning 

process involves the identification of 

actions that are necessary to halt and 

reverse the species’ decline by 

addressing the threats to its survival and 

recovery. The recovery plan also 

identifies recovery criteria for review of 

when a species may be ready for 

reclassification from endangered to 

threatened (‘‘downlisting’’) or removal 

from protected status (‘‘delisting’’), and 

methods for monitoring recovery 

progress. Recovery plans also establish 

a framework for agencies to coordinate 

their recovery efforts and provide 

estimates of the cost of implementing 

recovery tasks. Recovery teams 

(composed of species experts, Federal 

and State agencies, nongovernmental 

organizations, and stakeholders) may be 

established to develop recovery plans. 

Revisions of the plan may be done to 

address continuing or new threats to the 

species, as new substantive information 

becomes available. When completed, 

the recovery outline, draft recovery 

plan, and the final recovery plan will be 

available on our website (https://

www.fws.gov/program/endangeredspecies), or from our Colorado 

Ecological Services Field Office (see FOR

FURTHER INFORMATION CONTACT). 

Implementation of recovery actions 

generally requires the participation of a 

broad range of partners, including other 

Federal agencies, States, Tribes, 

nongovernmental organizations, 

businesses, and private landowners. 

Examples of recovery actions include 

habitat restoration (e.g., restoration of 

native vegetation), research, captive 

propagation and reintroduction, and 

outreach and education. The recovery of 

many listed species cannot be 

accomplished solely on Federal lands 

because their range may occur primarily 

or solely on non-Federal lands. For 

many listed species, achieving recovery 

requires cooperative conservation efforts 

on private, State, and Tribal lands. 

Once this subspecies is listed (see 

DATES above), funding for recovery 

actions will be available from a variety 

of sources, including Federal budgets, 

State programs, and cost-share grants for 

non-Federal landowners, the academic 

community, and nongovernmental 

organizations. In addition, pursuant to 

section 6 of the Act, the States of 

Colorado, New Mexico, and Utah will 

be eligible for Federal funds to 

implement management actions that 

promote the protection or recovery of 

the silverspot. Information on our grant 

programs that are available to aid the 

subspecies recovery can be found at: 

https://www.fws.gov/service/financialassistance. 

Please let us know if you are 

interested in participating in recovery 

efforts for the silverspot. Additionally, 

we invite you to submit any new 

information on this subspecies 

whenever it becomes available and any 

information you may have for recovery 

planning purposes (see FOR FURTHER

INFORMATION CONTACT). 

Section 7 of the Act is titled 

Interagency Cooperation and mandates 

all Federal action agencies to use their 

existing authorities to further the 

conservation purposes of the Act and to 

ensure that their actions are not likely 

to jeopardize the continued existence of 

listed species or adversely modify 

critical habitat. Regulations 

implementing section 7 are codified at 

50 CFR part 402. 

Section 7(a)(2) states that each Federal 

action agency shall, in consultation with 

the Secretary, ensure that any action 

they authorize, fund, or carry out is not 

likely to jeopardize the continued 

existence of a listed species or result in 

the destruction or adverse modification 

of designated critical habitat. Each 

Federal agency shall review its action at 

the earliest possible time to determine 

whether it may affect listed species or 

critical habitat. If a determination is 

made that the action may affect listed 

species or critical habitat, formal 

consultation is required (50 CFR 

402.14(a)), unless the Service concurs in 


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writing that the action is not likely to 

adversely affect listed species or critical 

habitat. At the end of a formal 

consultation, the Service issues a 

biological opinion, containing its 

determination of whether the federal 

action is likely to result in jeopardy or 

adverse modification. 

Examples of discretionary actions for 

the silverspot that may be subject to 

consultation procedures under section 7 

are land management or other 

landscape-altering activities on Federal 

lands administered by the U.S. Fish and 

Wildlife Service, Bureau of Land 

Management, Bureau of Indian Affairs, 

Bureau of Reclamation, National Park 

Service, and U.S. Forest Service as well 

as actions on State, Tribal, local, or 

private lands that require a Federal 

permit (such as a permit from the U.S. 

Army Corps of Engineers under section 

404 of the Clean Water Act (33 U.S.C. 

1251 et seq.) or a permit from the 

Service under section 10 of the Act) or 

that involve some other Federal action 

(such as funding from the Federal 

Highway Administration, Federal 

Aviation Administration, or the Federal 

Emergency Management Agency). 

Federal actions not affecting listed 

species or critical habitat—and actions 

on State, Tribal, local, or private lands 

that are not federally funded, 

authorized, or carried out by a Federal 

agency—do not require section 7 

consultation. Federal agencies should 

coordinate with the local Service Field 

Office (see FOR FURTHER INFORMATION

CONTACT) with any specific questions on 

Section 7 consultation and conference 

requirements. 

It is the policy of the Services, as 

published in the Federal Register on 

July 1, 1994 (59 FR 34272), to identify 

to the extent known at the time a 

species is listed, specific activities that 

will not be considered likely to result in 

violation of section 9 of the Act. To the 

extent possible, activities that will be 

considered likely to result in violation 

will also be identified in as specific a 

manner as possible. The intent of this 

policy is to increase public awareness of 

the effect of a listing on proposed and 

ongoing activities within the range of 

the species. Although most of the 

prohibitions in section 9 of the Act 

apply to endangered species, sections 

9(a)(1)(G) and 9(a)(2)(E) of the Act 

prohibit the violation of any regulation 

under section 4(d) pertaining to any 

threatened species of fish or wildlife, or 

threatened species of plant, 

respectively. Section 4(d) of the Act 

directs the Secretary to promulgate 

protective regulations that are necessary 

and advisable for the conservation of 

threatened species. As a result, we 

interpret our policy to mean that, when 

we list a species as a threatened species, 

to the extent possible, we identify 

activities that will or will not be 

considered likely to result in violation 

of the protective regulations under 

section 4(d) for that species. 

At this time, we are unable to identify 

specific activities that will or will not be 

considered likely to result in violation 

of section 9 of the Act beyond what is 

already clear from the descriptions of 

prohibitions and exceptions established 

by protective regulation under section 

4(d) of the Act. 

Questions regarding whether specific 

activities would constitute violation of 

section 9 of the Act should be directed 

to the Colorado Ecological Services 

Field Office (see FOR FURTHER

INFORMATION CONTACT). 

II. Final Rule Issued Under Section 4(d) 

of the Act 

Background 

Section 4(d) of the Act contains two 

sentences. The first sentence states that 

the Secretary shall issue such 

regulations as she deems necessary and 

advisable to provide for the 

conservation of species listed as 

threatened. The U.S. Supreme Court has 

noted that statutory language similar to 

the language in section 4(d) of the Act 

authorizing the Secretary to take action 

that she ‘‘deems necessary and 

advisable’’ affords a large degree of 

deference to the agency (see Webster v. 

Doe, 486 U.S. 592, 600 (1988)). 

Conservation is defined in the Act to 

mean the use of all methods and 

procedures which are necessary to bring 

any endangered species or threatened 

species to the point at which the 

measures provided pursuant to the Act 

are no longer necessary. Additionally, 

the second sentence of section 4(d) of 

the Act states that the Secretary may by 

regulation prohibit with respect to any 

threatened species any act prohibited 

under section 9(a)(1), in the case of fish 

or wildlife, or section 9(a)(2), in the case 

of plants. Thus, the combination of the 

two sentences of section 4(d) provides 

the Secretary with wide latitude of 

discretion to select and promulgate 

appropriate regulations tailored to the 

specific conservation needs of the 

threatened species. The second sentence 

grants particularly broad discretion to 

the Service when adopting the 

prohibitions under section 9. 

The courts have recognized the extent 

of the Secretary’s discretion under this 

standard to develop rules that are 

appropriate for the conservation of a 

species. For example, courts have 

upheld rules developed under section 

4(d) as a valid exercise of agency 

authority where they prohibited take of 

threatened wildlife or include a limited 

taking prohibition (see Alsea Valley 

Alliance v. Lautenbacher, 2007 U.S. 

Dist. Lexis 60203 (D. Or. 2007); 

Washington Environmental Council v. 

National Marine Fisheries Service, 2002 

U.S. Dist. Lexis 5432 (W.D. Wash. 

2002)). Courts have also upheld 4(d) 

rules that do not address all of the 

threats a species faces (see State of 

Louisiana v. Verity, 853 F.2d 322 (5th 

Cir. 1988)). As noted in the legislative 

history when the Act was initially 

enacted, ‘‘once an animal is on the 

threatened list, the Secretary has an 

almost infinite number of options 

available to [her] with regard to the 

permitted activities for those species. 

[She] may, for example, permit taking, 

but not importation of such species, or 

[she] may choose to forbid both taking 

and importation but allow the 

transportation of such species’’ (H.R. 

Rep. No. 412, 93rd Cong., 1st Sess. 

1973). 

The provisions of this 4(d) rule will 

promote conservation of the silverspot 

by encouraging management of the 

landscape in ways that meet both land 

management considerations and the 

conservation needs of the silverspot. 

The provisions of this rule are one of 

many tools that we will use to promote 

the conservation of the silverspot. 

As mentioned previously in 

‘‘Available Conservation Measures,’’ 

section 7(a)(2) of the Act requires 

Federal agencies, including the Service, 

to ensure that any action they fund, 

authorize, or carry out is not likely to 

jeopardize the continued existence of 

any endangered species or threatened 

species or result in the destruction or 

adverse modification of designated 

critical habitat of such species. 

These requirements are the same for 

a threatened species with a speciesspecific 4(d) rule. For example, as with 

an endangered species, if a Federal 

agency determines that an action is ‘‘not 

likely to adversely affect’’ a threatened 

species will require the Service’s 

written concurrence (50 CFR 402.13(c). 

Similarly, if a Federal agency 

determines that an action is ‘‘likely to 

adversely affect’’ a threatened species, 

the action will require formal 

consultation and the formulation of a 

biological opinion (50 CFR 402.14(a)). 

Provisions of the 4(d) Rule 

Exercising the Secretary’s authority 

under section 4(d), we have developed 

a rule that is designed to address the 

silverspot’s specific threats and 

conservation needs. As discussed above 

under ‘‘Summary of Biological Status 


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and Threats,’’ we have concluded that 

the silverspot is likely to become in 

danger of extinction within the 

foreseeable future primarily due to the 

individual and cumulative effects of 

habitat loss and fragmentation, 

incompatible livestock grazing, humancaused hydrologic alteration, genetic 

isolation, and climate change. Section 

4(d) requires the Secretary to issue such 

regulations as she deems necessary and 

advisable to provide for the 

conservation of each threatened species 

and authorizes the Secretary to include 

among those protective regulations any 

of the prohibitions that section 9(a)(1) of 

the Act prescribes for endangered 

species. We find that the protections, 

prohibitions, and exceptions in this rule 

as a whole satisfy the requirement in 

section 4(d) of the Act to issue 

regulations deemed necessary and 

advisable to provide for the 

conservation of the silverspot. 

The protective regulations for the 

silverspot incorporate prohibitions from 

section 9(a)(1) to address the threats to 

the species. Section 9(a)(1) prohibits the 

following activities for endangered 

wildlife: importing or exporting; take; 

possession and other acts with 

unlawfully taken specimens; delivering, 

receiving, carrying, transporting, or 

shipping in interstate or foreign 

commerce in the course of commercial 

activity; or selling or offering for sale in 

interstate or foreign commerce. This 

protective regulation includes all of 

these prohibitions because the 

silverspot is at risk of extinction in the 

foreseeable future and putting these 

prohibitions in place will help to 

preserve the subspecies’ remaining 

populations, slow their rate of decline, 

and decrease synergistic, negative 

effects from other threats. 

This 4(d) rule will provide for the 

conservation of the silverspot by 

prohibiting the following activities, 

except as otherwise authorized or 

permitted (e.g., allowed for in an 

exception or authorized by a permit 

issued under section 10(a)(1)(A) of the 

Act): importing or exporting; possession 

and other acts with unlawfully taken 

specimens; delivering, receiving, 

carrying, transporting, or shipping in 

interstate or foreign commerce in the 

course of commercial activity; or selling 

or offering for sale in interstate or 

foreign commerce. In addition, anyone 

taking, attempting to take, or otherwise 

possessing a silverspot, or parts thereof, 

in violation of section 9 of the Act will 

be subject to a penalty under section 11 

of the Act, with certain exceptions 

(discussed below). 

Under the Act, ‘‘take’’ means to 

harass, harm, pursue, hunt, shoot, 

wound, kill, trap, capture, or collect, or 

to attempt to engage in any such 

conduct. Some of these provisions have 

been further defined in regulation at 50 

CFR 17.3. Take can result knowingly or 

otherwise, by direct and indirect 

impacts, intentionally or incidentally. 

Regulating incidental and intentional 

take will help preserve the subspecies’ 

remaining populations, slow their rate 

of decline, and decrease synergistic, 

negative effects from other threats. 

Exceptions to the prohibition on take 

include all of the general exceptions to 

the prohibition on take of endangered 

wildlife, as set forth in 50 CFR 17.21 

and additional exceptions, as described 

below. 

The 4(d) rule will also provide for the 

conservation of the species by allowing 

exceptions that incentivize conservation 

actions or that, while they may have 

some minimal level of take of the 

silverspot, are not expected to rise to the 

level that would have a negative impact 

(i.e., would have only de minimis 

impacts) on the subspecies’ 

conservation. 

As discussed above under ‘‘Summary 

of Biological Status and Threats’’, 

livestock grazing, exotic plant invasion, 

prescribed burning, and use of 

pesticides affect the status of the 

silverspot both negatively and positively 

depending on how, when, and where 

they are done. Accordingly, this final 

4(d) rule addresses activities to facilitate 

conservation and management of the 

silverspot where the subspecies 

currently occurs and may occur in the 

future by excepting the activities from 

the Act’s take prohibition under certain 

specific conditions. These activities are 

intended to increase management 

flexibility and encourage support for the 

conservation and habitat improvement 

of the silverspot. Under this 4(d) rule, 

take will be prohibited, except for take 

incidental to an otherwise lawful 

activity described in the exceptions to 

prohibitions in the 4(d) rule for the 

purpose of silverspot conservation or 

recovery. 

The specific exceptions to the 

prohibitions for specific types of 

incidental take under this 4(d) rule are 

explained in more detail below. For all 

of these, reasonable care must be 

practiced to minimize the impacts from 

the actions. Reasonable care means 

limiting the impacts to the silverspot 

and its host plant (bog violet) by 

complying with any and all applicable 

Federal, State, and Tribal regulations for 

the activity in question; using methods 

and techniques that result in the least 

harm, injury, or death, as feasible; 

undertaking activities at the least 

impactful times (e.g., conducting 

activities that might impact habitat 

during the flight season) and locations, 

as feasible; ensuring the number of 

individuals affected does not impact the 

existing populations; minimizing the 

potential to introduce invasive plant 

species; and preserving the genetic 

diversity of populations. 

Under this 4(d) rule, incidental take of 

a silverspot will not be a violation of 

section 9 of the Act if it occurs as a 

result of the following activities. All 

activities and statements below only 

apply in habitat areas of silverspot that 

include wet meadow areas where bog 

violets are growing and immediately 

adjacent areas with nectar plants. 

Livestock Grazing 

By excepting take of the silverspot 

caused by grazing, we acknowledge the 

positive role that some ranchers have 

already played in conserving the 

silverspot and the importance of 

preventing any additional loss and 

fragmentation of native grasslands and 

riparian habitat. Grazing (and browsing) 

by livestock may improve silverspot 

habitat by opening up tree or shrub 

canopy cover in the habitat and 

removing herbaceous vegetation that 

shades and competes with the bog 

violet, thereby reducing its abundance. 

Grazing may be an effective tool to 

improve silverspot habitat when 

carefully applied in cooperation and 

consultation with private landowners, 

public land managers, and grazing 

experts. Moderate vegetative utilization 

(40–55 percent) in late fall to early 

spring (October 15 to May 31) is 

excepted under this 4(d) rule. Resting 

pastures that include silverspot habitat 

is preferred in summer through fall 

(June 1 to October 14), but light grazing 

(less than 30 percent utilization) during 

this timeframe is also excepted from 

take because it may reduce competition 

for the bog violet. Recovery of the 

silverspot will depend on the protection 

and restoration of high-quality habitats 

supporting the bog violet on private 

lands and on public lands that are 

grazed by private individuals under 

lease or other agreements. 

Annual Haying or Mowing 

Annual haying or mowing in early 

summer can be beneficial, or at least not 

detrimental, to the silverspot by 

removing vegetation that competes with 

the bog violet for light, nutrients, and 

water and reduces the violet’s 

abundance. Therefore, we except take 

from annual haying or mowing in 

silverspot habitat under the following 

conditions: activities must occur in the 

early summer (June 30 or earlier), and 

blade height must be a minimum of 6 


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inches above the ground, with 8 inches 

or higher preferred in areas with bog 

violet to avoid cutting the violet leaves. 

The timing of cutting also applies to 

adjacent drier habitat areas that contain 

nectar plants, an important food source 

for adult butterflies, but blade height 

may be lower than 6 inches where the 

bog violet is not present. However, 

haying or mowing from July 1 through 

October would be detrimental due to 

removal of nectar plants and cover for 

all silverspot life stages, and therefore is 

not excepted from the prohibitions in 

this 4(d) rule in and adjacent to bog 

violet habitat. 

Prescribed Burning 

Spring burning can be beneficial to 

remove thatch that may reduce or 

prevent growth of the bog violet. 

Prescribed burning in the spring (March 

1 to April 30) has limited impact to 

silverspots and is excepted from take. 

Fall burning (October 15 to December 

15) is also excepted if adequate 

monitoring (i.e., at least two surveys at 

times when butterflies are active) is 

performed on the property during the 

adult flight period of that year and does 

not detect the silverspot. 

Brush Control 

Some woody vegetation interspersed 

in silverspot habitat or at the margins of 

habitat can be beneficial for bog violet 

survival and growth by providing some 

protection from livestock grazing and 

trampling and a future substrate for 

violet establishment on old decaying 

logs (Ireland 2021a, pers. comm.). 

However, if allowed to become too 

dense, woody vegetation can crowd out 

bog violets and nectar plants. 

Consequently, brush removal every 4 to 

5 years is excepted from take and may 

occur at any time during the year. 

Removal can be by mechanical means, 

burning, grazing, or herbicide 

application if in compliance with other 

excepted activities in the 4(d) rule. If 

mechanical means such as a brush hog 

is used, the blade must be set to 8 

inches or higher above the ground. If 

herbicides are used, an appropriate 

systemic herbicide to prevent regrowth 

must be directly applied to cut stems. 

Broadcast spraying in silverspot habitat 

is prohibited because it may remove all 

nectar plants for the butterfly. 

Noxious Weed Control 

Although some noxious weeds like 

Canada thistle provide nectar sources 

for silverspot, spot spraying, hand 

pulling, or mechanical treatment of 

noxious weeds is excepted from take 

and may occur at any time during the 

year. High densities of noxious weeds 

can be detrimental to the bog violet and 

their control can benefit the silverspot. 

However, broadcast spraying in 

silverspot habitat is prohibited because 

it may remove all nectar plants for the 

butterfly. 

Fence Maintenance 

Excepted activities related to fence 

maintenance include replacement of 

poles and wire, and aboveground 

removal of woody vegetation along 

fence lines. These activities may occur 

at any time during the year. Fences help 

manage where cattle and other livestock 

can graze and reduce unwanted impacts 

to bog violet habitat. Removal of woody 

vegetation can prevent encroachment of 

vegetation into bog violet habitat and 

reduces competition with bog violet. If 

removal of woody vegetation is done by 

machine, such as a brush hog, the 

machine blade must be set 8 inches or 

higher above ground to avoid or 

minimize damage to the bog violet. If 

permanent removal of woody vegetation 

is desired, we recommend a systemic 

herbicide be directly applied to the cut 

stems of woody vegetation. However, as 

stated earlier, broadcast spraying in 

silverspot habitat is prohibited because 

it may remove all nectar plants for the 

butterfly. 

Maintenance and Operation of Existing 

Utility Corridors 

Maintenance and operation of existing 

utility infrastructure within and 

immediately adjacent to silverspot 

habitat are excepted from take within 

existing rights-of-way for standard 

activities to repair and maintain existing 

transmission towers, lines, access roads, 

and to perform brush control. These 

activities are excepted from take yearround and as needed with no restriction 

on frequency. Replacement of existing 

structures and the installation of new 

structures and infrastructure such as 

access roads are not excepted. Noxious 

weed control and fence maintenance 

must abide by the exceptions for these 

activities identified in the 4(d) rule. 

Maintenance of Other Structures 

Maintenance of other existing 

structures within and immediately 

adjacent to silverspot habitat is excepted 

if activities are kept within the confines 

of already disturbed ground so as to not 

disturb the subspecies or its habitat. 

Despite these prohibitions regarding 

threatened species, we may under 

certain circumstances issue permits to 

carry out one or more otherwise 

prohibited activities, including those 

described above. The regulations that 

govern permits for threatened wildlife 

state that the Director may issue a 

permit authorizing any activity 

otherwise prohibited with regard to 

threatened species. These include 

permits issued for the following 

purposes: for scientific purposes, to 

enhance propagation or survival, for 

economic hardship, for zoological 

exhibition, for educational purposes, for 

incidental taking, or for special 

purposes consistent with the purposes 

of the Act (50 CFR 17.32). The statute 

also contains certain exemptions from 

the prohibitions, which are found in 

sections 9 and 10 of the Act. 

We recognize the special and unique 

relationship with our State natural 

resource agency partners in contributing 

to conservation of listed species. State 

agencies often possess scientific data 

and valuable expertise on the status and 

distribution of endangered, threatened, 

and candidate species of wildlife and 

plants. State agencies, because of their 

authorities and their close working 

relationships with local governments 

and landowners, are in a unique 

position to assist us in implementing all 

aspects of the Act. In this regard, section 

6 of the Act provides that we must 

cooperate to the maximum extent 

practicable with the States in carrying 

out programs authorized by the Act. 

Therefore, any qualified employee or 

agent of a State conservation agency that 

is a party to a cooperative agreement 

with us in accordance with section 6(c) 

of the Act, who is designated by his or 

her agency for such purposes, will be 

able to conduct activities designed to 

conserve the silverspot that may result 

in otherwise prohibited take without 

additional authorization. 

Nothing in this 4(d) rule will change 

in any way the recovery planning 

provisions of section 4(f) of the Act, the 

consultation requirements under section 

7 of the Act, or the ability of the Service 

to enter into partnerships for the 

management and protection of the 

silverspot. However, interagency 

cooperation may be further streamlined 

through planned programmatic 

consultations for the subspecies 

between Federal agencies and the 

Service. 

III. Critical Habitat 

Section 4(a)(3) of the Act, as 

amended, and implementing regulations 

(50 CFR 424.12), require that, to the 

maximum extent prudent and 

determinable, the Secretary shall 

designate critical habitat at the time the 

species is determined to be an 

endangered or threatened species. Our 

regulations (50 CFR 424.12(a)(1)) state 

that the Secretary may, but is not 

required to, determine that a 


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Federal Register / Vol. 89, No. 32 / Thursday, February 15, 2024 / Rules and Regulations 11771 

designation would not be prudent in the 

following circumstances: 

• The species is threatened by taking 

or other human activity and 

identification of critical habitat can be 

expected to increase the degree of such 

threat to the species; 

• The present or threatened 

destruction, modification, or 

curtailment of a species’ habitat or range 

is not a threat to the species, or threats 

to the species’ habitat stem solely from 

causes that cannot be addressed through 

management actions resulting from 

consultations under section 7(a)(2) of 

the Act; 

• Areas within the jurisdiction of the 

United States provide no more than 

negligible conservation value, if any, for 

a species occurring primarily outside 

the jurisdiction of the United States; 

• No areas meet the definition of 

critical habitat; or 

• The Secretary otherwise determines 

that designation of critical habitat 

would not be prudent based on the best 

scientific data available. 

In this final rule, we affirm the 

prudency determination we made in our 

May 4, 2022, proposed rule (87 FR 

26319 at pp. 26335–26336) concerning 

the designation of critical habitat for the 

silverspot. We find that the designation 

of critical habitat is not prudent for the 

silverspot, in accordance with 50 CFR 

424.12(a)(1), because the silverspot faces 

a threat of unauthorized collection and 

trade, and designation can reasonably be 

expected to increase the degree of these 

threats to the subspecies. Designation of 

critical habitat requires the publication 

of maps and a narrative description of 

specific critical habitat areas in the 

Federal Register. The degree of detail in 

those maps and boundary descriptions 

is greater than the general location 

descriptions provided in this final rule. 

We find that the publication of maps 

and descriptions outlining the locations 

of the silverspot would likely facilitate 

unauthorized collection and trade, as 

collectors would know the exact 

locations where silverspots occur. The 

silverspot has been collected in the past, 

and there is potential for collection 

pressure to increase if specific locations 

of populations were to become widely 

known (Ellis 2020f, pers. comm.). 

Butterflies in general are highly sought 

after by collectors in the illegal animal 

trade (Courchamp et al. 2006, entire). 

We are concerned that the publicity 

from listing the silverspot may result in 

greater interest from collectors and 

make the subspecies more desirable for 

collection because of its rarity as has 

been documented for other rare 

butterflies (Hoekwater 1997, entire; 

Courchamp et al. 2006, entire; O’Neill 

2007, entire; Stratton 2012, entire; Lewis 

2018, entire). Therefore, a designation of 

critical habitat would be detrimental for 

the subspecies. For more information on 

the rationale for our determination that 

designation of critical habitat is not 

prudent, see the May 4, 2022, proposed 

rule (87 FR 26319 at pp. 26335–26336). 

Required Determinations 

National Environmental Policy Act (42 

U.S.C. 4321 et seq.) 

Regulations adopted pursuant to 

section 4(a) of the Act are exempt from 

the National Environmental Policy Act 

(NEPA; 42 U.S.C. 4321 et seq.) and do 

not require an environmental analysis 

under NEPA. We published a notice 

outlining our reasons for this 

determination in the Federal Register 

on October 25, 1983 (48 FR 49244). This 

includes listing, delisting, and 

reclassification rules, as well as critical 

habitat designations and speciesspecific protective regulations 

promulgated concurrently with a 

decision to list or reclassify a species as 

threatened. The courts have upheld this 

position (e.g., Douglas County v. 

Babbitt, 48 F.3d 1495 (9th Cir. 1995) 

(critical habitat); Center for Biological 

Diversity v. U.S. Fish and Wildlife 

Service., 2005 WL 2000928 (N.D. Cal. 

Aug. 19, 2005) (concurrent 4(d) rule)). 

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 

federally recognized Tribes on a 

government-to-government basis. In 

accordance with Secretary’s 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. 

Thirty-eight Tribes with cultural claims 

or affiliation to land or with lands 

currently in the range of the silverspot 

were contacted via letter to solicit input 

on the SSA report. One Tribe responded 

and stated that they do not have 

scientific data but would like to be kept 

informed of the SSA findings. We 

notified Tribes of the May 4, 2022, 

proposed listing determination and this 

final determination. 

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 Colorado 

Ecological Services Field Office (see FOR

FURTHER INFORMATION CONTACT). 

Authors 

The primary authors of this final rule 

are the staff members of the Fish and 

Wildlife Service’s Species Assessment 

Team and the Colorado 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. 

Regulation Promulgation 

Accordingly, we 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. 

■ 2. In § 17.11, in paragraph (h), amend 

the List of Endangered and Threatened 

Wildlife by adding an entry for 

‘‘Butterfly, silverspot’’ in alphabetical 

order under INSECTS to read as follows: 

§ 17.11 Endangered and threatened 

wildlife. 

* * * * * 

(h) * * * 


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11772 Federal Register / Vol. 89, No. 32 / Thursday, February 15, 2024 / Rules and Regulations 

Common name Scientific name Where listed Status Listing citations and 

applicable rules 

*******

INSECTS

* * * * * * * 

Butterfly, silverspot .................... Speyeria nokomis nokomis ...... Wherever found ....... T 89 FR [INSERT FEDERAL REGISTER 

PAGE WHERE THE DOCUMENT BEGINS], February 15, 2024; 50 CFR 

17.47(h).4d

* * * * * * * 

■ 3. Amend § 17.47 by adding paragraph 

(h) to read as follows: 

§ 17.47 Special rules—insects. 

* * * * * 

(h) Silverspot butterfly (Speyeria 

nokomis nokomis). (1) Prohibitions. The 

following prohibitions that apply to 

endangered wildlife also apply to the 

silverspot butterfly. Except as provided 

under paragraphs (h)(2) and (3) of this 

section and §§ 17.4 and 17.5, it is 

unlawful for any person subject to the 

jurisdiction of the United States to 

commit, to attempt to commit, to solicit 

another to commit, or cause to be 

committed, any of the following acts in 

regard to this species: 

(i) Import or export, as set forth at 

§ 17.21(b) for endangered wildlife. 

(ii) Take, as set forth at § 17.21(c)(1) 

for endangered wildlife. 

(iii) Possession and other acts with 

unlawfully taken specimens, as set forth 

at § 17.21(d)(1) for endangered wildlife. 

(iv) Interstate or foreign commerce in 

the course of commercial activity, as set 

forth at § 17.21(e) for endangered 

wildlife. 

(v) Sale or offer for sale, as set forth 

at § 17.21(f) for endangered wildlife. 

(2) General exceptions from 

prohibitions. In regard to this species, 

you may: 

(i) Conduct activities as authorized by 

a permit under § 17.32. 

(ii) Take, as set forth at § 17.21(c)(2) 

through (c)(4) for endangered wildlife. 

(iii) Take as set forth at § 17.31(b). 

(iv) Possess and engage in other acts 

with unlawfully taken wildlife, as set 

forth at § 17.21(d)(2) for endangered 

wildlife. 

(3) Exceptions from prohibitions for 

specific types of incidental take. You 

may take silverspot butterfly without a 

permit in wet meadow areas where bog 

violets (Viola nephrophylla/V. sororia 

var. affinis) are growing and 

immediately adjacent areas with nectar 

sources while carrying out the legally 

conducted activities set forth in this 

paragraph (h)(3), as long as the 

activities: 

(i) Are conducted with reasonable 

care. For the purposes of this paragraph, 

‘‘reasonable care’’ means limiting the 

impacts to the silverspot and bog violet 

by complying with any and all 

applicable Federal, State, and Tribal 

regulations for the activity in question; 

using methods and techniques that 

result in the least harm, injury, or death, 

as feasible; undertaking activities at the 

least impactful times (e.g., conducting 

activities that might impact habitat 

during the flight season) and locations, 

as feasible; ensuring the number of 

individuals affected does not impact the 

existing populations; minimizing the 

potential to introduce invasive plant 

species; and preserving the genetic 

diversity of populations; and 

(ii) Consist of one or more of the 

following: 

(A) Grazing: 

(1) Moderate grazing (40 to 55 percent 

vegetative utilization) in late fall to early 

spring (October 15 to May 31); or 

(2) Light grazing (less than 30 percent 

vegetative utilization) in summer 

through fall (June 1 to October 14). 

(B) Annual haying or mowing in 

silverspot habitat in the early summer 

(June 30 or earlier). Blade height must 

be a minimum of 6 inches above the 

ground, with 8 inches or higher 

preferred in areas with bog violet. In 

surrounding drier areas, blade height 

may be lower than 6 inches where the 

violet is not present. 

(C) Prescribed burning: 

(1) In the spring (March 1 to April 30); 

or 

(2) In the fall (October 15 to December 

15), if the silverspot butterfly has been 

shown to not be present in a given year 

through adequate monitoring (i.e., at 

least two surveys at times when 

butterflies are active). 

(D) Brush removal every 4 to 5 years. 

Brush removal may be conducted at any 

time during the year. Removal can be by 

mechanical means, burning, grazing, or 

herbicide application if in compliance 

with other excepted activities in this 

paragraph (h)(3). If mechanical means 

such as a brush hog is used, the blade 

must be set to 8 inches or higher above 

the ground. If herbicides are used, an 

appropriate systemic herbicide to 

prevent regrowth must be directly 

applied to cut stems; broadcast spraying 

is prohibited. 

(E) Spot spraying, hand pulling, or 

mechanical treatment of noxious weeds, 

which may be conducted at any time 

during the year. Broadcast spraying of 

noxious weeds is prohibited. 

(F) Replacement of fence poles and 

wire, and aboveground removal of 

woody vegetation along fence lines, 

which may be conducted at any time 

during the year. If removal of woody 

vegetation is done by machine, such as 

a brush hog, the machine blade must be 

set 8 inches or higher above the ground. 

For permanent removal of woody 

vegetation, a systemic herbicide may be 

applied directly to the cut stems of 

woody vegetation; broadcast spraying is 

prohibited. 

(G) Maintenance and operation of 

existing utility infrastructure within and 

immediately adjacent to silverspot 

habitat if activities are kept within the 

confines of existing rights-of-way. This 

exception applies to standard activities 

to repair and maintain existing 

transmission towers, lines, and access 

roads, and to perform brush control, that 

are conducted as needed at any time 

during the year. Replacement of existing 

structures and the installation of new 

structures and infrastructure such as 

access roads are not excepted. Noxious 

weed control and fence maintenance 

must abide by the exceptions for these 

activities identified in paragraphs 

(h)(3)(ii)(E) and (F) of this section. 

(H) Maintenance of other existing 

structures within and immediately 

adjacent to silverspot habitat if activities 

are kept within the confines of already 

disturbed ground. 

Martha Williams, 

Director, U.S. Fish and Wildlife Service. 

[FR Doc. 2024–03042 Filed 2–14–24; 8:45 am] 

BILLING CODE 4333–15–P 


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