100662 Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 

DEPARTMENT OF THE INTERIOR 

Fish and Wildlife Service 

50 CFR Part 17 

[Docket No. FWS–R3–ES–2024–0137; 

FXES1111090FEDR–256–FF09E21000] 

RIN 1018–BE30 

Endangered and Threatened Wildlife 

and Plants; Threatened Species Status 

With Section 4(d) Rule for Monarch 

Butterfly and Designation of Critical 

Habitat 

AGENCY: Fish and Wildlife Service, 

Interior. 

ACTION: Proposed rule. 

SUMMARY: We, the U.S. Fish and 

Wildlife Service (Service), propose to 

list the monarch butterfly (Danaus 

plexippus), the iconic orange and black 

butterfly, as a threatened species and 

designate critical habitat under the 

Endangered Species Act of 1973, as 

amended (Act). We propose to list the 

monarch butterfly as a threatened 

species with protective regulations 

under section 4(d) of the Act (a ‘‘4(d) 

rule’’). Finalizing this rule as proposed 

would add this species to the List of 

Endangered and Threatened Wildlife 

and extend the Act’s protections to the 

species. We also propose to designate 

critical habitat for the monarch butterfly 

under the Act. In total, approximately 

4,395 acres (1,778 hectares) in Alameda, 

Marin, Monterey, San Luis Obispo, 

Santa Barbara, Santa Cruz, and Ventura 

Counties, California, fall within the 

boundaries of the proposed critical 

habitat designation. We also announce 

the availability of an economic analysis 

of the proposed designation of critical 

habitat for the monarch butterfly. We 

also are notifying the public that we 

have scheduled two informational 

meetings followed by public hearings on 

the proposed rule. 

DATES: We will accept comments 

received or postmarked on or before 

March 12, 2025. Comments submitted 

electronically using the Federal 

eRulemaking Portal (see ADDRESSES, 

below) must be received by 11:59 p.m. 

eastern time on the closing date. 

Public informational meetings and 

public hearings: We will hold two 

public informational meetings followed 

by public hearings. The first meeting 

and hearing will be from 6 p.m. to 8:30 

p.m., eastern time, on January 14, 2025. 

To accommodate those in western time 

zones, the second meeting and hearing 

will be from 8 p.m. to 10:30 p.m., 

eastern time, on January 15, 2025. 

ADDRESSES: You may submit comments 

by one of the following methods: 

(1) Electronically: Go to the Federal 

eRulemaking Portal: https://

www.regulations.gov. In the Search box, 

enter FWS–R3–ES–2024–0137, which is 

the docket number for this rulemaking. 

Then, click on the Search button. On the 

resulting page, in the panel on the left 

side of the screen, under the Document 

Type heading, check the Proposed Rule 

box to locate this document. You may 

submit a comment by clicking on 

‘‘Comment.’’ 

(2) By hard copy: Submit by U.S. mail 

to: Public Comments Processing, Attn: 

FWS–R3–ES–2024–0137, U.S. Fish and 

Wildlife Service, MS: PRB/3W, 5275 

Leesburg Pike, Falls Church, VA 22041– 

3803. 

We request that you send comments 

only by the methods described above. 

We will post all comments on https:// 

www.regulations.gov. This generally 

means that we will post any personal 

information you provide us (see 

Information Requested, below, for more 

information). 

Availability of supporting materials: 

Supporting materials, such as the 

species status assessment report, are 

available at https://www.regulations.gov 

at Docket No. FWS–R3–ES–2024–0137. 

If we finalize the critical habitat 

designation, we will make the 

coordinates or plot points or both from 

which the maps are generated available 

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

No. FWS–R3–ES–2024–0137. 

Public informational meeting and 

public hearing: The public 

informational meeting and the public 

hearing will be held virtually using the 

Zoom platform. See Public Hearing, 

below, for more information. 

FOR FURTHER INFORMATION CONTACT: 

Barbara Hosler, Regional Listing 

Coordinator, U.S. Fish and Wildlife 

Service, Midwest Region Headquarters, 

5600 American Blvd., Bloomington, MN 

55437, telephone 517–580–0254, email: 

monarch@fws.gov. 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. Please see 

Docket No. FWS–R3–ES–2024–0137 on 

https://www.regulations.gov for a 

document that summarizes this 

proposed rule. 

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 an endangered species 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 monarch butterfly 

meets the Act’s definition of a 

threatened species; therefore, we are 

proposing to list it as such and 

proposing a designation of its critical 

habitat. Both listing a species as an 

endangered or threatened species and 

making a critical habitat designation can 

be completed only by issuing a rule 

through the Administrative Procedure 

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

seq.). 

What this document does. We 

propose to add the monarch butterfly as 

a threatened species to the List of 

Endangered and Threatened Wildlife 

with protective regulations under 

section 4(d) of the Act, and we propose 

the designation of critical habitat for the 

species. 

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 monarch 

butterfly meets the definition of a 

threatened species due to the following 

threats: the ongoing impacts from loss 

and degradation of breeding, migratory, 

and overwintering habitat (from past 

conversion of grasslands and shrublands 

to agriculture and widespread use of 

herbicides; logging/thinning at 

overwintering sites in Mexico; urban 

development, senescence (i.e., 

deterioration with age), and 

incompatible management of 

overwintering sites in California; and 

drought) (Factor A); exposure to 

insecticides (Factor E); and effects of 

climate change (Factor E). 

To improve future conditions so that 

the monarch migratory populations 

stabilize and grow, we need to (1) 


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achieve a significant increase in the 

availability of milkweed and nectar 

plants in monarch breeding and 

migratory areas; (2) protect and enhance 

overwintering habitat; (3) avoid and 

minimize impacts to monarchs and their 

habitat from insecticides and herbicides; 

and (4) maintain public support for the 

conservation of monarch butterflies. 

Because of the monarch butterfly’s 

general habitat use and wide 

distribution, all sectors of society, 

including the general public, have an 

opportunity to participate in a broad 

range of conservation efforts throughout 

the species’ range. 

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

Secretary of the Interior (Secretary), to 

the maximum extent prudent and 

determinable, concurrently with listing 

designate critical habitat for the species. 

Section 3(5)(A) of the Act defines 

critical habitat as (i) the specific areas 

within the geographical area occupied 

by the species, at the time it is listed, 

on which are found those physical or 

biological features (I) essential to the 

conservation of the species and (II) 

which may require special management 

considerations or protections; and (ii) 

specific areas outside the geographical 

area occupied by the species at the time 

it is listed, upon a determination by the 

Secretary that such areas are essential 

for the conservation of the species. 

Section 4(b)(2) of the Act states that the 

Secretary must make the designation on 

the basis of the best scientific data 

available and after taking into 

consideration the economic impact, the 

impact on national security, and any 

other relevant impacts of specifying any 

particular area as critical habitat. 

Information Requested 

We intend that any final action 

resulting from this proposed rule will be 

based on the best scientific and 

commercial data available and be as 

accurate and as effective as possible. 

Therefore, we request comments or 

information from other governmental 

agencies, Native American Tribes, the 

scientific community, industry, or any 

other interested parties concerning this 

proposed rule. We particularly seek 

comments concerning: 

(1) The species’ biology, range, and 

population trends, including: 

(a) Biological or ecological 

requirements of the species, including 

habitat requirements for feeding, 

breeding, and sheltering; 

(b) Genetics and taxonomy; 

(c) Historical and current range, 

including distribution patterns, 

alternative migratory pathways, and the 

locations of any additional populations 

of this species; 

(d) Population dynamics and 

contributions from the nonmigratory 

populations, specifically resident 

monarchs in southern Florida, the Gulf 

Coast, the southern Atlantic Coast, and 

the southern Pacific Coast; 

(e) Historical and current population 

levels, and current and projected trends; 

and 

(f) Past and ongoing conservation 

measures for the species, its habitat, or 

both. 

(2) Threats and conservation actions 

affecting the species, including: 

(a) Factors that may be affecting the 

continued existence of the species, 

which may include habitat modification 

or destruction, overutilization, disease, 

predation, the inadequacy of existing 

regulatory mechanisms, or other natural 

or manmade factors; 

(b) Biological, commercial trade, or 

other relevant data concerning any 

threats (or lack thereof) to this species; 

(c) Existing regulations or 

conservation actions that may be 

addressing threats to this species; and 

(d) Other potential threats that were 

not identified as key threats to the 

species. 

(3) Additional information concerning 

the historical and current status of this 

species. 

(4) Information to assist us with 

applying or issuing protective 

regulations under section 4(d) of the Act 

that may be necessary and advisable to 

provide for the conservation of the 

monarch butterfly. In particular, we 

seek information concerning: 

(a) The extent to which we should 

include any of the Act’s section 9 

prohibitions in the 4(d) rule; 

(b) Whether we should consider any 

modifications or additional exceptions 

from the prohibitions in the 4(d) rule; 

(c) Whether the provisions related to 

the maintenance, enhancement, 

removal, or establishment of milkweed 

should be revised to include spatial or 

temporal restrictions or deferments; 

(d) Whether we should include an 

exception for the use of pesticides and, 

if so, what measures are reasonable, 

feasible, and adequate to reduce or 

offset pesticide exposure to monarchs 

from agricultural and non-agricultural 

uses (e.g., rangeland, rights-of-way, 

forestry, commercial areas, and 

mosquito control), including measures 

for specific classes of pesticides (e.g., 

herbicides, insecticides), pesticide uses, 

and application methods; 

(e) Whether we should include an 

exception for direct impacts from 

transportation and energy infrastructure, 

including mortality from collisions with 

wind turbines; and 

(f) Whether we could improve or 

modify our approach to the 4(d) rule in 

any way to provide for greater public 

participation and understanding, or to 

better accommodate public concerns 

and comments. 

(5) Specific information related to 

critical habitat, such as the following: 

(a) The amount and distribution of 

monarch butterfly habitat; 

(b) Any additional areas occurring 

within the range of the species in the 

United States, especially in breeding, 

migratory, or overwintering areas, that 

should be included in the critical 

habitat designation because they (i) are 

occupied at the time of listing and 

contain the physical or biological 

features that are essential to the 

conservation of the species and that may 

require special management 

considerations, or (ii) are unoccupied at 

the time of listing and are essential for 

the conservation of the species; and 

(c) Special management 

considerations or protection that may be 

needed in critical habitat areas we are 

proposing, including managing for the 

potential effects of climate change. 

(6) Land use designations and current 

or planned activities in the subject areas 

and their possible impacts on proposed 

critical habitat. 

(7) Any probable economic, national 

security, or other relevant impacts of 

designating any area that may be 

included in the final designation, and 

the related benefits of including or 

excluding specific areas. 

(8) Information on the extent to which 

the description of probable economic 

impacts in the economic analysis is a 

reasonable estimate of the likely 

economic impacts and any additional 

information regarding probable 

economic impacts that we should 

consider. 

(9) Whether any specific areas we are 

proposing for critical habitat 

designation should be considered for 

exclusion under section 4(b)(2) of the 

Act, and whether the benefits of 

potentially excluding any specific area 

outweigh the benefits of including that 

area. If you think we should exclude 

any additional areas, please provide 

information supporting a benefit of 

exclusion. 

(10) Whether we could improve or 

modify our approach to designating 

critical habitat in any way to provide for 

greater public participation and 

understanding, or to better 

accommodate public concerns and 

comments. 

Please include sufficient information 

with your submission (such as scientific 

journal articles or other publications) to 


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allow us to verify any scientific or 

commercial information you include. 

Please note that submissions merely 

stating support for, or opposition to, the 

action under consideration without 

providing supporting information, 

although noted, do not provide 

substantial information necessary to 

support a determination. Section 

4(b)(1)(A) of the Act directs that 

determinations as to whether any 

species is an endangered or a threatened 

species must be made solely on the 

basis of the best scientific and 

commercial data available, and section 

4(b)(2) of the Act directs that the 

Secretary shall designate critical habitat 

on the basis of the best scientific data 

available. 

You may submit your comments and 

materials concerning this proposed rule 

by one of the methods listed in 

ADDRESSES. We request that you send 

comments only by the methods 

described in ADDRESSES. 

If you submit information via https:// 

www.regulations.gov, your entire 

submission—including any personal 

identifying information—will be posted 

on the website. If your submission is 

made via a hardcopy that includes 

personal identifying information, you 

may request at the top of your document 

that we withhold this information from 

public review. However, we cannot 

guarantee that we will be able to do so. 

We will post all hardcopy submissions 

on https://www.regulations.gov. 

Comments and materials we receive, 

as well as supporting documentation we 

used in preparing this proposed rule, 

will be available for public inspection 

on https://www.regulations.gov. 

Our final determination may differ 

from this proposal because we will 

consider all comments we receive 

during the comment period as well as 

any information that may become 

available after this proposal. Based on 

the new information we receive (and, if 

relevant, any comments on that new 

information), we may conclude that the 

species is endangered instead of 

threatened, or we may conclude that the 

species does not warrant listing as either 

an endangered species or a threatened 

species. For critical habitat, our final 

designation may not include all areas 

proposed, may include some additional 

areas that meet the definition of critical 

habitat, or may exclude some areas if we 

find the benefits of exclusion outweigh 

the benefits of inclusion and exclusion 

will not result in the extinction of the 

species. In addition, we may change the 

parameters of the prohibitions or the 

exceptions to those prohibitions in the 

protective regulations issued or applied 

under section 4(d) of the Act if we 

conclude it is appropriate in light of 

comments and new information 

received. For example, we may expand 

the prohibitions if we conclude that the 

protective regulation as a whole, 

including those additional prohibitions, 

is necessary and advisable to provide for 

the conservation of the species. 

Conversely, we may establish additional 

or different exceptions to the 

prohibitions in the final rule if we 

conclude that the activities would 

facilitate or are compatible with the 

conservation and recovery of the 

species. In our final rule, we will clearly 

explain our rationale and the basis for 

our final decision, including why we 

made changes, if any, that differ from 

this proposal. 

Public Hearing 

We have scheduled two public 

informational meetings with public 

hearings on this proposed rule for the 

monarch butterfly. We will hold the 

public informational meetings and 

public hearings on the dates and times 

listed above under Public informational 

meeting and public hearing in DATES. 

We are holding the public informational 

meetings and public hearings via the 

Zoom online video platform and via 

teleconference so participants can 

attend remotely. For security purposes, 

registration is required. To listen and 

view a meeting and hearing via Zoom, 

listen to a meeting and hearing by 

telephone, or provide oral public 

comments at a public hearing by Zoom 

or telephone, you must register. For 

information on how to register, or if you 

encounter problems joining Zoom the 

day of the meeting, visit https://

www.fws.gov/species/monarch-danausplexippus. Registrants will receive the 

Zoom link and the telephone number 

for the public informational meeting 

and public hearing for which they have 

registered. If applicable, interested 

members of the public not familiar with 

the Zoom platform should view the 

Zoom video tutorials (https://

support.zoom.us/hc/en-us/articles/ 

206618765-Zoom-video-tutorials) prior 

to the public informational meetings 

and public hearings. 

The public hearings will provide 

interested parties an opportunity to 

present verbal testimony (formal, oral 

comments) regarding this proposed rule. 

While the public informational meetings 

will be opportunities for dialogue with 

the Service, the public hearings are not: 

They are forums for accepting formal 

verbal testimony. In the event there is a 

large attendance, the time allotted for 

oral statements may be limited. 

Therefore, anyone wishing to make an 

oral statement at a public hearing for the 

record is encouraged to provide a 

prepared written copy of their statement 

to us through the Federal eRulemaking 

Portal, or U.S. mail (see ADDRESSES, 

above). There are no limits on the length 

of written comments submitted to us. 

Anyone wishing to make an oral 

statement at a public hearing must 

register before the hearing https://

www.fws.gov/species/monarch-danausplexippus. The use of a virtual public 

hearing is consistent with our 

regulations at 50 CFR 424.16(c)(3). 

Previous Federal Actions 

On August 26, 2014, we received a 

petition from the Center for Biological 

Diversity, Center for Food Safety, Xerces 

Society for Invertebrate Conservation, 

and Dr. Lincoln Brower, requesting that 

we list the monarch butterfly as a 

threatened species under the Act. On 

December 31, 2014, we published a 90- 

day finding that the petition presented 

substantial scientific or commercial 

information, indicating that listing the 

monarch butterfly may be warranted (79 

FR 78775). On December 17, 2020, we 

published a 12-month finding that 

listing the species as an endangered or 

threatened species is warranted but 

precluded by higher priority actions (85 

FR 81813). The species remained so 

designated in the annual candidate 

notices of review on May 3, 2022 (87 FR 

26152), and June 27, 2023 (88 FR 

41560). 

Peer Review 

A species status assessment (SSA) 

team prepared an SSA report for the 

monarch butterfly. The SSA team was 

composed of Service biologists, in 

consultation with other species experts. 

The SSA report represents a 

compilation of the best scientific and 

commercial data available concerning 

the status of the species, including the 

impacts of past, present, and future 

factors (both negative and beneficial) 

affecting the species. 

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 in listing actions under the Act 

(https://www.fws.gov/sites/default/files/ 

documents/peer-review-policy-directorsmemo-2016-08-22.pdf), we solicited 

independent scientific review of the 

information contained in the monarch 

butterfly SSA report. In 2018, we sent 

the first version (1.0) of the SSA report 

to 6 independent peer reviewers and 

received 5 responses. In 2020, we sent 

the second version (2.0) of the SSA 

report to 3 peer reviewers and received 

2 responses. In 2023, we sent the SSA 


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report version 2.2 to 13 peer reviewers 

and received 7 responses. No individual 

peer reviewed the SSA report more than 

once. Results of this structured peer 

review process can be found at https:// 

www.regulations.gov. In preparing this 

proposed rule, we incorporated the 

results of these reviews, as appropriate, 

into the SSA report, which is the 

foundation for this proposed rule. 

Summary of Peer Reviewer Comments 

As discussed in Peer Review above, 

we received comments from 14 total 

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. The peer 

reviewers provided additional 

references, clarifications, and 

suggestions. 

We updated the SSA report based on 

these peer reviewers’ comments, 

including restructuring several sections 

within the report, revising our 

description of adaptive capacity, 

clarifying specific points and 

terminology where appropriate, and 

adding additional details and suggested 

references when needed. Additional 

peer reviewer comments are addressed 

in the following summary, as well as 

throughout the Summary of Biological 

Status and Threats, below, and were 

incorporated into the SSA report as 

appropriate (Service 2024a, entire). 

Comment 1: Two reviewers asked us 

to elaborate on whether our assessment 

of resilience or the extinction threshold 

for western migratory monarchs should 

change based on a few years of numbers 

that have bounced back above 200,000 

after the low of less than 2,000 

individuals in the winter of 2019–2020. 

Our response: It is plausible that 

migratory monarchs experienced good 

weather that resulted in abundant and 

well-timed milkweed and nectar 

resources across their breeding habitat 

in western North America in 2021, 

which provided for a significant 

increase in the overwintering count 

from below 2,000 individuals in 2019– 

2020. With only a few years of improved 

population numbers, we are currently 

unable to determine whether the 

western migratory population’s status is 

improving or if these data support the 

continuation of its fluctuation and 

decline. While this does not change our 

current assessment of the population’s 

resilience, we have added text clarifying 

this uncertainty to our SSA report to 

further address this comment. 

We also revisited our extinction 

thresholds in western North America. In 

the model presented in our SSA, we use 

a range of extinction thresholds, which 

are informed by scientific literature (i.e., 

Schultz et al. 2017, entire; Wells et al. 

1990, p. 124). With the observed 

western population rebound, these 

estimates may be conservative. While 

the extinction thresholds we used are 

currently the best available, some 

uncertainty remains about the size of 

extinction thresholds and the time lag 

necessary to confirm assumptions about 

population stability or extinction 

trajectories. Therefore, we could be 

either overestimating or 

underestimating extinction risk 

depending on the accuracy of the 

thresholds. 

Comment 2: One reviewer questioned 

our reliance on overwintering counts to 

inform our understanding of eastern 

North American monarch butterfly 

population trends, in contrast to using 

surveys at other locations and at other 

times during the year. 

Our response: Monitoring at 

overwintering sites allows for the most 

practical and direct assessment of 

annual population levels, where the 

near-entirety of the migratory 

population can be evaluated 

consistently and comprehensively, 

reflecting the full range of threats and 

population dynamics encountered over 

the prior annual breeding and migration 

cycle. The question about the optimal 

approach for annual census of monarch 

butterfly populations (e.g., 

overwintering data v. non-overwintering 

data) has been addressed in a more 

recent review of the methodology, 

which concluded that the overwintering 

area of the eastern North American 

population is an accurate representation 

of the size of the population (Pleasants 

et al. 2024, p. 62). Our analysis of this 

topic based on the preponderance of 

scientific evidence is incorporated into 

the most recent version of the SSA 

report (Service 2024a, pp. 70–76). 

Comment 3: Two reviewers noted that 

the decline of the eastern North 

American monarchs may have slowed 

or stabilized for the past decade or 

more, potentially due to an associated 

slowing or plateau of habitat loss. With 

this potential slowing or stabilization, 

one of these reviewers asked if the 

extinction risk may have thus 

decreased. They also noted differences 

in population decline based on the 

modeling assumption of densitydependence or independence. 

Our response: The estimates of 

population viability (and extinction 

risk) presented in the SSA report are 

based on the overall population 

trajectory (growth rate), along with the 

current population size and the 

fluctuations exhibited year-to-year. 

Growth rate and variability are derived 

using time series data, which may be 

influenced by the number of years being 

analyzed. 

Different analyses have explored the 

possibility that past declines in 

milkweed, or habitat more generally, 

alongside the expansion of genetically 

modified crops and associated 

herbicides and pesticides, may have 

effectively plateaued in recent years. 

Some evidence has emerged of a change 

in trajectory for the eastern population 

since 2014, but as of 2020, statistical 

support for such a change was 

insufficient (Thogmartin et al. 2020, 

entire). More recently, an analysis of 

overwintering data for the eastern 

population estimated a median annual 

rate of growth of 0.93 (0.67–1.30, 95- 

percent confidence interval (CI)). These 

results indicate that the population is 

declining, even when assuming 

relatively stable land use and landcover 

change relative to the conditions that 

had driven steeper population declines 

in previous decades (Thogmartin 2024, 

entire). 

Other published analyses estimate 

monarch population growth rates and 

persistence/extinction risks using 

alternative models and different data 

sets. These include non-overwintering 

population data, different time-series of 

annual population estimates, different 

modeling assumptions about densitydependence, and different relationships 

between population size and growth 

(i.e., increased density of monarchs will 

result in decreased population growth 

and decreased density of monarchs will 

result in increased population growth). 

One recent analysis (Meehan and 

Crossley 2023, entire) used a variable 

change model to characterize the trend 

in eastern North American monarch 

abundance, suggesting that the monarch 

population has rebounded after a period 

of decline, thereby leading to a 

markedly lower risk of extinction 

relative to other assessments (e.g., 

Semmens et al. 2016, entire; Schultz et 

al. 2017, entire; Thogmartin 2024, 

entire), including our SSA analyses. 

Meehan and Crossley (2023, entire) 

assume density dependence, which 

constrains the uncertainty associated 

with the predicted abundance estimates 

(small populations recover faster under 

density-dependent assumptions than 

density-independent assumptions). 

Though their density dependent model 

provides a good fit for the 10-year 

dataset they analyzed, the models 

cannot identify the mechanism behind 

the apparent decline in growth rate as 

populations increase. The assessment by 

Meehan and Crossley (2023, entire) did 

not incorporate the impacts of changing 

future conditions. 


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Another analysis that also did not 

incorporate the impacts of changing 

future conditions assumes the 

variability in the population numbers is 

now driven by environmental and 

demographic stochasticity (Thogmartin 

2024, entire). This approach is more 

conservative because it results in 

increased variability at small 

populations sizes, as compared to the 

assumption of density dependence 

(which assumes increased per capita 

growth when populations are small). In 

this modeling approach, when 

population abundance has been reduced 

to a low level, demographic and 

environmental stochasticity alone (and 

not necessarily a declining trend) are 

now the driving factors, resulting in an 

increased risk of extinction. After 

careful examination, our estimates in 

the SSA for the annual rate of growth, 

population viability, and extinction risk 

continue to be in line with the best 

available information. 

Comment 4: One reviewer of a later 

version of the SSA asked for additional 

clarification on why the model for 

monarch butterfly extinction was not rerun with updated data that had been 

collected since the first version of the 

SSA. 

Our response: Based on our previous 

sensitivity testing of the model 

presented in the SSA, updated values 

would not significantly change the 

output and results, and thus would not 

change the outcomes in our report. 

Therefore, instead of rerunning the 

model, we instead prioritized evaluating 

new literature and information that 

might have changed the SSA analyses 

and conclusions. We provide further 

clarification and explanation in the 

updated SSA report (Service 2024a, p. 

149). 

Comment 5: One reviewer commented 

that nonmigratory monarch butterflies 

might persist, even if the migratory 

monarchs were to become extirpated. 

The reviewer also suggested that one 

potential reason for the declines in 

migratory individuals in the West could 

be due to a shift to more individuals 

existing in nonmigratory populations 

during winter. 

Our response: According to recent 

research, the resident (nonmigratory) 

population in California is not sufficient 

to make up for the loss of the migratory 

population in western North America; 

there are still orders of magnitude fewer 

butterflies now than in the recent past 

(Crone and Schultz 2021, p. 1535). Also, 

the resident population probably lacks 

the demographic capacity to expand its 

range inland during summer months. 

Resident populations of monarch 

butterflies build up high levels of a 

protozoan parasite, Ophryocystis 

elektroscirrha (OE), at least in part due 

to the absence of migratory culling and 

migratory escape (Satterfield et al. 2015, 

pp. 4–5). In California, about 8 percent 

of migratory monarch butterflies are 

infected with OE, compared to about 75 

percent of residents (Satterfield et al. 

2016, p. 346). Similarly, for the eastern 

North American population, less than 

10 percent of migratory monarch 

butterflies are infected with OE, 

compared to 75–100 percent of 

nonmigratory monarchs in Florida 

(Altizer and de Roode 2015, p. 91). OEinfected monarch butterflies experience 

lower survival, lower egg-laying rates, 

and produce about 0.8 adult daughters 

per female (Crone and Schultz 2021, 

Supplement S4). This rate of increase is 

enough for resident monarch butterfly 

populations to persist in urban areas, 

but it does not provide the ability to 

rapidly colonize the other Western 

States (Crone and Schultz 2021, p. 

1536). We acknowledge alternative 

overwintering strategies, including 

nonmigratory monarchs, in the 

uncertainties section of the SSA report 

(Service 2024a, pp. 70–76). 

I. Proposed Listing Determination 

Background 

A thorough review of the taxonomy, 

life history, and ecology of the monarch 

butterfly (Danaus plexippus; referred to 

as ‘‘monarch’’ or ‘‘monarch butterfly’’ 

herein) is presented in the SSA report 

version 2.3 (Service 2024a, entire). 

The monarch is a brightly colored 

butterfly species, native to North 

America, with a range that has 

expanded west via human assistance to 

many islands in the Pacific Ocean and 

to the east to the Iberian Peninsula to 

now occupy 90 countries, islands, and 

island groups. Despite the expansion, 

over 90 percent of monarchs worldwide 

continue to live and migrate in their 

native range in North America. The 

species requires habitat with milkweed 

(genus Asclepias or closely related 

genera) as a larval host plant and floral 

nectar sources for adults. Migratory 

monarchs in North America also use 

overwintering habitat, where the adults 

cluster on trees. 

Adult monarch butterflies are large 

and conspicuous, with bright-orange 

wings surrounded by a black border and 

covered with black veins. The black 

border has a double row of white spots, 

present on the upper side and lower 

side of forewings and hindwings 

(Bouseman and Sternburg 2001, p. 222). 

Adult monarchs are sexually dimorphic, 

with males having narrower wing 

venation and scent patches 

(Commission for Environmental 

Cooperation (CEC) 2008, p. 11). The 

monarch butterfly has bright and 

contrasting coloration, which serves as 

a warning to predators that eating them 

can be toxic. 

The migratory North American 

populations are located east and west of 

the Rocky Mountains and overwinter 

primarily at sites with specific 

microhabitats in central Mexico and 

California, respectively. In central 

Mexico, the species primarily 

overwinters in mountainous regions 

where the monarchs form dense clusters 

mainly on oyamel fir trees (Abies 

religiosa). Western monarchs spend the 

fall and winter at tree groves along the 

California coast, northern Baja 

California, Mexico, and at a few inland 

sites in the Saline Valley of California. 

These groves are populated by a variety 

of tree species, including blue gum 

eucalyptus (Eucalyptus globulus), 

Monterey pine (Pinus radiata), 

Monterey cypress (Cupressus 

macrocarpa), and others. The 

overwintering sites for both the eastern 

and western North American migratory 

monarch populations provide protection 

from the elements and a microhabitat 

conducive for winter survival. In 

contrast, monarchs in habitats with 

suitable winter climates (e.g., some 

areas in California and Florida) may 

breed year-round without migrating. 

During the breeding season for 

monarchs, adults lay their eggs on 

milkweed, and larvae emerge after 2 to 

5 days (Zalucki 1982, p. 242; CEC 2008, 

p. 12). Larvae develop through five 

larval instars (intervals between molts) 

over a period of 9 to 18 days, feeding 

on milkweed and sequestering toxic 

cardenolides as a defense against 

predators (Parsons 1965, p. 299). The 

larva then pupates into a chrysalis 

before eclosing 6 to 14 days later as an 

adult butterfly. Monarchs produce 

multiple generations during the 

breeding season, with most adult 

butterflies living approximately 2 to 5 

weeks; however, migrating and 

overwintering adults enter into 

reproductive diapause (suspended 

reproduction) and live 6 to 9 months 

(Cockrell et al. 1993, pp. 245–246; 

Herman and Tatar 2001, p. 2509). 

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 (CFR) set forth the 

procedures for determining whether a 

species is an endangered species or a 

threatened species, issuing protective 


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regulations for threatened species, and 

designating critical habitat for 

endangered and threatened species. 

The Act defines an ‘‘endangered 

species’’ as a species that is in danger 

of extinction throughout all or a 

significant portion of its range, and a 

‘‘threatened species’’ as a species that is 

likely to become an endangered species 

within the foreseeable future throughout 

all or a significant portion of its range. 

The Act requires that we determine 

whether any species is an endangered 

species or a threatened species because 

of any of the following factors: 

(A) The present or threatened 

destruction, modification, or 

curtailment of its habitat or range; 

(B) Overutilization for commercial, 

recreational, scientific, or educational 

purposes; 

(C) Disease or predation; 

(D) The inadequacy of existing 

regulatory mechanisms; or 

(E) Other natural or manmade factors 

affecting its continued existence. 

These factors represent broad 

categories of natural or human-caused 

actions or conditions that could have an 

effect on a species’ continued existence. 

In evaluating these actions and 

conditions, we look for those that may 

have a negative effect on individuals of 

the species, as well as other actions or 

conditions that may ameliorate any 

negative effects or may have positive 

effects. 

We use the term ‘‘threat’’ to refer in 

general to actions or conditions that are 

known to or are reasonably likely to 

negatively affect individuals of a 

species. The term ‘‘threat’’ includes 

actions or conditions that have a direct 

impact on individuals (direct impacts), 

as well as those that affect individuals 

through alteration of their habitat or 

required resources (stressors). The term 

‘‘threat’’ may encompass—either 

together or separately—the source of the 

action or condition or the action or 

condition itself. 

However, the mere identification of 

any threat(s) does not necessarily mean 

that the species meets the statutory 

definition of an ‘‘endangered species’’ or 

a ‘‘threatened species.’’ In determining 

whether a species meets either 

definition, we must evaluate all 

identified threats by considering the 

species’ expected response and the 

effects of the threats—in light of those 

actions and conditions that will 

ameliorate the threats—on an 

individual, population, and species 

level. We evaluate each threat and its 

expected effects on the species, then 

analyze the cumulative effect of all of 

the threats on the species as a whole. 

We also consider the cumulative effect 

of the threats in light of those actions 

and conditions that will have positive 

effects on the species, such as any 

existing regulatory mechanisms or 

conservation efforts. The Secretary 

determines whether the species meets 

the definition of an ‘‘endangered 

species’’ or a ‘‘threatened species’’ only 

after conducting this cumulative 

analysis and describing the expected 

effect on the species. 

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, which is 

further described in the 2009 

Memorandum Opinion on the 

foreseeable future from the Department 

of the Interior, Office of the Solicitor 

(M–37021, January 16, 2009; ‘‘MOpinion,’’ available online at https://

www.doi.gov/sites/ 

doi.opengov.ibmcloud.com/files/ 

uploads/M-37021.pdf). The foreseeable 

future extends as far into the future as 

the U.S. Fish and Wildlife Service and 

National Marine Fisheries Service 

(hereafter, the Services) can make 

reasonably reliable predictions about 

the threats to the species and the 

species’ responses to those threats. We 

need not identify the foreseeable future 

in terms of a specific period of time. We 

will describe the foreseeable future on a 

case-by-case basis, using the best 

available data and taking into account 

considerations such as the species’ lifehistory characteristics, threat projection 

timeframes, and environmental 

variability. In other words, the 

foreseeable future is the period of time 

over which we can make reasonably 

reliable predictions. ‘‘Reliable’’ does not 

mean ‘‘certain’’; it means sufficient to 

provide a reasonable degree of 

confidence in the prediction, in light of 

the conservation purposes of the Act. 

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 species, 

including an assessment of the potential 

threats to the species. The SSA report 

does not represent our decision on 

whether the species should be proposed 

for listing 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 monarch butterfly 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 the species to withstand 

environmental and demographic 

stochasticity (for example, wet or dry, 

warm or cold years); redundancy is the 

ability of the species to withstand 

catastrophic events (for example, 

droughts, large pollution events); and 

representation is the ability of the 

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 species’ 

ecological requirements for survival and 

reproduction at the individual, 

population, and species levels, and 

described the beneficial and risk factors 

influencing the species’ viability. 

The SSA process can be categorized 

into three sequential stages. During the 

first stage, we evaluated the individual 

species’ life-history needs. The next 

stage involved an assessment of the 

historical and current condition of the 

species’ demographics and habitat 

characteristics, including an 

explanation of how the species arrived 

at its current condition. The final stage 

of the SSA involved making predictions 

about the species’ responses to positive 

and negative environmental and 

anthropogenic influences. Throughout 

all of these stages, we used the best 

available information to characterize 

viability as the ability of a species to 

sustain populations in the wild over 

time, which we then used 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 FWS–R3–ES–2024–0137 on 

https://www.regulations.gov. 

Summary of Biological Status and 

Threats 

In this discussion, we review the 

biological condition of the species and 

its resources, and the threats that 

influence the species’ current and future 

condition, in order to assess the species’ 

overall viability and the risks to that 

viability. 

Species Needs 

Individual-Level Ecology 

The monarch life cycle varies by 

geographic location. Migratory 

monarchs in North America are the 


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ancestral population for all other 

monarch populations (Pierce et al. 2014, 

p. 4; Zhan et al. 2014, p. 318; Hemstrom 

et al. 2022, pp. 4551–4552), which 

dispersed from North America via 

human assistance, potentially aided 

through wind dispersal events (Brower 

1995, p. 354), and now occur in Central 

and South America; Australia; New 

Zealand; islands of the Pacific and 

Caribbean, and elsewhere (Malcolm and 

Zalucki 1993, pp. 3–5) where milkweed 

(their larval host plant) was already 

present or introduced. In a few parts of 

North America (such as parts of Florida, 

the Gulf Coast, and California) and in 

most areas outside North America, 

monarchs breed year-round, repeatedly 

following the above-referenced life cycle 

throughout the year. However, 

monarchs in temperate climates such as 

eastern and western North America 

undergo long-distance migration, where 

the migratory generation of adults is in 

reproductive diapause and lives for an 

extended period of time (Herman and 

Tatar 2001, p. 2509). 

In the fall, in both eastern and 

western North America, monarchs begin 

migrating to their respective 

overwintering sites. This migration can 

take monarchs distances of over 2,000 

miles (mi) (3,000 kilometers (km)) 

(Urquhart and Urquhart 1978, p. 1760) 

and last for over 2 months (Brower 

1996, p. 93). The vast majority of 

migratory individuals in eastern North 

America fly south or southwest to 

mountainous overwintering grounds in 

central Mexico, although some minor 

alternative migratory routes have also 

been suggested (Dockx et al. 2023, p. 

314). Migratory individuals in western 

North America generally fly shorter 

distances south and west to 

overwintering groves along the 

California coast into northern Baja 

California (Solensky 2004, p. 79). Data 

from monarchs tagged in the 

southwestern States in the fall suggest 

that those in Nevada migrate to 

California, those in New Mexico migrate 

to Mexico, and those in Arizona migrate 

to either Mexico or California 

(Southwest Monarch Study Inc. 2018, 

unpaginated). In early spring (February– 

March), surviving monarchs break 

diapause and mate at the overwintering 

sites before dispersing (Leong et al. 

1995, p. 46; van Hook 1996, pp. 16–17). 

The same individuals that undertook 

the initial southward migration begin 

flying back through the breeding 

grounds, and their offspring start the 

cycle of generational migration over 

again (Malcolm et al. 1993, p. 262). 

The spring monarch migrations in 

eastern and western North America 

represent massive annual range 

expansions. In eastern North America, 

monarchs travel north in the spring, 

from Mexico to Canada, over two to 

three successive generations, breeding 

along the way (Flockhart et al. 2013, pp. 

4–5). Individual monarchs may disperse 

as far north as they can physiologically 

tolerate based on climatic conditions 

and available vegetation; the most 

specific predictors of the northern 

distribution of individual monarchs are 

monthly mean temperature and 

precipitation (Flockhart et al. 2013, p. 4; 

Flockhart et al. 2017, p. 2570). The 

number of generations of monarchs 

produced in a given year in a migratory 

population can vary between three and 

five and is dependent upon 

environmental conditions (Brower 1996, 

p. 100). While a majority of the eastern 

monarchs shift to the more northern 

reaches of their range, western 

monarchs continue to occupy and breed 

in warmer climates throughout the 

summer, while also expanding to 

include the farther reaches of their 

range. In the spring in western North 

America, monarchs migrate north and 

east over multiple generations from 

coastal California toward the Rockies 

and to the Pacific Northwest (Urquhart 

and Urquhart 1977, p. 1585; Nagano et 

al. 1993, entire). In the southwestern 

States, migrating monarchs tend to 

occur more frequently near water 

sources such as rivers, creeks, roadside 

ditches, and irrigated gardens (Morris et 

al. 2015, p. 100). 

In addition to the monarchs that 

overwinter by clustering at known 

overwintering roost sites, some 

monarchs in North America also breed 

year-round or breed throughout the 

winter. These individuals require the 

breeding habitat and suitable climate 

(table 1) and are discussed further in 

Species-Level Ecology, below. 

To facilitate the massive annual 

spring range expansion, adult monarch 

butterflies require a diversity of 

blooming nectar resources, which they 

feed on both throughout their migration 

routes and in their breeding grounds 

(spring through fall). Monarchs also 

need milkweed (for both oviposition 

and larval feeding) embedded within 

this diverse nectaring habitat. The 

correct phenology, or timing, of both 

monarchs and nectar plants and 

milkweed is important for monarch 

survival. The position of these resources 

on the landscape is important as well 

(see Population-Level Ecology, below). 

In western North America, nectar and 

milkweed resources are often associated 

with riparian corridors, and milkweed 

may function as the principal nectar 

source for monarchs in more arid 

regions (Dingle et al. 2005, p. 494; 

Pelton et al. 2018, p. 18; Waterbury and 

Potter 2018, p. 38; Dilts et al. 2018, p. 

8). Individuals need nectar and 

milkweed resources year-round in 

nonmigratory populations. 

Additionally, many monarchs use a 

variety of roosting trees along the fall 

migration route (table 1). 

Migratory individuals of eastern and 

western North America require a 

specific microclimate at overwintering 

sites. The eastern population of 

monarchs overwinter in Mexico, where 

this microclimate is provided by forests 

primarily composed of oyamel fir trees, 

on which the monarchs form dense 

clusters (Williams and Brower 2015, pp. 

109–110). These cluster formations 

provide a buffer for individuals against 

freezing temperatures, lipid depletion, 

and desiccation (Brower et al. 2008, p. 

186). The sites used for overwintering 

primarily occur in mountainous areas 

west of Mexico City located between 

elevations of 9,500 feet (ft) (2,900 meters 

(m)) and 10,800 ft (3,300 m) (Slayback 

and Brower 2007, p. 147). The 

temperature must remain cool enough to 

prevent excessive lipid depletion 

(Alonso-Mejı ́a et al. 1997, p. 935), while 

at the same time staying warm enough 

to prevent freezing (Anderson and 

Brower 1996, pp. 111–113). Exposure to 

these cooler temperatures also helps 

orient the monarchs northward in the 

spring (Guerra and Reppert 2013, pp. 

421–422). The oyamel fir forest provides 

essential protection from the elements, 

including rain, snow, wind, hail, and 

excessive solar radiation (Williams and 

Brower 2015, p. 109). Many sites also 

provide a source of hydration via nectar 

plants or a water source (Brower et al. 

1977, pp. 237–238). Most of the 

observed overwintering sites are located 

within the Monarch Butterfly Biosphere 

Reserve, which covers more than 

138,000 acres (ac) (56,000 hectares (ha)) 

(Vidal and Rendo ́n-Salinas 2014, p. 169; 

Ramı ́rez et al. 2015, p. 158). 

Migratory monarchs in the western 

population primarily overwinter in 

groves along the coast of California and 

Baja California (Jepsen and Black 2015, 

p. 149). The location and structure of 

these sites provide the specific 

microclimate (although different from 

the Mexico overwintering microclimate) 

needed for survival in the western 

overwintering areas. Approximately 400 

groves have been known to be occupied, 

but only a portion of these sites is 

occupied in any given year. These sites, 

typically close to the coast, span 

approximately 761 mi (1,225 km) of 

coastline (COSEWIC 2010, p. 10). These 

groves are populated by a variety of tree 

species, including blue gum eucalyptus, 

Monterey pine, and Monterey cypress 


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(Griffiths and Villablanca 2015, pp. 41, 

46–47), all of which act as roost trees. 

These groves provide indirect sunlight 

for the overwintering monarchs, sources 

of moisture for hydration, defense 

against freezing temperatures, and 

protection against strong winds (Tuskes 

and Brower 1978, p. 149; Leong 1990, 

pp. 908–910, Leong 1999, p. 213). The 

close proximity to the coast (average 

distance of 1.47 mi (2.37 km)) also 

provides a mild winter climate (Leong et 

al. 2004, p. 180). 

TABLE 1—INDIVIDUAL-LEVEL REQUISITES FOR MONARCH SURVIVAL AND REPRODUCTION

Life stage Requirements Description 

Egg, larva, and adult— 

breeding.

Milkweed resources ........... Healthy and abundant milkweed is needed for oviposition and larval consumption. 

Adult—breeding and migration.Nectar resources ................ Sufficient quality and quantity of nectar from flowers is needed for adult feeding 

throughout the breeding and migration seasons. 

Adult—overwintering ............ Suitable habitat for overwintering.Habitat that provides a specific roosting microclimate for overwintering: protection 

from the elements (e.g., rain, wind, hail, excessive radiation) and moderate temperatures that are warm enough to prevent freezing yet cool enough to prevent 

lipid depletion. Nectar and clean water sources located near roosting sites. 

Adult—migration ................... Connectivity and phenology Nectar and milkweed resources along the migration route when butterflies are 

present; the size and spatial arrangement of habitat patches are generally 

thought to be important aspects, but currently unknown. Roosting sites may also 

be important for monarchs along their fall migration route. 

Population-Level Ecology 

Monarchs, like many insects, are 

sensitive to environmental conditions 

(temperature and precipitation) and can 

experience large swings in population 

numbers from year to year in response 

to these conditions (Rendo ́n-Salinas et 

al. 2015, p. 3; Schultz et al. 2017, pp. 

345–346). During favorable conditions, 

monarch survival and reproductive rates 

are high and population numbers 

increase; conversely, when 

environmental conditions are 

unfavorable, survival and reproductive 

rates are low and population numbers 

can plummet. Thus, to successfully 

recruit over generations and years, they 

must be capable of withstanding large 

swings in population sizes (N). 

Specifically, they need a positive 

population growth rate (lambda, or l) 

that is sufficient for the species to 

recover from annual stochasticity. 

To support a strong growth rate, 

monarch populations require 

sufficiently large population sizes and 

an adequate quantity and quality of 

habitat to support these large population 

sizes. Large population sizes also help 

maintain genetic health and facilitate 

thermoregulation during the winter, 

which is important for good physical 

health. A sufficiently large population 

size may also be important for finding 

mates and repelling predators (Malcolm 

2018, pers. comm.). Both migratory and 

breeding habitat need to be distributed 

throughout the landscape to ensure 

connectivity, allowing monarchs within 

a population to reach all portions of 

their range and to maximize lifetime 

fecundity (Zalucki and Lammers 2010, 

p. 84; Miller et al. 2012, p. 2). 

Species-Level Ecology 

The ecological requisites at the 

species level include having a sufficient 

number and distribution of healthy 

populations to ensure the species can 

withstand annual variation in its 

environment (resiliency), catastrophes 

(redundancy), and novel biological and 

physical changes in its environment 

(representation). We describe the 

monarch’s requirements for resiliency, 

redundancy, and representation below. 

Resiliency 

Monarch populations with a robust 

growth rate, large effective population 

size, and suitable quality, quantity, and 

distribution of habitat conditions are 

better able to withstand and recover 

from environmental variability and 

stochastic perturbations (e.g., storms, 

dry years) than those populations that 

are less demographically, genetically, or 

physically healthy. Given the monarch’s 

sensitivity to environmental conditions, 

which can cause large swings in 

population numbers year-to-year 

(Rendo ́n-Salinas et al. 2015, p. 3), 

monarchs occupying a diversity of 

environmental conditions and being 

widely distributed helps guard against 

populations being exposed to adverse 

conditions concurrently, and thus, 

fluctuating in synchrony. Asynchronous 

dynamics within and among 

populations minimizes the chances of 

concurrent losses, and thus, provides 

species resiliency. 

Redundancy 

Monarch redundancy is best achieved 

by having a broad geographic 

distribution of monarchs relative to the 

spatial occurrence of catastrophic 

events. For the eastern North American 

migratory population, potential 

catastrophic events include extreme 

storms when monarchs are densely 

congregated and widespread drought. 

For the western North American 

migratory population, potential 

catastrophic events include widespread 

drought and co-occurrence of poor 

environmental conditions and low 

population abundance. For dispersed 

non-migratory populations, potentially 

catastrophic events include sea level 

rise, which can inundate habitat, and 

lethal high temperatures. 

Migratory North American monarchs 

are distributed across vast and diverse 

habitats across much of North America 

during their breeding and migratory 

seasons. However, while overwintering, 

most migratory monarchs are highly 

concentrated at sites in Mexico and 

California. Nonmigratory monarchs in 

North America are distributed in 

warmer, suitable areas throughout the 

year, including in parts of Florida, the 

Gulf Coast, and California. A very small 

proportion of the species is also 

distributed in nonnative or naturalized 

populations across diverse habitats 

throughout 90 countries, islands, and 

island groups. 

Representation 

The monarch’s ability to withstand 

novel changes in its environment is 

influenced by its adaptive capacity, 

which is primarily a function of the 

species’ breadth of variation in 

biological traits and genetic diversity. 

Without such variation, species are less 

responsive to change and more prone to 

extinction (Spielman et al. 2004, p. 

15263). Additionally, as populations 

with higher genetic diversity can more 

quickly adapt to novel changes, species 

with genetically healthy populations are 

better able to adapt (Ofori et al. 2017, p. 


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2). Below we describe monarch adaptive 

capacity by using the best available 

data. 

Migratory monarchs in North America 

are the ancestral population for all other 

monarch populations around the world 

(Pierce et al. 2014, p. 4; Zhan et al. 2014, 

p. 318; Hemstrom et al. 2022, pp. 4551– 

4552). Their unique genetics separate 

them from nonmigratory monarchs 

(Freedman et al. 2021, p. 7). Genetic 

sampling indicates that the monarchs 

from eastern and western North 

America have continued interchange 

between the two populations 

contributing to low genetic 

differentiation (Talla et al. 2020, p. 

2573; Freedman et al. 2021, pp. 7–8). 

During the annual breeding season, the 

North American migratory populations 

use a vast and diverse array of habitats. 

Following a long-distance migration 

through more varied habitats and 

conditions, the North American 

migratory monarchs use sites with a 

diversity of physical structures and 

climatic conditions for overwintering. 

Having monarchs occupying areas of 

unique ecological diversity guards 

against losses of adaptive capacity due 

to stochastic or catastrophic events. 

Nonmigratory monarchs represent a lifehistory strategy that exposes them to 

selection pressures that differ from 

migratory monarchs. 

Eastern North American monarchs 

undergo long-distance migration every 

fall, a behavior that differentiates this 

population from nonmigratory 

populations or from migratory 

populations that fly shorter distances 

and to different locations. The migratory 

phenotype of monarchs in the eastern 

migratory population is distinct from 

monarchs in other populations that may 

have latent migratory phenotypes 

(Tenger-Trolander et al. 2019, p. 14673). 

This migratory phenotype consists of 

both reproductive diapause and 

directional flight orientation to the 

south, and this migratory behavior of 

monarchs is remarkably sensitive to 

genetic and environmental change 

(Tenger-Trolander et al. 2019, p. 14673). 

Monarchs from the eastern North 

American migratory population tend to 

have larger bodies and larger elongated 

wings compared to monarchs from most 

nonmigratory populations (Altizer and 

Davis 2010, pp. 1023–1025). Eastern 

North American migratory monarchs 

inhabit 70 percent or more of the total 

area occupied by monarch butterflies in 

North America. 

Western North American monarchs 

also migrate long distances, although 

their migration is shorter than monarchs 

in eastern North America. Whereas 

eastern monarchs may fly well over 

2,000 mi (3,000 km) to reach the 

Mexican overwintering sites, western 

monarchs reach the California coast by 

flying approximately 300 mi to 1,000 mi 

(500 km to 1,600 km) (Yang et al. 2016, 

p. 1002; Edwards et al. 2023, p. 5). 

Western monarchs occupy warmer 

climates throughout the summer to 

include the farther reaches of their range 

while they continue to breed in the 

hotter regions (expand their range). 

Eastern monarchs, in contrast, follow 

more of a stepping-stone path into the 

northern States, vacating areas as they 

warm and recolonizing their range. 

Western North American migratory 

monarchs occupy as much as 30 percent 

of the total area occupied by monarch 

butterflies in North America (Dilts et al. 

2019, p. 11). Western monarchs use 

ecologically different breeding, 

migrating, and overwintering habitats 

(Brower et al. 1995, p. 542) compared to 

monarchs in eastern North America. 

Differences in breeding habitat include 

climate (Zalucki and Rochester 2004, 

pp. 220–221) and availability and 

abundance of native nectar and native 

milkweed plants (Borders and LeeMa ̈der 2015, entire). The West is 

generally hotter and drier than the East, 

and the milkweed and nectar resources 

used by monarchs in the West and East 

differ (Dilts et al. 2019, entire). In the 

fall, western monarchs migrate from 

Canada and States west of the Rockies 

to overwintering groves located 

primarily along the California coast 

south into Baja California, Mexico 

(Jepsen and Black 2015, pp. 147–156). 

Roosting tree species used by western 

monarchs for overwintering are different 

than those used by the eastern 

population and include blue gum 

eucalyptus, Monterey pine, and 

Monterey cypress (Griffiths and 

Villablanca 2015, pp. 43–44). The 

western population has fewer monarchs, 

spread out among hundreds of 

overwintering sites compared to fewer 

than 20 sites in Mexico for the eastern 

population (Jepsen and Black 2015, pp. 

147–156; Vidal and Rendo ́n-Salinas 

2014, entire). 

Migratory monarchs in eastern and 

western North America may also 

contribute unique phenotypic variation 

in wing morphology/coloration, lipid 

reserves, and reproductive behavior 

(Talla et al. 2020, pp. 2572–2573; 

Freedman and Dingle 2018, p. 66; Davis 

2009, p. 3; Brower et al. 1995, p. 542; 

Herman et al. 1989, pp. 52–54; 56–57). 

Compared to monarchs in western 

North America and to nonmigratory 

monarchs in southern Florida, eastern 

North American monarchs have lower 

rates of infection by the protozoan 

parasite OE (<10 percent; Altizer et al. 

2000, p. 131), which may be due in part 

to their long-distance migration (Bartel 

et al. 2011, p. 348). Migratory monarchs 

in the West have OE infection rates 

(averaging 5–30 percent) that are lower 

than most nonmigratory populations but 

higher than the rates of infection in 

migratory monarchs in eastern North 

America (Altizer and de Roode 2015, p. 

91). 

Resident (nonmigratory) monarchs in 

North America now live in areas where 

milkweed availability and climate 

permit year-round breeding, and thus 

are able to reside continually without 

migrating. These nonmigratory 

monarchs in southern Florida are 

genetically distinct from the migratory 

North American monarchs, although the 

southern Florida population gets an 

annual influx of individuals from the 

eastern migratory monarch population 

(Knight and Brower 2009, p. 821; Zhan 

et al. 2014, p. 322). Also, some 

monarchs remain or become 

reproductively active and breed 

throughout the winter along the Gulf 

Coast, the southern Atlantic Coast, and 

the southern Pacific Coast (Howard et 

al. 2010, p. 3; Satterfield et al. 2016, p. 

346). These monarchs are more likely to 

be infected with OE (Satterfield et al. 

2016, p. 347; 2018, p. 1676), and there 

is some question of whether some of the 

offspring of these individuals might 

emerge in diapause and continue to 

Mexico or California overwintering sites 

later in the season (Batalden and 

Oberhauser 2015, p. 223). The best 

available information, including the 

quantity and quality of the habitat, 

indicates that the total number of 

resident monarchs appears to be quite 

small relative to the North American 

migratory populations that overwinter 

in Mexico and California. Some experts 

consider the resident monarch 

populations demographic sinks (see 

Crone and Schultz 2021, p. 1536), 

requiring continual influxes of 

monarchs from migratory populations to 

sustain them. 

Nonmigratory Florida monarchs 

experience some of the highest recorded 

OE infection rates compared to other 

monarchs worldwide and particularly 

high rates compared to migratory 

eastern and western North America 

monarch infection rates (75–100 percent 

average infection rates in Florida vs. 5– 

30 percent infection rates in the western 

North American population and less 

than 10 percent infection rates in the 

eastern North American population; 

Altizer and de Roode 2015, p. 91). This 

may be due both to their inability to 

escape infected habitat, as well as the 

nonmigratory behavior not leading to 

any migratory culling (the removal of 


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less fit individuals from a population 

due to their inability to migrate) (Bartel 

et al. 2011, entire). While we assume 

most monarchs found in southern 

Florida are nonmigratory, it is possible 

that some are migratory (Dockx et al. 

2023, pp. 314–317). 

In the West, the population of 

migratory monarchs has declined from 

several million butterflies in the 1980s 

(Schultz et al. 2017, p. 345) to current 

levels (figure 1b). Concurrently in the 

West, a portion of nonmigratory 

monarch butterflies in urban gardens 

has been growing (Crone and Schultz 

2021, entire). The increase in numbers 

of these nonmigratory monarchs do not 

seem to make up for the decline of the 

migratory population (Crone and 

Schultz 2021, entire). Additionally, the 

nonmigratory portion also probably 

lacks the demographic capacity to 

expand its range inland during summer 

months. Nonmigratory monarch 

butterflies build up high levels of OE, at 

least in part because of a lack of 

migratory culling and migratory escape 

(Satterfield et al. 2015, pp. 4–5). In 

California, about 8 percent of migratory 

monarch butterflies are infected with 

OE, compared to about 75 percent of 

nonmigratory individuals (Satterfield et 

al. 2016, p. 346). OE-infected monarch 

butterflies have both lower survival and 

lower egg-laying rates and produce only 

about 0.8 adult daughters per female on 

average (Crone and Schultz 2021, 

Supplement S4). While this rate of 

increase is enough for nonmigratory 

monarch butterflies to persist in urban 

areas, it does not allow them to expand 

to other western States (Crone and 

Schultz 2021, p. 1536). Additional 

information on the genetic structuring of 

monarchs outside of continental North 

America is available in the SSA report 

(Service 2024a, appendix 2). 

In order to better understand the 

population dynamics and contributions 

from the nonmigratory populations, we 

are requesting additional information on 

resident monarchs in southern Florida, 

the Gulf Coast, the southern Atlantic 

Coast, and the southern Pacific Coast. 

To submit information, see the 

Information Requested section. 

Threats 

We have little to no information on 

positive or negative influences acting 

upon monarchs occurring outside of the 

eastern and western North American 

populations. There is limited 

information on predation, parasitism, 

and disease outside of eastern and 

western North American populations. 

Given this limited information, we were 

unable to ascertain to what extent 

predation, parasitism, and disease 

impact the monarch populations outside 

of the eastern and western North 

American populations. Similarly, while 

data suggest global use of insecticides is 

increasing, we are unable to estimate the 

degree of overlap with monarch 

populations and thus derive a credible 

projection of impact on the monarch 

populations outside of the eastern and 

western North American populations. 

The primary drivers affecting the 

health of the two North American 

migratory populations are loss and 

degradation of breeding, migratory, and 

overwintering habitat (from past 

conversion of grasslands and shrublands 

to agriculture and widespread use of 

herbicides; logging/thinning at 

overwintering sites in Mexico; urban 

development, senescence, and 

incompatible management of 

overwintering sites in California; and 

drought); exposure to insecticides; and 

effects of climate change. Many other 

influences to monarchs were evaluated, 

including disease, parasitism, captive 

rearing, collection, impacts of tourism at 

overwintering sites, invasive swallowwort plants, vehicle mortality, and 

natural catastrophes. However, these 

other potential influences were not 

determined to be key population drivers 

(Service 2024a, pp. 109–111). 

Because the conversion of grasslands 

to agriculture was a key driver for past 

population declines, current and future 

activities that may remove milkweed 

and nectar resources within the 

breeding and migratory range, but that 

do not result in conversion of native or 

naturalized grassland, shrubland, or 

forested habitats and do not result in 

significant population-level mortality, 

are, therefore, not considered key 

population drivers. These include 

habitat restoration and management 

activities, livestock grazing and routine 

ranching activities, routine agricultural 

activities and conservation practices, 

fire management, silviculture and forest 

management, management of habitat on 

residential and other developed 

properties, and vegetation management 

activities when monarchs are not 

present. Given that so much milkweed 

has been lost historically and that 

monarchs are impacted by the ongoing 

effects of this past habitat loss and 

degradation, we need an approach that 

encourages landowners to add and 

maintain habitat in order to achieve a 

significant increase in the availability of 

milkweed and nectar resources. We 

expect localized removal of milkweed 

and nectar plants will be outweighed by 

an overall addition of these resources 

across the landscape, making broadscale 

public support for monarch 

conservation vitally important. For 

example, landscape-scale habitat 

restoration and management activities 

that provide for the habitat needs of 

monarch butterflies (e.g., mowing, 

haying native rangeland, prescribed and 

cultural burning, and control of invasive 

plants or noxious weeds) may remove 

milkweed and could result in loss of 

monarchs in the short term but would 

also increase the overall quality and 

quantity of breeding habitat, which is 

likely to benefit monarch populations in 

the long term. We are requesting 

information on both our identified key 

threats as well as other potential threats 

to the species, such as collisions with 

wind turbines (see Information 

Requested). The key influences for 

monarch butterflies are discussed 

below. 

Availability, Distribution, and Quality of 

Breeding Habitat and Migratory Habitat 

The availability of milkweed is 

essential to monarch reproduction and 

survival. Reductions in milkweed are 

cited as a key driver in monarch 

declines (Brower et al. 2012, p. 97; 

Pleasants and Oberhauser 2013, p. 141; 

Inamine et al. 2016, p. 1081; Thogmartin 

et al. 2017a, p. 12; Waterbury and Potter 

2018, pp. 42–44; Saunders et al. 2019, 

p. 8612). 

A majority of the past milkweed loss 

has occurred in agricultural lands, 

where intensive herbicide usage for 

weed control has resulted in widespread 

milkweed eradication. More than 860 

million milkweed stems were lost in the 

Midwest between 1999 and 2014, a 

decline of almost 40 percent (Pleasants 

2017, p. 48). Approximately 89 and 94 

percent of corn and soybean crop 

acreages, respectively, are planted as 

glyphosate (herbicide)-tolerant crops 

(USDA 2018, unpaginated). When 

glyphosate is sprayed in or near fields 

where crops are produced, it kills the 

milkweed without harming the 

glyphosate-tolerant crops. Glyphosate 

use in western agricultural lands has 

also increased dramatically since the 

1990s, especially within the Central 

Valley of California, Snake River Plain 

of Idaho, and the Columbia River Basin, 

which spans the border between 

Washington and Oregon (USGS 

NAWQA 2017, unpaginated; Waterbury 

and Potter 2018, p. 42). As weed species 

develop increasing resistance to 

glyphosate, other herbicide (e.g., 

dicamba)-tolerant crops are developed, 

which can lead to a corresponding 

increase in use of those herbicides. 

Accordingly, herbicide impacts to 

milkweed and nectar plants will 

continue to impact monarch resources 

in agricultural lands. 


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Milkweed has also been lost on the 

landscape through development and 

conversion of grasslands (Lark et al. 

2015, pp. 3–4). Between 2008 and 2016, 

a total of 4.9 million acres of grassland 

were converted to new cropland, 

including up to 3 million acres of 

Conservation Reserve Program land 

(Lark et al. 2015, p. 5). Past loss of 

agricultural milkweeds in the Midwest 

has resulted in an estimated 81 percent 

decline in monarch production, in part 

because monarch egg densities were 

higher on milkweed in agricultural 

fields (3.89 times more eggs than on 

non-agricultural milkweed; Pleasants 

and Oberhauser 2013, pp. 139–140). 

This situation particularly impacts the 

eastern monarch population because 

more Mexico overwintering monarchs 

originate from the Midwest crop belt 

region than any other region (with 

estimates ranging from 38 percent to 

over 85 percent of all overwintering 

monarchs originating from the Midwest; 

Wassenaar and Hobson 1998, pp. 

15438–15439; Flockhart et al. 2017, p. 

2568). Development and conversion of 

grasslands will continue to impact 

monarch resources in agricultural lands. 

Losses of nectar sources have also 

been implicated as a potential key 

driver in monarch declines (Inamine et 

al. 2016, p. 1081; Thogmartin et al. 

2017a, p. 12; Saunders et al. 2019, p. 

8612). Losses of nectar resources are due 

to the same stressors identified above 

for milkweed resources. Additionally, 

with a warming climate, drought 

impacts may affect the availability of 

nectar sources, especially in the western 

population and in the migratory 

bottleneck through Mexico and into 

Texas for the eastern population (see 

Climate Change Effects, below). 

Our future analyses forecast a range of 

projections for future nectar and 

milkweed throughout the monarch 

butterfly’s range. While these breeding 

and migratory habitat resources show 

signs of regional stabilization or 

increase, even the best case scenario 

increases are less than the amount of 

milkweed and nectar resources that 

have been lost. The reduced amount of 

breeding and migratory habitat 

continues to negatively impact the 

viability of the migratory North 

American monarchs. Monarch 

conservation needs an approach that 

encourages and incentivizes landowners 

to add milkweeds and nectar resources 

and implement actions to maintain this 

habitat. Unlike with some at-risk 

species, the monarch’s general habitat 

usage and wide distribution allow a 

broad range of landowners to participate 

in actions to support the species. 

Conservation for the species can occur 

on land parcels ranging from quite small 

to very large, including gardens, parks, 

grasslands, agricultural areas, and more. 

Availability, Distribution, and Quality of 

Overwintering Habitat 

Both western and eastern monarchs 

rely on the microclimate provided by 

the trees at their overwintering sites 

(Leong et al. 2004, entire; Williams and 

Brower 2015, entire). Loss of trees 

occurs at overwintering sites in Mexico 

primarily through small- and large-scale 

logging, storms, and an increasingly 

unsuitable climate (see Climate Change 

Effects below). Most overwintering sites 

used by eastern monarchs occur within 

the Monarch Butterfly Biosphere 

Reserve (Reserve), a 139,019-ac (56,259- 

ha) protected area in Central Mexico. 

Within this area, logging is banned 

within the 33,485-ac (13,551-ha) core 

zone (Ramı ́rez et al. 2015, p. 158). 

However, logging has continued to 

occur both legally (including salvage 

logging allowed after storms) and 

illegally at multiple colonies within the 

Reserve (Vidal et al. 2014, pp. 180–185; 

Brower et al. 2016, entire). 

Logging was estimated in the core 

zone of the Reserve from 2002 through 

2012 (Vidal et al. 2014, p. 180). Within 

this period, 5,384 acres (2,179 ha) of 

core zone were either deforested (less 

than 10 percent canopy cover remained; 

3,099 ac (1,254 ha)) or degraded (a 

decrease in canopy cover; 2,286 ac (925 

ha)). Most of these losses were 

attributed to illegal logging (5,083 ac 

(2,057 ha)), with the remaining 301 

acres (122 ha) lost due to floods, 

drought, strong winds, and fire. Current 

estimates of forest loss throughout the 

Reserve vary from 0–2.4 percent per 

year (Ramı ́rez et al. 2015, p. 163). While 

anti-logging and reforestation efforts are 

underway (Lo ́pez-Garcı ́a 2022, p. 245), 

logging is still ongoing within the 

Reserve (Brower et al. 2016, entire). 

Although clearcutting of forests destroys 

habitat directly, thinning of the forest 

also changes the microclimate needed 

by overwintering monarchs, making 

them more susceptible to winter 

mortality (Brower et al. 2011, p. 43). 

Western monarch overwintering 

habitat along the Pacific Coast has been 

subject to loss through various forms of 

development, particularly urban 

development (Sakai and Calvert 1991, p. 

149; Frey and Schaffner 2004, p. 172). 

Since the 1980s, development has 

caused the loss of at least 63 known 

California overwintering sites (Sakai 

and Calvert 1991, pp. 148–49, Meade 

1999, p. 97–100, Xerces Society 2024a, 

unpaginated). Habitat alteration, such as 

through natural tree senescence and 

improper grove management, can also 

alter the microclimate of the western 

overwintering sites, leading to less 

suitable habitat conditions (Jepsen et al. 

2015, p. 17). Many other stressors can 

work alone or in tandem on the western 

overwintering sites, including disease 

and pests that impact the trees used for 

overwintering. Fire is also a threat, both 

indirectly through habitat loss and 

directly to overwintering monarchs 

(Pelton et al. 2016, pp. 28, 32). Drought 

in the West can further exacerbate the 

stressors on the western overwintering 

sites (see Climate Change Effects below). 

Insecticide Exposure 

Insecticides are pesticides with 

chemical properties that are designed to 

kill insects and most are non-specific 

and broad-spectrum in nature. That is, 

insects exposed to these insecticides are 

susceptible to mortality or sublethal 

effects. Furthermore, the larvae of many 

lepidopterans (i.e., insects in the order 

that includes butterflies and moths) are 

considered major pest species, and 

insecticides are tested specifically on 

this taxon to ensure that they will 

effectively kill individuals at 

application rates indicated on product 

labels. Even though monarchs are not 

the target species of these products, they 

may be exposed to insecticides where 

they are applied and in areas beyond the 

insecticide application sites due to drift 

(Olaya-Arenas and Kaplan 2019, p. 1; 

Halsch et al. 2020, p. 3). 

Insecticide impacts to monarchs are 

primarily influenced by the extent to 

which monarchs are exposed to 

insecticides throughout their range. 

Although insecticide use is most often 

associated with agricultural production 

(e.g., between 2005 and 2012, 60 percent 

of insecticides applied occurred on 

agricultural lands; EPA 2017, p. 11), any 

habitat where monarchs are found may 

be subject to insecticide use. 

Insecticides can be used for insect pest 

control anywhere there is a pest 

outbreak or for general pest prevention. 

Homeowners may treat yards and 

gardens to protect plants from pests or 

purchase plants from nurseries that sell 

plants pre-treated or grown from seeds 

treated with insecticides as 

ornamentals. Natural areas, such as 

forests and parks, may be treated to 

control for insects that defoliate, bore 

into wood, or otherwise damage trees. 

Outbreaks of pests, such as spongy 

moths, mosquitoes, Mormon crickets, or 

grasshoppers, may trigger insecticide 

treatments over large areas to control 

populations. Use of insecticides in 

vector control, especially pyrethroids 

and organophosphates, may be 

significant in areas of the country where 

mosquitoes pose a public health threat 


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or reach nuisance levels. The most 

widely used classes of insecticides 

include organophosphates, pyrethroids, 

and neonicotinoids. Studies looking 

specifically at dose-response of 

monarchs to neonicotinoids, 

organophosphates, and pyrethroids have 

demonstrated monarch toxicity at 

product label application rates and field 

concentration levels (e.g., Krischik et al. 

2015, entire; James 2019, entire; 

Krishnan et al. 2020, entire; Bargar et al. 

2020, entire). 

Insecticides are a threat to monarchs 

based on their mode of action to target 

insects and their potential exposure to 

monarchs. Monarchs can be exposed to 

liquid insecticides from direct spray at 

the time of application, contact with 

vegetation contaminated with an 

insecticide, or ingestion of leaves or 

nectar contaminated with insecticide 

following a spray. This exposure can 

occur on the site of application or in 

adjacent areas as a result of insecticide 

drift. Biopesticides, another type of 

insecticide, generally affect only the 

target pest and closely related 

organisms. These products contrast with 

broad-spectrum and conventional 

insecticides that target all insects. The 

primary identified biopesticide 

exposure threat to monarchs is limited 

to the liquid application of certain types 

of Bacillus thuringiensis (Bt) that are 

active against lepidopterans and often 

used to control caterpillar pests (such as 

spongy moth). 

Monarchs may also be exposed to 

insecticides in forms other than liquids, 

such as those that have been 

systemically incorporated into plant 

tissues on which monarchs feed (e.g., 

milkweed leaves, flowers, pollen, and 

nectar) or dust that has drifted off 

treated seeds at the time of planting. 

Numerous types of insecticides may be 

incorporated into plants systemically or 

used to treat seeds, including 

neonicotinoids. However, there are 

limited data to suggest that insecticides 

used in this manner achieve 

concentrations likely to result in 

negative effects to monarchs. Thus, 

while monarchs may be exposed to 

insecticide residues from these 

application methods, the available 

information indicates that negative 

effects from insecticide residues are 

likely minimal. For insecticides applied 

in solid forms such as granules, no 

exposure is expected to monarchs; thus, 

negative effects from application of 

pesticides in solid forms are unlikely. 

Herbicides and fungicides are used 

within or near areas where monarchs 

may be present; however, only a subset 

of these have data showing direct 

negative effects to insects (i.e., as 

opposed to insecticides, where all 

pesticides within this class will cause 

negative effects to insects). As such, the 

information indicates the negative 

effects to monarchs from exposure to 

herbicides and fungicides is likely 

minor compared to the direct effects of 

exposure to insecticides. 

See Appendix 5—Supplementary 

Information About Pesticides in the 

monarch butterfly SSA report (Service 

2024a, pp. 123–146) for further 

discussion of the risk of pesticides to 

the monarch, including data, references, 

and supporting information. 

Climate Change Effects 

Climate change can affect monarchs 

both directly and indirectly (Nail and 

Oberhauser 2015, entire) on 

overwintering, migratory, and breeding 

grounds. Increasing storm frequency in 

the Mexican overwintering colonies can 

lead to catastrophic (up to 80 percent) 

mortality through the freezing 

temperatures that accompany these 

storms (Anderson and Brower 1996, p. 

112; Brower et al. 2004, entire). 

Precipitation is predicted to increase 

during the winter when monarchs are 

present in Mexico (Oberhauser and 

Peterson 2003, p. 14067). Severe 

drought can cause tree loss and 

degradation, decreasing the availability 

and quality of overwintering roosting 

habitat in California as well (Pelton et 

al. 2016, p. 29). Eucalyptus trees, the 

dominant tree species in many of the 

groves, are drought sensitive and 

become vulnerable to infestation by 

insect borers when they are stressed, 

which can exacerbate tree loss in these 

groves (Marcar et al. 1995, p. 46; Paine 

and Millar 2002, p. 148). Eucalyptus 

loss and degradation reduces 

availability of roosting habitat, lessens 

wind protection, and eliminates the 

primary overwintering source of nectar 

at many sites. Other dominant trees, 

such as Monterey pines and Monterey 

cypress, are more resistant to drought, 

but are the primary species in fewer 

than 25 percent of overwintering sites. 

Although overwintering grounds are 

widespread, drought could be equally as 

widespread, such that it could occur 

throughout many or most of the 

overwintering sites simultaneously. 

Given the above, extreme drought at 

overwintering sites poses a catastrophic 

risk for the western monarch 

population. 

Monarchs need a very specific 

microclimate at their overwintering sites 

not just to avoid storm mortality, but 

also to avoid early fat depletion. 

Changing precipitation patterns and 

temperatures may influence the 

microclimate needed by overwintering 

monarchs (Williams and Brower 2015, 

p. 116). For example, current modeling 

of the monarch’s fundamental niche 

predicts the loss of 38.6 to 69.8 percent 

of current suitable habitat within the 

Reserve due primarily to expected 

temperature changes (Zagorski 2016, p. 

17). In western North America, climate 

change is predicted to cause a 

significant change in the distribution of 

overwintering monarchs in coastal 

California (Fisher et al. 2018, p. 10). 

While modeling projections suggest an 

inland and upslope displacement of 

suitable overwintering conditions by the 

year 2050, the best available evidence 

does not indicate that monarchs would 

move to or use these upslope areas 

(Fisher et al. 2018, pp. 10, 13–14). 

In addition to the direct impact of 

climate change on overwintering 

monarchs, the Mexico overwintering 

sites are predicted to be less suitable for 

oyamel fir trees, the predominant 

monarch roosting tree. The 

overwintering sites are predicted to 

become increasingly warm throughout 

the year, potentially making 50 percent 

or more of the sites unsuitable for 

oyamel fir trees in 2030 (Sa ́enz-Romero 

et al. 2012, p. 102; Ramı ́rez et al. 2015, 

p. 167). Widespread drought is similarly 

likely to negatively impact trees in the 

western overwintering areas both 

directly and indirectly due to increased 

susceptibility to pests (Paine and Millar 

2002, p. 148). 

Direct effects of climate change, 

particularly increasing temperatures, 

may impact monarch fecundity 

(reproductive rate) (Oberhauser 1997, 

pp. 168–169), mating success (Solensky 

and Oberhauser 2009, p. 333), and 

survival during migration and while 

overwintering (Masters et al. 1988, 

entire; Alonso-Mejı ́a et al. 1997, entire). 

Laboratory studies indicate optimal 

temperatures for monarch range 

between 81–84 °F (27–29 °C) with 

sublethal effects beginning around 86– 

97 °F (30–36 °C) range and an upper 

lethal thermal limit of 108 °F (42 °C) 

(Zalucki 1982, p. 243; York and 

Oberhauser 2002, p. 294; Zalucki and 

Rochester 2004, p. 225; Nail et al. 2015, 

p. 101). Research also indicates that 

cooler nighttime temperatures provide 

respite from elevated daytime 

temperatures and are important in 

allowing monarchs to survive 

temperature stress (Nail et al. 2015, p. 

104). Temperatures consistently above 

91–95 °F (33–35 °C) are unsuitable for 

monarchs and may account for their 

general absence from the southern U.S. 

after spring (Malcolm et al. 1987, p. 78; 

Zalucki and Rochester 1999, pp. 155– 

157). 


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High temperatures and drought 

conditions may be particularly 

impactful during the crucial spring 

migration (Taylor 2020, pers. comm.). 

Spring temperatures and precipitation 

in the southern U.S. portion of the 

migratory range have been modeled to 

have a high relative importance 

affecting summer population size of 

eastern monarchs (a larger impact than 

compared to summer weather, summer 

herbicide use in cropland, and latewinter population size) (Zylstra et al. 

2021, p. 1443). However, considerable 

uncertainty remains regarding the 

extent, intensity, and biological impacts 

of climate change during spring 

migration (Neupane et al. 2022, pp. 10– 

14). While increased temperatures may 

reduce monarch habitat in some areas, 

the climatically suitable niche for 

monarchs may increase northward, 

potentially increasing their summer 

breeding grounds if both monarchs and 

milkweed are able to adapt and track 

this niche northward (Lemoine 2015, 

pp. 10–17). 

A warming climate may influence 

breeding habitat by altering suitable 

locations for both monarchs (Batalden et 

al. 2007, pp. 1369–1370) and their 

milkweed host plant (Lemoine 2015, 

entire). Nectar resources during 

migration may be reduced under climate 

conditions (decreased precipitation) 

projected for south-central Texas 

(Saunders et al. 2019, p. 8612). Drought 

may also influence the amount and 

availability of nectar needed for 

migrating butterflies (Brower et al. 2015, 

entire; Stevens and Frey 2010, p. 740; 

Espeset et al. 2016, p. 826). Widespread 

drought caused by climate change is 

expected to increase into the future 

(IPCC 2023, p. 69) negatively impacting 

monarchs and their habitat. 

Sea level rise is increasing due to 

climate change. These rising sea levels 

are likely to impact monarch 

populations in coastal areas (e.g., along 

the Gulf Coast) and low lying islands 

through loss of habitat (TBCSAP 2015, 

entire; IPCC 2023, p. 69). 

Climate change may additionally 

impact monarchs in ways that are more 

difficult to measure. This may include 

phenological mismatch (e.g., timing of 

milkweed and nectar sources not 

aligning with monarch migration; 

Thogmartin et al. 2017a, p. 13) or range 

mismatch with associated species. For 

example, a change in environmental 

suitability could cause a range shift for 

monarch predators and parasitoids, 

increasing or decreasing their overlap 

with the monarch’s range (McCoshum et 

al. 2016, p. 229–233). 

Conservation Efforts and Regulatory 

Mechanisms 

While many factors have been 

implicated in the decline in monarch 

populations, the loss of milkweed and 

nectar resources (i.e., breeding and 

migratory habitat) has been targeted as 

the threat that can be most easily 

addressed through conservation efforts. 

Because of the monarch butterfly’s 

general habitat use and wide 

distribution, all sectors of society, 

including the general public, have an 

opportunity to participate in a broad 

range of conservation efforts throughout 

the species’ range. Protection, 

restoration, enhancement, and creation 

of habitat is a central aspect of recent 

monarch conservation strategies, thus 

highlighting the importance of restoring 

and enhancing milkweed and nectar 

resources (Oberhauser et al. 2017, pp. 

56–58; Pleasants 2017, p. 43; 

Thogmartin et al. 2017a, pp. 2–3; 

MAFWA 2018, p. 52; Pelton et al. 2019, 

pp. 4–5, WAFWA 2019, p. 41). 

Management at overwintering sites in 

California has also been targeted to 

improve the status of western North 

American monarch butterflies (Pelton et 

al. 2019, p. 4; WAFWA 2019, pp. 37– 

40). We are not aware of conservation 

actions for the populations outside of 

eastern and western North America, but 

conservation measures for the eastern 

and western North American 

populations are described below. 

Major overarching landscape-level 

conservation plans and efforts include 

the Mid-America Monarch Conservation 

Strategy developed by the Midwest 

Association of Fish and Wildlife 

Agencies (MAFWA) and the Western 

Monarch Butterfly Conservation Plan 

developed by the Western Association 

of Fish and Wildlife Agencies 

(WAFWA). The Mid-America Monarch 

Conservation Strategy established a goal 

of adding 1.3 billion stems of milkweed 

on the landscape by 2038 (MAFWA 

2018, p. 42). The 1.3-billion-stem goal is 

an estimated target for adding enough 

breeding and migratory habitat to 

support 14.8 ac (6 ha) of forest occupied 

by overwintering monarchs for the 

eastern North American population 

(Thogmartin et al. 2017b, pp. 2–3). 

Twenty-nine States—including 

Arkansas, Connecticut, Delaware, 

Illinois, Indiana, Iowa, Kansas, 

Kentucky, Maine, Maryland, 

Massachusetts, Michigan, Minnesota, 

Missouri, Nebraska, New Hampshire, 

New Jersey, New York, North Dakota, 

Ohio, Oklahoma, Pennsylvania, Rhode 

Island, South Dakota, Texas, Vermont, 

Virginia, West Virginia, and 

Wisconsin—have agreed to participate 

in the effort to reach the 1.3-billion-stem 

goal, which will also need contributions 

from multiple sectors of society, 

including private landowners, 

agricultural and nongovernmental 

organizations, rights-of-way 

organizations, and Federal, State, and 

local governments. 

The Western Monarch Butterfly 

Conservation Plan currently 

encompasses the States of Arizona, 

California, Idaho, Nevada, Oregon, Utah, 

and Washington, which comprise the 

core of the western monarch range 

(WAFWA 2019, p. 3). The plan includes 

short-term goals of: (1) protecting and 

managing 50 percent of all currently 

known and active monarch 

overwintering sites, including 90 

percent of the most important 

overwintering sites by 2029; and (2) 

providing a minimum of 50,000 

additional acres of monarch-friendly 

habitat in California’s Central Valley 

and adjacent foothills by 2029. It also 

includes overwintering and breeding 

habitat conservation strategies, 

education and outreach strategies, and 

research and monitoring needs. Many 

land managers who oversee 

overwintering sites in California have 

developed and implemented grove 

management strategies or have included 

monarch groves in their general 

management plans. Conservation efforts 

in California’s Central Valley currently 

amount to nearly 9,000 ac (3,600 ha). As 

of September 2024, State agencies had 

implemented milkweed restoration 

efforts on over 8,780,404 ac (3,553,303 

ha), adding more than an estimated 546 

million milkweed stems to the 

landscape nationwide. 

In early 2020, the Nationwide 

Candidate Conservation Agreement for 

Monarch Butterfly on Energy and 

Transportation Lands: An Integrated 

Candidate Conservation Agreement with 

Assurances (CCAA) and Candidate 

Conservation Agreement (CCA) was 

finalized and is contributing to MAFWA 

Strategy and WAFWA Plan goals. Under 

this agreement, energy and 

transportation entities are providing 

habitat for the species along energy and 

transportation rights-of-way corridors 

across the country. Participants carry 

out conservation measures to reduce or 

remove threats to the species and create 

and maintain habitat annually. In 

exchange for implementing voluntary 

conservation efforts and meeting 

specific requirements and criteria, those 

businesses and organizations enrolled in 

this CCAA/CCA receive assurance from 

the Service that they will not have to 

implement additional conservation 

measures should the species be listed. 

The goal of this CCAA/CCA is 


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enrollment of up to 26 million acres of 

land in the agreement, providing more 

than 300 million additional stems of 

milkweed (Rights-of-Way as Habitat 

Working Group 2020, p. 3). As of June 

2024, this CCAA/CCA had 57 enrollees 

with over 981,812 ac (397,325 ha) of 

enrolled habitat. 

Many conservation efforts 

implemented under Federal, Tribal, 

State, or other programs, such as the 

Farm Service Agency’s Conservation 

Reserve Program; the Natural Resource 

Conservation Service’s Environmental 

Quality Incentives Program, 

Agricultural Conservation Easement 

Program and Conservation Stewardship 

Program; and the Service’s Partners for 

Fish and Wildlife Program, are expected 

to contribute to the overarching habitat 

and population goals of the MAFWA 

Strategy and WAFWA Plan. Smaller 

conservation efforts, such as pollinator 

gardens, implemented by local 

governments, nongovernmental 

organizations, private businesses, and 

interested individuals will also play an 

important role in reaching habitat and 

population goals established in the 

MAFWA Strategy and WAFWA Plan. 

Many land managers who oversee 

overwintering sites in California have 

developed and implemented grove 

management strategies or have included 

monarch groves in their general 

management plans. Many others are in 

the process of developing grove 

management plans. As of January 2024, 

grove management plans are being 

implemented at no fewer than 24 

overwintering sites and are currently 

being developed for at least a dozen 

more. Management and restoration of 

these sites may include activities such 

as replacing dead trees, modifying 

canopy structure, planting fall- and 

winter-blooming shrubs as nectar 

sources, and addressing monarch 

predation issues (Jepsen et al. 2017, 

entire). 

The Service developed the Monarch 

Conservation Database (MCD) to capture 

information about monarch 

conservation plans and efforts to inform 

the listing decision. As of September 

2024, the MCD had 145,455 complete 

monarch conservation effort records that 

have a status of completed, 

implemented, or planned since 2014 

and 126 monarch conservation plans. 

These efforts constitute a total of 

10,457,316 ac (4,231,926 ha) of land 

area in the United States (10,246,876 ac 

(4,146,764 ha) and 178,920 ac (72,406 

ha) in the eastern and western 

populations, respectively) enhanced or 

created for monarchs, with the most 

common conservation effort being direct 

planting of milkweed and other nectar 

resources (note that these values include 

all completed, implemented, and not yet 

completed efforts; completed and 

implemented efforts to date total 

7,415,731 ac (3,001,040 ha) nationally). 

These conservation efforts are 

increasing the amount of milkweed and 

nectar resources on the landscape. 

However, additional milkweed and 

nectar resources are required, as initial 

estimates of the amount of acreage 

needed to reach the 1.3-billion-stem 

goal within the MAFWA Strategy 

planning area were around 20 million 

acres. 

In addition to conservation measures 

for monarch butterflies, there are also 

mechanisms that regulate direct and 

indirect threats to the species. One such 

mechanism is the Federal Insecticide, 

Fungicide, and Rodenticide Act 

(FIFRA), which provides for Federal 

regulation of pesticide distribution, sale, 

and use. The term pesticide includes 

insecticides, which can directly kill 

monarchs upon exposure, and 

herbicides that can indirectly affect 

monarchs by impacting their milkweed 

and nectar resources. All pesticides 

distributed or sold in the United States 

must be registered (licensed) by the U.S. 

Environmental Protection Agency 

(EPA). Before the EPA registers a 

pesticide under FIFRA, the applicant 

must show, among other things, that 

using the pesticide according to 

specifications ‘‘will not generally cause 

unreasonable adverse effects on the 

environment.’’ 

In 2021, the EPA began developing a 

comprehensive, long-term approach to 

meeting its section 7(a)(2) obligations 

for FIFRA actions (EPA 2022, 

unpaginated). As part of that work, the 

EPA in August 2024 finalized its firstever strategy to identify which 

agricultural uses of conventional 

herbicides impact listed species and 

how to determine the amount and 

location of mitigation measures for 

those herbicides, hereon referred to as 

the Herbicide Strategy (EPA 2024a, 

entire). The strategy covers listed plants 

and listed animals whose survival 

depends on listed plants, including 

many insects that depend on plants for 

food. The EPA has begun applying the 

strategy to the registration of new 

pesticide registrations (EPA 2024d, 

unpaginated) and expects to apply the 

strategy when the agency reevaluates 

the registration of existing pesticides 

every 15 years. 

Similarly, in July 2024 the EPA 

released its draft Insecticide Strategy, 

which proposes a framework to identify 

which agricultural uses of conventional 

insecticides impact listed species and 

how to determine the amount and 

location of mitigation measures for 

those insecticides (EPA 2024b, entire). 

The EPA has agreed to finalize the 

Insecticide Strategy by March 31, 2025, 

and then expects to apply it when the 

agency registers a new insecticide or 

reevaluates an existing one. The EPA is 

also pursuing other initiatives to 

minimize pesticide impacts on listed 

species, including through section 

7(a)(2) consultations with FWS on 

individual pesticide active ingredients 

and through its Vulnerable Species 

Action Plan, which identifies mitigation 

measures for listed species particularly 

vulnerable to pesticides (EPA 2024c, 

entire). 

Under the authority of the Plant 

Protection Act, the U.S. Department of 

Agriculture (USDA) regulates the 

importation and movement of plant 

pests, which covers plant-feeding 

insects such as the monarch butterfly. 

Under this regulation, a permit from 

USDA-Animal and Plant Health 

Inspection Service (APHIS) is required 

for the importation, interstate 

movement, and environmental release 

of butterflies, including monarchs. 

However, multiple States, including 

Alaska, Arizona, Connecticut, Hawaii, 

Montana, and Nevada, plus Puerto Rico, 

the Virgin Islands, and Guam, prohibit 

importation and/or interstate movement 

of monarchs for the purpose of 

environmental release. In addition, 

APHIS does not allow the movement of 

monarchs across the Continental Divide 

for environmental release. 

Despite these conservation efforts and 

regulatory mechanisms, the continued 

threats facing the monarch butterfly 

have not been ameliorated. 

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 species. 

The best available scientific information 

indicates that there are synergistic and 

cumulative interactions among the 

factors influencing monarch butterfly 

viability. For example, climate change 

can impact the monarch directly 

through increased temperatures and can 

also impact other potential threats to the 

species, including habitat availability, 

disease, and predators. We incorporate 

the cumulative effects into our SSA 

analysis when we characterize the 

current and future condition of the 

species. To assess the current and future 

condition of the species, we evaluate the 

effects of all the relevant factors that 

may be influencing the species, 

including threats and conservation 


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100676 Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 

efforts. Because the SSA framework 

considers not just the presence of the 

factors, but to what degree they 

collectively influence risk to the entire 

species, our assessment integrates the 

cumulative effects of the factors and 

replaces a standalone cumulative-effects 

analysis. 

Current Condition 

Eastern North American Population 

Based on the past annual censuses, 

the eastern North American population 

has been generally declining over the 

last 30 years (figure 1a). Because it is not 

possible to count individual monarchs 

at the overwintering sites in Mexico, the 

size of the eastern North American 

population is measured based on the 

area occupied by clustered monarchs. 

Although the numbers at the 

overwintering sites have declined, we 

did not find a corresponding change in 

the spatial extent of the population 

during the breeding season. We 

developed a population model that 

incorporated the current size, growth 

rate, and year-to-year variability of the 

eastern North American population. The 

results indicate that the probability of 

the population abundance reaching the 

point at which extinction is inevitable 

(‘‘probability of extinction’’) in is less 

than 10 percent within 10 years (Service 

2024a, p. 29). The probability of 

extinction does not account for risks 

from catastrophic events (discussed 

below in Future Condition). 

Western North American Population 

Based on the past annual censuses, 

the western North American population 

has been generally declining over the 

last 27 years, despite an increasing 

number of sites being surveyed (figure 

1b). We developed a similar model for 

the western North American population 

as we did for the eastern population. 

Under current conditions, the risk of 

extinction is predicted to increase 

sharply over time, between 60 to 68 

percent within 10 years (Service 2024a, 

p. 30). The probability of extinction 

does not account for risks from 

catastrophic events (discussed below in 

Future Condition). 


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Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 100677 

Figure 1—(a.) Area occupied (in 

hectares) by eastern North American 

monarch butterflies at overwintering 

sites in Mexico. Year displayed is the 

beginning year for the winter (e.g., 

2017 represents the number for the 

winter of 2017–2018). (Data from 

Rendo ́n-Salinas et al. 2024 (p. 3).) 

(b.) Survey counts showing the number 

of western North American monarch 

butterflies observed at overwintering 

sites (bars). The black line shows the 

number of sites monitored (survey 

effort) for a given year. (Data from the 

Xerces Society for Invertebrate 

Conservation (2024a, entire).) 

Dispersed Nonmigratory Populations 

Limited information is available on 

the status and health of monarchs 

outside of the North American 

migratory populations or regarding the 

positive or negative influences acting 

upon these populations. Based on 

observations of the species throughout 

its range, 69 of the 90 countries, islands, 

and island groups are currently extant. 

Monarch presence within the remaining 

21 countries, islands, and island groups 

has not been confirmed since 2000, but 

with no evidence of extirpation, they are 

all presumed extant. Furthermore, we 

grouped occurrences into 31 

populations. Of the 29 populations 

outside of North America, 25 are 

confirmed extant and the remaining 4 

are presumed extant (Service 2024a, pp. 

40–42). We were not able to further 

assess the level of resiliency of these 

populations. 

Current Resiliency, Redundancy, and 

Representation 

The species’ redundancy is evident 

through its confirmed or presumed 

presence in all 90 of the countries, 

islands, and island groups where it 

occurred historically or to where it has 

dispersed. The species’ adaptive 

capacity (representation) is evident 

through its presence over a large 

geographical range made up of 31 

known populations (2 North American 

migratory populations and 29 

nonmigratory or dispersed populations) 

where the climatic conditions and 

habitat vary widely. The species’ 

resiliency varies between populations, 

with the estimated probability of 

extinction for the eastern migratory 

North American population at less than 

10 percent in 10 years and 60 to 68 

percent for the western migratory North 

American population in 10 years. For 

monarchs outside of the North 

American migratory populations, 69 of 

the 90 countries, islands, and island 

groups are considered currently extant, 

although we were not able to further 

assess the level of resiliency of these 

populations. 

Future Condition 

Future Scenarios and Catastrophic 

Events 

North American Migratory Populations 

To assess the future condition of 

monarch populations, we organized the 

key factors driving monarch population 

dynamics into six categories: (1) 

milkweed availability, (2) breeding 

nectar availability, (3) migration nectar 

availability, (4) overwintering habitat 

availability, (5) climate change effects, 

and (6) insecticide exposure. We then 

forecasted plausible increases and/or 

decreases, as appropriate, for each of 

these influences, using the best 

available information, including 

scientific literature and expert input. 

We also included conservation efforts 

outlined in large-scale monarch 

conservation plans, such as the 

MAFWA Strategy and WAFWA Plan. 

We did not evaluate these plans under 

the Policy for Evaluating Conservation 

Efforts (68 FR 15100; March 28, 2003) 

because these formalized conservation 

efforts have been implemented. Next, 

we combined the upper plausible limit 

and the lower plausible limit for each 

influence (changes in milkweed, nectar, 

and overwintering habitat; climate 

change; and insecticides) to form 

composite plausible best case and 

plausible worst case scenarios, 

respectively. Lastly, we incorporated 

these scenarios into the population 

models described in the Current 

Condition section, and forecasted 

population numbers to 60 years to 

determine the probability of extinction 

for both the eastern and western 

migratory North American populations 

to 2080 (Service 2024a, tables 6.1 and 

6.2, pp. 45–47). 

We also evaluated several potential 

events to determine if they were of 

sufficient magnitude and severity to 

cause a population collapse (i.e., a 

catastrophic event). We determined that 

extreme storm events and widespread 


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100678 Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 

drought have sufficient potential to pose 

a catastrophic risk to the eastern 

population, and widespread drought 

and co-occurrence of poor 

environmental conditions and low 

population abundance have sufficient 

potential to pose a catastrophic risk to 

the western population. 

Dispersed Nonmigratory Populations 

Due to a lack of information on 

current influences, we were unable to 

forecast future scenarios for the 

populations outside of eastern and 

western North America. However, we 

identified two potential catastrophic 

events, both of which are effects of 

climate change: sea level rise and lethal 

high temperatures. 

Future Conditions 

Eastern North American Population 

Under both best and worst case 

scenarios described above, the 

population continues to decline (l < 1). 

The greatest impact on the population 

occurs during the first 20 years for both 

scenarios; we had a slight increase in 

the growth rate from the current value 

under the best case scenario and a 

decrease of 4.5 percent under the worst 

case scenario. As expected under a 

declining growth rate, the probability of 

extinction increases over time (Service 

2024a, p. 64). In 30 years, probability of 

extinction ranges from 24 to 46 percent. 

In 60 years, the probability of extinction 

for the eastern North American 

population ranges from 56 to 74 percent. 

We were unable to incorporate direct 

effects from increasing temperatures and 

catastrophic risks into the population 

models, so we qualitatively discuss the 

implications of these factors on the 

future condition of the population. We 

evaluated the changes in the spatial 

extent and number of days with 

projected temperatures above lethal and 

sublethal thermal thresholds during 

critical time periods in monarch 

migration (Service 2024a, pp. 120–122). 

We assessed these changes under two 

future scenarios, using Representative 

Concentration Pathways (RCPs). RCPs 

reflect different levels of greenhouse gas 

emissions and the resulting climate 

change scenarios (IPCC 2014, p. 57). We 

used RCP4.5 and RCP8.5 scenarios 

projected to 2069 (Service 2024a, p. 

122). Under the RCP4.5 scenario, both 

the spatial extent and the average 

number of days above 38 °C (100 °F) (the 

threshold for sublethal effects and 

moderate reductions in survival) are 

projected to markedly increase 

throughout much of the range, including 

the southern and northeastern portions 

of the eastern North American monarch 

breeding range. Although in the 

northcentral area of the breeding range, 

there is a projected decrease in spatial 

extent and the average number of days 

above 38 °C (100 °F). Under the RCP8.5 

scenario, both the spatial extent and the 

average number of days above 38 °C 

(100 °F) have large increases throughout 

the entirety of the breeding range. The 

spatial extent and average number of 

days above 42 °C (107.6 °F) (the lethal 

threshold) are projected to increase 

dramatically in the southern U.S. during 

the same period under both scenarios. 

Given these results, monarch 

reproductive success and survival rates 

of the first generation of monarchs 

coming from the wintering grounds are 

likely to decline, although the extent to 

which these rates will decline is 

unknown. 

Similarly, given the projected 

population decline described above, the 

eastern population will be increasingly 

vulnerable to catastrophic losses due to 

extreme storm events at the 

overwintering grounds and widespread 

droughts during the breeding season 

and along the migratory route. Although 

we cannot quantify this increased risk, 

the longer the eastern population 

remains at low population abundance, 

the more likely it is that catastrophic 

losses will occur and the greater the 

extinction risk for the eastern 

population. 

Western North American Population 

Under both scenarios, the population 

continues to decline (l < 1). Under the 

best case scenario, monarchs have a 

slight increase in the growth rate from 

the current value; however, even with 

an increase, this was still a declining 

growth rate. Under the worst case 

scenario, the growth rate decreased to a 

lower rate than the current rate. As 

would be expected with a declining 

growth rate, the probability of extinction 

increases over time (Service 2024a, p. 

66). In 30 years, probability of 

extinction ranges from 92 percent to 95 

percent. By year 60, the probability of 

extinction reaches 99 percent for the 

western North American population. 

Under the RCP4.5 scenario, increases 

are projected for the average numbers of 

days above 38 °C (100.4 °F) (38 percent) 

and above 42 °C (107.6 °F) (11 percent). 

Given this, monarch reproductive 

success and survival rates are likely to 

decline, although the extent to which 

these rates will decline is unknown. 

Similarly, given the projections of 

monarch health described above, the 

western population is vulnerable to 

catastrophic losses due to both 

widespread drought events and the cooccurrence of poor environmental 

conditions and low population 

abundance. The risk of extinction due to 

these events increases the longer the 

population remains at the current low 

abundances. 

Dispersed Nonmigratory Populations 

We qualitatively assessed the impact 

due to predicted climate change effects. 

Fifteen of the 29 populations are 

classified as being ‘‘at risk’’ due to 

threats associated with climate change 

(6 due to sea level rise and 9 due to 

unsuitably high temperatures). The 

populations susceptible to sea level rise 

(Johnston Atoll, Kiribati, Marshall 

Islands, Nauru, Tokelau, and Tuvalu) 

are at risk of losing at least some of their 

monarch habitat; thus, redundancy 

could decrease with the loss of those 

areas. However, the best available 

information does not indicate if 

populations at risk to high temperatures 

will lose all or just a portion of their 

monarch habitat; thus, they may 

continue to contribute to redundancy. 

Each of the populations at risk due to 

sea level rise contains a single country, 

island, or island group. Therefore, in the 

dispersed nonmigratory populations the 

species will continue to have 

redundancy through continued presence 

in an estimated 84 of the 90 countries, 

islands, and island groups where it 

occurred historically or to where it has 

dispersed. We anticipate the species 

will continue to have adaptive capacity 

(representation) through its presence 

over a large geographical range where 

the climatic conditions and habitat vary 

widely. 

Future Resiliency, Redundancy, and 

Representation 

Both the eastern and western 

migratory North American populations 

become more vulnerable to catastrophic 

events (e.g., extreme storms at the 

overwintering habitat) into the future 

resulting in lower redundancy for the 

species. Under plausible climate change 

scenarios, monarch butterflies will be 

exposed to unsuitably high 

temperatures for more days each year 

and over larger areas of their range in 

North America. Outside of the two 

North American migratory populations, 

15 of the 29 nonmigratory or dispersed 

populations are at risk in the future due 

to threats associated with climate 

change (6 due to sea level rise and 9 due 

to unsuitably high temperatures). The 

populations susceptible to sea level rise 

are at risk of losing at least some of their 

monarch habitat; thus, redundancy 

could decrease with the loss of those 

areas. Rangewide, the species is likely to 

maintain considerable redundancy and 

adaptive capacity (representation) 


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through continued presence in an 

estimated 84 of the 90 countries, 

islands, and island groups where it 

occurred historically or to where it has 

dispersed. Despite uncertainties about 

resiliency at the nonmigratory and 

dispersed populations, the widespread 

distribution of monarch populations 

indicates that the species has low risk 

of becoming extirpated from multiple 

locations should a large-scale 

catastrophic event occur; thus, it is 

unlikely that a single catastrophic event 

would affect the entire species across its 

large range. 

In the future, the resiliency of the 

eastern and western North American 

migratory populations will continue to 

decline. The estimated probability of 

extinction for the eastern migratory 

North American population is 56–74 

percent in 60 years and greater than 99 

percent for the western migratory North 

American population in 60 years. 

Determination of Monarch Butterfly 

Status 

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

and its implementing regulations (50 

CFR part 424) set forth the procedures 

for determining whether a species meets 

the definition of an endangered species 

or a threatened species. The Act defines 

an ‘‘endangered species’’ as a species in 

danger of extinction throughout all or a 

significant portion of 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 an 

endangered species or a threatened 

species because of any of the following 

factors: (A) The present or threatened 

destruction, modification, or 

curtailment of its habitat or range; (B) 

overutilization for commercial, 

recreational, scientific, or educational 

purposes; (C) disease or predation; (D) 

the inadequacy of existing regulatory 

mechanisms; or (E) other natural or 

manmade factors affecting its continued 

existence. 

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 determined that the 

primary threats affecting the monarch 

and its habitat are the ongoing impacts 

from loss and degradation of breeding, 

migratory, and overwintering habitat 

(from past conversion of grasslands and 

shrublands to agriculture and 

widespread use of herbicides; logging/ 

thinning at overwintering sites in 

Mexico; urban development, 

senescence, and incompatible 

management of overwintering sites in 

California; and drought) (Factor A); 

exposure to insecticides (Factor E); and 

effects of climate change (Factor E). 

While the monarch butterfly is 

historically native to North America 

with migratory and nonmigratory 

populations, monarchs have dispersed 

via human assistance from North 

America in the past two centuries and 

their range now includes populations 

throughout 90 countries, islands, and 

island groups where milkweed was 

already present or introduced. 

Populations exist in Central and South 

America, Australia, New Zealand, 

islands of the Pacific and Caribbean, 

and elsewhere (see Service 2024a, pp. 

41–42). The primary threats have been 

affecting the resiliency of the eastern 

and western North American migratory 

populations over the last 20 years, and 

both populations now have lower 

abundances and declining population 

growth rates. However, in its current 

condition, the probability of extinction 

of the eastern migratory population is 

less than 10 percent over the next 10 

years. The probability of extinction of 

the western migratory population over 

that same time period is higher (60–68 

percent). 

For monarchs outside of the two 

North American migratory populations, 

69 of the 90 countries, islands, and 

island groups are considered currently 

extant. Monarch presence within the 

remaining 21 countries, islands, and 

island groups has not been confirmed 

since 2000, but the best available 

information does not indicate they are 

extirpated, and thus they are all 

presumed extant. Of the 29 populations 

outside of North America, 25 are 

confirmed extant, and the remaining 4 

are presumed extant (see Service 2024a, 

pp. 40–42). Although we were not able 

to further assess the level of resiliency 

of these 29 nonmigratory or dispersed 

populations, the species’ redundancy is 

evident through its confirmed or 

presumed presence in all 90 of the 

countries, islands, and island groups 

where it occurred historically or to 

where it has dispersed. The species’ 

adaptive capacity is evident through its 

presence over a large geographical range 

made up of 31 known populations (2 

North American migratory populations 

and 29 nonmigratory or dispersed 

populations) where the climatic 

conditions and habitat vary widely. 

Despite uncertainties about resiliency at 

some of the locations (i.e., the 29 

nonmigratory and dispersed 

populations), the number and 

distribution of populations at multiple 

locations makes it unlikely that a single 

catastrophic event would affect the 

entire species across its large range. 

Based on the best scientific and 

commercial data available, we conclude 

that the monarch butterfly is not 

currently in danger of extinction 

throughout all of its range. 

While the monarch butterfly is not 

currently in danger of extinction, under 

the Act we must determine whether the 

species is likely to become in danger of 

extinction within the foreseeable future 

throughout all of its range (i.e., whether 

the species warrants listing as 

threatened). In the foreseeable future, 

we anticipate the status of the eastern 

and western North American migratory 

populations will continue to decline 

due to the primary threats listed above. 

The probability of extinction of the 

eastern migratory population in the 

foreseeable future, which is 60 years, is 

estimated to be 56–74 percent, and the 

probability of extinction for the western 

migratory population is estimated to be 

99 percent. Outside of the two North 

American migratory populations, we 

found that 15 of the 29 nonmigratory or 

dispersed populations are at risk in the 

future due to threats associated with 

climate change (6 due to sea level rise 

and 9 due to unsuitably high 

temperatures). The populations 

susceptible to sea level rise are at risk 

of losing at least some of their monarch 

habitat; thus, redundancy could 

decrease with the loss of those areas. 

However, the best scientific and 

commercial data available do not 

indicate if populations susceptible to 

high temperatures are at risk of losing 

all or just a portion of their monarch 

habitat; thus, they may continue to 

contribute to redundancy. Therefore, 

rangewide, we conclude that the species 

is likely to maintain considerable 

redundancy through continued presence 

in an estimated 84 of the 90 countries, 

islands, and island groups where it 

occurred historically or to where it has 

dispersed. 

We find that the species will continue 

to have adaptive capacity 

(representation) through its presence 

over a large geographical range where 

the climatic conditions and habitat vary 

widely. Despite uncertainties about 

resiliency at the nonmigratory and 

dispersed populations, the widespread 

distribution of monarch populations 

indicates that the species has low risk 

of becoming extirpated from multiple 

locations should a large-scale 

catastrophic event occur; thus, it is 

unlikely that a single catastrophic event 

would affect the entire species across its 

large range. Thus, after assessing the 

best available information, we conclude 

that the monarch butterfly is not likely 


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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 within 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’’ (hereafter 

‘‘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 monarch butterfly, we 

choose to address the significance 

question first. We assessed whether any 

portions of the species’ range are 

biologically significant by considering 

them in terms of each portion’s 

contribution to resiliency, redundancy, 

or representation of the species as a 

whole. 

The monarch butterfly is historically 

native to North America, and, as 

discussed above, it now occurs in 

nonnative or naturalized populations 

throughout 90 countries, islands, and 

island groups, including parts of Central 

and South America, Australia, New 

Zealand, islands of the Pacific and 

Caribbean, and elsewhere (see Service 

2024a, pp. 41–42). To identify portions 

for evaluation, we considered these 

geographic areas independently and in 

various combinations to identify those 

which are biologically meaningful to the 

species. 

We found that monarch habitat in 

North America represents a significant 

portion of the range. This geographical 

portion is significant because it is 

physically large, representing a large 

proportion of the species’ range, and has 

unique habitat features that support 

monarch migration. The monarch’s 

North American portion of the range 

covers approximately 2.8 billion ac (1.1 

billion ha), encompasses an estimated 

62 percent of the species’ geographic 

range, and represents a vast majority of 

monarch butterflies worldwide. The 

portion is the ancestral source for 

migratory monarchs in North America 

and includes nonmigratory monarchs 

that have descended from migratory 

monarchs. The best available 

information indicates that the total 

number of nonmigratory monarchs in 

North America appears to be quite small 

relative to the North American 

migratory populations that overwinter 

in Mexico and California. The portion 

contains the entirety of breeding, 

migratory, and overwintering habitats 

used by monarchs in the eastern and 

western migratory populations. The 

monarchs within eastern and western 

North America have continued 

interchange between the two 

populations contributing to low genetic 

differentiation and forming an admixed 

population (Lyons et al. 2012, p. 3441; 

Talla et al. 2020, p. 2573; Freedman et 

al. 2021, pp. 7–8). These habitats in 

North America are unique because they 

facilitate massive annual range 

expansions during the breeding season. 

Temporary, seasonal resources allow 

monarchs to escape habitats as they 

become more heavily infected with 

diseases like OE (Bartel et al. 2011, 

entire). This seasonal movement also 

facilitates migratory culling where 

smaller and unhealthy individuals are 

removed from the breeding population 

because they are unable to survive longdistance migration (Bartel et al. 2011, 

entire; Majewska et al. 2021, p. 788). 

Years with favorable conditions across 

the broad and spatially diffuse breeding 

habitat in this portion have the potential 

to support rapid migratory monarch 

population increases (Yang et al. 2022, 

p. 20), which is important for 

population resiliency. 

We also considered eastern and 

western North America as individual 

portions. The portion of North America 

used by the eastern migratory 

population is the largest area used by a 

single population in terms of geographic 

size. It represents roughly 43 percent of 

the species’ global range. The portion of 

North America used by the western 

migratory population encompasses 

roughly 18 percent of the species’ global 

range. Individually, neither portion 

makes up a large enough geographic 

area relative to the remainder of the 

range. Both migratory populations 

require sufficient quality and quantity of 

milkweed and nectar resources, suitable 

habitat for overwintering, and adequate 

connectivity and aligned phenology. 

Both of these portions provide the 

resources and space needed to facilitate 

the massive annual migration and range 

expansions necessary to maintain the 

viability of the migratory populations, 

as described above. However, because 

these portions individually constitute 

smaller areas, they were not determined 

to be significant individually when 

compared to the portion encompassing 

both North American migratory 

populations. 

Having determined that North 

America is significant for the purposes 

of evaluating a significant portion of the 

monarch’s range, we then proceeded to 

address the status question by 

examining the threats in that portion to 

determine if the species is endangered 

or threatened in that portion. The 

statutory difference between an 

endangered species and a threatened 

species is the timeframe in which the 

species becomes in danger of extinction; 

an endangered species is in danger of 

extinction while a threatened species is 

likely to become so (i.e., endangered) 

within the foreseeable future. As 

discussed under Status Throughout All 

of Its Range, above, the primary current 

threats to the monarch butterfly are the 

ongoing impacts from loss and 

degradation of breeding, migratory, and 

overwintering habitat (from past 

conversion of grasslands to agriculture; 

widespread use of herbicides; logging/ 

thinning at overwintering sites in 

Mexico; urban development, 

senescence, and incompatible 

management of overwintering sites in 

California; and drought), exposure to 

insecticides, and effects of climate 

change. We examined those threats 

along with the effects from disease and 

cumulative effects, and we considered 

whether conservation efforts and 

regulatory mechanisms ameliorated any 

of the effects. 

Many of these factors and threats 

influence the monarch butterfly 

rangewide; however, because we 

identified the North America portion as 

being significant, we considered 

whether the threats are causing 

monarchs in the portion to have a 

different status than the remainder of 


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the range. As discussed above, this 

portion contains the eastern and 

western North American migratory 

populations. For the two migratory 

populations, we estimated the 

probability of the population abundance 

reaching the point at which extinction 

is inevitable for each population. In its 

current condition, the eastern migratory 

population has a probability of 

extinction of less than 10 percent over 

the next 10 years. The western 

migratory population has a higher risk 

of extinction due to current threats, with 

a probability of extinction of 60–68 

percent over the next 10 years. The 

probability of extinction estimates do 

not account for risks from catastrophic 

events; however, we do not anticipate 

these effects to significantly increase 

extinction risk of North American 

migratory monarchs in the near term. 

Based on the eastern migratory 

population’s level of resiliency in the 

near term and because monarchs are 

distributed across a broad geographic 

area contributing to the redundancy and 

representation of the species in the 

portion, we concluded that the monarch 

butterfly in North America is not in 

danger of extinction within this 

significant portion of its range and does 

not meet the definition of an 

endangered species. 

We next considered whether the 

monarch butterfly is likely to become an 

endangered species within the 

foreseeable future in the North America 

portion (i.e., if it meets the Act’s 

definition of a threatened species). 

Looking across the range of future 

conditions for which we can make 

reasonably reliable predictions, the 

probability of extinction for the eastern 

migratory population is estimated to be 

24–46 percent in 30 years and 56–74 

percent in 60 years. The probability of 

extinction for the western migratory 

population is estimated to be 92–95 

percent in 30 years and reaches 99 

percent in 60 years. These probability of 

extinction estimates incorporate the 

primary factors that influence the 

populations’ resiliency, including the 

ongoing impacts of availability of 

milkweed and nectar resources (losses 

as well as gains from conservation 

efforts), loss and degradation of 

overwintering habitat, insecticides, and 

effects of climate change. In addition to 

being affected by these factors, both the 

eastern and western migratory 

populations become more vulnerable to 

catastrophic events (e.g., extreme storms 

at the overwintering habitat) into the 

future. Under plausible climate change 

scenarios, monarch butterflies will be 

exposed to unsuitably high 

temperatures for more days each year 

and over larger areas of their range in 

North America. 

The best available scientific and 

commercial information indicates 

nonmigratory monarch populations in 

North America are very small compared 

to the size of the two migratory 

populations. In our assessment of the 

threats, we found that the three 

nonmigratory populations in Florida, 

the Caribbean, and countries in Central 

America are at risk due to unsuitably 

high temperatures associated with 

climate change. There is potential for 

nonmigratory monarch populations in 

North America to be demographic sinks 

(see Crone and Schultz 2021, p. 1536), 

requiring continual influxes of 

monarchs from migratory populations to 

sustain them. Therefore, the status of 

nonmigratory monarchs in the North 

American portion is also in decline. 

After assessing the best scientific and 

commercial data available, we found 

that migratory monarch butterflies in 

North America, which represent the vast 

majority of monarch butterflies 

worldwide, have a high likelihood of 

becoming extirpated in 60 years. 

Therefore, we conclude that the 

monarch butterfly is likely to become in 

danger of extinction within the 

foreseeable future throughout North 

America. Therefore, having determined 

that the North America portion is both 

(1) significant; and (2) likely to become 

in danger of extinction within the 

foreseeable future, we conclude that the 

monarch butterfly is in danger of 

extinction within the foreseeable future 

within a significant portion of its range. 

This is consistent with the courts’ 

holdings in Desert Survivors v. U.S. 

Department of the Interior, 321 F. Supp. 

3d 1011, 1070–74 (N.D. Cal. 2018) and 

Center for Biological Diversity v. Jewell, 

248 F. Supp. 3d, 946, 959 (D. Ariz. 

2017). 

Determination of Status 

Based on the best scientific and 

commercial data available, we 

determine that the monarch butterfly 

meets the Act’s definition of a 

threatened species. Therefore, we 

propose to add the monarch butterfly as 

a threatened species to the List of 

Endangered and Threatened Wildlife in 

50 CFR 17.11(h) 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, foreign 

governments, 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. 

The recovery planning process begins 

with development of a recovery outline 

made available to the public soon after 

a final listing determination. The 

recovery outline guides the immediate 

implementation of urgent recovery 

actions while a recovery plan is being 

developed. Recovery teams (composed 

of species experts, Federal and State 

agencies, nongovernmental 

organizations, and stakeholders) may be 

established to develop and implement 

recovery plans. 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 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. Revisions of the plan 

may be done to address continuing or 

new threats to the species, as new 

substantive information becomes 

available. The recovery outline, draft 

recovery plan, final recovery plan, and 

any revisions will be available on our 

website as they are completed (https:// 

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Headquarters (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. To 

achieve recovery of these species 

requires cooperative conservation efforts 

on private, State, and Tribal lands. 

To improve future conditions so that 

the monarch migratory populations 

stabilize and grow, we need to (1) 

achieve a significant increase in the 

availability of milkweed and nectar 

plants in monarch breeding and 

migratory areas; (2) protect and enhance 

overwintering habitat; (3) avoid and 

minimize impacts to monarchs and their 

habitat from insecticides and herbicides; 

and (4) maintain public support for the 

conservation of monarch butterflies. 

Because of the monarch butterfly’s 

general habitat use and wide 

distribution, all sectors of society, 

including the general public, have an 

opportunity to participate in a broad 

range of conservation efforts throughout 

the species’ range. 

If this species is listed, 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 Alabama, Arizona, 

Arkansas, California, Colorado, 

Connecticut, Delaware, Florida, Georgia, 

Hawaii, Idaho, Illinois, Indiana, Iowa, 

Kansas, Kentucky, Louisiana, Maine, 

Maryland, Massachusetts, Michigan, 

Minnesota, Mississippi, Missouri, 

Montana, Nebraska, Nevada, New 

Hampshire, New Jersey, New Mexico, 

New York, North Carolina, North 

Dakota, Ohio, Oklahoma, Oregon, 

Pennsylvania, Rhode Island, South 

Carolina, South Dakota, Tennessee, 

Texas, Utah, Vermont, Virginia, 

Washington, West Virginia, Wisconsin, 

and Wyoming; the U.S. Commonwealths 

of the Northern Mariana Islands and 

Puerto Rico; and the U.S. Territories of 

American Samoa, Guam, and the U.S. 

Virgin Islands would be eligible for 

Federal funds to implement 

management actions that promote the 

protection or recovery of the monarch 

butterfly. Information on our grant 

programs that are available to aid 

species recovery can be found at: 

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

Although the monarch butterfly is 

only proposed for listing under the Act 

at this time, please let us know if you 

are interested in participating in 

recovery efforts for this species. 

Additionally, we invite you to submit 

any new information on this species 

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 it 

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)(1) directs all Federal 

agencies, in consultation with the 

Secretary, to utilize their authorities to 

carry out ‘‘programs for the conservation 

of endangered and threatened species.’’ 

This provision provides an affirmative 

and broad mandate to all agencies to 

take action to conserve threatened and 

endangered species. This section affords 

broad discretion to agencies on the 

measures they undertake as part of their 

conservation programs within their 

existing authorities, and robust section 

7(a)(1) programs may assist Federal 

agencies with their obligations under 

section 7(a)(2). 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 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. 

In contrast, section 7(a)(4) of the Act 

requires Federal agencies to confer with 

the Service on any action which is likely 

to jeopardize the continued existence of 

any species proposed to be listed under 

the Act or result in the destruction or 

adverse modification of critical habitat 

proposed to be designated for such 

species. Although the conference 

procedures are required only when an 

action is likely to result in jeopardy or 

adverse modification, action agencies 

may voluntarily confer with the Service 

on actions that may affect species 

proposed for listing or critical habitat 

proposed to be designated. In the event 

that the subject species is listed or the 

relevant critical habitat is designated, a 

conference opinion may be adopted as 

a biological opinion and serve as 

compliance with section 7(a)(2) of the 

Act. 

Examples of discretionary actions for 

the monarch butterfly that may be 

subject to conference and consultation 

procedures under section 7 are 

management of Federal lands 

administered by the Army Corps of 

Engineers, Bureau of Land Management, 

Department of Defense (DoD), National 

Park Service, Office of Surface Mining, 

and U.S. Forest Service as well as 

actions 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 actions funded by Federal 

agencies such as the Federal Highway 

Administration, Federal Aviation 

Administration, U.S. Department of 

Agriculture, or the Federal Emergency 

Management Agency. We also anticipate 

conferencing or consultation by the EPA 

as part of their pesticide registration 

actions under FIFRA. 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 or Midwest Region 

Headquarters (see FOR FURTHER

INFORMATION CONTACT) with any specific 

questions on section 7 consultation and 

conference requirements. 

II. Protective Regulations 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 species. Conservation is 

defined in the Act to mean the use of 

all methods and procedures which are 


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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. 

With these two sentences in section 

4(d), Congress delegated broad authority 

to the Secretary to determine what 

protections would be necessary and 

advisable to provide for the 

conservation of threatened species, and 

even broader authority to put in place 

any of the section 9 prohibitions, for a 

given species. 

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, as a valid exercise of agency 

authority, rules developed under section 

4(d) that included limited prohibitions 

against takings (see Alsea Valley 

Alliance v. Lautenbacher, 2007 WL 

2344927 (D. Or. 2007); Washington 

Environmental Council v. National 

Marine Fisheries Service, 2002 WL 

511479 (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 species’ 

proposed protective regulations under 

section 4(d) of the Act are one of many 

tools that we would use to promote 

conservation of the monarch butterfly 

by encouraging creation and 

management of habitat in ways that 

address threats to the species and 

maintain public support for its 

conservation. To achieve a significant 

increase in the availability of milkweed 

and nectar plants in monarch breeding 

areas, we need to incentivize return of 

milkweed to large portions of the 

landscape where it is now nonexistent 

or where what remains is highly 

fragmented. Given that so much 

milkweed has been lost historically and 

that monarchs are impacted by the 

ongoing effects of this past habitat loss 

and degradation, we need an approach 

that encourages landowners to add 

milkweeds and nectar plants and 

implement actions to maintain them. 

Creation, enhancement, and 

maintenance of higher quality habitat by 

the public may lead to the temporary 

destruction of milkweed and nectar 

plants and incidental take of monarchs. 

Private landowner and general public 

support are crucial because the species 

is wide-ranging and needs broad 

conservation action, from small- to 

large-scale efforts, throughout its range. 

Conservation for the species can occur 

on land parcels ranging from quite small 

to very large, including gardens, parks, 

grasslands, agricultural areas, and more. 

Because of the monarch butterfly’s 

general habitat use and wide 

distribution, all sectors of society, 

including the general public, have an 

opportunity to participate in a broad 

range of conservation efforts throughout 

the species’ range. The proposed 4(d) 

rule allows for the general public to take 

action to participate in the recovery of 

monarchs without fear of unintentional 

violation for the Act. Public action is 

necessary for the conservation of the 

species. 

The proposed protective regulations 

would apply only if and when we make 

final the listing of the monarch butterfly 

as a threatened species. Nothing in 4(d) 

rules changes 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 monarch butterfly. 

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 authorize, fund, 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. In addition, even before the 

listing of any species or the designation 

of its critical habitat is finalized, section 

7(a)(4) of the Act requires Federal 

agencies to confer with the Service on 

any agency action which is likely to 

jeopardize the continued existence of 

any species proposed to be listed under 

the Act or result in the destruction or 

adverse modification of critical habitat 

proposed to be designated for such 

species. These requirements are the 

same for a threatened species regardless 

of what is included in its 4(d) rule. 

Section 7 consultation is required for 

Federal actions that ‘‘may affect’’ a 

listed species regardless of whether take 

caused by the activity is prohibited or 

excepted by a 4(d) rule (under 

application of a ‘‘blanket rule’’ (for more 

information, see 89 FR 23919, April 5, 

2024) or a species-specific 4(d) rule). A 

4(d) rule does not change the process 

and criteria for informal or formal 

consultations and does not alter the 

analytical process used for biological 

opinions or concurrence letters. For 

example, as with an endangered species, 

if a Federal agency determines that an 

action is ‘‘not likely to adversely affect’’ 

a threatened species, this will require 

the Service’s written concurrence (50 

CFR 402.13(c)). Similarly, if a Federal 

agency determinates that an action is 

‘‘likely to adversely affect’’ a threatened 

species, the action will require formal 

consultation with the Service and the 

formulation of a biological opinion (50 

CFR 402.14(a)). Because consultation 

obligations and processes are unaffected 

by 4(d) rules, we may consider 

developing tools to streamline future 

intra-Service and interagency 

consultations for actions that result in 

forms of take that are not prohibited by 

the 4(d) rule (but that still require 

consultation). These tools may include 

consultation guidance; streamlined, 

online consultation processes via the 

Service’s digital project planning tool 

(Information for Planning and 

Consultation; https://ipac.ecosphere.

fws.gov/); template language for 

biological opinions; or programmatic 

consultations. Nonetheless, section 

7(a)(1) authority provides a great deal of 

unrealized potential in achieving 

recovery goals, and this 4(d) rule 

incentivizes agencies to fully utilize 

their authorities to design and 

implement conservation programs that 

meaningfully benefit monarch 

butterflies. 

Provisions of the Proposed 4(d) Rule 

Exercising the Secretary’s authority 

under section 4(d) of the Act, we have 

developed a proposed rule that is 

designed to address the monarch 

butterfly’s conservation needs. As 

discussed previously in Summary of 

Biological Status and Threats, we have 

concluded that the monarch butterfly is 

likely to become in danger of extinction 

within the foreseeable future primarily 

due to the ongoing impacts of loss and 

degradation of breeding, migratory, and 

overwintering habitat (from past 

conversion of grasslands and shrublands 

to agriculture and widespread use of 

herbicides; logging/thinning at 

overwintering sites in Mexico; urban 

development, senescence, and 


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incompatible management of 

overwintering sites in California; and 

drought), exposure to insecticides, and 

effects of 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 are not required to make a 

‘‘necessary and advisable’’ 

determination when we apply or do not 

apply specific section 9 prohibitions to 

a threatened species (In re: Polar Bear 

Endangered Species Act Listing and 4(d) 

Rule Litigation, 818 F. Supp. 2d 214, 

228 (D.D.C. 2011) (citing Sweet Home 

Chapter of Communities for a Great 

Oregon v. Babbitt, 1 F.3d 1, 8 (D.C. Cir. 

1993), rev’d on other grounds, 515 U.S. 

687 (1995))). Nevertheless, even though 

we are not required to make such a 

determination, we have chosen to be as 

transparent as possible and explain 

below why we find that, if finalized, the 

protections, prohibitions, and 

exceptions in this proposed 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 

monarch butterfly. 

The protective regulations we are 

proposing for the monarch butterfly 

incorporate prohibitions from section 

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

species. The prohibitions of section 

9(a)(1), and the implementing 

regulations codified at 50 CFR 17.21, 

make it illegal for any person subject to 

the jurisdiction of the United States to 

commit, to attempt to commit, to solicit 

another to commit or to cause to be 

committed any of the following acts 

with regard to any endangered wildlife: 

(1) import into or export from, the 

United States; (2) take (which includes 

harass, harm, pursue, hunt, shoot, 

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

to attempt to engage in any such 

conduct) within the United States, 

within the territorial sea of the United 

States, or on the high seas; (3) possess, 

sell, deliver, carry, transport, or ship, by 

any means whatsoever, any such 

wildlife that has been taken illegally; (4) 

deliver, receive, carry, transport, or ship 

in interstate or foreign commerce, by 

any means whatsoever and in the course 

of commercial activity; or (5) sell or 

offer for sale in interstate or foreign 

commerce. This protective regulation 

includes all these prohibitions because 

the eastern and western North America 

monarch populations are at risk of 

extinction within the foreseeable future 

and putting these prohibitions in place 

will help to prevent further declines, 

slow the rate of decline, and decrease 

negative effects from other ongoing or 

future threats. 

In particular, this proposed 4(d) rule 

would provide for the conservation of 

the monarch butterfly by prohibiting the 

following activities, unless they fall 

within specific exceptions or are 

otherwise authorized or permitted: 

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. We are proposing to 

prohibit these activities in the 

contiguous United States, Puerto Rico, 

and the U.S. Virgin Islands. We are not 

proposing to prohibit these activities in 

Hawaii or other U.S. Territories because 

these areas are outside the historical 

range of the species and monarchs in 

these areas will not contribute to 

recovery of the species in North 

America. We are also not proposing to 

prohibit these activities in Alaska 

because the species does not occur 

there. Further, import and interstate 

movement of monarch butterflies is 

regulated by the U.S. Department of 

Agriculture, and monarchs may not be 

transported to Hawaii, Alaska, or any of 

the U.S. Territories under existing 

regulations in 7 CFR part 330. 

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 regulations at 50 

CFR 17.3. Take can result knowingly or 

otherwise, by direct and indirect 

impacts, intentionally or incidentally. 

Regulating take would help to preserve 

the species’ migratory populations, slow 

their rates of decline, and decrease 

synergistic, negative effects from other 

ongoing or future threats. Therefore, we 

propose to prohibit take of the monarch 

butterfly, except for take resulting from 

those actions and activities specifically 

excepted by the 4(d) rule. 

Exceptions to the prohibition on take 

would include all 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. 

Despite these prohibitions regarding 

threatened species, we may under 

certain circumstances issue permits to 

carry out one or more otherwiseprohibited 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. 

In addition, to further the 

conservation of the species, any 

employee or agent of the Service, any 

other Federal land management agency, 

the National Marine Fisheries Service, a 

State conservation agency, or a federally 

recognized Tribe, who is designated by 

their agency or Tribe for such purposes, 

may, when acting in the course of their 

official duties, take threatened wildlife 

without a permit if such action is 

necessary to: (i) Aid a sick, injured, or 

orphaned specimen; or (ii) dispose of a 

dead specimen; or (iii) salvage a dead 

specimen that may be useful for 

scientific study; or (iv) remove 

specimens that constitute a 

demonstrable but nonimmediate threat 

to human safety, provided that the 

taking is done in a humane manner. 

Such taking may involve killing or 

injuring only if it has not been 

reasonably possible to eliminate such 

threat by live-capturing and releasing 

the specimen unharmed, in an 

appropriate area. 

We recognize the special and unique 

relationship that we have 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, would be able to 

conduct activities designed to conserve 

monarch butterflies that may result in 


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otherwise prohibited take without 

additional authorization. 

The main threats affecting the two 

North American migratory populations 

of monarch butterflies are the ongoing 

impacts from loss and degradation of 

breeding, migratory, and overwintering 

habitat (from past conversion of 

grasslands and shrublands to agriculture 

and widespread use of herbicides; 

logging/thinning at overwintering sites 

in Mexico; urban development, 

senescence; and incompatible 

management of overwintering sites in 

California; and drought), exposure to 

insecticides, and effects of climate 

change. To improve future conditions so 

that the monarch migratory populations 

stabilize and grow, we need to (1) 

achieve a significant increase in the 

availability of milkweed and nectar 

plants in monarch breeding and 

migratory areas; (2) protect and enhance 

overwintering habitat; (3) avoid and 

minimize impacts to monarchs and their 

habitat from insecticides and herbicides; 

and (4) maintain public support for the 

conservation of monarch butterflies. 

The proposed 4(d) rule would 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 monarch butterfly, 

are not expected to rise to the level that 

would have a negative impact (i.e., 

would have only de minimis impacts) 

on the species’ conservation. The 

proposed exceptions to these 

prohibitions include take resulting from 

activities conducted for the benefit of 

monarch butterflies or with only de 

minimis impacts that may maintain, 

enhance, remove, or establish milkweed 

and nectar plants within the breeding 

and migratory range; implementation of 

a comprehensive conservation plan 

developed by or in coordination with a 

State agency or implementation of a 

conservation program developed by a 

Federal agency; maintenance or 

improvement of monarch overwintering 

habitat in the United States consistent 

with a site-specific Service-approved 

Overwintering Site Land Management 

Plan; monarch mortality due to vehicle 

strikes; small-scale (250 or fewer 

butterflies) collection, possession, 

captive-rearing, and release of 

monarchs; scientific research; 

educational activities; possession of 

dead monarchs; and sale of captively 

reared monarchs. 

In this proposed rule, the range of the 

monarch where these exceptions would 

apply include all areas under the 

jurisdiction of the U.S. Government 

where the monarch occurred 

historically and were not aided by 

human dispersal (i.e., the contiguous 

United States, Puerto Rico, and the U.S. 

Virgin Islands). These exceptions would 

not apply to States that are not part of 

the contiguous United States (e.g., 

Hawaii) or territories that are outside 

the historical range of the species (e.g., 

American Samoa) because, as noted 

above, these activities would not be 

prohibited there. 

(1) Activities that may maintain, 

enhance, remove, or establish milkweed 

and nectar plants within the breeding 

and migratory range that do not result 

in conversion of native or naturalized 

grassland, shrubland, or forested 

habitats. 

These activities include the following: 

(a) Habitat restoration and 

management activities, such as mowing 

and haying native rangeland, that 

sustain monarch butterfly habitat, 

including activities to eliminate plant 

communities that contain invasive 

plants or noxious weeds as part of site 

preparations or habitat enhancement 

activities. 

(b) Livestock grazing and routine 

ranching activities, including rotational 

grazing, patch-burn grazing, vegetation 

and invasive species management, other 

grazing practices implemented to make 

pasture and rangelands productive, 

construction and maintenance of fences, 

the gathering and management of 

livestock, and the development and 

maintenance of watering facilities for 

livestock. 

(c) Routine agricultural activities, 

including plowing, drilling, disking, 

mowing, and other mechanical 

manipulation and management of lands 

already in use for agricultural 

production (e.g., conventional row 

crops, pasture, hay fields, orchards, and 

vineyards). This also includes other 

mechanical manipulation and land 

management activities in direct support 

of cultivated agriculture, such as 

replacement, upgrades, maintenance, 

and operation of existing infrastructure 

(e.g., buildings, irrigation conveyance 

structures, fences, and roads), and 

routine implementation and 

maintenance of agricultural 

conservation practices, such as terraces, 

dikes, grassed waterways, and 

conservation tillage. 

(d) Fire management actions (e.g., 

prescribed burns, cultural burns, 

hazardous fuel reduction activities, 

vegetation management, maintenance of 

fuel breaks and minimum clearance 

requirements, and other fuels reduction 

activities). 

(e) Silviculture practices and forest 

management activities that use Stateapproved best management practices. 

(f) Maintenance, enhancement, 

removal, and establishment of milkweed 

and nectar plants on residential and 

other developed properties. 

(g) Vegetation management activities, 

such as mowing, ground disturbance, 

and other management activities, that 

remove milkweed and/or nectar plants 

when conducted at times of year when 

monarchs are not likely present. 

We intend for this proposed exception 

to encourage numerous small- and largescale projects that will increase the 

quality and quantity of breeding habitat 

on the landscape in the long term. We 

expect localized removal of milkweed 

and nectar plants will be outweighed by 

an overall addition of these resources 

across the landscape, making broadscale 

public support for monarch 

conservation vitally important. For 

example, landscape-scale habitat 

restoration and management activities 

that provide for the habitat needs of 

monarch butterflies (e.g., mowing, 

haying native rangeland, prescribed and 

cultural burning, and control of invasive 

plants or noxious weeds) may remove 

milkweed and could result in take of 

monarchs in the short term but would 

also increase the overall quality and 

quantity of breeding habitat, which is 

likely to benefit monarch populations in 

the long term. Similarly, forest, fuels 

and wildland management activities, 

and rangeland management may have 

some minimal level of take of monarch 

butterflies but are not expected to rise 

to the level that would have a negative 

impact (i.e., would have only de 

minimis impacts) on the species’ 

conservation. These activities can help 

maintain and manage native, 

naturalized, and restored grassland, 

shrubland, and forested habitats, which 

is a conservation benefit to the species. 

Routine agricultural activities on 

lands already in use for agricultural 

production, not including conversion of 

native or naturalized grassland, 

shrubland, and forested habitats, would 

result in loss of milkweed and nectar 

plants that we consider inconsequential 

to the conservation of the species. 

Monarchs are impacted by the ongoing 

effects of past habitat loss and 

degradation; therefore, routine 

agricultural activities on lands already 

in use for agricultural production will 

not result in significant additional 

habitat loss and degradation. This is 

also true for maintenance, enhancement, 

removal, or establishment of milkweed 

and nectar plants on residential and 

other developed properties. Vegetation 

management activities that remove 

milkweed and/or nectar plants when 

conducted at times of year when 

monarchs are not likely present and that 


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do not result in conversion of native or 

naturalized grassland, shrubland, or 

forested habitats would also result in a 

level of take considered inconsequential 

to the conservation of the species. In 

addition, some activities may provide 

both conservation benefits to the species 

while also contributing to an 

inconsequential level of take (e.g., 

livestock grazing). 

While the goal of substantially 

increasing the breeding habitat available 

to monarchs and reducing fragmentation 

of their habitat will require working 

with people in many different sectors, a 

high priority needs to be placed on 

working with farmers as well as the 

Natural Resources Conservation Service, 

Farm Service Agency, and other 

partners who work with private 

landowners. We will especially focus on 

the key monarch breeding and migratory 

areas to encourage support for voluntary 

efforts to create suitable habitat and 

improve connectivity of these habitat 

patches to increase the productivity of 

monarchs and increase the carrying 

capacity of monarch habitat on the 

landscape in important parts of the 

species’ range. 

Under this proposed 4(d) rule, 

incidental take caused by activities that 

may maintain, enhance, remove, or 

establish milkweed and nectar plants 

within the breeding and migratory range 

that do not result in conversion of 

native or naturalized grassland, 

shrubland, or forested habitats will not 

be prohibited. These exceptions to the 

prohibitions are intended to encourage 

widespread adoption of voluntary 

milkweed and nectar restoration and 

maintenance as well as reduce the 

regulatory requirements for the public 

on forms of take that are considered 

inconsequential to the conservation of 

the species. 

(2) Implementation of comprehensive 

conservation plans and programs. 

When making a determination as to 

whether incidental take from 

implementation of a conservation plan 

or program would be excepted pursuant 

to this 4(d) rule, we would consider the 

following: 

• Whether the plan comprehensively 

addresses the threats affecting the 

monarch within the plan area; 

• Whether the plan establishes 

objective, measurable biological goals 

and objectives for population and 

habitat necessary to ensure a net 

conservation benefit, and provides the 

mechanisms by which those goals and 

objectives will be achieved; 

• Whether the plan administrators 

demonstrate the capability and funding 

mechanisms for effectively 

implementing all elements of the plan, 

including enrollment of participating 

landowners, monitoring of activities, 

and enforcement of plan requirements, 

as applicable; 

• Whether the plan employs an 

adaptive management strategy to ensure 

future program adaptation as necessary 

and appropriate; and 

• Whether the plan includes 

appropriate monitoring of effectiveness 

and compliance. 

To achieve a significant increase in 

the availability of monarch breeding 

areas that is required for improvement 

in the status of the species, breeding 

habitat needs to be returned to large 

portions of the landscape where it is 

now nonexistent or where what remains 

is highly fragmented. Given that so 

much milkweed has been lost 

historically and that monarchs are 

impacted by the ongoing effects of this 

past habitat loss and degradation, we 

need an approach that encourages 

landowners to add milkweeds and 

nectar plants and implement actions to 

maintain them, and comprehensive 

plans and projects to conserve the 

monarch butterfly could be important 

sources of that conservation across the 

broader landscape. State-wide plans 

developed by or in coordination with 

States and implemented by State agents 

and enrolled participants (e.g., private 

landowners, local governments) are 

opportunities for large-scale 

conservation. Likewise, programs 

developed by Federal agencies in 

fulfillment of their section 7(a)(1) 

responsibilities are also opportunities 

for large-scale conservation. Therefore, 

we intend for this proposed exception to 

encourage implementation of 

conservation plans and programs that 

comprehensively address threats 

affecting the monarch within the plan 

area. 

(3) Maintenance or improvement of 

overwintering habitat. 

Overwintering habitat is defined as 

habitat that provides overwintering 

monarch butterflies with the abiotic and 

biotic conditions necessary for 

clustering, aggregating, and feeding 

(nectaring). An overwintering site is 

defined as an area where migratory 

monarch butterflies cluster on trees 

during the fall and/or winter. Unlike 

breeding habitat, which is widely 

dispersed across the continental United 

States and can be quickly created in a 

variety of locations, overwintering 

habitat in Mexico (for the eastern 

migratory population) and California 

(for the western migratory population) is 

usually restricted to specific areas and 

consists of tree groves that are not easily 

created in new locations. Migratory 

monarchs require a very specific 

microclimate at overwintering sites. 

Maintenance and improvement of 

overwintering habitat will aid 

conservation and recovery of the species 

by maintaining and enhancing those 

specific conditions at existing groves. 

We do not regulate take in foreign 

countries; therefore, we do not prohibit 

incidental take resulting from 

management, including logging, of 

monarch overwintering habitat in 

Mexico. Our proposed 4(d) exceptions 

apply only to incidental take resulting 

from maintenance or improvement of 

monarch overwintering habitat in 

California or elsewhere in the United 

States. Under this proposed 4(d) rule, 

incidental take resulting from 

maintenance or improvement of 

monarch overwintering habitat in the 

United States that is consistent with the 

goals and objectives of a site-specific 

Service-approved overwintering site 

land management plan at the site would 

not be prohibited. Our current 

Overwintering Site Land Management 

Plan template and an example plan are 

available on https://

www.regulations.gov under Docket No. 

FWS–R3–ES–2024–0137. 

(4) Vehicle strikes. 

It is common for monarchs to be 

struck by vehicles and killed in the 

course of normal driving activities. 

Research suggests there may be roadkill 

hotspots where monarch vehicle 

mortality is particularly high, especially 

during periods of migration (Kantola et 

al. 2019, pp. 153 and 158). The best 

available information shows that 

mortality due to vehicle strikes is not 

one of the primary drivers of changes in 

monarch populations, and it was not 

identified as a primary driver by 

monarch experts (Service 2024a, p. 39). 

At this time the impacts from monarch 

deaths due to vehicle strikes are 

considered minimal and not affecting 

the monarch butterfly at a population or 

species level. Furthermore, research 

suggests that roadside monarch habitat 

can still provide a net benefit to the 

species, despite losses due to collisions, 

through strategic improvements to 

roadside vegetation management 

(Kasten et al. 2016, entire; Phillips et al. 

2019, entire). Habitat along roadsides 

may provide milkweed and nectar 

resources in otherwise heavily 

developed and agricultural regions, as 

well as provide needed habitat 

connectivity across the landscape (WuSmart & Schacht 2019, entire; Ding & 

Eldridge 2022, entire). 

We conclude that the overall impact 

of vehicle strikes is not expected to 

negatively affect conservation and 

recovery efforts for the monarch 

butterfly. Therefore, we propose that 


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take due to vehicle strikes not be 

prohibited under this 4(d) rule. 

(5) Non-lethal collection, possession, 

captive-rearing, and release of a limited 

number of monarchs. 

Monarch butterflies are collected nonlethally, held in captivity (and in some 

cases sold), and released for a variety of 

purposes, including educational 

purposes. Collecting (defined in this 

rulemaking as the non-lethal capture 

and holding of live monarchs at any life 

stage), captively rearing (defined in this 

rulemaking as the holding of 

caterpillars, pupae, or adults and raising 

them in captivity long enough for them 

to move to the next life stage or to 

reproduce), and releasing monarchs has 

inspirational and educational value and 

can foster lifelong connections to 

nature. Collection of monarchs at any 

life stage from the wild has the potential 

to pose a risk to population numbers. 

After evaluating the threat of collection, 

we determined there is no evidence that 

the current rate of collection, in 

combination with the current rate of 

release, is affecting monarch 

populations (Service 2024a, p. 109). 

However, we assume that the collection 

of clustering monarchs could have 

greater impacts to the populations and 

species’ viability, as the migratory 

populations are at their smallest when 

monarchs are clustering and 

overwintering clusters contain 

concentrated numbers of individuals; 

thus, wild clustering monarchs may not 

be collected as part of this exception. 

Captive-rearing can also pose risks to 

wild monarch populations, such as 

through the spread of diseases and loss 

of genetic diversity (Altizer et al. 2015, 

p. 1), and potential negative effects to 

the fitness of individuals and their 

migratory capabilities (Altizer et al. 

2015, p. 2). The negative effects can 

greatly impact wild monarch 

populations when rearing is conducted 

on a large scale (Altizer et al. 2015, pp. 

1–3). However, captive-rearing on a 

small scale can achieve all the 

inspirational and educational benefits 

while reducing the risk of negatively 

affecting populations, particularly if 

protocols are followed to minimize 

disease and genetic impacts. For the 

purposes of this proposed rule, we 

describe small-scale captive-rearing as 

collection, raising, and releasing 250 or 

fewer monarchs in a given year. We 

consider the collection, raising, and 

releasing of more than 250 monarchs 

per year to be a large-scale endeavor, for 

which a permit would be required 

through section 10(a)(1)(A) of the Act. 

We conclude that the overall impact 

of collecting, possessing, captively 

rearing, and releasing 250 or fewer 

individual monarchs at one location or 

facility (e.g., home, botanical garden, 

school, or business) is not expected to 

negatively affect conservation and 

recovery efforts for the monarch 

butterfly. Therefore, take due to these 

activities would not be prohibited under 

this proposed 4(d) rule. However, 

collection of clustered monarchs would 

be prohibited. Clustered monarchs are 

typically the individuals that will 

produce the next year’s first migratory 

generation. The migratory populations 

are at their smallest during the 

overwintering time period when 

monarchs cluster (typically September 

through March), and it is especially 

important that these individuals survive 

the winter to breed in the spring. 

Therefore, our proposed exception does 

not include take resulting from handling 

or collection of clustered monarchs; a 

permit to do so would be required 

through section 10(a)(1)(A) of the Act. 

(6) Non-lethal scientific research and 

educational activities involving a 

limited number of monarchs. 

Future scientific research on monarch 

butterflies and their use in educational 

activities in the contiguous United 

States will aid conservation and 

recovery by leading to a better 

understanding and appreciation of the 

biology and ecology of the species. 

Activities associated with scientific 

research and education may include 

non-lethal collection for purposes of 

handling, netting, sampling for disease, 

tagging of monarchs, and conducting 

life cycle and specimen observations of 

captive monarchs. The same restrictions 

related to possession and release of 

monarchs (i.e., limiting activities to 250 

or fewer monarchs per year) would 

apply to scientific research and 

educational activities. To encourage 

continued and further scientific 

research and educational activities, we 

are proposing to include exceptions in 

the 4(d) rule that allow these activities 

without requiring additional permits; 

however, we do not include take of 

clustered monarchs in the exception. As 

discussed in the previous section, it is 

especially important that clustered 

overwintering monarchs survive the 

winter to breed in the spring. Therefore, 

we do not include handling or 

collection of clustered monarchs for 

scientific research from this exception; 

a permit to do so would be required 

through section 10(a)(1)(A) of the Act. 

(7) Possession of dead monarchs. 

Though overwintering monarchs can 

live longer, the average life expectancy 

of monarchs during the breeding season 

is 2 to 5 weeks. It is common for people 

to find and collect dead adult monarchs 

or pieces of wing. Collection and 

possession of this type is not currently 

a threat to the species. In some cases, 

with other species, we might be 

concerned about collection becoming a 

threat due to collectors capturing live 

butterflies and preserving them because 

the species is listed and likely to 

become more rare. However, the 

monarch has historically occurred in 

such large numbers and across such a 

large range that the species is already a 

common specimen in butterfly 

collections. The potential impacts from 

collection and possession of dead 

monarchs are considered minimal and 

not likely to affect the monarch butterfly 

at a population or species level. 

Collection of live wild adult monarchs 

and intentionally killing them for 

preservation purposes would be 

prohibited. We are proposing in this 

4(d) rule that possession of dead 

monarchs collected in a lawful manner 

would not be prohibited. 

(8) Sale of captively reared monarchs. 

We propose to limit the sale of 

captively reared monarchs to 250 or 

fewer individuals per year from a single 

location or facility. It is common for 

individuals and organizations such as 

garden groups, schools, and small 

businesses to sell captively reared 

monarchs during the breeding season. 

These activities provide inspirational 

and educational value for the public but 

have the same risks as discussed above. 

We find that if these activities are 

conducted on a small scale (limited to 

250 or fewer monarchs in a given year), 

the potential for negative impacts would 

be minimal. 

We conclude that the overall impact 

of selling 250 or fewer individual 

monarchs at one location or facility 

(e.g., home, botanical garden, school, or 

business) is not expected to negatively 

affect conservation and recovery efforts 

for the monarch butterfly. Therefore, 

take due to these activities would not be 

prohibited under this proposed 4(d) 

rule. 

Public Comment Requested on 

Exception for Pesticide Use 

We seek public comment on how to 

address pesticide use under a 4(d) rule 

for the monarch. We recognize that 

certain types of pesticide use can have 

direct or indirect negative effects on 

monarchs, including aerial broadcast 

application of insecticides, use of 

herbicides that remove milkweeds, and 

use of some biopesticides. However, not 

all uses and application methods will 

impact monarchs. For example, 

insecticide application using hand-held 

sprayers, soil injection, in furrow 

sprays, tree trunk drenching, or tree 

injection, are unlikely to result in 


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pesticide exposure to monarchs. We 

seek comment on which pesticide uses 

and application methods result in 

exposure and adverse effects to 

monarchs, whether to except take from 

those uses in a 4(d) rule, and whether 

the exceptions for those uses should 

include measures to mitigate the effects 

of pesticides on monarchs. We also seek 

comment on whether we should tailor 

any measures according to the areas and 

times of the year when monarchs are 

present and, if so, what is the most 

feasible method to convey this 

information to pesticide users. Further, 

any measures should focus on 

minimizing impacts to monarchs by 

reducing exposure to the species, but we 

also seek comment on whether it is 

appropriate to offset unavoidable 

impacts such as through habitat 

restoration and, if so, how to 

accomplish this in a 4(d) rule. 

If we include mitigation measures for 

excepted uses and application methods 

in a 4(d) rule, we also seek comment on 

how to align those measures with the 

EPA’s work under FIFRA to minimize 

the effects of pesticides on listed species 

and to ensure that FIFRA registration 

and registration review decisions 

comply with section 7(a)(2) (see 

Conservation Efforts and Regulatory 

Mechanisms, above). FIFRA, not the 

ESA, is the primary Federal law that 

determines the conditions under which 

pesticides may be used. Given all the 

EPA’s ongoing work to address pesticide 

impacts on listed species (e.g., 

Herbicide Strategy, Insecticide Strategy, 

Vulnerable Species Action Plan), we 

seek to minimize confusion and 

regulatory burdens for pesticide users as 

a result of any mitigation measures we 

may include in a 4(d) rule for any 

excepted pesticide uses. Rather than 

include specific pesticide mitigation 

measures in the proposed 4(d) rule, we 

seek comment on how best to identify 

those measures in a manner that aligns 

with the EPA’s ongoing work on this 

issue. 

To inform public comments, we 

provide additional information on 

certain pesticide uses that impact 

monarchs. Many insecticides are a 

threat to monarchs based on their mode 

of action to target insects and their 

potential exposure to monarchs. 

Conventional insecticides have active 

ingredients used to control insects by 

killing or otherwise preventing them 

from engaging in behaviors that are 

undesirable or destructive. Insecticides 

are used in areas where monarchs occur 

and can drift off intended use sites with 

certain methods of application. They are 

likely to cause lethal and sublethal 

effects to nontarget lepidopterans (i.e., 

the order of insects that includes 

butterflies and moths) that are exposed 

(Service 2024a, appendix 5). Even 

though monarchs are not typically the 

target of insecticides, they can be killed 

by these chemicals if they are 

incidentally exposed. Many 

conventional insecticides have 

nonspecific modes of action and are 

expected to result in mortality to most 

or all insect species when exposure 

exceeds a certain threshold. 

In contrast, biopesticides are typically 

less toxic than conventional pesticides 

and generally affect only the specific 

target insect pest and closely related 

organisms. Biopesticides include 

naturally occurring substances that 

control pests by nontoxic mechanisms 

(e.g., biochemical pesticides), 

microorganisms that control pests (e.g., 

microbial pesticides), and pesticidal 

substances produced by plants 

containing added genetic material (e.g., 

plant-incorporated protectants). While 

application of most biopesticides is not 

expected to affect monarchs, certain 

forms of the microbial pesticide Bacillus 

thuringiensis (Bt) are active against 

lepidopterans. Lepidoptera-active Bt 

strains produce a specific mix of 

insecticidal proteins that are active 

against caterpillars due to taxa-specific 

biological properties and are used to 

control pests such as the spongy moth. 

At present, Lepidoptera-active strains 

include Bacillus thuringiensis kurstaki 

(Btk) and Bacillus thuringiensis azawai 

(Bta), though additional Lepidopteraactive Bt products may be registered in 

the future. Other currently registered Bt 

products, such as Bacillus thuringienses 

israelensis (Bti), are not active against 

Lepidoptera and thus are not expected 

to cause negative effects to monarchs. 

Products incorporated with Bt, such as 

Bt-corn, are also not expected to cause 

negative effects to monarchs because the 

toxin expression in Bt-corn is limited to 

pollen, where it occurs at such low 

concentrations that exposure presents a 

low risk to monarchs. In addition to 

direct exposure to insecticide residues 

from spray application, monarchs may 

be exposed via diet to systemic 

insecticides that are absorbed by nectar 

and milkweed plants from the soil and 

become incorporated into tissues (e.g., 

leaves, flowers, pollen, and nectar). 

While numerous types of insecticides 

may be incorporated into plants 

systemically, neonicotinoids are a class 

of insecticides that is particularly 

known to distribute throughout plant 

tissues in this manner. Laboratory 

studies demonstrate that exposure to 

neonicotinoids can negatively affect 

adult, larval, and pupal survival of 

monarchs. However, concentrations of 

neonicotinoids in the environment from 

systemic incorporation have not been 

found to reach levels known to elicit the 

negative effects seen in laboratory 

studies. 

Another application of systemic 

insecticides is the direct application or 

coating of seeds with insecticides prior 

to planting to control or repel disease 

organisms, insects, and pests that attack 

crops or desirable plants. Because seeds 

are broadly treated and often used 

prophylactically (i.e., not in response to 

a documented pest outbreak), their use 

is widespread for certain crops. 

Insecticide applications by wet or liquid 

seed-coatings and slurry seed treatment 

create limited exposure pathways to the 

monarch. Dust-treated seed applications 

incur a potential for the dust to drift at 

the time of planting. Treated seed dust 

could drift off the field, exposing 

monarchs by direct contact with the 

insecticide or from systemic 

incorporation into nearby milkweed or 

nectar plants. However, the exposure 

potential to the monarch from treated 

seeds is orders of magnitude lower 

compared to exposure potential from 

aerial broadcast applications, and 

concentrations of insecticides detected 

in pollen and nectar following seed 

treatments are below known thresholds 

for negative effects in monarchs (Beedle 

and Harbin 2011, p. 8; EPA 2016, pp. 

14–22; EPA 2020, pp. 87–88). 

Other pesticide formulation types, in 

contrast to liquid forms that can result 

in direct exposure, are less likely to lead 

to exposure of monarchs through 

contact or dietary routes and are 

therefore not expected to negatively 

affect monarchs. For example, solid 

forms of pesticides, such as granules or 

baits, are applied directly to the soil or 

turf grass typically by hand or a 

spreader specifically designed for the 

size of the carrier particle and provide 

little opportunity for contact with 

monarch adults or larvae. In addition, 

solid formulations are not expected to 

result in drift. 

For other pesticide classes, such as 

herbicides and fungicides, our review of 

the scientific information available 

indicates a limited number of individual 

monarchs will experience negative 

effects from direct exposure to these 

pesticides. We do not expect the low 

number of individuals affected from 

direct exposure to other classes of 

pesticides to impact the monarch 

butterfly at a population or species 

level. Certain herbicide uses, however, 

have resulted in the loss of milkweed 

and nectar, which is discussed in the 

Activities that may maintain, enhance, 

remove, or establish milkweed and 


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nectar plants within the breeding and 

migratory range that do not result in 

conversion of native or naturalized 

grassland, shrubland, or forested 

habitats section. As a result, we are 

considering what mitigation measures, 

if any, from the EPA’s Herbicide 

Strategy (EPA 2024a, entire) and the 

agency’s other ESA work (EPA 2024b, 

entire; EPA 2024c, entire), should 

inform any exceptions for herbicide use 

in a 4(d) rule for the monarch. Further, 

the EPA is considering how habitat 

restoration and other forms of 

compensatory mitigation may address 

unavoidable pesticide impacts to listed 

species. We thus seek comment on 

whether and how we should consider 

habitat restoration or creation as an 

offset for unavoidable pesticide impacts 

to the monarch under a 4(d) rule. 

Summary 

To promote conservation of monarch 

butterflies in the contiguous United 

States, we need to (1) achieve a 

significant increase in the availability of 

milkweed and nectar plants in monarch 

breeding and migratory areas; (2) protect 

and enhance overwintering habitat; (3) 

avoid and minimize impacts to 

monarchs and their habitat from 

insecticides and herbicides; and (4) 

maintain public support for the 

conservation of monarch butterflies. 

Therefore, we focus our efforts in this 

proposed 4(d) rule on incentivizing 

known beneficial actions for the species, 

as well as reducing the regulatory 

requirements for the public on forms of 

take that are considered inconsequential 

to the conservation of the species in the 

contiguous United States, Puerto Rico, 

and the U.S. Virgin Islands. These 

exceptions would not apply to States or 

territories that are outside the historical 

range of the species because the 

excepted activities would not be 

prohibited there. 

We find that the activities resulting in 

take that are excepted by this proposed 

4(d) rule will have a de minimis impact 

to the species and will promote 

conservation and recovery of monarch 

butterflies in the contiguous United 

States. The following activities are 

expected to result in low levels of take 

of individuals or will aid conservation 

and recovery of the species: activities 

that may maintain, enhance, remove, or 

establish milkweed and nectar plants 

within the breeding and migratory 

range; implementation of a 

comprehensive conservation plan 

developed by or in coordination with a 

State agency or implementation of a 

conservation program developed by a 

Federal agency; maintenance or 

improvement of monarch overwintering 

habitat in the United States consistent 

with a site-specific Service-approved 

Overwintering Site Land Management 

Plan; monarch mortality due to vehicle 

strikes; small-scale (250 or fewer 

butterflies) collection, possession, 

captive-rearing, and release of 

monarchs; scientific research; 

educational activities; possession of 

dead monarchs; and sale of captively 

reared monarchs. In order to identify 

how the effects of these activities on 

monarch butterflies may differ from our 

current understanding and what 

additional activities we should consider 

excepting in a 4(d) rule, we are 

requesting additional information on the 

exceptions in this proposed 4(d) rule. 

We specifically request public 

comments on how to address pesticide 

use under a 4(d) rule for the monarch. 

To submit information, see the 

Information Requested section. 

III. Critical Habitat 

Background 

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

that, to the maximum extent prudent 

and determinable, we designate a 

species’ critical habitat concurrently 

with listing the species. Critical habitat 

is defined in section 3(5)(A) of the Act 

as: 

(1) The specific areas within the 

geographical area occupied by the 

species, at the time it is listed in 

accordance with the Act, on which are 

found those physical or biological 

features 

(a) Essential to the conservation of the 

species, and 

(b) Which may require special 

management considerations or 

protection; and 

(2) Specific areas outside the 

geographical area occupied by the 

species at the time it is listed, upon a 

determination that such areas are 

essential for the conservation of the 

species. 

Our regulations at 50 CFR 424.02 

define the geographical area occupied 

by the species as an area that may 

generally be delineated around species’ 

occurrences, as determined by the 

Secretary (i.e., range). Such areas may 

include those areas used throughout all 

or part of the species’ life cycle, even if 

not used on a regular basis (e.g., 

migratory corridors, seasonal habitats, 

and habitats used periodically, but not 

solely by vagrant individuals). 

Conservation, as defined under 

section 3(3) of the Act, means to use and 

the use of all methods and procedures 

that are necessary to bring an 

endangered or threatened species to the 

point at which the measures provided 

pursuant to the Act are no longer 

necessary. Such methods and 

procedures include, but are not limited 

to, all activities associated with 

scientific resources management such as 

research, census, law enforcement, 

habitat acquisition and maintenance, 

propagation, live trapping, and 

transplantation, and, in the 

extraordinary case where population 

pressures within a given ecosystem 

cannot be otherwise relieved, may 

include regulated taking. 

Critical habitat receives protection 

under section 7 of the Act through the 

requirement that each Federal action 

agency ensure, in consultation with the 

Service, that any action they authorize, 

fund, or carry out is not likely to result 

in the destruction or adverse 

modification of designated critical 

habitat. The designation of critical 

habitat does not affect land ownership 

or establish a refuge, wilderness, 

reserve, preserve, or other conservation 

area. Such designation also does not 

allow the government or public to 

access private lands. Such designation 

does not require implementation of 

restoration, recovery, or enhancement 

measures by non-Federal landowners. 

Rather, designation requires that, where 

a landowner requests Federal agency 

funding or authorization for an action 

that may affect an area designated as 

critical habitat, the Federal agency 

consults with the Service under section 

7(a)(2) of the Act. If the action may 

affect the listed species itself (such as 

for occupied critical habitat), the 

Federal agency would have already been 

required to consult with the Service 

even absent the designation because of 

the requirement to ensure that the 

action is not likely to jeopardize the 

continued existence of the species. Even 

if the Service were to conclude after 

consultation that the proposed activity 

is likely to result in destruction or 

adverse modification of the critical 

habitat, the Federal action agency and 

the landowner are not required to 

abandon the proposed activity, or to 

restore or recover the species; instead, 

they must implement ‘‘reasonable and 

prudent alternatives’’ to avoid 

destruction or adverse modification of 

critical habitat. 

Under the first prong of the Act’s 

definition of critical habitat, areas 

within the geographical area occupied 

by the species at the time it was listed 

are included in a critical habitat 

designation if they contain physical or 

biological features (1) which are 

essential to the conservation of the 

species and (2) which may require 

special management considerations or 

protection. For these areas, critical 


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habitat designations identify, to the 

extent known using the best scientific 

data available, those physical or 

biological features that are essential to 

the conservation of the species (such as 

space, food, cover, and protected 

habitat). 

Under the second prong of the Act’s 

definition of critical habitat, we can 

designate critical habitat in areas 

outside the geographical area occupied 

by the species at the time it is listed, 

upon a determination that such areas 

are essential for the conservation of the 

species. 

Section 4(b)(2) of the Act requires that 

we designate critical habitat on the basis 

of the best scientific data available. 

Further, our Policy on Information 

Standards Under the Endangered 

Species Act (published in the Federal 

Register on July 1, 1994 (59 FR 34271)), 

the Information Quality Act (section 515 

of the Treasury and General 

Government Appropriations Act for 

Fiscal Year 2001 (Pub. L. 106–554; H.R. 

5658)), and our associated Information 

Quality Guidelines provide criteria, 

establish procedures, and provide 

guidance to ensure that our decisions 

are based on the best scientific data 

available. They require our biologists, to 

the extent consistent with the Act and 

with the use of the best scientific data 

available, to use primary and original 

sources of information as the basis for 

recommendations to designate critical 

habitat. 

When we are determining which areas 

should be designated as critical habitat, 

our primary source of information is 

generally the information from the SSA 

report and information developed 

during the listing process for the 

species. Additional information sources 

may include any generalized 

conservation strategy, criteria, or outline 

that may have been developed for the 

species; the recovery plan for the 

species; articles in peer-reviewed 

journals; conservation plans developed 

by States and counties; scientific status 

surveys and studies; biological 

assessments; other unpublished 

materials; or experts’ opinions or 

personal knowledge. 

Habitat is dynamic, and species may 

move from one area to another over 

time. We recognize that critical habitat 

designated at a particular point in time 

may not include all of the habitat areas 

that we may later determine are 

necessary for the recovery of the 

species. For these reasons, a critical 

habitat designation does not signal that 

habitat outside the designated area is 

unimportant or may not be needed for 

recovery of the species. Areas that are 

important to the conservation of the 

species, both inside and outside the 

critical habitat designation, will 

continue to be subject to: (1) 

Conservation actions implemented 

under section 7(a)(1) of the Act; (2) 

regulatory protections afforded by the 

requirement in section 7(a)(2) of the Act 

for Federal agencies to ensure their 

actions are not likely to jeopardize the 

continued existence of any endangered 

or threatened species; and (3) the 

prohibitions found in the 4(d) rule. 

Federally funded or permitted projects 

affecting listed species outside their 

designated critical habitat areas may 

still result in jeopardy findings in some 

cases. These protections and 

conservation tools will continue to 

contribute to recovery of the species. 

Similarly, critical habitat designations 

made on the basis of the best available 

information at the time of designation 

will not control the direction and 

substance of future recovery plans, 

habitat conservation plans (HCPs), or 

other species conservation planning 

efforts if new information available at 

the time of those planning efforts calls 

for a different outcome. 

Physical or Biological Features 

Essential to the Conservation of the 

Species 

In accordance with section 3(5)(A)(i) 

of the Act and regulations at 50 CFR 

424.12(b), in determining which areas 

we will designate as critical habitat from 

within the geographical area occupied 

by the species at the time of listing, we 

consider the physical or biological 

features that are essential to the 

conservation of the species and which 

may require special management 

considerations or protection. The 

regulations at 50 CFR 424.02 define 

‘‘physical or biological features essential 

to the conservation of the species’’ as 

the features that occur in specific areas 

and that are essential to support the lifehistory needs of the species, including, 

but not limited to, water characteristics, 

soil type, geological features, sites, prey, 

vegetation, symbiotic species, or other 

features. A feature may be a single 

habitat characteristic or a more complex 

combination of habitat characteristics. 

Features may include habitat 

characteristics that support ephemeral 

or dynamic habitat conditions. Features 

may also be expressed in terms relating 

to principles of conservation biology, 

such as patch size, distribution 

distances, and connectivity. For 

example, physical features essential to 

the conservation of the species might 

include gravel of a particular size 

required for spawning, alkaline soil for 

seed germination, protective cover for 

migration, or susceptibility to flooding 

or fire that maintains necessary earlysuccessional habitat characteristics. 

Biological features might include prey 

species, forage grasses, specific kinds or 

ages of trees for roosting or nesting, 

symbiotic fungi, or absence of a 

particular level of nonnative species 

consistent with conservation needs of 

the listed species. The features may also 

be combinations of habitat 

characteristics and may encompass the 

relationship between characteristics or 

the necessary amount of a characteristic 

essential to support the life history of 

the species. 

In considering whether features are 

essential to the conservation of the 

species, we may consider an appropriate 

quality, quantity, and spatial and 

temporal arrangement of habitat 

characteristics in the context of the lifehistory needs, condition, and status of 

the species. These characteristics 

include, but are not limited to, space for 

individual and population growth and 

for normal behavior; food, water, air, 

light, minerals, or other nutritional or 

physiological requirements; cover or 

shelter; sites for breeding, reproduction, 

or rearing (or development) of offspring; 

and habitats that are protected from 

disturbance. 

Recovery of monarch butterflies will 

require maintaining and, where 

necessary, improving habitat across the 

range to ensure the long-term viability 

of the species. The physical or 

biological features that are essential to 

the conservation of the species and 

which may require special management 

considerations or protection are a subset 

of the habitat across the range necessary 

for species recovery. We have 

determined that the areas occupied by 

the monarch butterfly during the winter 

are the subset of habitat across the range 

needed for recovery that are essential to 

the conservation of the species (Service 

2024b, entire). Monarchs exhibit high 

annual site fidelity, densely cluster at 

these sites, and are especially 

vulnerable to their environment (e.g., 

severe storm events, temperature 

fluctuations, predation, etc.) during the 

overwintering phase of their life cycle. 

Because we do not designate critical 

habitat outside of the United States, we 

are only designating overwintering 

habitat in the United States and not 

designating any areas used by migratory 

monarchs for overwintering in Mexico 

or elsewhere. 

We are not proposing to designate 

critical habitat within monarch butterfly 

breeding and migratory areas or in areas 

used by nonmigratory monarchs in the 

winter. Although breeding and 

migratory habitats are important and 

support the species’ life cycle, this kind 


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of habitat in North America is broad and 

spatially diffuse. The specific 

geographic areas that contain essential 

breeding and migratory habitat can 

change in relatively short timeframes 

due to many reasons, including weather 

conditions, natural succession, 

disturbance, and habitat creation. The 

breeding habitats used by nonmigratory 

monarchs in the winter (e.g., southern 

Florida, Gulf Coast, southern Atlantic 

Coast, and southern Pacific Coast) have 

the same characteristics of being 

expansive in nature, having variability 

in the suitability of specific locations 

from year to year, and being used by 

monarchs opportunistically. Due to the 

expansive nature of the habitat (existing 

and potential), the variability in the 

suitability of specific locations from 

year to year, and the opportunistic 

nature of monarch habitat use, we are 

not proposing to designate critical 

habitat in breeding and migratory areas. 

Migratory monarchs in the western 

population primarily overwinter in 

groves along the coast of California and 

Baja California (Jepsen and Black 2015, 

p. 149). These groves are populated by 

a variety of tree species, including blue 

gum eucalyptus (Eucalyptus globulus), 

Monterey pine (Pinus radiata), and 

Monterey cypress (Hesperocyparis 

macrocarpa) (Griffiths and Villablanca 

2015, pp. 41, 46–47), all of which act as 

roost trees. These groves provide 

indirect sunlight for the overwintering 

monarchs, sources of moisture for 

hydration, defense against freezing 

temperatures, and protection against 

strong winds (Tuskes and Brower 1978, 

p. 149; Leong 1990, pp. 908–910, Leong 

1999, p. 213). The close proximity to the 

coast (average distance of 1.47 mi (2.37 

km) also provides a mild winter climate 

(Leong et al. 2004, p. 180). 

To support overwintering western 

monarchs, we identified a support zone, 

which is an area of overwintering 

habitat surrounding an overwintering 

site that provides essential resources for 

monarchs, such as nectar plants, 

hydration sources, and protective 

landscape features that lessen the 

impacts from prevailing winds on 

groves of trees. Support zones contain 

the nectar resources close to the 

overwintering site (within 152 m (500 ft) 

of the shelter zone and core zone). 

Summary of Essential Physical or 

Biological Features 

We derive the specific physical or 

biological features essential to the 

conservation of the monarch butterfly 

from studies of the species’ habitat, 

ecology, and life history as described 

below. Additional information can be 

found in the SSA report (Service 2024a, 

entire; available on https://

www.regulations.gov under Docket No. 

FWS–R3–ES–2024–0137). We have 

determined that the following physical 

or biological features are essential to the 

conservation of the monarch butterfly: 

1. Groves of trees (e.g., blue gum 

eucalyptus, Monterey pine, Monterey 

cypress, Coast redwood, coast live oak, 

Douglas fir, Torrey pine, western 

sycamore, bishop pine) that serve as 

sites for overwintering monarchs to 

cluster along the coast of California. 

2. Trees, herbaceous or shrubby 

vegetation, and/or topography 

surrounding overwintering groves that 

contribute to the following microclimate 

conditions: 

a. Indirect or dappled sunlight, 

b. Water sources (e.g., stream, pond, 

moist soil) for hydration, 

c. Defense against freezing 

temperatures, and 

d. Protection from strong winds. 

3. Supportive features nearby (i.e., 

within 152 m (500 ft) of) overwintering 

groves, including the following: 

a. Flowering plants for nectar, 

b. Water sources (e.g., stream, pond, 

moist soil) for hydration, and 

c. Protective landscape features (e.g., 

topography and vegetation that lessen 

the impacts of prevailing winds on 

groves of trees. 

Special Management Considerations or 

Protection 

When designating critical habitat, we 

assess whether the specific areas within 

the geographical area occupied by the 

species at the time of listing contain 

features which are essential to the 

conservation of the species and which 

may require special management 

considerations or protection. The 

features essential to the conservation of 

the monarch butterfly may require 

special management considerations or 

protection to reduce the following 

threats: the ongoing impacts of loss and 

degradation of breeding, migratory, and 

overwintering habitat and the effects of 

climate change. 

Special management considerations 

or protection may be required within 

critical habitat areas to address these 

threats. Management activities that 

could ameliorate these threats include, 

but are not limited to, protecting 

overwintering habitats and maintaining 

the tree groves and the surrounding 

habitat; protecting and maintaining 

landscape features that contribute to the 

microclimate conditions of groves; 

proactively planting trees and shrubs or 

removing and replacing dead trees, 

where appropriate, to support long-term 

habitat suitability of overwintering sites; 

restoring or enhancing nectar habitat 

near overwintering areas using native, 

insecticide-free plants; reducing fuel 

loads and minimizing the risk of 

catastrophic wildfire within 

overwintering habitat through selective 

thinning; avoiding use of pesticides near 

overwintering sites or nectar habitat 

when monarchs may be present; and 

minimizing the likelihood that 

development projects will impact the 

quality or quantity of the habitat. 

Criteria Used To Identify Critical 

Habitat 

As required by section 4(b)(2) of the 

Act, we use the best scientific data 

available to designate critical habitat. In 

accordance with the Act and our 

implementing regulations at 50 CFR 

424.12(b), we review available 

information pertaining to the habitat 

requirements of the species and identify 

specific areas within the geographical 

area occupied by the species at the time 

of listing and any specific areas outside 

the geographical area occupied by the 

species to be considered for designation 

as critical habitat. We are not currently 

proposing to designate any areas outside 

the geographical area occupied by the 

species because we have not identified 

any unoccupied areas that meet the 

definition of critical habitat. 

Our conservation strategy and rule set 

for determining critical habitat for the 

monarch butterfly evaluated quantity 

and quality of areas, distribution of 

areas, and landscape-level 

considerations needed to conserve and 

maintain a sufficient number of 

overwintering sites with habitat 

characteristics to support high 

population resiliency and redundancy 

over time across the core overwintering 

range. We also attempted to capture 

latitudinal diversity across the core 

overwintering range. Because 

aggregations of many individuals can 

moderate climatic conditions 

experienced by overwintering monarchs 

and offer some protection, we gave 

priority to the largest sites (i.e., those 

having the most monarchs or largest 

aggregations). Overwintering sites that 

have consistently supported the largest 

overwintering aggregations through time 

will most likely continue to do so in the 

future. We propose to designate as 

critical habitat lands that we have 

determined are occupied at the time of 

listing (i.e., currently occupied) and that 

contain one or more of the physical or 

biological features that are essential to 

the conservation of the species. 

We selected sites for critical habitat 

based upon maximum occupancy rates 

of overwintering butterflies in California 

observed during the Western Monarch 

Count from 2013 to 2022 (see Xerces 


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Society 2024a, unpaginated). The 

criteria for selection were all 

overwintering sites that contained 1,000 

or more butterflies during at least 3 

years in the 10-year period, 5,000 or 

more butterflies in 1 year of the 10-year 

period, or 1,000 or more butterflies 

during at least 2 years if the sites were 

discovered less than 10 years ago. We 

consider 1,000 monarchs to be a 

reasonable threshold for a site to be 

described as large; however, we require 

sites to meet the large-site threshold in 

2 (if there are data limitations) or 3 years 

to demonstrate the site is suitable for 

overwintering (i.e., that the number 

observed was not an anomaly). 

Similarly, we require sites to meet the 

higher threshold of 5,000 monarchs in 1 

year because 5,000 is sufficient to 

demonstrate sites are suitable for 

overwintering without needing to be 

repeated. We chose 10 years as the 

timeframe because a large portion of the 

overwintering sites were monitored 

during this period as part of the Western 

Monarch Count (Xerces Society 2024a, 

unpaginated) and 10 years is long 

enough to capture the variability of site 

use by butterflies. Additionally, the 

timeframe is short enough that we 

expect the majority of sites still 

maintain conditions that support large 

numbers of monarchs. 

For each overwintering site that met 

the abundance criteria, we identified the 

size and location of the site based on 

mapping data collected as part of the 

annual Western Monarch Count (see 

Xerces Society 2024b, unpaginated) to 

identify the core and shelter zones of 

each site. The core zone is the general 

area within an overwintering site that 

contains the trees where monarchs 

cluster. The shelter zone is the larger 

area where trees, other vegetation, and 

topography provide wind protection 

and other microclimate conditions that 

support monarch clustering and/or 

aggregation in the core zone. We then 

applied a 152-meter (500-foot) buffer to 

identify the approximate location of the 

support zone surrounding each 

overwintering site. The support zone 

provides essential resources for 

monarchs, such as nectar plants, 

hydration sources, and protective 

landscape features that lessen the 

impacts from prevailing winds on 

groves of trees. The size of the support 

zone is recommended by species experts 

based on observations of monarch 

movements and overwintering resources 

(Xerces Society and Service 2023, 

entire). Each area proposed for 

designation as critical habitat includes 

the core, shelter, and support zones for 

one or more overwintering sites. 

Together, the three zones provide all of 

the physical and biological features 

essential to the conservation of 

monarchs at each overwintering site, 

though the condition of the features 

vary by site. The areas proposed for 

designation as critical habitat meet the 

occupancy criteria because they hosted 

overwintering monarchs in the recent 

past and over a reasonable timeframe for 

observation; therefore, they are 

considered occupied. No unoccupied 

areas meet the definition of critical 

habitat because they are unlikely to be 

suitable for overwintering. 

When determining proposed critical 

habitat boundaries, we made every 

effort to avoid including developed 

areas such as lands covered by 

buildings, pavement, and other 

structures because, in most cases, such 

lands lack physical or biological 

features necessary for the monarch 

butterfly. The scale of the maps we 

prepared under the parameters for 

publication within the Code of Federal 

Regulations may not reflect the 

exclusion of such developed lands. Any 

such lands inadvertently left inside 

critical habitat boundaries shown on the 

maps of this proposed rule have been 

excluded by text in the proposed rule 

and are not proposed for designation as 

critical habitat. Therefore, if the critical 

habitat is finalized as proposed, a 

Federal action involving these lands 

would not trigger section 7 consultation 

with respect to critical habitat and the 

requirement of no adverse modification 

unless the specific action would affect 

the physical or biological features in the 

adjacent critical habitat. 

The proposed critical habitat 

designation is defined by the map or 

maps, as modified by any accompanying 

regulatory text, presented at the end of 

this document under Proposed 

Regulation Promulgation. 

Proposed Critical Habitat Designation 

We are proposing seven units as 

critical habitat for the monarch 

butterfly. The critical habitat areas we 

describe below constitute our current 

best assessment of areas that meet the 

definition of critical habitat for the 

monarch butterfly. The areas we 

propose as critical habitat are within the 

following seven units: (1) Ventura 

County, (2) Santa Barbara County, (3) 

San Luis Obispo County, (4) Monterey 

County, (5) Santa Cruz County, (6) 

Alameda County, and (7) Marin County. 

Table 2 shows the proposed critical 

habitat units and the approximate area 

of each unit. 

TABLE 2—PROPOSED CRITICAL HABITAT UNITS FOR MONARCH BUTTERFLY

[All proposed units are occupied by the species. Area estimates reflect all land within critical habitat unit and subunit boundaries.] 

Critical habitat unit Land ownership by type 

Size of unit in 

acres 

(hectares) 

1. Ventura County .................................................................... Public (Local) ..........................................................................

Private .....................................................................................

98 (39) 

395 (160) 

2. Santa Barbara County: 

Subunit 2a ......................................................................... Public (State, Local) ................................................................

Private .....................................................................................

139 (56) 

826 (334) 

Subunit 2b ......................................................................... Public (State) ...........................................................................

Private .....................................................................................

42 (17) 

389 (158) 

3. San Luis Obispo County: 

Subunit 3a ......................................................................... Public (State) ...........................................................................

Private .....................................................................................

86 (35) 

384 (155) 

Subunit 3b ......................................................................... Public (State, Local) ................................................................

Private .....................................................................................

365 (148) 

274 (111) 

Subunit 3c ......................................................................... Public (Federal, State, Local) .................................................

Private .....................................................................................

258 (105) 

145 (59) 

4. Monterey County ................................................................. Public (State, Local) ................................................................

Private .....................................................................................

54 (22) 

150 (61) 

5. Santa Cruz County .............................................................. Public (Federal, State, Local) .................................................

Private .....................................................................................

114 (46) 

175 (71) 


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TABLE 2—PROPOSED CRITICAL HABITAT UNITS FOR MONARCH BUTTERFLY—Continued 

[All proposed units are occupied by the species. Area estimates reflect all land within critical habitat unit and subunit boundaries.] 

Critical habitat unit Land ownership by type 

Size of unit in 

acres 

(hectares) 

6. Alameda County .................................................................. Public (Local) ..........................................................................

Private .....................................................................................

54 (22) 

207 (84) 

7. Marin County ....................................................................... Public (Federal, State, Local) .................................................

Private .....................................................................................

53 (21) 

189 (77) 

Total .................................................................................. .................................................................................................. 4,395 (1,778) 

Note: Area sizes may not sum due to rounding. 

We present brief descriptions of all 

units, and reasons why they meet the 

definition of critical habitat for the 

monarch butterfly, below. The site 

names and numbers listed below match 

those used for the Western Monarch 

Count, an annual survey conducted 

since the 1980s that is now coordinated 

by Mia Monroe and the Xerces Society. 

We use the same site names because 

that is how these locations are 

colloquially known to the public, but it 

is important to note that the geographic 

boundaries of the critical habitat units 

do not match the boundaries of the 

overwintering sites that may be found 

online. 

Unit 1: Ventura County 

Unit 1 consists of 493 ac (199 ha) in 

Ventura County, California, and is 

composed of lands in city (98 ac (39 ha)) 

and private ownership (395 ac (160 ha)). 

It includes four areas: Arrundel 

Barranca (site #3142), Camino Real Park 

(site #3143), Harmon Barranca (site 

#3144), and Harbor Boulevard (site 

#3151). Part of the areas at Harmon 

Barranca and Camino Real Park are 

owned and managed by the City of 

Ventura. The monarch butterfly 

occupies the entire unit, and the unit 

contains all of the physical or biological 

features essential to the conservation of 

the species. 

Special management considerations 

or protection may be required within 

Unit 1 to address coastal development, 

unsuitable management practices in 

overwintering habitat, insecticide 

applications, herbicide applications 

resulting in loss of nectar sources, and 

impacts from climate change (e.g., 

drought, increased storm severity, 

extreme temperatures). Management 

activities, such as incompatible tree 

trimming or removal, nectar plant 

removal, and tropical milkweed 

planting, have the potential to impact 

the suitability of overwintering habitat 

used by monarchs in Unit 1. Special 

management focused on maintaining 

and/or enhancing the monarch 

overwintering groves, vegetation and/or 

topography that surround the groves, 

and habitat features nearby that support 

overwintering monarchs will benefit the 

physical or biological features essential 

to the conservation of the species in this 

unit. 

Unit 2: Santa Barbara County 

Unit 2 consists of two subunits in 

Santa Barbara County, California. The 

monarch butterfly occupies each of the 

subunits in this unit, and the subunits 

contain all of the physical or biological 

features essential to the conservation of 

the species. 

Special management considerations 

or protection may be required within 

Unit 2 to address coastal development, 

unsuitable management practices in 

overwintering habitat, insecticide 

applications, herbicide applications 

resulting in loss of nectar sources, and 

impacts from climate change (e.g., 

drought, increased storm severity, 

extreme temperatures). Management 

activities, such as incompatible tree 

trimming or removal, nectar plant 

removal, and tropical milkweed 

planting, have the potential to impact 

the suitability of overwintering habitat 

used by monarchs in Unit 2. Special 

management focused on maintaining 

and/or enhancing the monarch 

overwintering groves, vegetation and/or 

topography that surround the groves, 

and habitat features nearby that support 

overwintering monarchs will benefit the 

physical or biological features essential 

to the conservation of the species in this 

unit. 

Subunit 2a consists of 964 ac (390 ha) 

and is composed of lands in city (123 ac 

(50 ha)), county (1 ac (less than 1 ha)), 

State (14 ac (6 ha)), and private or other 

ownership (825 ac (334 ha)). It includes 

the following areas: Las Varas Ranch 

(site #2741), Ellwood/Sandpiper Golf 

Course (site #2747), Ellwood Central 

and West (site #2750), Ellwood Main 

(site #2751), Ellwood East (site #2752), 

Atascadero Creek (site #2765), Honda 

Valley (site #2772), Via Real and Padaro 

(site #2782), Lambert Road (site #2783), 

Carpinteria Creek (site #2799), Oil and 

Gas Buffer Zone (site #2800), Padaro 

Lane 2 (site #3223), and Padaro Lane 3 

(site #3224). Ellwood Mesa and the 

Sperling Preserve, which includes four 

areas in this subunit (Ellwood/ 

Sandpiper Golf Course, Ellwood Central 

and West, Ellwood Main, and Ellwood 

East), is partially owned by the City of 

Goleta, the Land Trust for Santa Barbara 

County, and the University of 

California, and is managed for 

recreation and conservation. Part of the 

area at Atascadero Creek is within 

Goleta Beach County Park, owned by 

Santa Barbara County. Part of the area 

at Carpinteria Creek is within 

Carpinteria State Beach, owned by the 

State of California and managed by the 

California Department of Parks and 

Recreation. Part of the area at the Oil 

and Gas Buffer Zone is within Tar Pits 

Park, owned by the City of Goleta. 

Subunit 2b consists of 431 ac (174 ha) 

and is composed of lands in State (42 ac 

(17 ha)) and private or other ownership 

(389 ac (158 ha)). It includes the 

following areas: The Nature 

Conservancy Preserve (site #2723), 

Rancho San Augustine (site #2725), 

Santa Anita Creek (site #2728), Gaviota 

State Beach (site #2731), Lower 

Cementario (site #2732), and Canada 

Alcatraz (north) (site #2733). Gaviota 

State Park, which includes part of three 

areas in this subunit (Gaviota State 

Beach, Lower Cementario, and Canada 

Alcatraz (north)), is owned by the State 

of California and managed by the 

California Department of Parks and 

Recreation. Part of the area identified as 

The Nature Conservancy Preserve is 

within the Jack and Laura Dangermond 

Preserve, owned by The Nature 

Conservancy. 

Unit 3: San Luis Obispo County 

Unit 3 consists of three subunits in 

San Luis Obispo County, California. The 

monarch butterfly occupies each of the 

subunits in this unit, and the subunits 

contain all of the physical or biological 


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features essential to the conservation of 

the species. 

Special management considerations 

or protection may be required within 

Unit 3 to address coastal development, 

unsuitable management practices in 

overwintering habitat, insecticide 

applications, herbicide applications 

resulting in loss of nectar sources, and 

impacts from climate change (e.g., 

drought, increased storm severity, 

extreme temperatures). Management 

activities, such as incompatible tree 

trimming or removal, nectar plant 

removal, and tropical milkweed 

planting, have the potential to impact 

the suitability of overwintering habitat 

used by monarchs in Unit 3. Special 

management focused on maintaining 

and/or enhancing the monarch 

overwintering groves, vegetation and/or 

topography that surround the groves, 

and habitat features nearby that support 

overwintering monarchs will benefit the 

physical or biological features essential 

to the conservation of the species in this 

unit. 

Subunit 3a consists of 470 ac (190 ha) 

and is composed of lands in State (86 ac 

(35 ha)) and private or other ownership 

(384 ac (155 ha)). It includes the 

following areas: Pismo Beach (North 

Beach Campground) (site #3060), 

Halcyon Hill (site #3067), overwintering 

site in Oceano (site #3082), Blacklake I 

(site #3083), Blacklake II (site #3089), 

Woodlands Village Monarch Habitat 

(site #3167), and Callendar Road (site 

#3214). Pismo State Beach (which 

includes parts of two areas in this 

subunit: Pismo Beach (North Beach 

Campground) and the overwintering site 

in Oceano) and Oceana Dunes State 

Vehicular Recreation Area (which 

includes part of Blacklake II and 

Callendar Road areas) are owned by 

California Department of Parks and 

Recreation. The Sand and Surf County 

Park encompasses a part of the 

overwintering sites in Oceano and is 

owned by the County of San Luis 

Obispo. The Land Conservancy of San 

Luis Obispo County owns part of three 

areas in this subunit (Blacklake I and II, 

and Callendar Road). 

Subunit 3b consists of 639 ac (258 ha) 

and is composed of lands in city (15 ac 

(6 ha)), county (29 ac (12 ha)), State (321 

ac (130 ha)), and private ownership (274 

ac (111 ha)). It includes the following 

areas: Pecho Road (site #3043), Toro 

Creek (site #3051), Hazard Cove (site 

#3052), Monarch Lane (site #3053), 

Morro Bay State Park Campground (site 

#3055), Morro Bay Golf Course (site 

#3056), Camp Keep at Montana De Oro 

State Park (site #3058), Main and Surf 

Street (site #3076), Del Mar Park (site 

#3233), San Luis Obispo Creek (site 

#3245), and Cayucos Creek Road and 

State Highway 1 (site #3266). California 

Department of Parks and Recreation 

manages areas within this subunit, 

including areas within Montan ̃ a de Oro 

State Park (Hazard Cove, Monarch Lane, 

and Camp Keep) and Morro Bay State 

Park (Morro Bay State Park Campground 

and Morro Bay Golf Course). The 

County of San Luis Obispo owns the 

Toro Creek Preserve (which includes the 

Toro Creek area), the Monarch Grove 

Natural Area (which includes the 

Monarch Lane area), and Hardie Park 

(which includes the Cayucos Creek 

Road and State Highway 1 area). The 

City of Morro Bay owns Del Mar Park, 

which contains part of the Del Mar Park 

area. Part of the area at San Luis Obispo 

Creek is within the Dana Abode land, 

which is owned by the City of San Luis 

Obispo. 

Subunit 3c consists of 403 ac (163 ha) 

and is composed of lands in State (126 

ac (51 ha)), Federal (15 ac (6 ha)), village 

(117 ac (47 ha)) and private ownership 

(145 ac (59 ha)). It includes the 

following areas: Sebastian’s Store (site 

#3045), Fiscalini Ranch (site #3046), 

Whitaker Flat (site #3071), Hamlet (site 

#3073), and overwintering site at Ragged 

Point 3 (site #3258). Hearst San Simeon 

State Park, which is owned by the 

California Department of Parks and 

Recreation, contains portions of both the 

Whitaker Flat and Hamlet areas. The 

Fiscalini Ranch area is partially owned 

by the village of Cambria Community 

Services District. A portion of the 

overwintering sites at Ragged Point 3 is 

in the Los Padres National Forest, which 

is owned by the U.S. Forest Service. 

Unit 4: Monterey County 

Unit 4 consists of 204 ac (83 ha) in 

Monterey County and is composed of 

lands in city (2 ac (1 ha)), State (52 ac 

(21 ha)), and private ownership (150 ac 

(61 ha)). It includes the following areas: 

overwintering site near Big Sur (site 

#2920), Andrew Molera State Park (site 

#2924), Pacific Grove Monarch Butterfly 

Sanctuary (site #2935), and 

overwintering site in Monterey (site 

#3192). A portion of the Andrew Molera 

State Park is owned and managed by the 

California Department of Parks and 

Recreation. Part of the area at the Pacific 

Grove Monarch Butterfly Sanctuary is in 

the baseball park, which is owned by 

the City of Pacific Grove. The monarch 

butterfly occupies the entire unit, and 

the unit contains all of the physical or 

biological features essential to the 

conservation of the species. 

Special management considerations 

or protection may be required within 

Unit 4 to address coastal development, 

unsuitable management practices in 

overwintering habitat, insecticide 

applications, herbicide applications 

resulting in loss of nectar sources, and 

impacts from climate change (e.g., 

drought, increased storm severity, 

extreme temperatures). Management 

activities, such as incompatible tree 

trimming or removal, nectar plant 

removal, and tropical milkweed 

planting, have the potential to impact 

the suitability of overwintering habitat 

used by monarchs in Unit 4. Special 

management focused on maintaining 

and/or enhancing the monarch 

overwintering groves, vegetation and/or 

topography that surround the groves, 

and habitat features nearby that support 

overwintering monarchs will benefit the 

physical or biological features essential 

to the conservation of the species in this 

unit. 

Unit 5: Santa Cruz County 

Unit 5 consists of 289 ac (117 ha) in 

Santa Cruz County and is composed of 

lands in city (3 ac (1 ha)), county (7 ac 

(3 ha)), State (87 ac (35 ha)), Federal (16 

ac (7 ha)), and private ownership (175 

ac (71 ha)). It includes the following 

areas: Moran Lake (site #2983), Natural 

Bridges State Beach (site #2998), 

Lighthouse Field (site #3000), and 

Ocean View and Marine Drive (site 

#3010). Part of the area of Moran Lake 

is in Moran Lake Park, which is owned 

by the County of Santa Cruz. The City 

of Santa Cruz owns parts of three of 

these areas in this subunit (Moran Lake, 

Natural Bridges State Park, and 

Lighthouse Field). A portion of both the 

Natural Bridges State Beach and the 

Lighthouse Field are owned and 

managed by the California Department 

of Parks and Recreation. Part of the 

Ocean View and Marine Drive area is 

contained in the California Coastal 

National Monument, which is owned by 

the United States Bureau of Land 

Management. The monarch butterfly 

occupies the entire unit, and the unit 

contains all of the physical or biological 

features essential to the conservation of 

the species. 

Special management considerations 

or protection may be required within 

Unit 5 to address coastal development, 

unsuitable management practices in 

overwintering habitat, insecticide 

applications, herbicide applications 

resulting in loss of nectar sources, and 

impacts from climate change (e.g., 

drought, increased storm severity, 

extreme temperatures). Management 

activities, such as incompatible tree 

trimming or removal, nectar plant 

removal, and tropical milkweed 

planting, have the potential to impact 

the suitability of overwintering habitat 

used by monarchs in Unit 5. Special 


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management focused on maintaining 

and/or enhancing the monarch 

overwintering groves, vegetation and/or 

topography that surround the groves, 

and habitat features nearby that support 

overwintering monarchs will benefit the 

physical or biological features essential 

to the conservation of the species in this 

unit. 

Unit 6: Alameda County 

Unit 6 consists of 261 ac (105 ha) in 

Alameda County and is composed of 

lands in city (54 ac (22 ha)) and private 

ownership (207 ac (84 ha)). It includes 

the following areas: Ardenwood 

Historical Farm (site #2831), Chuck 

Corica Golf Course (site #2832), and San 

Leandro Golf Course (site #2833). A 

portion of the Ardenwood Historical 

Farm is owned by the City of Fremont. 

A part of the San Leandro Golf Course 

is within Marina Park, which is owned 

by the city of San Leandro. The 

monarch butterfly occupies the entire 

unit, and the unit contains all of the 

physical or biological features essential 

to the conservation of the species. 

Special management considerations 

or protection may be required within 

Unit 6 to address coastal development, 

unsuitable management practices in 

overwintering habitat, insecticide 

applications, herbicide applications 

resulting in loss of nectar sources, and 

impacts from climate change (e.g., 

drought, increased storm severity, 

extreme temperatures). Management 

activities, such as incompatible tree 

trimming or removal, nectar plant 

removal, and tropical milkweed 

planting, have the potential to impact 

the suitability of overwintering habitat 

used by monarchs in Unit 6. Special 

management focused on maintaining 

and/or enhancing the monarch 

overwintering groves, vegetation and/or 

topography that surround the groves, 

and habitat features nearby that support 

overwintering monarchs will benefit the 

species physical or biological features 

essential to the conservation of the in 

this unit. 

Unit 7: Marin County 

Unit 7 consists of 242 ac (98 ha) in 

Marin County and is composed of lands 

in county (8 ac (3 ha)), State (1 ac (less 

than 1 ha)), Federal (43 ac (18 ha)), and 

private ownership (189 ac (77 ha)). It 

includes the following areas: Purple 

Gate (site #2899), Chapman Ravine (site 

#2903), Alder Road (site #2912), 

Charlotte near Muir Beach (site #3226), 

and Juniper Road and Kale Road (site 

#3227). The United States National Park 

Service owns and manages the Point 

Reyes National Seashore (which 

contains a portion of the Purple Gate 

and Alder Road areas) and the Golden 

Gate National Recreation Area (which 

contains a portion of the Chapman 

Ravine and Charlotte near Muir Beach 

areas). A part of the Chapman Ravine 

area is contained in Stinson Beach, 

which is owned by the California 

Department of Fish and Wildlife. 

Portions of the Chapman Ravine area are 

also contained in the Upton County 

Beach and Village Green, both of which 

are owned by the Marin County Parks 

Department. The Marin County Parks 

Department also owns Agate Beach, 

which contains a portion of the Alder 

Road area. The monarch butterfly 

occupies the entire unit, and the unit 

contains all of the physical or biological 

features essential to the conservation of 

the species. 

Special management considerations 

or protection may be required within 

Unit 7 to address coastal development, 

unsuitable management practices in 

overwintering habitat, insecticide 

applications, herbicide applications 

resulting in loss of nectar sources, and 

impacts from climate change (e.g., 

drought, increased storm severity, 

extreme temperatures). Management 

activities, such as incompatible tree 

trimming or removal, nectar plant 

removal, and tropical milkweed 

planting, have the potential to impact 

the suitability of overwintering habitat 

used by monarchs in Unit 7. Special 

management focused on maintaining 

and/or enhancing the monarch 

overwintering groves, vegetation and/or 

topography that surround the groves, 

and habitat features nearby that support 

overwintering monarchs will benefit the 

physical or biological features essential 

to the conservation of the species in this 

unit. 

Effects of Critical Habitat Designation 

Section 7 Consultation 

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

Federal agencies, including the Service, 

to ensure that any action they authorize, 

fund, 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. In 

addition, section 7(a)(4) of the Act 

requires Federal agencies to confer with 

the Service on any agency action which 

is likely to jeopardize the continued 

existence of any species proposed to be 

listed under the Act or result in the 

destruction or adverse modification of 

proposed critical habitat. 

Destruction or adverse modification 

means a direct or indirect alteration that 

appreciably diminishes the value of 

critical habitat as a whole for the 

conservation of a listed species (50 CFR 

402.02). 

Compliance with the requirements of 

section 7(a)(2) is documented through 

our issuance of: 

(1) A concurrence letter for Federal 

actions that may affect, but are not 

likely to adversely affect, listed species 

or critical habitat; or 

(2) A biological opinion for Federal 

actions that may affect, and are likely to 

adversely affect, listed species or critical 

habitat. 

When we issue a biological opinion 

concluding that a project is likely to 

jeopardize the continued existence of a 

listed species and/or destroy or 

adversely modify critical habitat, we 

provide reasonable and prudent 

alternatives to the project, if any are 

identifiable, that would avoid the 

likelihood of jeopardy and/or 

destruction or adverse modification of 

critical habitat. We define ‘‘reasonable 

and prudent alternatives’’ (at 50 CFR 

402.02) as alternative actions identified 

during formal consultation that: 

(1) Can be implemented in a manner 

consistent with the intended purpose of 

the action, 

(2) Can be implemented consistent 

with the scope of the Federal agency’s 

legal authority and jurisdiction, 

(3) Are economically and 

technologically feasible, and 

(4) Would, in the Service Director’s 

opinion, avoid the likelihood of 

jeopardizing the continued existence of 

the listed species or avoid the likelihood 

of destroying or adversely modifying 

critical habitat. 

Reasonable and prudent alternatives 

can vary from slight project 

modifications to extensive redesign or 

relocation of the project. Costs 

associated with implementing a 

reasonable and prudent alternative are 

similarly variable. 

Regulations at 50 CFR 402.16 set forth 

requirements for Federal agencies to 

reinitiate consultation. Reinitiation of 

consultation is required and shall be 

requested by the Federal agency, where 

discretionary Federal involvement or 

control over the action has been 

retained or is authorized by law and: (1) 

If the amount or extent of taking 

specified in the incidental take 

statement is exceeded; (2) if new 

information reveals effects of the action 

that may affect listed species or critical 

habitat in a manner or to an extent not 

previously considered; (3) if the 

identified action is subsequently 

modified in a manner that causes an 

effect to the listed species or critical 

habitat that was not considered in the 

biological opinion or written 


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concurrence; or (4) if a new species is 

listed or critical habitat designated that 

may be affected by the identified action. 

As provided in 50 CFR 402.16, the 

requirement to reinitiate consultations 

for new species listings or critical 

habitat designation does not apply to 

certain agency actions (e.g., land 

management plans issued by the Bureau 

of Land Management in certain 

circumstances). 

Destruction or Adverse Modification of 

Critical Habitat 

The key factor related to the 

destruction or adverse modification 

determination is whether 

implementation of the proposed Federal 

action directly or indirectly alters the 

designated critical habitat in a way that 

appreciably diminishes the value of the 

critical habitat for the conservation of 

the listed species. As discussed above, 

the role of critical habitat is to support 

physical or biological features essential 

to the conservation of a listed species 

and provide for the conservation of the 

species. 

Section 4(b)(8) of the Act requires that 

our Federal Register documents ‘‘shall, 

to the maximum extent practicable also 

include a brief description and 

evaluation of those activities (whether 

public or private) which, in the opinion 

of the Secretary, if undertaken may 

adversely modify [critical] habitat, or 

may be affected by such designation.’’ 

Activities that may be affected by 

designation of critical habitat for the 

monarch butterfly include those that 

may affect the physical or biological 

features of the monarch butterfly’s 

critical habitat (see Physical or 

Biological Features Essential to the 

Conservation of the Species). 

Exemptions 

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

The Sikes Act Improvement Act of 

1997 (Sikes Act) (16 U.S.C. 670a) 

required each military installation that 

includes land and water suitable for the 

conservation and management of 

natural resources to complete an 

integrated natural resources 

management plan (INRMP) by 

November 17, 2001. An INRMP 

integrates implementation of the 

military mission of the installation with 

stewardship of the natural resources 

found on the base. Each INRMP 

includes: 

(1) An assessment of the ecological 

needs on the installation, including the 

need to provide for the conservation of 

listed species; 

(2) A statement of goals and priorities; 

(3) A detailed description of 

management actions to be implemented 

to provide for these ecological needs; 

and 

(4) A monitoring and adaptive 

management plan. 

Among other things, each INRMP 

must, to the extent appropriate and 

applicable, provide for fish and wildlife 

management; fish and wildlife habitat 

enhancement or modification; wetland 

protection, enhancement, and 

restoration where necessary to support 

fish and wildlife; and enforcement of 

applicable natural resource laws. 

The National Defense Authorization 

Act for Fiscal Year 2004 (Pub. L. 108– 

136) amended the Act to limit areas 

eligible for designation as critical 

habitat. Specifically, section 4(a)(3)(B)(i) 

of the Act provides that the Secretary 

shall not designate as critical habitat 

any lands or other geographical areas 

owned or controlled by the DoD, or 

designated for its use, that are subject to 

an INRMP prepared under section 101 

of the Sikes Act, if the Secretary 

determines in writing that such plan 

provides a benefit to the species for 

which critical habitat is proposed for 

designation. 

We consult with the military on the 

development and implementation of 

INRMPs for installations with listed 

species. We analyzed INRMPs 

developed by military installations 

located within the range of the proposed 

critical habitat designation for the 

monarch butterfly to determine if they 

meet the criteria for exemption from 

critical habitat under section 4(a)(3) of 

the Act. The following areas are DoD 

lands with completed, Service-approved 

INRMPs within the proposed critical 

habitat designation. 

Approved INRMPs 

Vandenberg Space Force Base, Santa 

Barbara County, California 

Vandenberg Space Force Base (VSFB) 

occupies approximately 99,579 ac 

(40,298 ha) and extends along 42 mi (68 

km) of the California coast in Santa 

Barbara County and varies from 5 mi (8 

km) to 15 mi (24 km) in width. Monarch 

breeding and nectaring habitat is widely 

distributed throughout VSFB, and there 

are currently 34 known overwintering 

sites. Overwintering groves on the 

facility range in size from 0.13 to 556 ac 

(0.05 to 25 ha), and the dominant tree 

species include blue gum eucalyptus, 

Monterey pine, Monterey cypress, and 

coast live oak. We have identified 439 

ac (178 ha) of overwintering habitat on 

the facility that meets the definition of 

critical habitat for the monarch 

butterfly. 

The INRMP for VSFB was recently 

updated in coordination with the 

Service (VSFB 2024, entire). The INRMP 

includes measures for management of 

threatened and endangered species and 

their habitats through a specific 

management plan called the Threatened 

and Endangered Species Management 

Plan (Management Plan). The 

Management Plan addresses all specialstatus plant and wildlife species (i.e., 

species that are federally listed species 

or legally protected be other regulations) 

that are known or have potential to 

occur at VSFB, including monarch 

butterflies, and provides resource 

managers a framework for implementing 

an effective, long-term management 

program for protection and conservation 

of special-status plants and animals and 

their habitats. The primary objective of 

the natural resources program on VSFB 

is to ensure continued access to land 

and airspace required to accomplish the 

facility’s mission by maintaining these 

resources in a healthy condition. 

Natural resources management, in 

particular threatened and endangered 

species management, has been 

identified by the facility as a critical 

mission component because 

biodiversity conservation contributes to 

overall ecosystem integrity and 

sustainability, which in turn supports 

the facility’s mission by maintaining 

natural landscapes for realistic military 

testing, training, and operations. 

The Management Plan provides a 

conservation benefit for the monarch 

butterfly and its breeding and 

overwintering habitats that occur on 

VSFB and outlines a clear, measurable 

path to implementation of the actions 

being taken to conserve the species and 

its habitats (VSFB 2024, addendum to 

Tab D). 

Key threats identified in the INRMP to 

the monarch butterfly include habitat 

degradation, loss, or lack of active 

management to maintain grove 

conditions; harassment and disturbance; 

pest management; and woodcutting 

practices. Management actions 

identified and implemented through the 

INRMP for these threats include (1) 

conserving, managing, enhancing, and 

restoring monarch butterfly 

overwintering sites and surrounding 

habitat; (2) using only native, 

insecticide-free plants for habitat 

restoration and enhancement actions; 

(3) conducting overwintering site 

habitat assessments and developing and 

implementing long-term management 

plans; (4) avoiding the use of pesticides 

within 152 m (500 ft) of overwintering 

sites, particularly when monarchs may 

be present; (5) not planting any type of 

milkweed at or adjacent to 

overwintering sites (to assist in 

maintaining normal migration 


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behavior); (6) monitoring monarchs and 

assessing conditions of overwintering 

sites during the Western Monarch 

Count, and monitoring monarch 

populations before and after launches 

that occur during the overwintering 

time period; (7) conserving known areas 

with milkweed stands from disturbance, 

including pesticides; (8) planting 

insecticide- and fungicide-free native 

milkweed and nectar plants in 

migratory and breeding areas; (9) 

conducting management actions within 

monarch breeding and migratory habitat 

outside of the time when monarchs are 

likely to be present; and (10) 

implementing grazing best management 

practices to avoid negative impacts on 

breeding monarchs. 

Based on the above considerations, 

and in accordance with section 

4(a)(3)(B)(i) of the Act, we have 

determined that the identified lands are 

subject to the VSFB INRMP and that 

conservation efforts identified in the 

INRMP will provide a benefit to the 

monarch butterfly. Therefore, lands 

within this installation are exempt from 

critical habitat designation under 

section 4(a)(3) of the Act. We are not 

including approximately 439 ac (178 ha) 

of habitat in this proposed critical 

habitat designation because of this 

exemption. 

Consideration of Impacts Under Section 

4(b)(2) of the Act 

Section 4(b)(2) of the Act states that 

the Secretary shall designate and make 

revisions to critical habitat on the basis 

of the best available scientific data after 

taking into consideration the economic 

impact, the impact on national security, 

and any other relevant impact of 

specifying any particular area as critical 

habitat. The Secretary may exclude any 

area from critical habitat if the benefits 

of exclusion outweigh those of 

inclusion, so long as exclusion will not 

result in extinction of the species 

concerned. Exclusion decisions are 

governed by the regulations at 50 CFR 

424.19 and the Policy Regarding 

Implementation of Section 4(b)(2) of the 

Endangered Species Act (hereafter, the 

‘‘2016 Policy’’; 81 FR 7226, February 11, 

2016), both of which were developed 

jointly with the National Marine 

Fisheries Service (NMFS). We also refer 

to a 2008 Department of the Interior 

Solicitor’s opinion entitled ‘‘The 

Secretary’s Authority to Exclude Areas 

from a Critical Habitat Designation 

under Section 4(b)(2) of the Endangered 

Species Act’’ (M–37016). 

In considering whether to exclude a 

particular area from the designation, we 

identify the benefits of including the 

area in the designation, identify the 

benefits of excluding the area from the 

designation, and evaluate whether the 

benefits of exclusion outweigh the 

benefits of inclusion. If the analysis 

indicates that the benefits of exclusion 

outweigh the benefits of inclusion, the 

Secretary may exercise discretion to 

exclude the area only if such exclusion 

would not result in the extinction of the 

species. In making the determination to 

exclude a particular area, the statute on 

its face, as well as the legislative history, 

are clear that the Secretary has broad 

discretion regarding which factor(s) to 

use and how much weight to give to any 

factor. In our final rules, we explain any 

decision to exclude areas, as well as 

decisions not to exclude, to make clear 

the rational basis for our decision. We 

describe below the process that we use 

for taking into consideration each 

category of impacts and any initial 

analyses of the relevant impacts. 

Consideration of Economic Impacts 

Section 4(b)(2) of the Act and its 

implementing regulations require that 

we consider the economic impact that 

may result from a designation of critical 

habitat. To assess the probable 

economic impacts of a designation, we 

must first evaluate specific land uses or 

activities and projects that may occur in 

the area of the critical habitat. We then 

must evaluate the impacts that a specific 

critical habitat designation may have on 

restricting or modifying specific land 

uses or activities for the benefit of the 

species and its habitat within the areas 

proposed. We then identify which 

conservation efforts may be the result of 

the species being listed under the Act 

versus those attributed solely to the 

designation of critical habitat for this 

particular species. The probable 

economic impact of a proposed critical 

habitat designation is analyzed by 

comparing scenarios both ‘‘with critical 

habitat’’ and ‘‘without critical habitat.’’ 

The ‘‘without critical habitat’’ 

scenario represents the baseline for the 

analysis, which includes the existing 

regulatory and socio-economic burden 

imposed on landowners, managers, or 

other resource users potentially affected 

by the designation of critical habitat 

(e.g., under the Federal listing as well as 

other Federal, State, and local 

regulations). Therefore, the baseline 

represents the costs of all efforts 

attributable to the listing of the species 

under the Act (i.e., conservation of the 

species and its habitat incurred 

regardless of whether critical habitat is 

designated). The ‘‘with critical habitat’’ 

scenario describes the incremental 

impacts associated specifically with the 

designation of critical habitat for the 

species. The incremental conservation 

efforts and associated impacts would 

not be expected without the designation 

of critical habitat for the species. In 

other words, the incremental costs are 

those attributable solely to the 

designation of critical habitat, above and 

beyond the baseline costs. These are the 

costs we use when evaluating the 

benefits of inclusion and exclusion of 

particular areas from the final 

designation of critical habitat should we 

choose to conduct a discretionary 

4(b)(2) exclusion analysis. 

Executive Order (E.O.) 14094 amends 

and reaffirms E.O. 12866 and E.O. 13563 

and directs Federal agencies to assess 

the costs and benefits of available 

regulatory alternatives in quantitative 

(to the extent feasible) and qualitative 

terms. Consistent with the E.O. 

regulatory analysis requirements, our 

effects analysis under the Act may take 

into consideration impacts to both 

directly and indirectly affected entities, 

where practicable and reasonable. If 

sufficient data are available, we assess 

to the extent practicable the probable 

impacts to both directly and indirectly 

affected entities. Section 3(f) of E.O. 

12866 identifies four criteria when a 

regulation is considered a ‘‘significant 

regulatory action’’ and requires 

additional analysis, review, and 

approval if met. The criterion relevant 

here is whether the designation of 

critical habitat may have an economic 

effect of $200 million or more in any 

given year (section 3(f)(1) of E.O. 12866 

as amended by E.O. 14094). Therefore, 

our consideration of economic impacts 

uses a screening analysis to assess 

whether a designation of critical habitat 

for the monarch butterfly is likely to 

exceed the threshold for a regulatory 

action significant under section 3(f)(1) 

of E.O. 12866, as amended by E.O. 

14094. 

For this particular designation, we 

developed an incremental effects 

memorandum (IEM) considering the 

probable incremental economic impacts 

that may result from this proposed 

designation of critical habitat. The 

information contained in our IEM was 

then used to develop a screening 

analysis of the probable effects of the 

designation of critical habitat for the 

monarch butterfly (IEc 2024, entire). We 

began by conducting a screening 

analysis of the proposed designation of 

critical habitat in order to focus our 

analysis on the key factors that are 

likely to result in incremental economic 

impacts. The purpose of the screening 

analysis is to filter out particular 

geographical areas of critical habitat that 

are already subject to such protections 

and are, therefore, unlikely to incur 

incremental economic impacts. In 


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particular, the screening analysis 

considers baseline costs (i.e., absent 

critical habitat designation) and 

includes any probable incremental 

economic impacts where land and water 

use may already be subject to 

conservation plans, land management 

plans, best management practices, or 

regulations that protect the habitat area 

as a result of the Federal listing status 

of the species. Ultimately, the screening 

analysis allows us to focus our analysis 

on evaluating the specific areas or 

sectors that may incur probable 

incremental economic impacts as a 

result of the designation. 

The presence of the listed species in 

occupied areas of critical habitat means 

that any destruction or adverse 

modification of those areas is also likely 

to jeopardize the continued existence of 

the species. Therefore, designating 

occupied areas as critical habitat 

typically causes little if any incremental 

impacts above and beyond the impacts 

of listing the species. As a result, we 

generally focus the screening analysis 

on areas of unoccupied critical habitat 

(unoccupied units or unoccupied areas 

within occupied units). Overall, the 

screening analysis assesses whether 

designation of critical habitat is likely to 

result in any additional management or 

conservation efforts that may incur 

incremental economic impacts. This 

screening analysis combined with the 

information contained in our IEM 

constitute what we consider to be our 

economic analysis of the proposed 

critical habitat designation for the 

monarch butterfly; our economic 

analysis is summarized in the narrative 

below. 

As part of our screening analysis, we 

considered the types of economic 

activities that are likely to occur within 

the areas likely affected by the critical 

habitat designation. In our evaluation of 

the probable incremental economic 

impacts that may result from the 

proposed designation of critical habitat 

for the monarch butterfly, first we 

identified, in the IEM dated June 7, 

2024, probable incremental economic 

impacts associated with the following 

categories of activities: (1) Federal lands 

management including coastal 

development, road and bridge 

maintenance, and railroad maintenance 

projects (Army Corps of Engineers, 

Bureau of Land Management, 

Department of Defense, Federal 

Highway Administration, Federal Rail 

Administration, National Park Service, 

U.S. Forest Service); (2) management 

practices in overwintering habitat; (3) 

recreation activities; (4) insecticide 

applications; (5) herbicide applications; 

(6) habitat restoration activities; (7) 

pipeline and utility crossing 

maintenance and/or installation (Army 

Corps of Engineers, Federal Energy 

Regulatory Commission); and (8) 

maintenance of interstate pipeline rights 

of way and electrical transmission lines 

(Federal Energy Regulatory 

Commission) (Service 2024c, pp. 8–9). 

We considered each industry or 

category individually. Additionally, we 

considered whether their activities have 

any Federal involvement. Critical 

habitat designation generally will not 

affect activities that do not have any 

Federal involvement; under the Act, 

designation of critical habitat affects 

only activities conducted, funded, 

permitted, or authorized by Federal 

agencies. If we list the species, in areas 

where the monarch butterfly is present, 

Federal agencies would be required to 

consult with the Service under section 

7 of the Act on activities they authorize, 

fund, or carry out that may affect the 

species. If, when we list the species, we 

also finalize this proposed critical 

habitat designation, Federal agencies 

would be required to consider the 

effects of their actions on the designated 

habitat, and if the Federal action may 

affect critical habitat, our consultations 

would include an evaluation of 

measures to avoid the destruction or 

adverse modification of critical habitat. 

In our IEM, we attempted to clarify 

the distinction between the effects that 

would result from the species being 

listed and those attributable to the 

critical habitat designation (i.e., 

difference between the jeopardy and 

adverse modification standards) for the 

monarch butterfly’s critical habitat 

(Service 2024c, entire). Because the 

designation of critical habitat for 

monarch butterfly is being proposed 

concurrently with the listing, it has been 

our experience that it is more difficult 

to discern which conservation efforts 

are attributable to the species being 

listed and those which will result solely 

from the designation of critical habitat. 

However, the following specific 

circumstances in this case help to 

inform our evaluation: (1) The essential 

physical or biological features identified 

for critical habitat are the same features 

essential for the life requisites of the 

species, and (2) any actions that would 

likely adversely affect the essential 

physical or biological features of 

occupied critical habitat are also likely 

to adversely affect the species itself. The 

IEM outlines our rationale concerning 

this limited distinction between 

baseline conservation efforts and 

incremental impacts of the designation 

of critical habitat for this species. This 

evaluation of the incremental effects has 

been used as the basis to evaluate the 

probable incremental economic impacts 

of this proposed designation of critical 

habitat. 

The proposed critical habitat 

designation for the monarch butterfly 

totals 4,395 ac (1,778 ha) in seven units, 

all of which are occupied by the species 

during their migratory season of fall and 

winter. In these areas, any actions that 

may affect the species’ habitat would 

also affect designated critical habitat. 

We anticipate consultations for projects 

where the species is temporarily absent 

(e.g., during the summer months) but 

critical habitat is present to allow for 

movement of the species to be largely 

informal and resulting in mostly 

administrative costs and minor project 

adjustments to minimize impacts. For 

those formal consultations that may 

occur, they would most likely be of a 

magnitude that would involve both the 

species and critical habitat, and any 

reasonable and prudent alternatives to 

avoid jeopardy and/or adverse 

modification would be the same. Based 

on historical economic activity levels 

within the seven counties overlapping 

proposed critical habitat for the 

monarch butterfly, staff may be required 

to complete 27 formal consultations and 

17 informal consultations per year on 

average. The cost of addressing critical 

habitat as part of these consultations 

may range from $42,000 to $290,000 per 

year, depending on how many 

consultations are triggered by critical 

habitat alone. While this additional 

analysis will require time and resources 

by both the Federal action agency and 

the Service, it is believed that, in most 

circumstances, these costs would 

predominantly be administrative in 

nature and would not exceed $200 

million in any single year; therefore, 

they would not be significant. 

The entities most likely to incur 

incremental costs are parties to section 

7 consultations, including Federal 

action agencies and, in some cases, third 

parties, most frequently State agencies 

or municipalities. Activities we expect 

would be subject to consultations that 

may involve private entities as third 

parties are coastal development that 

may occur on private lands. However, 

based on coordination efforts with State 

and local agencies, the cost to private 

entities within these sectors is expected 

to be relatively minor (administrative 

costs of less than $3,500 per 

consultation effort); therefore, they 

would not be significant (i.e., exceed 

$200 million in a single year). 

In conclusion, the probable 

incremental economic impacts of the 

monarch butterfly critical habitat 

designation are expected to be limited to 

additional administrative effort as well 


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as minor costs of conservation efforts 

resulting from future section 7 

consultations. Because all of the 

proposed critical habitat units are 

considered to be occupied by the 

species, and incremental economic 

impacts of critical habitat designation, 

other than administrative costs, are 

expected to be limited, few actions are 

anticipated to result in section 7 

consultation for critical habitat only and 

associated project modifications. Thus, 

the annual administrative burden is 

unlikely to reach $200 million, which is 

the threshold for a significant regulatory 

action under E.O. 12866. 

We are soliciting data and comments 

from the public on the economic 

analysis discussed above. During the 

development of a final designation, we 

will consider the information presented 

in the economic analysis and any 

additional information on economic 

impacts we receive during the public 

comment period to determine whether 

any specific areas should be excluded 

from the final critical habitat 

designation under authority of section 

4(b)(2), our implementing regulations at 

50 CFR 424.19, and the 2016 Policy. We 

may exclude an area from critical 

habitat if we determine that the benefits 

of excluding the area outweigh the 

benefits of including the area, provided 

the exclusion will not result in the 

extinction of this species. 

Consideration of National Security 

Impacts 

Section 4(a)(3)(B)(i) of the Act may 

not cover all DoD lands or areas that 

pose potential national-security 

concerns (e.g., a DoD installation that is 

in the process of revising its INRMP for 

a newly listed species or a species 

previously not covered). If a particular 

area is not covered under section 

4(a)(3)(B)(i), then national-security or 

homeland-security concerns are not a 

factor in the process of determining 

what areas meet the definition of 

‘‘critical habitat.’’ However, we must 

still consider impacts on national 

security, including homeland security, 

on those lands or areas not covered by 

section 4(a)(3)(B)(i) because section 

4(b)(2) requires the Service to consider 

those impacts whenever it designates 

critical habitat. Accordingly, if DoD, 

Department of Homeland Security 

(DHS), or another Federal agency has 

requested exclusion based on an 

assertion of national-security or 

homeland-security concerns, or we have 

otherwise identified national-security or 

homeland-security impacts from 

designating particular areas as critical 

habitat, we generally have reason to 

consider excluding those areas. 

However, we cannot automatically 

exclude requested areas. When DoD, 

DHS, or another Federal agency requests 

exclusion from critical habitat on the 

basis of national-security or homelandsecurity impacts, we must conduct an 

exclusion analysis if the Federal 

requester provides information, 

including a reasonably specific 

justification of an incremental impact 

on national security that would result 

from the designation of that specific 

area as critical habitat. That justification 

could include demonstration of 

probable impacts, such as impacts to 

ongoing border-security patrols and 

surveillance activities, or a delay in 

training or facility construction, as a 

result of compliance with section 7(a)(2) 

of the Act. If the agency requesting the 

exclusion does not provide us with a 

reasonably specific justification, we will 

contact the agency to recommend that it 

provide a specific justification or 

clarification of its concerns relative to 

the probable incremental impact that 

could result from the designation. If we 

conduct an exclusion analysis because 

the agency provides a reasonably 

specific justification or because we 

decide to exercise the discretion to 

conduct an exclusion analysis, we will 

defer to the expert judgment of DoD, 

DHS, or another Federal agency as to: 

(1) Whether activities on its lands or 

waters, or its activities on other lands or 

waters, have national-security or 

homeland-security implications; (2) the 

importance of those implications; and 

(3) the degree to which the cited 

implications would be adversely 

affected in the absence of an exclusion. 

In that circumstance, in conducting a 

discretionary section 4(b)(2) exclusion 

analysis, we will give great weight to 

national-security and homeland-security 

concerns in analyzing the benefits of 

exclusion. 

Under section 4(b)(2) of the Act, we 

also consider whether a national 

security or homeland security impact 

might exist on lands owned or managed 

by DoD or DHS. In preparing this 

proposal, we have determined that, 

other than the land exempted under 

section 4(a)(3)(B)(i) of the Act based 

upon the existence of an approved 

INRMP (see Exemptions, above), the 

lands within the proposed designation 

of critical habitat for the monarch 

butterfly are not owned or managed by 

DoD or DHS. Therefore, we anticipate 

no impact on national security or 

homeland security. 

Consideration of Other Relevant 

Impacts 

Under section 4(b)(2) of the Act, we 

consider any other relevant impacts, in 

addition to economic impacts and 

impacts on national security discussed 

above. To identify other relevant 

impacts that may affect the exclusion 

analysis, we consider a number of 

factors, including whether there are 

approved and permitted conservation 

agreements or plans covering the 

species in the area—such as safe harbor 

agreements (SHAs), CCAAs, 

‘‘conservation benefit agreements’’ or 

‘‘conservation agreements’’ (CBAs) 

(CBAs are a new type of agreement 

replacing SHAs and CCAAs in use after 

April 2024 (89 FR 26070; April 12, 

2024)), or HCPs—or whether there are 

non-permitted conservation agreements 

and partnerships that would be 

encouraged by designation of, or 

exclusion from, critical habitat. In 

addition, we look at whether Tribal 

conservation plans or partnerships, 

Tribal resources, or government-togovernment relationships of the United 

States with Tribal entities may be 

affected by the designation. We also 

consider any State, local, social, or other 

impacts that might occur because of the 

designation. 

Summary of Exclusions Considered 

Under 4(b)(2) of the Act 

In preparing this proposal, we have 

determined that no HCPs or other 

management plans for the monarch 

butterfly currently exist that cover lands 

included in the proposed critical habitat 

designation, and the proposed 

designation does not include any Tribal 

lands or trust resources or any lands for 

which designation would have any 

economic or national security impacts. 

Therefore, we anticipate no impact on 

Tribal lands, partnerships, or HCPs from 

this proposed critical habitat 

designation and thus, as described 

above, we are not considering excluding 

any particular areas on the basis of the 

presence of conservation agreements or 

impacts to trust resources. 

However, if through the public 

comment period we receive information 

that we determine indicates that there 

are potential economic, national 

security, or other relevant impacts from 

designating particular areas as critical 

habitat, then as part of developing the 

final designation of critical habitat, we 

will evaluate that information and may 

conduct a discretionary exclusion 

analysis to determine whether to 

exclude those areas under authority of 

section 4(b)(2) and our implementing 

regulations at 50 CFR 424.19. If we 

receive a request for exclusion of a 

particular area and after evaluation of 

supporting information we do not 

exclude, we will fully describe our 

decision in the final rule for this action. 


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100700 Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 

Required Determinations 

Clarity of the Rule 

We are required by E.O.s 12866 and 

12988 and by the Presidential 

Memorandum of June 1, 1998, to write 

all rules in plain language. This means 

that each rule we publish must: 

(1) Be logically organized; 

(2) Use the active voice to address 

readers directly; 

(3) Use clear language rather than 

jargon; 

(4) Be divided into short sections and 

sentences; and 

(5) Use lists and tables wherever 

possible. 

If you feel that we have not met these 

requirements, send us comments by one 

of the methods listed in ADDRESSES. To 

better help us revise the rule, your 

comments should be as specific as 

possible. For example, you should tell 

us the numbers of the sections or 

paragraphs that are unclearly written, 

which sections or sentences are too 

long, the sections where you feel lists or 

tables would be useful, etc. 

Regulatory Planning and Review 

(Executive Orders 12866, 13563 and 

14094) 

Executive Order 14094 amends and 

reaffirms the principles of E.O. 12866 

and E.O. 13563 and states that 

regulatory analysis should facilitate 

agency efforts to develop regulations 

that serve the public interest, advance 

statutory objectives, and are consistent 

with E.O. 12866 and 13563, and the 

Presidential Memorandum of January 

20, 2021 (Modernizing Regulatory 

Review). Regulatory analysis, as 

practicable and appropriate, shall 

recognize distributive impacts and 

equity, to the extent permitted by law. 

E.O. 13563 emphasizes further that 

regulations must be based on the best 

available science and that the 

rulemaking process must allow for 

public participation and an open 

exchange of ideas. We have developed 

this proposed rule in a manner 

consistent with these requirements. 

Regulatory Flexibility Act (5 U.S.C. 601 

et seq.) 

Under the Regulatory Flexibility Act 

(RFA; 5 U.S.C. 601 et seq.), as amended 

by the Small Business Regulatory 

Enforcement Fairness Act of 1996 

(SBREFA; title II of Pub. L. 104–121, 

March 29, 1996), whenever an agency is 

required to publish a notice of 

rulemaking for any proposed or final 

rule, it must prepare and make available 

for public comment a regulatory 

flexibility analysis that describes the 

effects of the rule on small entities (i.e., 

small businesses, small organizations, 

and small government jurisdictions). 

However, no regulatory flexibility 

analysis is required if the head of the 

agency certifies the rule will not have a 

significant economic impact on a 

substantial number of small entities. 

The SBREFA amended the RFA to 

require Federal agencies to provide a 

certification statement of the factual 

basis for certifying that the rule will not 

have a significant economic impact on 

a substantial number of small entities. 

According to the Small Business 

Administration, small entities include 

small organizations such as 

independent nonprofit organizations; 

small governmental jurisdictions, 

including school boards and city and 

town governments that serve fewer than 

50,000 residents; and small businesses 

(13 CFR 121.201). Small businesses 

include manufacturing and mining 

concerns with fewer than 500 

employees, wholesale trade entities 

with fewer than 100 employees, retail 

and service businesses with less than $5 

million in annual sales, general and 

heavy construction businesses with less 

than $27.5 million in annual business, 

special trade contractors doing less than 

$11.5 million in annual business, and 

agricultural businesses with annual 

sales less than $750,000. To determine 

whether potential economic impacts to 

these small entities are significant, we 

considered the types of activities that 

might trigger regulatory impacts under 

this designation as well as types of 

project modifications that may result. In 

general, the term ‘‘significant economic 

impact’’ is meant to apply to a typical 

small business firm’s business 

operations. 

Under the RFA, as amended, and as 

understood in light of recent court 

decisions, Federal agencies are required 

to evaluate the potential incremental 

impacts of rulemaking on those entities 

directly regulated by the rulemaking 

itself; in other words, the RFA does not 

require agencies to evaluate the 

potential impacts to indirectly regulated 

entities. The regulatory mechanism 

through which critical habitat 

protections are realized is section 7 of 

the Act, which requires Federal 

agencies, in consultation with the 

Service, to ensure that any action 

authorized, funded, or carried out by the 

agency is not likely to destroy or 

adversely modify critical habitat. 

Therefore, under section 7, only Federal 

action agencies are directly subject to 

the specific regulatory requirement 

(avoiding destruction and adverse 

modification) imposed by critical 

habitat designation. Consequently, only 

Federal action agencies would be 

directly regulated if we adopt the 

proposed critical habitat designation. 

The RFA does not require evaluation of 

the potential impacts to entities not 

directly regulated. Moreover, Federal 

agencies are not small entities. 

Therefore, because no small entities 

would be directly regulated by this 

rulemaking, the Service certifies that, if 

made final as proposed, the proposed 

critical habitat designation will not have 

a significant economic impact on a 

substantial number of small entities. 

In summary, we have considered 

whether the proposed designation 

would result in a significant economic 

impact on a substantial number of small 

entities. For the above reasons and 

based on currently available 

information, we certify that, if made 

final, the proposed critical habitat 

designation would not have a significant 

economic impact on a substantial 

number of small business entities. 

Therefore, an initial regulatory 

flexibility analysis is not required. 

Energy Supply, Distribution, or Use— 

Executive Order 13211 

Executive Order 13211 (Actions 

Concerning Regulations That 

Significantly Affect Energy Supply, 

Distribution, or Use) requires agencies 

to prepare statements of energy effects 

‘‘to the extent permitted by law’’ when 

undertaking actions identified as 

significant energy actions (66 FR 28355; 

May 22, 2001). E.O. 13211 defines a 

‘‘significant energy action’’ as an action 

that (i) meets the definition of a 

‘‘significant regulatory action’’ under 

E.O. 12866, as amended by E.O. 14094; 

and (ii) is likely to have a significant 

adverse effect on the supply, 

distribution, or use of energy. In our 

economic analysis, we did not find that 

this proposed critical habitat 

designation would significantly affect 

energy supplies, distribution, or use. 

Therefore, this action is not a significant 

energy action, and no statement of 

energy effects is required. 

Unfunded Mandates Reform Act (2 

U.S.C. 1501 et seq.) 

In accordance with the Unfunded 

Mandates Reform Act (2 U.S.C. 1501 et 

seq.), we make the following finding: 

(1) This proposed rule would not 

produce a Federal mandate. In general, 

a Federal mandate is a provision in 

legislation, statute, or regulation that 

would impose an enforceable duty upon 

State, local, or Tribal governments, or 

the private sector, and includes both 

‘‘Federal intergovernmental mandates’’ 

and ‘‘Federal private sector mandates.’’ 

These terms are defined in 2 U.S.C. 

658(5)–(7). ‘‘Federal intergovernmental 


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Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 100701 

mandate’’ includes a regulation that 

‘‘would impose an enforceable duty 

upon State, local, or Tribal 

governments’’ with two exceptions. It 

excludes ‘‘a condition of Federal 

assistance.’’ It also excludes ‘‘a duty 

arising from participation in a voluntary 

Federal program,’’ unless the regulation 

‘‘relates to a then-existing Federal 

program under which $500,000,000 or 

more is provided annually to State, 

local, and Tribal governments under 

entitlement authority,’’ if the provision 

would ‘‘increase the stringency of 

conditions of assistance’’ or ‘‘place caps 

upon, or otherwise decrease, the Federal 

Government’s responsibility to provide 

funding,’’ and the State, local, or Tribal 

governments ‘‘lack authority’’ to adjust 

accordingly. At the time of enactment, 

these entitlement programs were: 

Medicaid; Aid to Families with 

Dependent Children work programs; 

Child Nutrition; Food Stamps; Social 

Services Block Grants; Vocational 

Rehabilitation State Grants; Foster Care, 

Adoption Assistance, and Independent 

Living; Family Support Welfare 

Services; and Child Support 

Enforcement. ‘‘Federal private sector 

mandate’’ includes a regulation that 

‘‘would impose an enforceable duty 

upon the private sector, except (i) a 

condition of Federal assistance or (ii) a 

duty arising from participation in a 

voluntary Federal program.’’ 

The designation of critical habitat 

does not impose a legally binding duty 

on non-Federal Government entities or 

private parties. Under the Act, the only 

regulatory effect is that Federal agencies 

must ensure that their actions are not 

likely to destroy or adversely modify 

critical habitat under section 7. While 

non-Federal entities that receive Federal 

funding, assistance, or permits, or that 

otherwise require approval or 

authorization from a Federal agency for 

an action, may be indirectly impacted 

by the designation of critical habitat, the 

legally binding duty to avoid 

destruction or adverse modification of 

critical habitat rests squarely on the 

Federal agency. Furthermore, to the 

extent that non-Federal entities are 

indirectly impacted because they 

receive Federal assistance or participate 

in a voluntary Federal aid program, the 

Unfunded Mandates Reform Act would 

not apply, nor would critical habitat 

shift the costs of the large entitlement 

programs listed above onto State 

governments. 

(2) We do not believe that this 

rulemaking would significantly or 

uniquely affect small governments 

because it is not anticipated to produce 

a Federal mandate of $100 million or 

more (adjusted annually for inflation) in 

any given year; that is, it is not a 

‘‘significant regulatory action’’ under 

the Unfunded Mandates Reform Act. 

The designation of critical habitat 

imposes no obligations on State or local 

governments. By definition, Federal 

agencies are not considered small 

entities, although the activities they 

fund or permit may be proposed or 

carried out by small entities. 

Consequently, we do not believe that 

the proposed critical habitat designation 

would significantly or uniquely affect 

small government entities. Therefore, a 

small government agency plan is not 

required. 

Takings—Executive Order 12630 

In accordance with E.O. 12630 

(Government Actions and Interference 

with Constitutionally Protected Private 

Property Rights), we have analyzed the 

potential takings implications of 

designating critical habitat for the 

monarch butterfly in a takings 

implications assessment. The Act does 

not authorize the Services to regulate 

private actions on private lands or 

confiscate private property as a result of 

critical habitat designation. Designation 

of critical habitat does not affect land 

ownership, or establish any closures, or 

restrictions on use of or access to the 

designated areas. Furthermore, the 

designation of critical habitat does not 

affect landowner actions that do not 

require Federal funding or permits, nor 

does it preclude development of habitat 

conservation programs or issuance of 

incidental take permits to permit actions 

that do require Federal funding or 

permits to go forward. However, Federal 

agencies are prohibited from carrying 

out, funding, or authorizing actions that 

would destroy or adversely modify 

critical habitat. A takings implications 

assessment has been completed for the 

proposed designation of critical habitat 

for the monarch butterfly, and it 

concludes that, if adopted, this 

designation of critical habitat does not 

pose significant takings implications for 

lands within or affected by the 

designation. 

Federalism—Executive Order 13132 

In accordance with E.O. 13132 

(Federalism), this proposed rule does 

not have significant federalism effects. 

A federalism summary impact statement 

is not required. In keeping with 

Department of the Interior and 

Department of Commerce policy, we 

requested information from, and 

coordinated development of this 

proposed critical habitat designation 

with, appropriate State resource 

agencies. From a federalism perspective, 

the designation of critical habitat 

directly affects only the responsibilities 

of Federal agencies. The Act imposes no 

other duties with respect to critical 

habitat, either for States and local 

governments, or for anyone else. As a 

result, the proposed rule does not have 

substantial direct effects on the States, 

or on the relationship between the 

Federal Government and the States, or 

on the distribution of powers and 

responsibilities among the various 

levels of government. The proposed 

designation may have some benefit to 

these governments because the areas 

that contain the features essential to the 

conservation of the species are more 

clearly defined, and the physical or 

biological features of the habitat 

necessary for the conservation of the 

species are specifically identified. This 

information does not alter where and 

what federally sponsored activities may 

occur. However, it may assist State and 

local governments in long-range 

planning because they no longer have to 

wait for case-by-case section 7 

consultations to occur. 

Where State and local governments 

require approval or authorization from a 

Federal agency for actions that may 

affect critical habitat, consultation 

under section 7(a)(2) of the Act would 

be required. While non-Federal entities 

that receive Federal funding, assistance, 

or permits, or that otherwise require 

approval or authorization from a Federal 

agency for an action, may be indirectly 

impacted by the designation of critical 

habitat, the legally binding duty to 

avoid destruction or adverse 

modification of critical habitat rests 

squarely on the Federal agency. 

Civil Justice Reform—Executive Order 

12988 

In accordance with E.O. 12988 (Civil 

Justice Reform), the Office of the 

Solicitor has determined that the rule 

would not unduly burden the judicial 

system and that it meets the 

requirements of sections 3(a) and 3(b)(2) 

of the Order. We have proposed 

designating critical habitat in 

accordance with the provisions of the 

Act. To assist the public in 

understanding the habitat needs of the 

species, this proposed rule identifies the 

physical or biological features essential 

to the conservation of the species. The 

proposed areas of critical habitat are 

presented on maps, and the proposed 

rule provides several options for the 

interested public to obtain more 

detailed location information, if desired. 

Paperwork Reduction Act of 1995 (44 

U.S.C. 3501 et seq.) 

This rulemaking does not contain 

information collection requirements, 


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100702 Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 

and a submission to the Office of 

Management and Budget (OMB) under 

the Paperwork Reduction Act of 1995 

(44 U.S.C. 3501 et seq.) is not required. 

We may not conduct or sponsor and you 

are not required to respond to a 

collection of information unless it 

displays a currently valid OMB control 

number. 

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 document 

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, May 4, 

1994), E.O. 13175 (Consultation and 

Coordination with Indian Tribal 

Governments), the President’s 

memorandum of November 30, 2022 

(Uniform Standards for Tribal 

Consultation; 87 FR 74479, December 5, 

2022), and the Department of the 

Interior’s manual at 512 DM 2, we 

readily acknowledge our responsibility 

to communicate meaningfully with 

federally recognized Tribes and Alaska 

Native Corporations (ANCs) 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. 

We have determined that no Tribal 

lands fall within the boundaries of the 

proposed critical habitat for the 

monarch butterfly, so no Tribal lands 

would be affected by the proposed 

designation. 

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 Midwest 

Region Headquarters (see FOR FURTHER

INFORMATION CONTACT). 

Authors 

The primary authors of this proposed 

rule are the staff members of the Fish 

and Wildlife Service’s Species 

Assessment Team and the Midwest 

Region Headquarters. 

List of Subjects in 50 CFR Part 17 

Endangered and threatened species, 

Exports, Imports, Plants, Reporting and 

recordkeeping requirements, 

Transportation, Wildlife. 

Proposed Regulation Promulgation 

Accordingly, we propose to amend 

part 17, subchapter B of chapter I, title 

50 of the Code of Federal Regulations, 

as set forth below: 

PART 17—ENDANGERED AND 

THREATENED WILDLIFE AND PLANTS 

■ 1. The authority citation for part 17 

continues to read as follows: 

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

1544; and 4201–4245, unless otherwise 

noted. 

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

adding an entry for ‘‘Butterfly, 

monarch’’ to the List of Endangered and 

Threatened Wildlife in alphabetical 

order under INSECTS to read as follows: 

§ 17.11 Endangered and threatened 

wildlife. 

* * * * * 

(h) * * * 

Common name Scientific name Where listed Status Listing citations and applicable rules 

*******

INSECTS

* * * * * * * 

Butterfly, monarch ..................... Danaus plexippus ..................... Wherever found ....... T Federal Register citation when published 

as a final rule]; 50 CFR 17.47(k); 4d 50 

CFR 17.95(i).CH

* * * * * * * 

■ 3. Further amend § 17.47, as proposed 

to be amended at 89 FR 63888 (August 

6, 2024) and 89 FR 79857 (October 10, 

2024), by adding paragraph (k) to read 

as follows: 

§ 17.47 Species-specific rules—insects. 

* * * * * 

(k) Monarch butterfly (Danaus 

plexippus)—(1) Prohibitions. The 

following prohibitions that apply to 

endangered wildlife also apply to the 

monarch butterfly in the contiguous 

United States, Puerto Rico, and the U.S. 

Virgin Islands. Except as provided 

under paragraph (k)(2) 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 a 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) 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 (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 


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Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 100703 

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

wildlife. 

(v) Take incidental to an otherwise 

lawful activity caused by: 

(A) Activities that may maintain, 

enhance, remove, or establish milkweed 

and nectar plants within the breeding 

and migratory range that do not result 

in conversion of native or naturalized 

grassland, shrubland, or forested 

habitats, which for the purposes of this 

paragraph (k) includes the contiguous 

United States (except overwintering 

sites), Puerto Rico, and the U.S. Virgin 

Islands. These activities include the 

following: 

(1) Habitat restoration and 

management activities, such as mowing 

and haying native rangeland, that 

sustain grassland, shrubland, or forested 

land with monarch butterfly habitat. 

(2) Livestock grazing and routine 

ranching activities, including rotational 

grazing, patch-burn grazing, vegetation 

and invasive species management, other 

grazing practices implemented to make 

pasture and rangelands productive, 

construction and maintenance of fences, 

the gathering and management of 

livestock, and the development and 

maintenance of watering facilities for 

livestock. 

(3) Routine agricultural activities, 

including plowing, drilling, disking, 

mowing, and other mechanical 

manipulation and management of lands 

already in use for agricultural 

production (e.g., conventional row 

crops, pasture, hay fields, orchards, and 

vineyards). This exception also includes 

activities in direct support of cultivated 

agriculture, such as replacement, 

upgrades, maintenance, and operation 

of existing infrastructure (e.g., buildings, 

irrigation conveyance structures, fences, 

and roads), and routine implementation 

and maintenance of agricultural 

conservation practices (e.g., terraces, 

dikes, grassed waterways, and 

conservation tillage). 

(4) Fire management actions (e.g., 

prescribed burns, cultural burns, 

hazardous fuel reduction activities, 

vegetation management, maintenance of 

fuel breaks and minimum clearance 

requirements, and other fuels reduction 

activities). 

(5) Silviculture practices and forest 

management activities that use Stateapproved best management practices. 

(6) Maintenance, enhancement, 

removal, and establishment of milkweed 

and nectar plants on residential and 

other developed properties. 

(7) Vegetation management activities, 

such as mowing, ground disturbance, 

and other management activities, that 

remove milkweed and/or nectar plants 

when conducted at times of year when 

monarchs are not likely present. 

(B) Activities intended to conserve the 

species conducted by participants in a 

comprehensive conservation plan for 

the monarch butterfly developed by or 

in coordination with a State agency or 

agencies, or their agent(s), or 

implementation of a conservation 

program for the monarch butterfly 

developed by a Federal agency in 

fulfillment of their responsibilities 

under section 7(a)(1) of the Act. 

(C) Maintenance or improvement of 

monarch overwintering habitat in the 

United States consistent with a sitespecific Service-approved overwintering 

site land management plan for the 

conservation of monarchs at the site. 

Overwintering habitat is defined as 

habitat that provides overwintering 

monarch butterflies with the abiotic and 

biotic conditions necessary for 

clustering, aggregating, and feeding 

(nectaring). 

(D) Vehicle strikes. 

(vi) Take caused by: 

(A) Nonlethal collection, possession, 

or captive-rearing of 250 or fewer 

monarchs per year at any one location 

or facility (such as a home, botanical 

garden, school, or business). Collection 

is defined as nonlethal capture and 

holding of live monarchs at any life 

stage. Captive-rearing is defined as the 

holding of caterpillars, pupae 

(chrysalises), or adults and raising them 

in captivity long enough for them to 

move to the next life stage or to 

reproduce. This exception does not 

apply to wild clustering monarchs. 

(B) Release of 250 or fewer captively 

reared or held monarch adults per year 

by any one location or facility (such as 

a home, botanical garden, school, or 

business). 

(C) Nonlethal scientific research and 

educational activities involving 250 or 

fewer monarchs per year at any one 

location or facility (such as a home, 

botanical garden, school, business, or 

research facility). Activities associated 

with scientific research and education 

may include collection for purposes of 

handling, netting, sampling for disease, 

tagging of monarchs, and life cycle and 

specimen observations of monarchs. 

This exception does not apply to wild 

clustering monarchs. 

(vii) Possess dead monarchs. 

(viii) Sell or offer for sale 250 or fewer 

captively reared monarchs per year from 

any one location or facility (such as a 

home, botanical garden, school, 

business). 

■ 4. Amend § 17.95 in paragraph (i) by 

adding an entry for ‘‘Monarch Butterfly 

(Danaus plexippus)’’ after the entry for 

‘‘Island Marble Butterfly (Euchloe 

ausonides insulanus)’’ to read as 

follows: 

§ 17.95 Critical habitat—fish and wildlife. 

* * * * * 

(i) Insects. 

* * * * * 

Monarch Butterfly (Danaus plexippus) 

(1) Critical habitat units are depicted 

for Alameda, Marin, Monterey, San Luis 

Obispo, Santa Barbara, Santa Cruz, and 

Ventura Counties, California, on the 

maps in this entry. 

(2) Within these areas, the physical or 

biological features essential to the 

conservation of monarch butterfly 

consist of the following components: 

(i) Groves of trees (e.g., blue gum 

eucalyptus, Monterey pine, Monterey 

cypress, Coast redwood, coast live oak, 

Douglas fir, Torrey pine, western 

sycamore, bishop pine) that serve as 

sites for overwintering monarchs to 

cluster along the coast of California. 

(ii) Trees, herbaceous or shrubby 

vegetation, and/or topography 

surrounding overwintering groves that 

contribute to the following microclimate 

conditions: 

(A) Indirect or dappled sunlight; 

(B) Water sources (e.g., stream, pond, 

or moist soil) for hydration; 

(C) Defense against freezing 

temperatures; and 

(D) Protection from strong winds. 

(iii) Supportive features nearby (i.e., 

within 152 meters (500 feet) of) 

overwintering groves, including the 

following: 

(A) Flowering plants for nectar; 

(B) Water sources (e.g., stream, pond, 

or moist soil) for hydration; and 

(C) Protective landscape features (e.g., 

topography or vegetation) that lessen the 

impacts of prevailing winds on groves of 

trees. 

(3) Critical habitat does not include 

manmade structures (such as buildings, 

aqueducts, runways, roads, and other 

paved areas) and the land on which they 

are located existing within the legal 

boundaries on [EFFECTIVE DATE OF 

THE FINAL RULE]. 

(4) Data layers defining map units 

were created using mapping data 

collected as part of the annual Western 

Monarch Count (see Xerces Society 

2024b, unpaginated). Critical habitat 

units were then mapped using ‘‘NAD 

1983 California (Teale) Albers (Meters).’’ 

The site names and numbers on the 

maps in this entry match those used for 

the Western Monarch Count annual 

survey. The maps in this entry, as 

supplemented by text in this entry, 

establish the boundaries of the critical 

habitat designation. The coordinates or 

plot points or both on which each map 


ddrumheller on DSK120RN23PROD with PROPOSALS2
100704 Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 

is based are available to the public at 

https://www.regulations.gov at Docket 

No. FWS–R3–ES–2024–0137, and at the 

regional office responsible for this 

designation. You may obtain regional 

office location information by 

contacting one of the Service regional 

offices, the addresses of which are listed 

at 50 CFR 2.2. 

(5) Index map follows: 

Figure 1 to Monarch Butterfly (Danaus 

plexippus) paragraph (5) 

BILLING CODE 4333–15–P 

(6) Unit 1: Ventura County. 

(i) Unit 1 consists of 493 ac (199 ha) 

in Ventura County, California. It 

includes four areas: Arrundel Barranca 

(site #3142), Camino Real Park (site 

#3143), Harmon Barranca (site #3144), 

and Harbor Boulevard (site #3151). 

(ii) Map of Unit 1 follows: 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP12DE24.002</GPH>

Index Map of Critical Habitat Units for 

Monarch Butterfly (Danaus plexlppus) 

I Unit S: Santa Cruz I 

CALIFORNIA 

Juntt 3: San Luis Obispo I 

0 Critical Habitat Unit 

, .... • • Critical Habitat Subunit .u.... .... ··~ 

LocatiOO 

The sites designated as critical habitat are too small to be 

vistl>le on this map. See corresponding unit and subumt 

maps to ,iew those locations. 
Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 100705 

Figure 2 to Monarch Butterfly (Danaus 

plexippus) paragraph (6)(ii) 

(7) Unit 2: Santa Barbara County. 

(i) Unit 2 consists of the following two 

subunits in Santa Barbara County, 

California: 

(A) Subunit 2a consists of 964 ac (390 

ha). It includes the following areas: Las 

Varas Ranch (site #2741), Ellwood/ 

Sandpiper Golf Course (site #2747), 

Ellwood Central and West (site #2750), 

Ellwood Main (site #2751), Ellwood East 

(site #2752), Atascadero Creek (site 

#2765), Honda Valley (site #2772), Via 

Real and Padaro (site #2782), Lambert 

Road (site #2783), Carpinteria Creek 

(site #2799), Oil and Gas Buffer Zone 

(site #2800), Padaro Lane 2 (site #3223), 

and Padaro Lane 3 (site #3224). 

(B) Subunit 2b consists of 431 ac (174 

ha). It includes the following areas: The 

Nature Conservancy Preserve (site 

#2723), Rancho San Augustine (site 

#2725), Santa Anita Creek (site #2728), 

Gaviota State Beach (site #2731), Lower 

Cementario (site #2732), and Canada 

Alcatraz (north) (site #2733). 

(ii) Maps of Unit 2 follow: 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP12DE24.003</GPH>

Critical Habitat for Monarch Butterfly 

Unit 1: Ventura County, California 

• Critical Habitat 

'""'"'"'"' U.S. Highway 

State Road 
100706 Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 

Figure 3 to Monarch Butterfly (Danaus 

plexippus) paragraph (7)(ii) 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP12DE24.004</GPH>

• 

Critical Habitat for Monarch Butterfly 

Unit 2: Santa Barbara County, California 

Habitat 

Highway 

Road 

The sites ues:1gru:1ted as critical habitat are .sho,,m as 

sm.atl dots on this .map. See couesponding subunit maps 

to view those locations. 
Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 100707 

Figure 4 to Monarch Butterfly (Danaus 

plexippus) paragraph (7)(ii) 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP12DE24.005</GPH>

Critical Habitat for Monarch Butterfly 

Subunit 2a: Santa Barbara County, California 

• Critical Hat11rat 

U.S. Highway 

Road 

Santa Barbara 
100708 Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 

Figure 5 to Monarch Butterfly (Danaus 

plexippus) paragraph (7)(ii) 

(8) Unit 3: San Luis Obispo County. 

(i) Unit 3 consists of the following 

three subunits in San Luis Obispo 

County, California: 

(A) Subunit 3a consists of 470 ac (190 

ha). It includes the following areas: 

Pismo Beach (North Beach 

Campground) (site #3060), Halcyon Hill 

(site #3067), overwintering site in 

Oceano (site #3082), Blacklake I (site 

#3083), Blacklake II (site #3089), 

Woodlands Village Monarch Habitat 

(site #3167), and Callendar Road (site 

#3214). 

(B) Subunit 3b consists of 639 ac (258 

ha). It includes the following areas: 

Pecho Road (site #3043), Toro Creek 

(site #3051), Hazard Cove (site #3052), 

Monarch Lane (site #3053), Morro Bay 

State Park Campground (site #3055), 

Morro Bay Golf Course (site #3056), 

Camp Keep at Montana De Oro State 

Park (site #3058), Main and Surf Street 

(site #3076), Del Mar Park (site #3233), 

San Luis Obispo Creek (site #3245), and 

Cayucos Creek Road and State Highway 

1 (site #3266). 

(C) Subunit 3c consists of 403 ac (163 

ha). It includes the following areas: 

Sebastian’s Store (site #3045), Fiscalini 

Ranch (site #3046), Whitaker Flat (site 

#3071), Hamlet (site #3073), and 

overwintering site at Ragged Point 3 

(site #3258). 

(ii) Maps of Unit 3 follow: 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP12DE24.006</GPH>

Critical Habitat for Monarch Butterfly 

Subunit 2b: Santa Barbara County, California 

• Critical Habitat 

= U.S. Highway 

_,_.., state Road 
Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 100709 

Figure 6 to Monarch Butterfly (Danaus 

plexippus) paragraph (8)(ii) 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP12DE24.007</GPH>

- - - - - - - '"'le, 

I 

I 

I 

I 

I 

I 

f 

• Critical Habitat 

U.S. Highway 

State Road 

The aitea de,ignated a& critical habitat ~ shown as 

Rmall dots on this ma:p. SN! correl\ponding gubunit maps 

t.o view those iocatiomL 

l . --·-·--·---·, • 3a1 

I 

I 

I ' . I 

. .'. • •• : :. "\.• \ I :;·:·'I'"''. i, ', ">/:'\~.·.~,, - -)-- - -
100710 Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 

Figure 7 to Monarch Butterfly (Danaus 

plexippus) paragraph (8)(ii) 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP12DE24.008</GPH>

Critical Habitat for Monarch Butterfly 

Subunit 3a: San Luis Obispo County, California 

101 

• Critical Habitat 

U.S. Highway 

State Road 

~"-

'h 

'-\\ 

'Ct 

'0, 

rroyo Grande 
Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 100711 

Figure 8 to Monarch Butterfly (Danaus 

plexippus) paragraph (8)(ii) 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP12DE24.009</GPH>

Critical Habitat for Monarch Butterfly 

Subunit 3b: San Luis Obispo County, California 

Site: 3266 1 

• Critical Habitat 

= U.S. Highway 

State Road 
100712 Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 

Figure 9 to Monarch Butterfly (Danaus 

plexippus) paragraph (8)(ii) 

(9) Unit 4: Monterey County. 

(i) Unit 4 consists of 204 ac (83 ha) in 

Monterey County, California. It includes 

the following areas: overwintering site 

near Big Sur (site #2920), Andrew 

Molera State Park (site #2924), Pacific 

Grove Monarch Butterfly Sanctuary (site 

#2935), and overwintering site in 

Monterey (site #3192). 

(ii) Map of Unit 4 follows: 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP12DE24.010</GPH>

Critical Habitat for Monarch Butterfly 

Subunit 3c: San Luis Obispo County, California 

• Critical Habitat 

U.S. Highway 

State Road 
Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 100713 

Figure 10 to Monarch Butterfly (Danaus 

plexippus) paragraph (9)(ii) 

(10) Unit 5: Santa Cruz County. 

(i) Unit 5 consists of 289 ac (117 ha) 

in Santa Cruz County, California. It 

includes the following areas: Moran 

Lake (site #2983), Natural Bridges State 

Park (site #2998), Lighthouse Field (site 

#3000), and Ocean View and Marine 

Drive (site #3010). 

(ii) Map of Unit 5 follows: 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP12DE24.011</GPH>

Critical Habitat for Monarch Butterfly 

Unit 4: Monterey County, California 

• Critical Habitat 

== U.S. Highway 

,, ,, State Road 

Site: 2924 

Site: 2920 
100714 Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 

Figure 11 to Monarch Butterfly (Danaus 

plexippus) paragraph (10)(ii) 

(11) Unit 6: Alameda County. 

(i) Unit 6 consists of 261 ac (105 ha) 

in Alameda County, California. It 

includes the following areas: 

Ardenwood Historical Farm (site 

#2831), Chuck Corica Golf Course (site 

#2832), and San Leandro Golf Course 

(site #2833). 

(ii) Map of Unit 6 follows: 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP12DE24.012</GPH>

Critical Habitat for Monarch Butterfly 

Unit 5: Santa Cruz County, California 

Site: 3010 

• Critical Habitat 

c= U.S. Highway 

, .. -.,. State Road 
Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 100715 

Figure 12 to Monarch Butterfly (Danaus 

plexippus) paragraph (11)(ii) 

(12) Unit 7: Marin County. 

(i) Unit 7 consists of 242 ac (98 ha) in 

Marin County, California. It includes the 

following areas: Purple Gate (site 

#2899), Chapman Ravine (site #2903), 

Alder Road (site #2912), Charlotte near 

Muir Beach (site #3226), and Juniper 

Road and Kale Road (site #3227). 

(ii) Map of Unit 7 follows: 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP12DE24.013</GPH>

Critical Habitat for Monarch Butterfly 

Unit 6: Alameda County, California 

• Critical Habitat 

= U.S. Highway 

State Road 
100716 Federal Register / Vol. 89, No. 239 / Thursday, December 12, 2024 / Proposed Rules 

Figure 13 to Monarch Butterfly (Danaus 

plexippus) paragraph (12)(ii) 

* * * * * 

Martha Williams, 

Director, U.S. Fish and Wildlife Service. 

[FR Doc. 2024–28855 Filed 12–11–24; 8:45 am] 

BILLING CODE 4333–15–C 


ddrumheller on DSK120RN23PROD with PROPOSALS2EP12DE24.014</GPH>

Critical Habitat for Monarch Butterfly 

Unit 7: Marin County, California 

• Critical Habitat 

<----· U.S. Highway 

State Road