Federal Register, Volume 89 Issue 242 (Tuesday, December 17, 2024)

[Federal Register Volume 89, Number 242 (Tuesday, December 17, 2024)]
[Proposed Rules]
[Pages 102074-102091]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-28729]

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R7-ES-2024-0117; FXES1111090FEDR-256-FF09E21000]
RIN 1018-BI15

Endangered and Threatened Wildlife and Plants; Endangered Species
Status for Suckley's Cuckoo Bumble Bee

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to
list the Suckley's cuckoo bumble bee (Bombus suckleyi), an invertebrate
species from North America, as an endangered species under the
Endangered Species Act of 1973, as amended (Act). This determination
also serves as our 12-month finding on a petition to list the Suckley's
cuckoo bumble bee. After a review of the best available scientific and
commercial information, we find that listing the species is warranted.
Accordingly, we propose to list the species as an endangered species
under the Act. If we finalize this rule as proposed, it would add this
species to the List of Endangered and Threatened Wildlife and extend
the Act's protections to the species. Due to the current lack of data
sufficient to perform required analyses, we conclude that the
designation of critical habitat for the species is not determinable at
this time.

DATES: We will accept comments received or postmarked on or before
February 18, 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. We must receive requests for a
public hearing, in writing, at the address shown in FOR FURTHER
INFORMATION CONTACT by January 31, 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-R7-ES-
2024-0117, 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-R7-ES-2024-0117, 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-R7-ES-2024-0117.

FOR FURTHER INFORMATION CONTACT: Mike Daigneault, Acting Field
Supervisor, Southern Alaska Fish and Wildlife Field Office, 4700 BLM
Road, Anchorage, AK 99507; telephone 907-271-1467. Individuals in the
United States who are deaf, deafblind, hard of hearing, or have a
speech disability may dial 711 (TTY, TDD, or TeleBraille) to access
telecommunications relay services. Individuals outside the United
States should use the relay services offered within their country to
make international calls to the point-of-contact in the United States.
Please see Docket No. FWS-R7-ES-2024-0117 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
Suckley's cuckoo bumble bee meets the Act's definition of an endangered
species; therefore, we are proposing to list it as such. Listing a
species as an endangered or threatened species can be completed only by
issuing a rule through the Administrative Procedure Act rulemaking
process (5 U.S.C. 551 et seq.).
What this document does. We propose to list Suckley's cuckoo bumble
bee as an endangered species under the Act.
The basis for our action. Under the Act, we may determine that a
species is an endangered or a 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 Suckley's cuckoo bumble
bee meets the Act's definition of an endangered species due to threats

[[Page 102075]]

from host species decline, pathogens, pesticides, habitat fragmentation
and conversion, and climate change.
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.
We have not yet obtained the necessary economic information needed to
develop a proposed critical habitat designation for the Suckley's
cuckoo bumble bee, although we are in the process of obtaining this
information. At this time, we find that designation of critical habitat
for the Suckley's cuckoo bumble bee is not determinable. When critical
habitat is not determinable, the Act allows the Service an additional
year to publish a critical habitat designation (16 U.S.C.
1533(b)(6)(C)(ii)).

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
and the locations of any additional populations of this species;
(d) Historical and current population levels, and current and
projected trends; and
(e) 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; and
(c) Existing regulations or conservation actions that may be
addressing threats to this species.
(3) Additional information concerning the historical and current
status of this species.
(4) The reasons why we should or should not designate habitat as
``critical habitat'' under section 4 of the Act (16 U.S.C. 1531 et
seq.), including information to inform the following factors that the
regulations identify as reasons why designation of critical habitat may
be not prudent:
(a) The species is threatened by taking or other human activity and
identification of critical habitat can be expected to increase the
degree of such threat to the species;
(b) The present or threatened destruction, modification, or
curtailment of a species' habitat or range is not a threat to the
species, or threats to the species' habitat stem solely from causes
that cannot be addressed through management actions resulting from
consultations under section 7(a)(2) of the Act;
(c) Areas within the jurisdiction of the United States provide no
more than negligible conservation value, if any, for a species
occurring primarily outside the jurisdiction of the United States; or
(d) No areas meet the definition of critical habitat.
Please include sufficient information with your submission (such as
scientific journal articles or other publications) to allow us to
verify any scientific or commercial information you include.
Please note that submissions merely stating support for, or
opposition to, the action under consideration without providing
supporting information, although noted, 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.
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 threatened
instead of endangered, or we may conclude that the species does not
warrant listing as either an endangered species or a threatened
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

Section 4(b)(5) of the Act provides for a public hearing on this
proposal, if requested. Requests must be received by the date specified
in DATES. Such requests must be sent to the address shown in FOR
FURTHER INFORMATION CONTACT. We will schedule a public hearing on this
proposal, if requested, and announce the date, time, and place of the
hearing, as well as how to obtain reasonable accommodations, in the
Federal Register and local newspapers at least 15 days before the
hearing. We may hold the public hearing in person or virtually via
webinar. We will announce any public hearing on our website, in
addition to the Federal Register. The use of virtual public hearings is
consistent with our regulations at 50 CFR 424.16(c)(3).

Previous Federal Actions

We were petitioned on April 23, 2020, by the Center for Biological
Diversity to list Suckley's cuckoo bumble bee as an endangered species
and to designate critical habitat for this species under the Act. On
May 11, 2021, we announced in the Federal Register (86 FR 25833) that
the petition presented substantial information indicating that this
species may be warranted for listing; that document also announced the
initiation of a status review for the species. On April 22, 2022, the
Center for Biological Diversity filed a complaint that the Service
failed to meet our statutory deadline to complete a 12-month finding on
the petition. On September 27, 2022, the Service agreed to submit a
finding to the Federal Register by December 10, 2024. This action
constitutes our 12-month finding on the

[[Page 102076]]

2020 petition to list Suckley's cuckoo bumble bee.

Peer Review

A species status assessment (SSA) team prepared an SSA report for
Suckley's cuckoo bumble bee. 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 and recovery actions under the Act (https://www.fws.gov/sites/default/files/documents/peer-review-policy-directors-memo-2016-08-22.pdf), we solicited independent scientific review of the information
contained in the Suckley's cuckoo bumble bee SSA report. We sent the
SSA report to nine independent peer reviewers and received seven
responses. 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 seven
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 generally concurred with our methods and conclusions, and
provided additional information, clarifications, and suggestions. These
suggestions included providing more detailed explanations of
assumptions and uncertainties, more discussion of model strengths and
limitations, and clarifications in terminology and discussions of
genetic diversity; they also made other minor editorial suggestions.
Otherwise, no substantive changes to our analysis and conclusions
within the SSA report were deemed necessary, and peer reviewer comments
are addressed in version 1.0 of the SSA report (Service 2024, entire).

I. Proposed Listing Determination

Background

A thorough review of the taxonomy, life history, and ecology of
Suckley's cuckoo bumble bee is presented in the SSA report (version
1.0; Service 2024, pp. 11-28). Suckley's cuckoo bumble bee is an
obligate social parasite (it depends on social hosts for survival and
raising young) in the subgenus Psithyrus. Bumble bees in this subgenus
lack a mechanism to carry pollen and are unable to produce worker bees,
so they are entirely dependent on social bumble bee hosts to collect
pollen to rear their young (Lhomme and Hines 2019, p. 126). Since
Suckley's cuckoo bumble bees are entirely dependent on host bumble bee
colonies, host colony availability is critical for the species'
survival and overall viability. Cuckoo bumble bees are generally
observed in low abundance at the margins of a host species' range, and
cuckoo bumble bee distributions are less than that of the host species
(Antonovics and Edwards 2011, p. 1003).
Cuckoo bumble bee females emerge from hibernation in the spring and
usurp the nest of a suitable host colony, where host workers care for
their young. Suckley's cuckoo bumble bee is described as a semi-
specialist parasite (Lhomme and Hines 2019, p. 129) and is confirmed to
usurp nests of western bumble bees (Bombus occidentalis) and Nevada
bumble bees (B. nevadensis), with other potential hosts in subgenus
Bombus throughout the extent of its range (see Host Species Decline,
below).
The species has a broad historical distribution across North
America and it has been found in various habitat types including
prairies, grasslands, meadows, urban and agricultural areas, and
woodlands from 2 to 3,200 meters (6 to 10,500 feet) in elevation
(Williams et al. 2014, pp. 164-165; Committee on the Status of
Endangered Wildlife in Canada (COSEWIC) 2019, p. 26; Martin et al.
2023, p. 22; Montana Natural Heritage Program 2023, entire; Service
2024, pp. 17-19). The analytical units and occurrences of Suckley's
cuckoo bumble bee are shown below in figure 1.

[[Page 102077]]

[GRAPHIC] [TIFF OMITTED] TP17DE24.075

[[Page 102078]]

Regulatory and Analytical Framework

Regulatory Framework

Section 4 of the Act (16 U.S.C. 1533) and the implementing
regulations in title 50 of the Code of Federal Regulations set forth
the procedures for determining whether a species is an endangered
species or a threatened species, issuing protective regulations for
threatened species, and designating critical habitat for endangered and
threatened species.
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; ``M-Opinion,'' 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' life-history 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 the viability of Suckley's cuckoo bumble bee, 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 No. FWS-R7-
ES-2024-0117 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

[[Page 102079]]

condition, in order to assess the species' overall viability and the
risks to that viability.

Species Needs

There have been few studies focused specifically on understanding
Suckley's cuckoo bumble bee biology and needs. Thus, we relied on
information available for cuckoo bumble bees (subgenus Psithyrus) or
bumble bees (genus Bombus) where appropriate.
Host Species
Suckley's cuckoo bumble bees cannot successfully reproduce without
the availability of suitable host bumble bee colonies. Female cuckoo
bumble bees invade host bumble bee nests where they will often
eliminate the host queen, destroy host eggs, and eject host larvae from
the nest. This may be driven by the need to create space for parasitic
eggs and/or to increase the incubation effort of host workers towards
parasitic eggs. Cuckoo bumble bees lack a mechanism to carry pollen and
are unable to produce worker bees, and thus depend on social bee hosts
to collect the pollen on which they rear their young (Lhomme and Hines
2019, p. 126). Thus, survival of Suckley's cuckoo bumble bees is
dependent upon the survival and health of the host colony.
Food Resources
Cuckoo bumble bees require diverse native floral resources (pollen
and nectar) for nutrition. Limited information exists regarding key
forage plants for cuckoo bumble bees (Dozier et al. 2023, p. 643), but
abundant spring floral resources are important to cuckoo bumble bee
females for ovary development (Lhomme and Hines 2019, p. 132) and
abundant fall floral resources are important to the fitness of the
colony (Hatfield and LeBuhn 2007, pp. 156-157), since this is when new
gynes (the primary reproductive females) and drones (male bees that are
solely responsible for reproduction) are produced (Goulson 2010a, pp.
6-8). In addition, fall floral resources are important for females who
must survive an overwintering diapause (a period of suspended
development) without foraging (Beekman et al. 1998, p. 207; Ogilvie and
CaraDonna 2022, p. 2419). Because cuckoo bumble bees are dependent on
host workers to raise their offspring, females tend to emerge from
hibernation later than their hosts to feed on nectar and pollen in
preparation for laying eggs (Lhomme and Hines 2019, p. 132). While
specific requirements for overwintering sites are unknown, Suckley's
cuckoo bumble bee females likely overwinter in and under mulch or other
decomposing vegetation that is separated from nesting habitat (COSEWIC
2019, p. 27; Liczner and Colla 2019, p. 793; Martin et al. 2023, p.
25).
Habitat and Population Connectivity
Dispersal of bees is necessary to find unrelated mates and is aided
by the proximity of other usurped colonies and the presence of suitable
dispersal corridors. Bumble bee reproductive individuals (drones and
gynes) can disperse up to 10.0 kilometer (km) (6.2 mile (mi)) (Darvill
et al. 2006, p. 606; Jha and Kremen 2013, p. 2490; Lepais et al. 2010,
p. 287). Dispersal distance can vary widely across species, and it has
not yet been described for Suckley's cuckoo bumble bees. The
indiscriminate cuckoo bumble bee (B. insularis) was found to disperse
up to 7.0 km (4.3 mi) which is comparable to research on other Bombus
species (Koch et al. 2021, p. 5). Connectivity is a constraint for
cuckoo bumble bees because they live in small, fragmented populations
as a result of their dependence on host bumble bee colonies (Suhonen et
al. 2016, p. 529). Population connectivity is important for Suckley's
cuckoo bumble bee's viability as it increases the likelihood of genetic
diversity, which promotes successful reproduction. Bumble bees are
prone to producing unviable sterile males when genetic diversity
between mating pairs is low (Zayed 2009, p. 239). Sterile males are
unable to contribute to the following year's cohort, which can have
negative impacts to the population and overall species viability.
Dispersal of bees to find unrelated mates is aided by the proximity
of other usurped colonies. Consequently, the sharp historical decrease
in the prevalence of both Suckley's cuckoo bumble bee, and many of its
confirmed and potential host species (see Historical, Current, and
Near-term Condition of Suckley's Cuckoo Bumble Bee, below), has likely
reduced population connectivity relative to historical conditions.
Reduced gene flow may have consequences on the genetic diversity of
Suckley's cuckoo bumble bee, because small populations can experience
stronger genetic drift (Zayed 2009, p. 246). This is important because
high genetic diversity reduces prevalence of some pathogens (Parsche
and Lattorff 2018, p. 900), and the risk of matched mating, which
produces sterile males that do not contribute to population growth
(Zayed 2009, p. 239).
Thermal Suitability
Bumble bees require temperatures to be within a suitable range
throughout their lifecycle; however, this temperature range appears to
be highly variable both across and within bumble bee species (Service
2024, pp. 20-22). Based on occupancy modeling results for Suckely's
cuckoo bumble bee, occupancy is greatest when the average maximum
temperature is near 20 Celsius ([deg]C) (68 Fahrenheit ([deg]F)) and
declines when temperatures are lower and higher than the average
maximum temperature (Service 2024, p. 64). In general, as bumble bees
approach the lower end of their thermal limits, they become lethargic
(Oyen et al. 2016, p. 53). Additionally, extreme cold can affect
foraging behavior; exposure to cold (approximately 4[deg]C (39[deg]F)
for 5 minutes) reduced bumble bee foraging for days after exposure
(Wilson et al. 2006, p. 171). The upper end of some bumble bee thermal
limits, where loss of muscle control occurs, ranged from approximately
38 to 53[deg]C (100-129[deg]F) (Hamblin et al. 2017, p. supplemental
dataset; Oyen et al. 2016, p. 54; Oyen and Dillon 2018, p. 4). Compared
to other bee species, bumble bees may be particularly sensitive to
increases in temperature (Hamblin et al. 2017, p. 3). Further, bumble
bee abundance was observed to decrease following heat waves in Europe
(Rasmont and Iserbyt, 2012, p. 276).
Nest temperatures are important to the maintenance and growth of
the colony (Heinrich 1979, p. 68; Vogt 1986, p. 64). Temperatures in
underground bumble bee nests fluctuate less than in the surrounding
environment, maintaining around 30[deg]C (86[deg]F) (Vogt, 1986, p. 61;
Goulson, 2010a, p. 20; Heinrich 1979, p. 66), due to insulating
qualities and colony behavior. Nest temperatures outside of ideal
thermal ranges can slow larvae development and colony growth (Heinrich
1979, p. 68; Vanderplanck et al. 2019, p. 3; Vogt 1986, p. 64). The
brood is most susceptible to cold temperatures earlier in the season
when ambient temperatures are low, and the colony is small.
In summary, Suckley's cuckoo bumble bee must have availability of
suitable host colonies, sufficient food resources, connectivity, and
thermal suitability to support viability. Highly resilient populations
consist of many genetically diverse individuals that have all their
basic resource needs met (host colony availability, floral resource
abundance and diversity, overwintering site availability, population
connectivity, and thermal suitability). This translates into a diverse
collection of individuals on the landscape with high survival and
reproduction success, which ultimately results in population

[[Page 102080]]

growth and larger populations. Survival and reproduction of Suckley's
cuckoo bumble bees depend on the survival and health of the host
colony. Host colony workers are paramount to the growth and survival of
new generations of Suckley's cuckoo bumble bees because they forage and
care for the brood of parasite larva.
Redundancy for Suckley's cuckoo bumble bee is described as having
multiple, healthy populations widely distributed across the breadth of
adaptive diversity relative to the spatial occurrence of catastrophic
events (e.g., pathogen outbreak, wildfire, or drought events). In
addition to guarding against a single or series of catastrophic
event(s) extirpating all populations of Suckley's cuckoo bumble bee,
redundancy is important to protect against losing irreplaceable sources
of adaptive diversity. Having multiple populations distributed across
the range of the species will help preserve the breadth of adaptive
diversity and, hence, the evolutionary flexibility of the species.
The adaptive capacity, as it relates to representation, of
Suckley's cuckoo bumble bee is a function of the amount and spatial
distribution of genetic and phenotypic diversity. Based on genetic
studies of other bumble bee species with similar ecologies, and given
the potential dispersal capability, Suckley's cuckoo bumble bee may not
exhibit much genetic differentiation across its broad range. Genetic
variation can be negatively affected by genetic drift; small
populations experience stronger drift (Zayed 2009, p. 246). Thus,
preserving the genetic diversity of Suckley's cuckoo bumble bee may
require maintaining relatively large populations and connectivity among
them.

Threats

Host Species Decline
Cuckoo bumble bees have higher threat indices (higher extinction
vulnerability) than host species because they are entirely dependent on
host colonies for reproduction (Suhonen et al. 2015, pp. 238-239). The
presence of parasitic bees depends on the presence of their hosts; any
stressor effects on the host will be reflected in the status of the
parasite (Sheffield et al. 2013, p. 508). Because cuckoo bumble bees
depend on host species, there is a co-extinction risk for host and
parasite species (Suhonen et al. 2015, p. 238). Thus, signs that host
species are declining are of major concern to the viability of
Suckley's cuckoo bumble bee. The effect of all the stressors impacting
Suckley's cuckoo bumble bee are compounded through the additional
effects of these stressors on host species availability (Service 2024,
p. 33).
Suckley's cuckoo bumble bee is part of a group in the subgenus
Psithyrus which primarily parasitizes bumble bees in the subgenus
Bombus (Lhomme and Hines 2019, p. 129). Bumble bee nests are rare to
encounter at a baseline, and usurped nests are even rarer to encounter,
making observations supporting host choice limited (Lhomme and Hines
2019, pp. 132-133). Additionally, cuckoo bumble bee females may shelter
in nests they do not usurp, leading to inconclusive observations.
Given these challenges, our current understanding is that Suckley's
cuckoo bumble bee has two confirmed hosts and numerous potential hosts.
The western bumble bee is the most widely known host of Suckley's
cuckoo bumble bee (Hobbs 1968, p. 164; Williams et al. 2014, p. 165;
Lhomme and Hines 2019, p. 128). The western bumble bee occurs
throughout the core of Suckley's cuckoo bumble bee's range in western
North America. There are also three records of Suckley's cuckoo bumble
bee nesting successfully (i.e., rearing young) in Nevada bumble bee
nests (Hobbs 1965, p. 127).
Aside from these two confirmed hosts, there are numerous potential
hosts (Service 2024, pp. 35-37) including yellow-banded bumble bee (B.
terricola), red-belted bumble bee (B. rufocinctus), yellow bumble bee
(B. fervidus), and white-shouldered bumble bee (B. appositus) (Hobbs
1968, pp. 157, 164; Williams et al. 2014, p. 165). Suckley's cuckoo
bumble bees are also observed in locations beyond the range of these
confirmed and potential hosts (based on nest observations). Because of
this, it is reasonable to assume there are additional hosts not yet
confirmed through observations. The following additional potential
hosts have been identified for Suckley's cuckoo bumble bee: rusty
patched bumble bee (B. affinis), McKay's bumble bee (B. mckayi), and
cryptic bumble bee (B. cryptarum) (COSEWIC 2019, p. 17; Service 2024,
pp. 5-6).
Over the past century, many species parasitized by Suckley's cuckoo
bumble bee have documented declines (Hatfield et al. 2014, p. 46;
Hatfield et al. 2015, p. 4; COSEWIC 2019, p. vi). Trends observed
across North America suggest subgenus Bombus species are experiencing
widespread declines (Giles and Ascher 2006, pp. 217-218; Colla and
Packer 2008, p. 1387; Schweitzer et al. 2012, p. 7; Janousek et al.
2023, p. 2). For the SSA report, we updated a multi-species occupancy
model (Jackson et al. 2022, entire) to evaluate host species declines
for two confirmed hosts (western bumble bee and Nevada bumble bee), and
four potential hosts in the subgenus Bombus (rusty patched bumble bee,
McKay's bumble bee, yellow-banded bumble bee, and cryptic bumble bee).
The western bumble bee, McKay's bumble bee, rusty patched bumble bee,
and yellow-banded bumble bee all exhibited statistically significant
temporal declines in occupancy rangewide (Service 2024, pp. 69-70).
Since Suckley's cuckoo bumble bee is dependent on host species for
survival, declines in host species abundance is having significant
impacts to Suckley's cuckoo bumble bee viability.
Managed Bees
Generally, the term ``managed bees'' describes hives or colonies of
bees that are used commercially to provide pollination services for a
wide variety of crops over the growing season. Some hives or colonies
are moved within and between States multiple times throughout a single
growing season. Within the range of Suckley's cuckoo bumble bee,
managed bees are used for a wide variety of crops including, but not
limited to, alfalfa, almonds, apples, avocado, canola, cherries,
sunflowers, squash, melon, berries, cucumbers, and clover (Bond et al.
2014, entire). The use of managed bees is expanding in some portions of
the range of Suckley's cuckoo bumble bee, including western Canada
(COSEWIC 2019, p. 49). Managed bees also include hobby or backyard bee
keeping, as well as small-scale greenhouse operations. Managed bees
include many different species of bees, such as the introduced European
honey bee (Apis mellifera) and several species of native North American
bumble bees, including common eastern bumble bee (B. impatiens), an
eastern species that has recently been moved into the range of
Suckley's cuckoo bumble bee for commercial pollination services
(Palmier and Sheffield 2019, p. 9).
Managed bees are a threat to Suckley's cuckoo bumble bee in two
primary contexts--as a pathway for pathogen introduction and spread,
and competition for resources (Thomson 2004, p. 467; Winter et al.
2006, entire; Goulson et al. 2008, p. 193; Goulson 2010b, p. 10;
F[uuml]rst et al. 2014, p. 365; Goulson et al. 2015, p. 11). For
example, wild bumble bees located more closely to managed honey bee
colonies had significantly higher disease rates than wild bumble bees
located farther away (Alger et al. 2019, p. 5). Similarly, infection
rates for several bumble bee pathogens were higher in multiple

[[Page 102081]]

Bombus species near commercial greenhouses where managed bees were used
than in areas located far away from commercial greenhouses (Colla et
al. 2006, pp. 462-464).
While individual Suckley's cuckoo bumble bees need floral resources
for nectar and pollen, competition for resources likely more directly
affects the hosts for Suckley's cuckoo bumble bees, such as western
bumble bees, whose colonies may have hundreds of foraging workers. As a
result of competition, populations of wild Bombus species have been
shown to decrease with an increase in honey bee density (Thomson 2016,
p. 1251). In particular, western bumble bee colonies that were found
near higher densities of managed honey bees had reduced reproductive
success (Thomson 2004, p. 464).
Pathogens
Bumble bees are susceptible to a variety of pathogens including
fungal pathogens, parasites, tracheal mites, viruses, and nematodes.
Many of these pathogens are widespread and cause lethal and sublethal
effects for Bombus species. We provide a brief summary below of some
pathogens that are known to affect Suckley's cuckoo bumble bee, its
hosts, or both. Please see the SSA report for a detailed review of all
pathogens affecting Suckley's cuckoo bumble bees (Service 2024, pp. 38-
34).
The fungal pathogens Vairimorpha bombi (formerly Nosema bombi;
Tokarev et al. 2020, p. 11) and V. ceranae (formerly Nosema ceranae;
Tokarev et al. 2020, p. 11) which are caused by microsporidian
parasites, can have lethal and sublethal effects on bumble bees,
including disabled wings and impacts to reproduction (Otti and Schmid-
Hempel 2007, p. 122), suppressed immune response, and increased
mortality (Graystock et al. 2013, pp. 116-117; Graystock et al. 2014,
p. 9; Rotheray et al. 2017, p. 294; Service 2018, p. 52). Vairimopha
bombi has been documented in Suckley's cuckoo bumble bee, one confirmed
host species (western bumble bee), and four suspected host species
(rusty patched bumble bee, yellow bumble bee, red-belted bumble bee,
yellow-banded bumble bee) (Kissinger et al. 2011, p. 222; Cordes et al.
2012, p. 212), and it is classified as an emerging infectious disease
(Sachman-Ruiz et al. 2015, p. 2044; Wilfert et al. 2016, pp. 595-596).
Many protozoan parasites have been documented in bumble bees in
North America and can negatively affect populations by reducing colony
founding success, lowering colony fitness and growth, causing delayed
reproduction and inadequate fat reserves in hibernating queens, and
causing adult mortality (Shykoff and Schmid-Hempel 1991, p. 242;
Schmid-Hempel 2001, pp. 148, 150-154; Brown et al. 2003, pp. 995-1000).
In particular, Apicystis bombi is a protozoan parasite classified as an
emerging infectious disease (Sachman-Ruiz et al. 2015, p. 2044; Wilfert
et al. 2016, pp. 595-596). This disease has not been documented in
Suckley's cuckoo bumble bee, but it has been documented in Nevada
bumble bee, one of two confirmed host species (Maxfield-Taylor et al.
2011, p. 4).
Several honey bee viruses (e.g., deformed wing virus, black queen
cell virus, sacbrood virus, Kashmire bee virus, Israeli acute paralysis
virus, and acute bee paralysis virus) are also known to infect bumble
bees (Singh et al. 2010, p. 8; Robson-Hyska 2017, pp. 124-125; Tehel et
al. 2022, p. 4). These viruses have not been documented in Suckley's
cuckoo bumble bee, but they have been documented in several of its
potential hosts, including red-belted bumble bee, yellow bumble bee,
and yellow-banded bumble bee (Robson-Hyska 2017, pp. 63-65, 124-125).
Parasitic nematodes, such as Sphaerularia bombi, can result in
multiple negative effects to bumble bee queens, including changes in
gene expression affecting energy usage, translation, and circadian
rhythm (Colgan et al. 2020, p. 170), and in endocrine gland function
involved in growth and development in the larva and pupa (Maxfield-
Taylor et al. 2011, p. 134). Sphaerularia bombi has not been documented
in Suckley's cuckoo bumble bee, but it has been documented in western
bumble bee (Poinar 1974, p. 305).
In summary, bumble bees are susceptible to a variety of pathogens
and parasites, many of which are widespread and cause lethal and
sublethal effects for Bombus species. Although we lack information on
pathogen studies specific to Suckley's cuckoo bumble bee (Dozier et al.
2023, p. 642), we know many of these pathogens and parasites have
negative impacts to host species.
Pesticides
A variety of pesticides are widely used in agricultural, urban, and
natural environments, including herbicides, insecticides, fungicides,
miticides, rodenticides, and adjuvants. The pesticides with greatest
effects on bumble bees are herbicides and insecticides (particularly,
neonicotinoids, see below for more detail). Herbicide use can cause
changes in vegetation and the loss or reduction of flowers needed to
provide consistent sources of pollen, nectar, and nesting material
(Johansen 1977, p. 188; Kearns et al. 1998, pp. 91-92; Kearns and
Inouye 1997, p. 302; Plowright et al. 1978, p. 1145; Smallidge and
Leopold 1997, p. 264). Insecticides are specifically designed to
directly kill insects, which includes bumble bees, and herbicides
reduce available floral resources, thus indirectly affecting bumble
bees. For a full review of pesticides and the effects on bumble bees,
please see the SSA report (Service 2024, pp. 42-44).
Neonicotinoids are a class of insecticides that are used in a wide
variety of agricultural applications, including common use as seed
coatings in corn, wheat, soybeans, and cotton (Alford and Krupke, 2017,
p. 1) and have been strongly implicated in the decline of several
Bombus species (Colla and Packer 2008, p. 10; Goulson 2013, pp. 7-8;
Pisa et al. 2015, p. 69). Neonicotinoids are currently used throughout
the range of Suckley's cuckoo bumble bee in North America.
Neonicotinoids kill insects by interfering with the receptors of their
nervous systems, causing overstimulation, paralysis, and death
(Buszewski et al. 2019, p. 34728). Sublethal effects of neonicotinoids
to bumble bees can include impairments to reproduction (Whitehorn et
al. 2012, pp. 351-352; Baron et al. 2017, p. 4; Raine 2018, p. 40; Wu-
Smart and Spivak 2018, pp. 4-5). Suckley's cuckoo bumble bee have been
observed in and around regions of agricultural production, including
those involved in the production of crops commonly treated with
neonicotinoids.
Habitat Conversion and Fragmentation
The conversion of natural habitat to agricultural and urban areas
is the primary cause of bumble bee habitat loss (Goulson et al. 2015,
p. 2). Suckley's cuckoo bumble bee is associated with a wide variety of
habitats including prairies, grasslands, meadows, and woodlands as well
as urban and agricultural areas (COSEWIC 2019, p. 26; Martin et al.
2023, p. 22; Montana Natural Heritage Program 2023, entire). Habitat
conversion and fragmentation reduce the amount and/or accessibility of
suitable host nests and foraging and overwintering habitat. Habitat
conversion and fragmentation also reduce the connectivity required for
healthy populations to expand in response to environmental or
demographic changes and to maintain genetic diversity. High populations
of bumble bee species are associated with diverse floral resources,
particularly when surrounded by a complexity of

[[Page 102082]]

natural habitats across the landscape (Hines and Hendrix 2005, pp.
1481-1483; Hatfield and LeBuhn 2007, pp. 154-157). Due to their
foraging, nesting and overwintering requirements, bumble bees are
sensitive to the negative effects of habitat fragmentation (Kearns and
Inouye 1997, p. 298).
Habitat loss is commonly cited as a long-term contributor to bee
declines through the 20th century, and it may continue to contribute to
current declines, at least for some species (Goulson et al. 2008, pp.
191-198; Brown and Paxton 2009, pp. 411-412; Goulson et al. 2015, p.
2). As generalist foragers, Suckley's cuckoo bumble bee and its
confirmed host species may not be as severely affected by historical
and ongoing habitat loss compared to habitat specialists. However,
habitat loss or degradation reduces bee diversity and abundance (Potts
et al. 2010, pp. 348-349), and small, isolated patches of habitat may
not be sufficient to support healthy bee populations ([Ouml]ckinger and
Smith 2006, pp. 55-56; Hatfield and LeBuhn 2007, pp. 154-156).
Habitat conversion leads to the reduction of abundant and diverse
floral resources, which can lead to a lack of sufficient nutritional
resources; can reduce colony growth, health, and reproduction; and can
negatively influence long-term bee populations (Vaudo et al. 2015, p.
4040). Food shortfalls because of habitat loss can induce longer larval
development, can produce smaller and fewer individuals, and can cause
an early shift to male production (Beekman and van Stratum 1998,
entire; Sutcliffe and Plowright 1990, pp. 1056-1057). Larval and colony
growth can be significantly affected by pollen type (plant species),
pollen diversity, and the varying nutritional quality and quantity.
Nutritional stress caused by habitat loss can affect learning and
memory that can lead to reduced foraging efficiency, increased
competition, and overall decline in colony fitness (Townsend-Mehler and
Dyer 2011, pp. 275-286; Colla 2016, p. 413).
Monoculture farming is another factor that impacts plant community
changes and thus reduces nesting opportunities for host colonies
(Kearns and Inouye 1997, p. 298). Agricultural manipulation and changes
across various landscape types likely impacted the availability of host
nest sites in North America in the 20th century due to habitat
degradation, modification, conversion, and loss (Goulson 2003, p. 142).
These are important changes because diet breadth and coexistence in
bumble bees can become limited due to habitat loss (Goulson et al.
2008, pp. 193-200) and coexistence is important for parasitic species
such as the Suckley's cuckoo bumble bee that rely on host colonies to
raise their young. Decreases in foraging habitat increases competition
among bumble bee species, because there is overlap in resources that
these species use (Goulson et al. 2008, p. 196).
While habitat conversion and fragmentation are well documented
throughout the range of Suckley's cuckoo bumble bee, limited recent
observations show Suckley's cuckoo bumble bee, western bumble bee, and
rusty patched bumble bee populations do occur in urban and agricultural
settings. However, these areas may not represent high-quality habitat
with diverse native floral resources, and records of species in these
habitats may represent refugia from the primary threats in these areas
(i.e., application of pesticides in agricultural settings) (Everett
2023, pers. comm.).
Climate Change
Changes in ambient temperatures and heatwaves--Global annual
surface temperatures have risen an average of 0.09 [deg]C (0.17
([deg]F)) each decade from 1901 to 2020 (U.S. Environmental Protection
Agency (EPA) 2021, n.p.). Temperature increases in the contiguous
United States since the late 1970s have surpassed the global rates for
that period, increasing from 0.17 [deg]C to 0.30 [deg]C (0.31 [deg]F to
0.54 [deg]F) each decade. The northern and western parts of the United
States have experienced the greatest temperature increases (EPA 2021,
n.p.), representing much of the range of Suckley's cuckoo bumble bee.
Suckley's cuckoo bumble bee has been observed at latitudes up to 68.9
degrees North, within the Arctic Circle. Based on the most recent
climate models, temperatures in the Arctic have increased at three
times the global rate, and are expected to continue to increase at a
higher rate than the global average, with surface temperatures
exceeding 6 [deg]C (42.9 [deg]F) above preindustrial times by the end
of the 21st century (Ma et al. 2022, pp. 1, 7; Hayhoe et al. 2018, pp.
91-92). Climate change is contracting temperate, arctic, and alpine
zones (Staten et al. 2018, p. 770) in which bumble bees are distributed
and to which they are adapted (Goulson 2010a, p. 2).
In addition to increasing average temperatures, heatwaves in the
United States have become more frequent, more intense, and longer in
duration (EPA 2021, n.p.). Rising ambient temperatures and heatwaves
can negatively affect bumble bee individuals and colonies by reducing
survival, increasing energy expenditures, reducing flight and foraging,
reducing reproduction, and impacting when bees enter diapause
(Bartomeus et al. 2011, p. 20645; Maebe et al. 2021, p. 4229; Service
2024, pp. 20-22).
Bumble bees have low variation in heat stress resistance and,
therefore, may have low capacity to adapt physiologically to warming
temperatures (Martinet et al. 2021, p. 7). Bumble bee species that
occur across a relatively broad climatic range, such as Suckley's
cuckoo bumble bee, likely have a greater capacity to adapt to warming
temperatures than species with narrow ranges. While we do not know how
well Suckley's cuckoo bumble bee will adapt to rising temperatures,
their main host species, the western bumble bee, appears to be
sensitive to temperature (Janousek et al. 2023, p. 2). Heat waves are
projected to increase, particularly in the western portions of North
America (Hicke et al. 2022, p. 1937), which represents the bulk of the
Suckley's cuckoo bumble bee's range.
Temperature changes could make the southern portions of the
Suckley's cuckoo bumble bee's range less suitable for the species,
while additional habitat may become more suitable in the northern
portions of the range and at higher elevations. Colonizing new areas
may be dependent on dispersal ability and may require adapting to novel
communities where Suckley's cuckoo bumble bees could be exposed to new
environmental conditions (e.g., extreme heat or extreme cold) and
potential hosts (Cameron et al. 2011, pp. 39-40; Pradervand et al.
2014, p. 5). Additionally, warming ambient temperatures and heatwaves
commonly co-occur with drought, another influence that could compound
the effects of any one of the other threats to this species (see
Drought frequency and intensity, below) (Cameron et al. 2011, pp. 39-
40; Pradervand et al. 2014, p. 5).
While northern areas may become suitable in the future, an analysis
of long-term observations of 67 bumble bee species from Europe and
North America showed southern range contractions as a result of climate
change, with no change in northern limits (Kerr et al. 2015, p. 178).
Future projections of the distribution of bumble bee species under
different climate scenarios and dispersal assumptions also predict
widespread declines, and possible extirpations, in the southern
portions of species ranges. (Sirois-Delisle and Kerr 2018, pp. 4-5;
Soroye et al. 2020, pp. 685, 687).
Warming temperatures could additionally affect Suckley's cuckoo
bumble bee and its hosts by affecting floral resources. Shifts in
flowering

[[Page 102083]]

times (in response to warming temperatures) could result in
phenological mismatch between pollinators and their foraging resources
(Service 2024, pp. 47-48). Heatwave conditions directly reduce bumble
bee foraging, as well as have indirect effects on bumble bee foraging
from heat-stressed flowering resources (Williams and Hemberger 2023, p.
597). Decreased pollination due to phenological mismatch could reduce
plant reproduction and further affect floral resource availability
(Forrest et al. 2010, p. 438; Thomson 2010, p. 3197).
Drought frequency and intensity--Drought negatively impacts floral
resources and the pollinators that depend on them. A large portion of
Suckley's cuckoo bumble bee's range is within water-limited areas of
western North America where drought is frequent and has major
implications for floral resources. The frequency of biologically
significant drought events is projected to increase within the range of
Suckley's cuckoo bumble bee and its host species due to changes in
climate and resource impacts (Swain and Hayhoe 2015, pp. 2737-2750).
Drought indirectly impacts bumble bees by altering or reducing
floral resources, including reductions to the quality, quantity, and
availability of pollen and nectar (Carroll et al. 2001, p. 443; Waser
and Price 2016, p. 1405; Phillips et al. 2018, pp. 3226-3235) Shifts in
the spatial and temporal patterns of flowering, which result in mid-
summer floral gaps (Aldridge et al. 2011, entire), highlight that
drought-stress impacts on a plant community could reduce pollen and
nectar resources needed for successful pollinator reproduction. Since
droughts have a direct effect on floral resources, this in turn has an
effect on pollinators at the population level (Roulston and Goodell
2011, p. 305). Drought may also lead to increased competition with
honey bees in areas where their resources overlap. When drought
conditions impact preferred floral resources, bumble bees will forage
on less preferred, drought-resistant species sought after by the more
populous honey bees (Thomson 2016, pp. 1247-1255).
A model of cumulative effects of climate changes, landcover, and
pesticide use on western bumble bee occupancy found that consecutive
years of severe drought was the second most influential cause of
occupancy declines (Janousek et al. 2023, pp. 2-3). In addition,
suitable habitats may be restricted with rising temperatures, reducing
the range of some bumble bee species, especially at range edges where
abundance may decline when floral resources decline in response to
drought (Thomson 2016, pp. 1247-1255). Although drought may be locally
and temporarily alleviated by precipitation, the impacts to the growing
season may persist and reduced floral resources could impact Suckley's
cuckoo bumble bees that require pollen and nectar to overwinter with
adequate body mass (Service 2024, pp. 22-23).
Droughts, especially in consecutive years (Janousek et al. 2023, p.
2), will likely amplify biologically significant negative effects on
Suckley's cuckoo bumble bee resources and host species, though the
direct drought impacts on Suckley's cuckoo bumble bee individuals and
populations are unstudied. Droughts are expected to negatively affect
floral resources, alter floral communities to less preferred flowering
conditions or timing, increase competition between pollinators, and
negatively impact Suckley's cuckoo bumble bee and its hosts throughout
much of the species' range.
Wildfire--Wildfires pose complex effects to bumble bees, from
decreasing resource availability (Mola and Williams 2018, p. 7;
Galbraith et al. 2019, p. 15; Mola et al. 2020, p. 1807) to increasing
floral and bee abundance and diversity (Mola and Williams 2018, pp. 4-
8; Carbone et al. 2019, entire; Galbraith et al. 2019, entire; Mola et
al. 2020, pp. 1804-1808). Fire disturbance can temporarily increase
floral resources, thereby enhancing bee body size, reproductive output,
genetic diversity, and population size (Carbone et al. 2019, entire;
Mola et al. 2020, pp. 1804-1808), although these effects may vary by
habitat type (i.e., forested vs. grassland habitats). The relative
effect of high-intensity fires varies based on the ecological
conditions in which they occur. Since Suckley's cuckoo bumble bee is a
broad-ranging species with multiple hosts, fire is likely to have
variable and diverse effects throughout its range.
Early spring frosts--Early spring frosts pose a risk to bumble
bees, specifically to new queens and newly established colonies, by
damaging floral resources (CaraDonna and Bain 2015, pp. 61-62).
Flowers, compared to vegetative parts, are generally more sensitive to
damage from frost events (CaraDonna and Bain 2015, pp. 61-62), and
spring frosts reduce the overall availability of floral resource
abundance across the subsequent summer (CaraDonna et al. 2014, p.
4919).
Despite some plants with early phenology exhibiting some tolerance
to freezing temperatures (CaraDonna and Bain 2015, pp. 61-63), an
advancing bloom date for plants triggered by climate change (CaraDonna
et al. 2014, p. 4919) exposes early floral growth to an additional risk
of frost damage (Willmer 2012, p. R131). The increased frost damage to
flowering plants could also contribute to an observed change in
flowering dates across small geographic and altitudinal distributions
(Inouye 2008, pp. 357, 361).
Floral resources are important throughout the lifecycles of both
Suckley's cuckoo bumble bee and its hosts, but they are particularly
important for host colony establishment in early spring. Negative
effects of early spring frost on host colony queens, workers, and
overall colony size may reduce their ability to persist within season,
and to successfully support Suckley's cuckoo bumble bee. Spring frost
damage to floral resources has been linked to within-season declines in
wild bee populations (Graham et al. 2021, p. 6). Spring frosts could
have a negative impact on the success of local bumble bee colonies
(Inouye 2008, p. 361) by reducing existing and future within-season
availability of pollen and nectar resources on which pollinators,
including host colonies for Suckley's cuckoo bumble bee, rely.
Inadequate floral resources could especially affect colony
establishment and growth if they occur during critical times, such as
early spring when new queens emerge from diapause and are establishing
their colonies. Delays in emergence or colony initiation after
emergence may hinder the ability of bees to complete their life cycle
before the end of the relatively short subarctic season (Vogt et al.
1994, p. 1554).
Livestock Grazing
Livestock grazing occurs throughout much of the historical range of
Suckley's cuckoo bumble bee, primarily by cattle, sheep and wild
horses, and it can have complex effects on bumble bees. In general,
grazed sites have reduced floral resources and lower bumble bee
diversity and abundance (Hatfield and LeBuhn 2007, p. 150; Sj[ouml]din
2007, pp. 2110-2113; Sj[ouml]din et al. 2008, p. 763). Although grazing
can be a useful management tool for maintaining early successional
habitat, benefits are dictated by frequency, intensity, species (i.e.
sheep, cattle, horses, etc.) and timing (Carvell 2002, p. 44; Kimoto et
al. 2012, pp. 9-13). Low-intensity grazing preserves floral resources
benefiting bumble bees (Scohier et al. 2012, pp. 287-292), while
increased intensity of grazing can reduce bee species richness as a
result of altered floral composition, including invasive species
establishment and soil

[[Page 102084]]

compaction (Hatfield and LeBuhn 2007, p. 156; V[aacute]zquez and
Simberloff 2003, p. 1080). Bumble bees are sensitive to grazing
intensity early in the season, potentially because of altered foraging
behavior (Kimoto et al. 2012, pp. 9-13). Intense summer grazing,
compared to areas only grazed in winter, reduces vegetation height and
floral resources, leading to fewer bee visits to preferred food plants
and decreased bumble bee diversity (Xie et al. 2008, pp. 699-700). The
reduction of vegetation height and structure from high-intensity
grazing in the Pacific Northwest bunchgrass prairies has been linked to
declines in bumble bee richness and abundance (Kimoto et al. 2012, pp.
12-13).
Grazing may compact soil and change plant communities (Connors
2016, pers. comm.), thus impacting nesting habitat for Suckley's cuckoo
bumble bee hosts (Defenders of Wildlife 2015, p. 14). Livestock may
also trample nesting sites (Kearns et al. 1998, p. 90) and negatively
impact ground-nesting rodents (Johnson and Horn 2008, p. 444), which in
turn may reduce the number of nest sites available for bumble bees (The
Xerces Society and Thorp 2010, p. 13). Livestock grazing also impacts
hydrology through compaction of soils and degraded riparian areas and
may lead to increased fire cycles through the introduction of exotic
species (Dwire et al. 1999, pp. 319-321).
In summary, grazing can assist in maintaining open habitat, and
low-intensity grazing can preserve floral resources. However, high-
intensity grazing can have a negative impact on floral resources and
can negatively impact nest site availability. Thus, grazing has varied
and complex effects on bumble bees, which makes the impacts difficult
to analyze.

Conservation Efforts and Regulatory Mechanisms

Suckley's cuckoo bumble bee is assessed as threatened in Canada
(COSEWIC, 2019, p. iii) and is listed as critically endangered by the
International Union for Conservation of Nature (Hatfield et al., 2015,
p. 1). In the United States, Suckley's cuckoo bumble bee is on the
sensitive species list for the U.S. Forest Service and Bureau of Land
Management Interagency Special Status/Sensitive Species Program
(ISSSSP) in the Pacific Northwest (ISSSSP 2021, entire). It is also
listed as a species of greatest conservation need in Idaho, Washington,
Colorado, and California, where it is also a candidate for listing
under the California Endangered Species Act (Colorado Parks and
Wildlife 2015, p. B-1; Washington Department of Fish and Wildlife 2015,
pp. 3-39; Idaho Department of Fish and Game 2017, p. xvii; California
Natural Diversity Database (CNDDB) 2023, p. 6). These States generally
outline research and conservation needs for species of greatest
conservation need in State Wildlife Action Plans, but these plans do
not offer regulatory protection.
Some States regulate the import of nonnative bee species, which can
help protect native bee species, including Suckley's cuckoo bumble bee.
The Oregon Department of Agriculture restricts some potential sources
of the pathogen Vairimorpha bombi from entering the State; only Bombus
species native to Oregon are permitted for commercial pollination
purposes (Oregon Department of Agriculture 2017, p. 5). California
requires permits to import some bee species for pollination services
(California Department of Food and Agriculture 2023, entire).
The U.S. Forest Service has taken steps to reduce impacts of
nonnative bee species. The Pacific Northwest Region of the U.S. Forest
Service is working on finalizing apiary guidelines, which include
recommendations for management practices and considerations to protect
native pollinators and minimize negative effects from managed bees and
apiaries on lands managed by the U.S. Forest Service (Everett 2023,
pers. comm.). Additionally, at least one U.S. Forest Service National
Forest in the Pacific Northwest already restricts commercial and
privately owned bees on their managed lands (Everett 2023, pers.
comm.). For example, the Colville National Forest plan directs that
apiaries should not be placed where they would pose a risk to native
pollinators, butterflies, or rare bee species (U.S. Forest Service
2019, p. 67). These measures highlight that the U.S. Forest Service
takes the threat of managed bees seriously and is actively working in
some regions to protect native bees.
States have also begun implementing strategies to limit pesticide
effects on bees. The Oregon Bee Project was initiated in 2017, as a
collaboration between the Oregon Department of Agriculture, the Oregon
State University Extension Service, and the Oregon Department of
Forestry. One project goal is to mitigate bee exposure to pesticides
through increased pesticide label comprehension, adoption of new
application practices, and increasing coordination between beekeepers
and pesticide applicators (Oregon Department of Agriculture et al.
2022, pp. 2-3). Washington State has established similar goals, as
stated in their Managed Pollinator Protection Plan, which offers best
management practices for beekeepers, growers, and pesticide applicators
to help protect pollinators from pesticides (Washington State
Department of Agriculture 2018, p. 5). Washington State also adopted
additional recommendations and funding for pollinator health
(Washington State Bill 5253, effective July 25, 2021).
In Washington, neither the Managed Pollinator Protection Plan nor
State Bill 5253 restrict the use of pesticides, but several other
States have begun passing regulations on pesticides that are harmful to
bees and other pollinators. For example, California recently developed
regulations that will implement mitigation measures to protect
pollinators by limiting the agricultural uses of certain neonicotinoid
pesticides, which went into effect January 1, 2024 (California
Department of Pesticide Regulation 2024, entire). Other States that
have enacted various regulations on neonicotinoid pesticides to reduce
impacts to bees and other pollinators include Colorado, Connecticut,
Maine, Minnesota, Massachusetts, Maryland, Nevada, New York, New
Jersey, Rhode Island, and Vermont (Malfi 2023, entire).
Other recent efforts aim to better understand bees at risk and
implement broader protections. The Pacific Northwest Bumble Bee Atlas
(a collaborative effort between the Washington Department of Fish and
Wildlife, the Idaho Department of Fish and Game, the Oregon Department
of Fish and Wildlife, and the Xerces Society for Invertebrate
Conservation) seeks to increase understanding of bumble bee
distributions and their habitats (Washington Department of Fish and
Wildlife et al. 2023, entire). This effort has contributed to the
creation of a statewide strategy to protect bumble bee species of
conservation concern in Washington, with one of the focal species being
Suckley's cuckoo bumble bee (Martin et al. 2023, p. 12). In Alaska, the
Alaska Center for Conservation Science at the University of Alaska
Anchorage and the Bureau of Land Management have developed the Alaska
Bee Atlas. The program aims to collect data on bee biodiversity within
Alaska; these data can eventually be used to inform sensitive species
lists and management (Fulkerson et al. 2023, p. 18). The number of
bumble bee atlases is increasing across the United States and
increasingly covering the range of Suckley's cuckoo bumble bee. The
expanding coverage of these atlases will

[[Page 102085]]

increase understanding of bumble bee status and distribution in North
America.
On a broader scale, the Colla Laboratory at York University in
Toronto has released a national pollinator strategy for Canada. This
national strategy identifies specific goals and actions to protect
pollinators and needed research to fill knowledge gaps (Colla and
Nalepa 2023, p. 5). The Service is also working on a nationwide plan
through a bumble bee conservation benefit agreement, known as The
Nationwide Conservation Benefit Agreement for Bumble Bees on Energy and
Transportation Lands. This conservation benefit agreement is modeled
after the nationwide monarch butterfly candidate conservation agreement
with assurances, which is a voluntary agreement with transportation and
utility landowners that provides incentives for monarch conservation
measures on their lands. The bumble bee conservation benefit agreement
will likely include many of the same acres enrolled for the protection
of several bumble bee species, including Suckley's cuckoo bumble bee
and some of its host species (i.e., western bumble bee, rusty patched
bumble bee, and yellow-banded bumble bee). The Nationwide Conservation
Benefit Agreement for Bumble Bees on Energy and Transportation Lands is
expected to be completed in 2024 (Everett 2023, pers. comm.).
Together, these voluntary and regulatory measures highlight an
increase in effort to protect native bumble bee species across North
America. Some of these measures specifically target Suckley's cuckoo
bumble bee, its host species, or both for conservation. Broad efforts
to protect and conserve native pollinators and bees will also likely
benefit Suckley's cuckoo bumble bee.

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. 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
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.

Historical, Current, and Near-Term Condition of Suckley's Cuckoo Bumble
Bee

We assessed Suckley's cuckoo bumble bee viability by evaluating the
historical and current condition and identifying the primary influences
leading to the species' current and near-term condition. We delineated
15 analytical units for Suckley's cuckoo bumble bee: 4 in eastern North
America and 11 in western North America (figure 1). Analytical units
are based on ecoregions and further detailed in the SSA report (Service
2024, pp. 55-56).
We used a published multi-species occupancy model (Jackson et al.
2022, entire) with updated Suckley's cuckoo bumble bee occurrence
records (Service 2024, pp. 56-57) to understand trends in both
Suckley's cuckoo bumble bee and host species occupancy. Our dataset
included 2,317 occurrence records of Suckley's cuckoo bumble bee. The
occupancy model also incorporated floral resources and climate
variables. For a detailed review of the methods, please refer to the
SSA report (Service 2024, pp. 56-57, 120-123). We provide a summary
below of the methods and key findings.
We used the output of the multi-species occupancy model to assess
historical trends, and to support our assessment of current and near-
term condition. We used decadal projections of rangewide probability of
occupancy to visualize and characterize overall, rangewide trends in
occupancy from 1900-2020 (Service 2024, pp. 63-64). We used spatially
explicit estimates of probability of occupancy from 1900-1960 to
characterize the historical probability of occupancy in each analytical
unit; we specifically used 1900-1960 to represent the historical
baseline, as this is the period before declines were apparent (Service
2024, pp. 63-64). We used spatially explicit occupancy estimates in
each analytical unit for the 2000-2020 period to provide a current
snapshot or baseline of species condition relative to historical. We
used spatially explicit projections of near-term (2020-2040) occupancy
in each analytical unit to assess near-term risk of extinction.
The near-term occupancy projections were made under two scenarios.
Scenario 1 assumes moderate climate warming under representative
concentration pathway (RCP) 4.5. Scenario 2 assumes a high warming
scenario (RCP 8.5), and also projects the observed, historical rates of
decline due to other, non-climatic (i.e., trend momentum) forward. Both
scenarios hold floral resources constant at their 2020 levels, as data
are not available to project this variable forward. Thus, under
scenario 1, any changes in occupancy are based solely on changes in
climate (RCP 4.5), while under scenario 2, any changes in occupancy are
based on both climate change (RCP 8.5), as well as historical rates of
change due to non-climatic factors. Projections for all host species
followed the same procedures.
Suckley's cuckoo bumble bee has exhibited a statistically
significant decline, resulting in lower occupancy from historical
condition. Historically, the median probability of occupancy of
Suckley's cuckoo bumble bee rangewide was 0.65. By the 2000-2020 period
all analytical units are estimated to have lower probability of
occupancy, with median probability of occupancy less than 0.16 for all
analytical units and 0.13 rangewide (table 1).

Table 1--Median Estimated Probability of Occupancy for Suckley's Cuckoo Bumble Bee in Each Analytical Unit
During the Historical Period (Average From 1900-1960) and the Current (2000-2020) Period
[The percent change in median occupancy from historical to current period is also noted for each analytical
unit, as is the total land area of each analytical unit (square kilometers (km\2\)) and the percent of the range
the unit represents, in terms of land area.]
----------------------------------------------------------------------------------------------------------------
Median Median
Analytical unit Area (km\2\) Percent of Last historical current Percent
range detection occupancy occupancy change
----------------------------------------------------------------------------------------------------------------
Atlantic Highlands (East)...... 44,482 0.6 1924 0.712 0.149 -79
Boreal Cordillera.............. 532,782 7.4 2019 0.706 0.147 -79
Boreal Plains.................. 772,369 10.8 2022 0.661 0.145 -78
Brooks Range Tundra............ 99,755 1.4 2019 0.705 0.147 -79
Cold Deserts................... 1,047,895 14.7 2011 0.485 0.061 -87
Hudson Plains (East)........... 55,863 0.8 1949 0.682 0.133 -80
Marine West Coast Forests...... 250,206 3.5 1982 0.580 0.095 -84

[[Page 102086]]

Mixed Wood Plains (East)....... 360,958 5.0 1971 0.640 0.106 -83
Mixed Wood Shield.............. 205,107 2.9 1995 0.590 0.098 -83
Softwood Shield (East)......... 119,152 1.7 2010 0.685 0.142 -79
South Central Semi-Arid 208,917 2.9 2014 0.118 0.013 -89
Prairies......................
Taiga Plains................... 905,619 12.7 1969 0.708 0.161 -77
Temperate Prairies............. 501,088 7.0 2018 0.263 0.028 -89
West Central Semi-Arid Prairies 832,871 11.6 2022 0.577 0.100 -83
Western Cordillera............. 1,214,900 17.0 2018 0.692 0.140 -80
--------------------------------------------------------------------------------
Rangewide.................. 7,151,965 100 \1\ 2022 0.653 0.128 \2\-85
----------------------------------------------------------------------------------------------------------------
\1\ The last detection of Suckley's cuckoo bumble bee in our dataset was 2022. However, field data from across
the country from the 2023 field season or beyond had not been fully curated in time to include in the SSA.
\2\ Rangewide decline from 1900 to present, based on an analysis of all Suckley's cuckoo bumble bee occurrence
records (Service 2024, pp. 63-68).

Suckley's cuckoo bumble bee has not been observed in the United
States since 2016, despite widespread historical occurrence records and
increased sampling effort for bumble bees. Additionally, the species
has only been detected since 2000 (detections after 2000 are considered
modern detections) in 9 of the 15 analytical units (60 percent of the
total analytical units; see table 1, above). We considered analytical
units to be quasi-extirpated (when the density of reproductive
individuals in a population becomes so small that extirpation is likely
inevitable without intervention) if there were no detections since
2000. In the species' eastern range, three of the four analytical units
of Suckley's cuckoo bumble bee were considered quasi-extirpated,
including the Atlantic Highlands (last detection in 1924), Hudson
Plains (last detection in 1949), Mixed Wood Plains (last detection in
1971).
In the west of the species' range, 3 of the 11 analytical units
lack modern detections (i.e., since 2000) of Suckley's cuckoo bumble
bee. Notably, the Marine West Coast Forest analytical unit has 515
historical occurrence records (23 percent of total occurrences), but no
occurrence records after 1982. The Mixed Wood Shield analytical unit
has two historical records of the species, with the most recent
occurrence in 1995. Thus, we consider the Marine West Coast Forest and
the Mixed Wood Shield analytical units to be quasi-extirpated. Although
the species has not been observed in the Taiga Plains since 1962, this
area has not been extensively sampled for bees, and, therefore, we did
not consider it to be quasi-extirpated.
Additionally, four (western bumble bee, McKay's bumble bee, rusty
patched bumble bee, and yellow-banded bumble bee) of six host species
exhibited statistically significant temporal declines in occupancy
rangewide (Service 2024, pp. 69-70). These results are similar to other
studies that found rangewide population declines for bumble bees in the
subgenus Bombus (Giles and Ascher 2006, pp. 217-218; Colla and Packer
2008, p. 1387; Schweitzer et al. 2012, p. 7; Janousek et al. 2023, p.
2;).
In the near-term (by 2040), probability of occupancy is expected to
continue to decline. Under scenario 1, median probability of occupancy
is estimated to be less than 0.11 across all analytical units. This
represents a 26 to 77 percent decline relative to 2000-2020 estimates.
Under scenario 2, median probability of occupancy is estimated to be
less than 0.05 across all analytical units. This represents a 73 to 92
percent decline relative to 2000-2020 estimates.

Resiliency

Suckley's cuckoo bumble bee has experienced a statistically
significant, rangewide, 85 percent decline in occupancy. Additionally,
the species has not been observed in the contiguous United States since
2016, despite widespread historical occurrence records and increased
sampling effort for bumble bees. These results suggest that the species
is currently found in fewer locations across its range than
historically. High abundance and survival are demographic needs of
healthy Suckley's cuckoo bumble bee populations. While there are some
areas in Canada where the species is still regularly observed, these
results suggest resiliency is low across all analytical units. In the
near-term, resiliency is projected to continue to decline, further
reducing the species ability to sustain populations over time.

Redundancy

Redundancy buffers the species against catastrophic events and can
be summarized based on the spatial distribution of sufficiently
resilient populations relative to catastrophic events. Currently, three
eastern analytical units and two western analytical units are
considered quasi-extirpated. This apparent contraction of the range
results in a loss of redundancy for the species. In the near-term, the
continued decline in occupancy projected will likely further reduce
redundancy. Given that one confirmed host species (western bumble bee)
and three potential host species (rusty patched bumble bee, McKay's
bumble bee, and yellow-banded bumble bee) are in decline, redundancy in
terms of host species is considered low. For instance, if a
catastrophic event wipes out one host species in an area, then there is
less likely to be an alternative host species available for the
Suckley's cuckoo bumble bee.

Representation

Due to estimated and observed declines in occupancy, Suckley's
cuckoo bumble bee has substantially lower connectivity, and
representation than historically. Population connectivity is important
for Suckley's cuckoo bumble bee's viability as it increases the
likelihood of genetic diversity and promotes successful haplodiploid
reproduction (genetic sex-determination system in which females develop
from fertilized (diploid) eggs and males from unfertilized (haploid)
eggs). Loss of connectivity, genetic drift, and inbreeding may be
particularly consequential for bumble bees due to their low effective
population size and their haplodiploid sex determination (Goulson et
al. 2008, p. 205). However,

[[Page 102087]]

population connectivity is naturally a constraint for cuckoo bumble
bees because they live in small, fragmented populations due to their
dependence on host bumble bee colonies (Suhonen et al. 2016, p. 529).
Dispersal of bees to find unrelated mates is aided by the proximity of
other usurped host colonies. Consequently, the sharp decrease in the
prevalence of both Suckley's cuckoo bumble bee and many of its
confirmed and potential host species has likely reduced population
connectivity relative to historical conditions. Reduced gene flow may
have consequences on the genetic diversity of Suckley's cuckoo bumble
bee, because small populations can experience stronger genetic drift
(Zayed 2009, p. 246). This is important because high genetic diversity
reduces prevalence of some pathogens (Parsche and Lattorff 2018, p.
900), and the risk of matched mating, which produces diploid males that
do not contribute to population growth (Zayed 2009, p. 239).
Given the observed 85 percent decrease in the species' occupancy
relative to historical conditions, the low current and projected near-
term occupancy across all analytical units, and the potential that the
species is extirpated or quasi-extirpated in portions of its range, the
species has likely lost representation across longitudinal and
ecological gradients.
The adaptive capacity of Suckley's cuckoo bumble bee is also
dependent on host species, as the distribution of the parasitic bee is
restricted by the geographic distribution and population health of host
bees, and parasite abundance is low where host abundance is low
(Antonovics and Edwards 2011, p. 1003). Therefore, availability of host
species may also indirectly restrict the adaptive capacity of Suckley's
cuckoo bumble bee, given that four of the six host species are also in
decline.

Future Condition

As part of the SSA, the same methods to model near-term condition
were also used to mode the two future condition scenarios out to the
year 2100. Our scenarios assumed a moderate to major increase in
climate change (warming conditions) and either a continuation of
factors that resulted in the historical decline of the species, or no
continuation of these factors (just the impacts of climate change) to
the species. Because we determined that the current and near-term
condition of Suckley's cuckoo bumble bee is consistent with the Act's
definition of an endangered species (see Determination of Suckley's
Cuckoo Bumble Bee's Status, below), we are not presenting the results
of the future scenarios beyond 2040 in this proposed rule. Please refer
to the SSA report (Service 2024, pp. 73-83) for the full analysis of
future conditions.

Determination of Suckley's Cuckoo Bumble Bee's Status

Section 4 of the Act (16 U.S.C. 1533) and its implementing
regulations (50 CFR part 424) set forth the procedures for determining
whether a species meets the definition of an endangered species or a
threatened species. The Act defines an ``endangered species'' as a
species 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.
We presented summary evaluations of the main drivers of the
species' current and near-term condition analyzed in the SSA report
including habitat conversion and fragmentation (Factor A), livestock
grazing (Factor A), pathogens (Factor C), host species decline (Factor
E), climate change (Factor E), and pesticides (Factor E). We also
evaluated existing regulatory mechanisms (Factor D) and ongoing
conservation measures.

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 have determined that Suckley's cuckoo bumble bee has
limited resiliency, redundancy, and representation to maintain
viability over time. Suckley's cuckoo bumble bee has exhibited a
statistically significant decline (85 percent) in probability of
occupancy rangewide. Historically, the median probability of occupancy
of Suckley's cuckoo bumble bee rangewide was 0.65. By the current time
period (2000-2020), all analytical units are estimated to have lower
probability of occupancy, with median probability of occupancy less
than 0.16 for all analytical units and 0.13 rangewide. In the near-term
(by 2040), the probability of occupancy is projected to continue to
decline, with probability of occupancy for all analytical units
projected to be below 0.05 (scenario 1) and 0.11 (scenario 2).
Additional analyses of host species occupancy indicate that four of six
known or potential host species exhibited statistically significant
temporal declines in probability of occupancy rangewide. Thus,
resiliency for all analytical units is considered low.
Suckley's cuckoo bumble bee has lost redundancy because 5 of the 15
analytical units are currently considered to be in a quasi-extirpated
state, the species has not been observed in the contiguous United
States since 2016, and the remaining analytical units are all
considered to have low resiliency. Near-term projections indicate
continued declines in occupancy, further reducing redundancy.
Representation has also declined as a result of range contraction
and occupancy decline, as phenotypic, genetic, and ecological diversity
have declined. As host colonies become less common across the
landscape, Suckley's cuckoo bumble bees will likely have lower
likelihood of finding unrelated mates. Population fragmentation,
genetic drift, and inbreeding are likely to be exacerbated in the near-
term as the species becomes even less prevalent. Finally, it is
important to note that the viability of Suckley's cuckoo bumble bee is
also highly dependent on its host species, many of which have declined
historically, and are expected to continue to do so in the near-term.
We do not find Suckley's cuckoo bumble bee meets the Act's
definition of a threatened species because the species currently has
low resiliency, redundancy, and representation and near-term
projections are estimated to further reduce overall species viability.
Because Suckley's cuckoo bumble bee has low redundancy and
representation, the species is vulnerable to even a single catastrophic
event such as a pathogen outbreak, wildfire, or drought event. Thus,
after assessing the best scientific and commercial data available, we
determine that Suckley's cuckoo bumble bee is in danger of extinction
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. We have determined that Suckley's cuckoo bumble bee is in
danger of extinction throughout all of its range and

[[Page 102088]]

accordingly did not undertake an analysis of any significant portion of
its range. Because Suckley's cuckoo bumble bee warrants listing as
endangered throughout all of its range, our determination does not
conflict with the decision in Center for Biological Diversity v.
Everson, 435 F. Supp. 3d 69 (D.D.C. 2020), because that decision
related to significant portion of the range analyses for species that
warrant listing as threatened, not endangered, throughout all of their
range.

Determination of Status

Based on the best scientific and commercial data available, we
determine that Suckley's cuckoo bumble bee meets the Act's definition
of an endangered species. Therefore, we propose to list Suckley's
cuckoo bumble bee as an endangered species in accordance with sections
3(6) 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, self-sustaining, 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://www.fws.gov/program/endangered-species) or from our Southern Alaska Fish and Wildlife Field
Office (see FOR FURTHER INFORMATION CONTACT).
Implementation of recovery actions generally requires the
participation of a broad range of partners, including other Federal
agencies, States, Tribes, nongovernmental organizations, businesses,
and private landowners. Examples of recovery actions include habitat
restoration (e.g., restoration of native vegetation), research, captive
propagation and reintroduction, and outreach and education. The
recovery of many listed species cannot be accomplished solely on
Federal lands because their range may occur primarily or solely on non-
Federal lands. To achieve recovery of these species requires
cooperative conservation efforts on private, State, and Tribal lands.
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 Washington, Oregon,
Idaho, California, Colorado, Nevada, Utah, Arizona, Wyoming, Montana,
North Dakota, South Dakota, Nebraska, and Minnesota would be eligible
for Federal funds to implement management actions that promote the
protection or recovery of the Suckley's cuckoo bumble bee. Information
on our grant programs that are available to aid species recovery can be
found at: https://www.fws.gov/service/financial-assistance.
Although Suckley's cuckoo bumble bee 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)(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

[[Page 102089]]

opinion and serve as compliance with section 7(a)(2) of the Act.
Examples of discretionary actions for Suckley's cuckoo bumble bee
that may be subject to conference and consultation procedures under
section 7 are management of Federal lands administered by the National
Park Service, U.S. Fish and Wildlife Service, 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,
or the Federal Emergency Management Agency. Federal actions not
affecting listed species or critical habitat--and actions on State,
Tribal, local, or private lands that are not federally funded,
authorized, or carried out by a Federal agency--do not require section
7 consultation. Federal agencies should coordinate with the Southern
Alaska Fish and Wildlife Field Office (see FOR FURTHER INFORMATION
CONTACT) with any specific questions on section 7 consultation and
conference requirements.
The Act and its implementing regulations set forth a series of
general prohibitions and exceptions that apply to endangered wildlife.
The prohibitions of section 9(a)(1) of the Act, and the Service's
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. Certain exceptions to these
prohibitions apply to employees or agents of the Service, the National
Marine Fisheries Service, other Federal land management agencies, and
State conservation agencies.
We may issue permits to carry out otherwise prohibited activities
involving endangered wildlife under certain circumstances. Regulations
governing permits for endangered wildlife are codified at 50 CFR 17.22,
and general Service permitting regulations are codified at 50 CFR part
13. With regard to endangered wildlife, a permit may be issued: for
scientific purposes, for enhancing the propagation or survival of the
species, or for take incidental to otherwise lawful activities. The
statute also contains certain exemptions from the prohibitions, which
are found in sections 9 and 10 of the Act.

II. 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 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 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
consult 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
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

[[Page 102090]]

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 compiled in 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 section 9 of the Act.
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
continue to contribute to recovery of the species. Similarly, critical
habitat designations made on the basis of the best scientific data
available 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.

Critical Habitat Determinability

Our regulations at 50 CFR 424.12(a)(2) state that critical habitat
is not determinable when one or both of the following situations exist:
(i) Data sufficient to perform required analyses are lacking, or
(ii) The biological needs of the species are not sufficiently well
known to identify any area that meets the definition of ``critical
habitat.''
We reviewed the available information pertaining to the biological
needs of the species and habitat characteristics where this species is
located. A careful assessment of the economic impacts that may occur
due to a critical habitat designation is still ongoing, and we are in
the process of acquiring the complex information needed to perform that
assessment. Therefore, due to the current lack of data sufficient to
perform required analyses, we conclude that the designation of critical
habitat for Suckley's cuckoo bumble bee is not determinable at this
time. The Act allows the Service an additional year to publish a
critical habitat designation that is not determinable at the time of
listing (16 U.S.C. 1533(b)(6)(C)(ii)).

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.

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 sent letters to all Tribes within the range of the
species. We received responses back from the Tsleil-Waututh Nation and
the Nottawaseppi Huron Band of the Potawatomi; both Tribes provided
support for our SSA efforts, but no new data or information. We will
continue to work with Tribal entities during the development of any
subsequent rules for Suckley's cuckoo bumble bee.

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 Southern Alaska Fish and Wildlife Field Office (see FOR FURTHER
INFORMATION CONTACT).

Authors

The primary authors of this proposed rule are the staff members of
the Fish and Wildlife Service's Species

[[Page 102091]]

Assessment Team and the Southern Alaska Fish and Wildlife Field Office.

List of Subjects in 50 CFR Part 17

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

Proposed Regulation Promulgation

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

PART 17--ENDANGERED AND THREATENED WILDLIFE AND PLANTS

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

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

0
2. In Sec. 17.11, in paragraph (h), amend the List of Endangered and
Threatened Wildlife by adding an entry for ``Bee, cuckoo bumble,
Suckley's'' in alphabetical order under INSECTS to read as follows:

Sec. 17.11 Endangered and threatened wildlife.

* * * * *
(h) * * *

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

* * * * * * *
----------------------------------------------------------------------------------------------------------------
Insects
----------------------------------------------------------------------------------------------------------------

* * * * * * *
Bee, cuckoo bumble, Suckley's... Bombus suckleyi.... Wherever found..... E [Federal Register
citation when
published as a final
rule].

* * * * * * *
----------------------------------------------------------------------------------------------------------------

* * * * *

Martha Williams,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2024-28729 Filed 12-16-24; 8:45 am]
BILLING CODE 4333-15-P