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Hoary marmot

The hoary marmot (Marmota caligata) is a large, diurnal ground squirrel in the family Sciuridae, native to alpine and subalpine regions of western North America, where it is recognized for its robust build, social colonies, and prolonged hibernation periods of up to eight months annually.^[1]^[2] Characterized by a dense pelage of black and white hairs tipped with frosted gray, giving it a distinctive "hoary" appearance, adults typically measure 620–820 mm in total length, with a tail of 170–252 mm, hind feet of 90–113 mm, and body mass ranging from 1.25–7.0 kg depending on age, sex, and season, with males generally larger than females.^[1]^[2] This species features short legs, small rounded ears, small eyes, a black muzzle and feet, and a white patch between the eyes, adaptations suited to its rocky, high-elevation habitats.^[2] Distributed from southeastern Alaska and the Yukon Territory southward through British Columbia to Washington, Idaho, and Montana, hoary marmots occupy elevations from sea level in Alaska to over 2,500 m in southern ranges, favoring talus slopes, boulder fields, and meadows near the treeline for burrowing and foraging.^[1]^[2] They construct complex burrow systems under rocks for protection from predators like grizzly bears and wolverines, emerging in mid-May after hibernation to graze on grasses, sedges, forbs, and occasionally lichens or mosses during their brief active season.^[2]^[3] Highly social, hoary marmots live in colonies typically comprising one dominant adult male, several adult females, a satellite male, and juveniles, exhibiting behaviors such as vigilant surveillance, alarm calls, and greeting rituals to maintain group cohesion.^[2]^[1] Reproduction occurs annually in spring following hibernation, with polygynous or occasionally monogamous mating; gestation lasts 25–30 days, yielding litters of 2–5 young (average 3.9) born in late May to mid-June, which are weaned by July–August and may disperse the following year.^[1]^[2]^[4] Globally, the hoary marmot is assessed as Least Concern by the IUCN due to its stable populations across a broad range, though certain populations in Alaska face localized threats from habitat alteration and predation.^[5] Three subspecies are recognized: M. c. caligata (northern), M. c. cascadensis (Cascades), and M. c. okanagana (northern Rockies).^[1]

Taxonomy and phylogeny

Classification

The hoary marmot bears the binomial name Marmota caligata (Eschscholtz, 1829).^[1] The specific epithet caligata derives from the Latin term meaning "clothed in boots" or "booted," alluding to the species' distinctive dark lower legs and feet.^[2] The hoary marmot is classified within the order Rodentia, suborder Sciuromorpha, family Sciuridae (squirrels), subfamily Xerinae (ground squirrels), tribe Marmotini, genus Marmota (marmots), and subgenus Petromarmota.^[1] Phylogenetically, the genus Marmota originated in North America during the Early Miocene approximately 16.3 million years ago, diverging from other squirrel lineages before dispersing to Eurasia across the Bering Land Bridge in the Pliocene around 3–4 million years ago.^[6] The hoary marmot shares its genus with 14 other extant species, including the North American yellow-bellied marmot (M. flaviventris) and Vancouver Island marmot (M. vancouverensis).^[1]

Subspecies and genetic relationships

The hoary marmot (Marmota caligata) is divided into three recognized subspecies, distinguished primarily by their geographic distributions and subtle morphological variations. The nominate subspecies, M. c. caligata, inhabits northern mainland regions spanning Alaska, the Yukon Territory, the Northwest Territories, and northern British Columbia (including former synonyms such as vigilis for coastal populations near Glacier Bay and sheldoni for some island groups). M. c. cascadensis occupies the Cascade Mountains of Washington and Oregon. M. c. okanagana is found in the northern Rocky Mountains and interior British Columbia.^[1]^[7] Recent genetic analyses have illuminated the evolutionary relationships and connectivity among hoary marmots and closely related taxa, revealing a history of isolation punctuated by gene flow. Studies employing ultraconserved elements (UCEs) have demonstrated that hoary marmots belong to a superspecies complex with the Olympic marmot (M. olympus) and Vancouver Island marmot (M. vancouverensis), with shared ancestry and evidence of ancient divergence followed by intermittent hybridization.^[6] Microsatellite-based research from 2025 further corroborates historic gene flow between hoary marmots and both Olympic and Vancouver Island marmots, though it detects no ongoing contemporary exchange, highlighting the role of Pleistocene glacial cycles in facilitating past interbreeding across now-fragmented landscapes.^[8]^[9] Hybridization has left detectable signatures in the genome, particularly through mitochondrial DNA introgression, which suggests historical connectivity between hoary marmot populations and their relatives during periods of expanded suitable habitat. For instance, mitochondrial haplotypes from Vancouver Island marmots form a monophyletic clade closely allied with one hoary marmot lineage, indicating unidirectional gene flow from hoary to Vancouver Island marmots in the past.^[10] These patterns of introgression imply that species boundaries within this complex remain porous at evolutionary timescales, with low-level gene flow potentially persisting in overlapping or adjacent habitats despite current isolation. Such findings complicate taxonomic delimitations and underscore the need for integrated genomic approaches in conservation planning for these alpine rodents.^[8]^[11]

Physical characteristics

Size and morphology

The hoary marmot (Marmota caligata) possesses a robust build characterized by a thick body, short broad head, and short stout legs adapted for a terrestrial lifestyle.^[1] Its feet are robust with slightly curved claws, the forefoot claws being stouter than those on the hind feet, while the ears are small, broad, rounded, and well-haired.^[1] The incisors are large and range from ivory yellow to orange buff in color, complemented by high-crowned cheek teeth suitable for processing vegetation.^[1] Total body length measures 62–82 cm, comprising a head-body length of 45–70 cm and a tail length of 17–25 cm.^[1] Hind foot length is 90–113 mm, with males slightly larger than females.^[1] Adult weight varies seasonally from a low of 3.75 kg in May following hibernation emergence to 7 kg in September prior to hibernation, with exceptional individuals reaching up to 13.5 kg.^[1]^[12] This substantial summer weight gain, nearly doubling body mass through fat accumulation, enables survival during extended periods of hibernation lasting up to eight months.^[1] Sexual dimorphism is evident, with males significantly larger than females in both body size and cranial dimensions across most subspecies.^[1] Yearlings and juveniles follow similar seasonal patterns but at smaller scales, weighing 1.5 kg in early summer and up to 4.25 kg by autumn.^[1]

Coloration and sensory adaptations

The hoary marmot (Marmota caligata) exhibits a distinctive pelage characterized by grizzled silver-gray fur on the back and shoulders, which gives the species its common name derived from "hoary," meaning frosted or grayish-white. The head is typically blackish, with a prominent white patch on the muzzle and white fur around the chin and lips, while the feet and lower legs are dark. The tail is bushy and often reddish-brown, and the underparts are lighter gray. This coloration arises from long guard hairs with white or pale tips overlying a base of darker fur, creating the frosted appearance. Beneath the guard hairs lies a dense, soft underfur that provides essential insulation against cold temperatures.^[2]^[13]^[14] Coloration varies slightly among subspecies and with age. Northern populations of the nominate subspecies M. c. caligata tend to be paler overall compared to southern forms, which exhibit darker tones, reflecting geographic adaptations in base fur color. Juveniles possess softer, denser fur at around six weeks of age, lacking the full grizzled texture of adults until their pelage matures. These variations influence the overall appearance but maintain the species' characteristic frosted look across its range.^[1]^[13] Sensory adaptations support the hoary marmot's alpine lifestyle. The eyes are small and circular, positioned on the sides of the head to enable a wide field of view for vigilant scanning of the surroundings while perched on rocks. Sensitive vibrissae, or whiskers, around the muzzle aid in navigation and tactile exploration within rocky terrain and burrows. The short, rounded ears facilitate acute hearing, allowing detection of predator movements from afar, which is crucial for initiating alarm responses.^[2] These traits confer key survival advantages. The grizzled gray-brown coloration provides crypsis against lichen-covered alpine rocks and boulder fields, helping marmots blend into their talus habitats and evade visual predators. The dense underfur minimizes heat loss during the prolonged hibernation period, supporting metabolic efficiency in subalpine environments where temperatures drop below freezing for months.^[15]^[14]^[16]

Distribution and ecology

Geographic range

The hoary marmot (Marmota caligata) occupies a broad geographic range across northwestern North America, extending from central Alaska southward through the Yukon Territory and western Northwest Territories in Canada, to southern British Columbia, northeastern Washington, central Idaho, and western Montana.^[1]^[17] In Alaska, populations are found south of the Yukon River, reaching coastal areas down to sea level, while farther south, the species inhabits higher elevations primarily near the treeline.^[13] The distribution is discontinuous, interrupted by extensive glaciers, dense forests, and unsuitable lowland habitats.^[1] Elevational limits vary latitudinally, from sea level along Alaskan coasts to approximately 2,500 m in the Cascade, Rocky, and coastal mountains of the southern range.^[1] The species favors rocky alpine and subalpine terrains, with populations often concentrated in areas like the Alaska Range, Ogilvie Mountains, and Bitterroot Mountains.^[2] Isolated colonies occur on coastal islands, such as those in Glacier Bay National Park, contributing to fragmented distributions in southeastern Alaska.^[1] Historically, the hoary marmot expanded northward from southern refugia during post-glacial periods following the Last Glacial Maximum, colonizing much of its current range as alpine habitats became available after ice retreat around 12,000–10,000 years ago. Pleistocene fossils from sites like Prince of Wales Island indicate pre-glacial presence in parts of Alaska dating back over 21,000 years.^[1] In recent decades, ongoing climate shifts have further fragmented the range by reducing alpine habitat availability, leading to increasingly isolated populations, particularly on islands where connectivity to mainland groups is limited.^[10] Subspecies distributions reflect regional variations within this range: M. c. caligata in northern areas including Alaska, Yukon, and northern British Columbia; M. c. cascadensis in the Cascade Mountains of Washington and southern British Columbia; and M. c. okanagana in the northern Rocky Mountains of Canada, Idaho, and Montana.^[1]^[2]

Habitat preferences

Hoary marmots primarily inhabit rocky alpine and subalpine meadows near the treeline, where boulder fields and talus slopes provide protection for burrows adjacent to areas rich in grasses, forbs, sedges, and flowering plants such as silky lupine, Indian paintbrush, and glacier lily.^[18]^[2] These sites offer ample forage during the short growing season while allowing escape from predators in rugged terrain.^[15] Key habitat features include shallow slopes and south-facing aspects, which marmots prefer for enhanced solar exposure and longer growing periods, with occupancy rates higher on southern slopes (0.34 probability) compared to northern ones (0.21).^[15] Proximity to water sources is also critical, as occupancy decreases with greater distance to streams or moist areas, supporting hydration and lush vegetation in otherwise arid alpine environments.^[19] Marmots avoid dense forests and areas prone to excessive snow accumulation, favoring open meadows that balance winter snow cover for hibernation insulation without overwhelming burrow access. The presence of shrubs further boosts habitat suitability, increasing occupancy by providing additional cover and forage.^[15]^[19] In microhabitats, hoary marmots excavate extensive burrow systems in talus slopes and boulder fields, with hibernation chambers reaching depths of up to 5–7 meters to maintain stable temperatures during prolonged dormancy.^[20] These burrows often feature multiple entrances hidden among rocks, serving as refuges, and marmots use elevated rock outcrops as vantage points for vigilance, particularly in larger colonies where group monitoring enhances predator detection.^[2] Foraging typically occurs within 50 meters of burrows, linking microhabitat structure directly to daily survival needs.^[15] Adapted to harsh climates with short summers and long winters, hoary marmots thrive in environments with reliable snowpack for insulation but face vulnerability from snow droughts that reduce forage availability and alter vegetation composition toward less palatable species.^[18]^[19] Their habitat selections reflect a trade-off between summer productivity on warmer slopes and winter protection under snow, underscoring sensitivity to climatic shifts.^[15]

Behavior and lifestyle

Hoary marmots exhibit a colonial social structure, living in groups ranging from 5 to 36 individuals within a defined area, typically comprising one dominant breeding male, 1 to 4 reproductive adult females, and subordinate non-breeding adults, yearlings, and juveniles. These colonies often consist of matrilineal kin groups, with genetic analyses revealing high maternal relatedness (up to 94.4% agreement between observed and molecular parentage), promoting cohesion through familial bonds. Social interactions include frequent greetings such as nose-to-nose contacts for individual recognition, reinforcing group stability.^[21]^[2] Territoriality is pronounced, particularly among males, who defend home ranges of approximately 10 hectares through aggressive chases, vocal threats, and scent marking to secure access to females and resources. Females maintain overlapping ranges within the colony but vigorously defend specific burrows and immediate vicinity against intruders, contributing to spatial organization. Dominance hierarchies are established primarily based on age, body size, and tenure, with the resident male maintaining control over breeding; subordinates, often younger or smaller, may face eviction and disperse to peripheral areas or neighboring colonies to avoid conflict.^[22]^[23]^[21] Group living confers key advantages, including enhanced predator vigilance, as colony members allocate about 30% of aboveground time to scanning and issuing alarm calls, reducing individual risk through collective monitoring. In some colonies, subordinates provide alloparental care, such as huddling with pups during early post-emergence periods or assisting in thermoregulation, which boosts juvenile survival rates in the harsh alpine environment. These dynamics underscore the adaptive value of sociality in this species.^[2]^[24]

Diet and foraging

The hoary marmot (Marmota caligata) is a diurnal herbivore that primarily consumes a variety of alpine vegetation, including grasses such as rough fescue (Festuca altaica), sedges (Carex spp.), forbs like alpine arnica (Arnica alpina), locoweed/milkvetch (Oxytropis/Astragalus spp.), and fleabanes (Erigeron spp.), as well as flowers from plants including Sitka valerian (Valeriana sitchensis), fireweed (Chamerion angustifolium), Indian paintbrush (Castilleja spp.), and yellow avalanche-lily (Erythronium grandiflorum) ^[1]. In certain regions, such as the Kenai Peninsula in Alaska, over 90% of the diet comprises these items along with mosses, lichens (Cladonia spp.), mountain-avens (Dryas spp.), and willows (Salix spp.), while occasional consumption of berries, roots, or even insects and scavenged material occurs but remains minimal https://www.science.smith.edu/departments/biology/VHAYSSEN/msi/pdf/884_Marmota_caligata.pdf. This selective foraging prioritizes nutrient-rich plants over abundant ones, with marmots spending about 97% of their aboveground time engaged in "crop-search" activities, moving slowly through meadows or feeding intensively in preferred patches, often within 50 m of burrows https://www.science.smith.edu/departments/biology/VHAYSSEN/msi/pdf/884_Marmota_caligata.pdf https://www.adfg.alaska.gov/index.cfm?adfg=hoarymarmot.printerfriendly. Foraging activity peaks in July, accounting for roughly 40% of daily time, with most effort concentrated in early mornings and late afternoons to avoid midday heat and insects, though overall time decreases by mid-August as fat reserves build https://www.science.smith.edu/departments/biology/VHAYSSEN/msi/pdf/884_Marmota_caligata.pdf. Seasonal shifts in diet align with plant phenology: upon emergence in mid-May, marmots target emerging herbaceous leaves and greens in snow-free areas for initial recovery; midsummer emphasizes flowers of herbaceous plants for higher energy content; and late summer focuses on mature herbs, forbs, seeds, and roots to maximize caloric intake before hibernation, with minimal to no foraging during the winter dormancy period https://www.science.smith.edu/departments/biology/VHAYSSEN/msi/pdf/884_Marmota_caligata.pdf https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2.1977. Nutritionally, hoary marmots rely on hindgut fermentation in a large, undivided cecum featuring deep transverse rugae, which supports microbial breakdown of fibrous vegetation and yields dry matter digestibility rates of 50-81% depending on fiber content (e.g., 57.6% for 22% fiber diets), with digesta transit times of 13-29 hours https://www.science.smith.edu/departments/biology/VHAYSSEN/msi/pdf/884_Marmota_caligata.pdf. This adaptation, combined with a voluminous gut relative to body size, enables efficient nutrient extraction from low-quality forage, facilitating rapid mass accumulation during the short active season https://www.science.smith.edu/departments/biology/VHAYSSEN/msi/pdf/884_Marmota_caligata.pdf. Individuals gain weight quickly post-hibernation, with yearlings averaging 31 g per day in July and 28 g per day in August, while adults build fat layers comprising up to 20% of body mass by late summer to sustain the 7-8 month hibernation https://www.science.smith.edu/departments/biology/VHAYSSEN/msi/pdf/884_Marmota_caligata.pdf https://www.adfg.alaska.gov/index.cfm?adfg=hoarymarmot.printerfriendly.

Communication and anti-predator strategies

Hoary marmots exhibit a rich vocal repertoire comprising seven distinct call types: long calls, descending calls, ascending calls, flat calls, trills, mouth blows, and teeth chatters. These vocalizations facilitate various social and defensive functions, with alarm calls playing a central role in anti-predator communication. Longer calls, such as flat calls lasting over 0.5 seconds, are typically elicited by ground predators like coyotes and wolverines, prompting quicker responses due to the higher immediacy of terrestrial danger. Shorter calls may be used in response to aerial predators such as golden eagles. Trills, often multi-note sequences, are more commonly associated with social interactions but can reinforce group cohesion during low-level alerts.^[25] Non-vocal signals complement these vocalizations in threat communication. Upright postures, in which individuals stand on hind legs to scan horizons, serve as sentinel-like alerts, allowing for elevated predator detection while minimizing foraging disruption. Scent marking via cheek glands on rocks and plants delineates territories, indirectly supporting anti-predator efforts by maintaining stable group boundaries and reducing inter-colony conflicts that could expose individuals to predation. Anti-predator behaviors emphasize collective vigilance and rapid evasion. Individuals often assume sentinel roles, performing frequent look-ups to monitor for predators, with younger marmots exhibiting higher vigilance rates than adults. Group living amplifies this defense, as proximity to conspecifics reduces individual scanning frequency and increases feeding efficiency, thereby diluting per capita predation risk across larger colonies of up to 36 individuals. Upon detecting threats, marmots swiftly retreat to burrows, with adults escaping more quickly than juveniles, highlighting age-based vulnerabilities. Key predators include golden eagles, which primarily target juveniles; grizzly bears and coyotes, which prey on all age classes during foraging; and wolverines, opportunistic hunters that exploit burrow systems.^[13] Juveniles face the highest mortality from aerial attacks, underscoring the adaptive value of communal vigilance in colonial groups.^[13]

Reproduction and life history

Breeding and parental care

Hoary marmots exhibit a flexible mating system that varies from monogamous to polygynous pairings, influenced by resource availability and population density in local colonies. Breeding typically occurs in early May, shortly after emergence from hibernation, when dominant males compete for mates through vocalizations, postural displays, and physical confrontations to establish access to receptive females.^[21]^[26] Gestation lasts 25–30 days, after which females give birth to litters of 2–5 pups, with an average of about 4, in concealed natal burrows during late May to mid-June. Females breed annually or biennially, though studies indicate a roughly equal probability of breeding each year regardless of prior reproductive success, challenging earlier views of strict biennial patterns.^[4]^[18]^[1] Pups are born altricial—naked, blind, and toothless—and receive exclusive nursing from the mother for 20–25 days in the burrow. They first emerge aboveground at 4–5 weeks of age, becoming more mobile, and are fully weaned by approximately 6 weeks, transitioning to solid foods while remaining dependent on the family unit. In social colonies, subordinate group members, including yearlings and non-breeding adults, provide allomaternal care such as vigilance against predators and occasional huddling with pups, which supports overall offspring survival without delving into broader social dynamics.^[2]^[27]^[28] Hoary marmots reach sexual maturity at 2 to 3 years of age; wild individuals may live up to 15 years, though survival rates decline with age and environmental stressors.^[27]^[2]

Hibernation cycle

The hoary marmot (Marmota caligata) exhibits one of the longest hibernation periods among North American mammals, typically spanning 7–8 months from early September or October to April or May.^[2] During this extended dormancy, entire family groups huddle together in deep burrow chambers to minimize heat loss and conserve energy.^[2] This social clustering enhances survival by reducing individual metabolic demands in the cold, insulated environment of their alpine hibernacula.^[29] Physiologically, hibernation in the hoary marmot involves profound metabolic suppression, with body temperature dropping to near 0–5°C and heart rate slowing to 3–5 beats per minute during torpor bouts.^[30]^[31] These low levels reflect adaptations to endure prolonged food scarcity, as the animals rely solely on pre-stored fat reserves for energy.^[20] Periodic arousals interrupt torpor roughly every 2–3 weeks, lasting several hours to a day, during which marmots briefly restore euthermic conditions (body temperature around 37°C) for essential maintenance like waste elimination and neural repair.^[29] These arousals, while energetically costly, are critical for long-term survival and account for about 10–15% of total hibernation energy expenditure.^[32] Prior to hibernation, hoary marmots accumulate substantial fat reserves through intensive summer foraging, which can constitute up to 20–25% of their body mass and sustain them through torpor.^[20] Post-hibernation, individuals experience significant weight loss of up to 30–37% from their pre-hibernation mass, reflecting the depletion of fat stores during dormancy.^[20] Hibernation timing and duration vary geographically.^[33]

Conservation and human interactions

Population status

The hoary marmot (Marmota caligata) is classified as Least Concern on the IUCN Red List, with the assessment conducted in 2016 and the population considered stable as of recent evaluations. No comprehensive global population estimate is available, though the species is described as locally common and widespread across its range in suitable alpine habitats.^[2]^[13] Overall population trends are stable, with no evidence of major range contraction, although local declines have been documented in specific regions such as North Cascades National Park, where abundance decreased by 74% between 2007–2008 and 2016–2017.^[13]^[34] In Alaska, populations remain stable, comprising an estimated 25–74% of the global total, supported by the species' occurrence in extensive suitable habitat exceeding 400,000 km².^[35] Monitoring efforts, including fecal pellet counts and point surveys, indicate typical densities in core habitats ranging from low to moderate, with colonies supporting up to 36 individuals across home ranges averaging about 14 hectares.^[2] Certain subspecies face heightened concerns due to isolation. For instance, M. c. sheldoni on Montague Island, Alaska, is vulnerable, with no confirmed observations since a 1978 sight record despite its endemic status, raising risks from limited habitat and potential extirpation.^[20] Similarly, isolated populations in areas like Glacier Bay exhibit limited genetic exchange, contributing to localized vulnerabilities, though broader trends remain stable.^[35] Local extirpations have occurred in some developed areas, but the species' adaptability to alpine environments supports ongoing persistence without widespread decline.^[36]

Threats and management

Hoary marmots face several anthropogenic and environmental threats that impact their alpine habitats across their range in western North America. Climate change poses a significant risk through alterations in snowpack and temperature regimes, which affect hibernation and foraging. Declining snowpack reduces insulation in burrows, increasing the risk of freezing during winter hibernation, while sparse winter snow cover heightens mortality rates by exposing marmots to colder temperatures. Additionally, earlier snowmelt leads to snow droughts that diminish forage availability, as prolonged vernal snow cover limits the growing season for vegetation essential to their diet. These changes also facilitate greater access for low-elevation predators to marmot colonies, potentially exacerbating survival pressures in areas like the North Cascades. Habitat fragmentation from human development further threatens hoary marmot populations by disrupting connectivity between colonies. Roads associated with mining operations and resource extraction cause direct mortality through vehicle collisions and fragment suitable alpine meadows, limiting dispersal and gene flow among subpopulations. In regions with active mining, such as parts of British Columbia and Alaska, new access roads exacerbate habitat loss and increase edge effects that degrade foraging areas. Human interactions with hoary marmots often stem from their proximity to recreational areas, where they exhibit tolerance toward tourists but face elevated risks from associated disturbances. In unhunted zones, marmots readily habituate to human presence, allowing close approaches that can lead to unintended consequences, such as attraction to human urine sites for salt content, which draws them into vulnerable positions. Off-leash domestic dogs pose a particular predation risk, as habituated individuals may not flee promptly, increasing encounters in popular sites like national parks. Historically, intensive fur trapping during the 19th and early 20th centuries reduced populations across Alaska and Canada, with hoary marmots targeted for their pelts in the fur trade until regulatory protections curtailed such activities. Conservation management for hoary marmots emphasizes protection within large, intact landscapes, given their IUCN Least Concern status, which indicates no need for broad targeted recovery programs. Substantial portions of their range overlap with national parks, including Denali National Park and Preserve in Alaska, where populations benefit from restricted development and monitoring efforts to track hibernation success and habitat use. In Olympic National Park, ongoing surveys assess colony occupancy and inform guidelines for ecotourism to minimize habituation risks, such as leashing dogs and maintaining distance from burrows. Subspecies-specific monitoring, particularly for isolated groups like those in the North Cascades, focuses on genetic diversity to detect early signs of decline. Looking ahead, warming temperatures may drive northward range shifts for hoary marmots, potentially expanding suitable habitat in northern latitudes while contracting it at southern edges due to upslope habitat compression. Gene flow among connected populations, including between hoary and closely related subspecies like Olympic marmots, could buffer against isolation in fragmented areas, supporting resilience to environmental changes.

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Hoary marmots were neither obligate nor facultative biennial breeders, and breeding probability was insensitive to evolved, environmental, or social factors.
[28]
Hoary Marmot Species Profile, Alaska Department of Fish and Game
A marmot leaves its winter sleep very thin but quickly gains weight, with fat ... hibernation making up 20 percent of its body weight at the end of summer.Missing: pre- | Show results with:pre-
[29]
Mammals | Idaho State University
Diet: Feeds on seeds, flowers, stems, leaves, roots of grasses, forbs, and shrubs. Will also eat insects, especially in late summer. Sometimes eats carrion ...
[30]
Hibernation as a major determinant of life-history traits in marmots
Mar 21, 2017 · Hibernation is a life-history trait that may allow marmots to escape changes in climate and effectively expand their ecological niches.
[31]
Did you know? CSU groundhog expert offers fascinating facts
Feb 1, 2017 · They also reduce their respiration and heart rate one hundred-fold: from 300 beats per minute to as low as just three beats per minute.
[32]
[PDF] The Theories and Physiology of Hibernation
In deep hiber- nation the minimum heart rate is 4 to 5 beats per minute and the minimum res- piration rate is 0.2 per minute, the aver- age being not more than ...
[33]
Regulation of body temperature and energy requirements of ...
Figure 2 shows the time course of MR and Tb of a hibernating Alpine marmot over a time period of 13 days. Tawithin the climate chamber was ∼7°C at the end of ...Missing: hoary cycle
[34]
Natural History of the Groundhog - Journey North Signs of Spring
The elder males emerge first, followed by the elder females and finally, a ... The Whistler or Hoary marmot is found in Northwestern North America. The ...Missing: territory | Show results with:territory
[35]
[PDF] Climate change and the conservation of marmots
Marmot physiology is highly adapted to coping with low environmental temperatures; they are stressed by high heat loads. Global warming since the last ice age ...
[36]
Contrasting effects of climate change on seasonal survival of a ... - NIH
Marmots are too small to store sufficient fat to remain active during winter, and therefore hibernate for about 8 mo during this long period of food scarcity ...Missing: hoary southern
[37]
Hoary marmots can't cope with snow droughts - The Wildlife Society
Mar 2, 2021 · Johnston and his team estimated marmot abundance at 19 sites in North Cascades National Park from the period of 2007-2008 as well as in 2016 and ...Missing: size | Show results with:size
[38]
[PDF] Hoary marmot - Alaska Center for Conservation Science
Occurs from southeast Alaska north to the Yukon River and from Canada west to Bethel and the eastern Alaska Peninsula (Gunderson et al.
[39]
Hoary Marmot (U.S. National Park Service)
Jul 1, 2020 · Hoary marmots are large rodents, about the size of a house cat. If you're from the eastern US, they are basically alpine versions of woodchucks or groundhogs.Missing: subspecies | Show results with:subspecies