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Ground squirrel

Ground squirrels are small to medium-sized rodents in the family Sciuridae, characterized by their terrestrial lifestyle, burrowing behavior, and adaptation to open habitats where they construct extensive underground tunnel systems for shelter, reproduction, and overwintering.^[1] They belong to the tribe Marmotini within the subfamily Xerinae and are distinguished from tree squirrels by their shorter tails, less arboreal habits, and preference for ground-level foraging.^[2] The group encompasses approximately 68 species across multiple genera, including Urocitellus (North American ground squirrels), Spermophilus (Eurasian ground squirrels), Ictidomys (southern North American species), and others, following taxonomic revisions that split the formerly broad genus Spermophilus due to phylogenetic evidence of paraphyly.^[3] These species are distributed throughout the Holarctic region, from North America and Europe to Asia, inhabiting diverse environments such as grasslands, meadows, deserts, and alpine tundra, where friable soils facilitate burrowing.^[2] Ground squirrels are primarily herbivorous but opportunistic omnivores, consuming seeds, nuts, roots, leaves, and occasionally insects or small vertebrates; their diet supports seed dispersal and influences plant community dynamics.^[1] Behaviorally, many ground squirrels exhibit colonial or semi-social structures, with females often forming kin-based groups while males are more solitary or territorial.^[3] They are diurnal and employ a variety of vocalizations, including high-pitched alarm calls, to warn conspecifics of predators such as raptors, snakes, and carnivores, enhancing group survival.^[1] Reproduction typically occurs in spring, with litters of 4–10 young born in natal burrows after a gestation of 25–30 days; many northern species hibernate for 6–9 months annually, a key adaptation to seasonal food scarcity.^[3] Ecologically, ground squirrels serve as vital prey for numerous predators and contribute to soil aeration through burrowing, though some species face threats from habitat loss and human conflict.^[1]

Taxonomy and evolution

Phylogenetic history

Ground squirrels, belonging to the tribe Marmotini within the family Sciuridae, trace their origins to the broader radiation of squirrels during the late Eocene to Oligocene epochs, approximately 35-25 million years ago, when the Sciuridae family first diversified in North America and Eurasia. Early sciurids exhibited a mix of arboreal and terrestrial traits, but the lineage leading to ground squirrels began adapting to fossorial lifestyles by the Oligocene, as evidenced by fossil forms like the genus Hesperocallis, which represents one of the earliest known squirrels with potential ground-dwelling characteristics from deposits in the White River Formation of Wyoming.^[4] The tribe Marmotini itself emerged during the Miocene epoch, around 20-15 million years ago, marking a key divergence from tree-dwelling squirrels (Sciurini) through the evolution of burrowing adaptations, such as stronger limbs for digging and reduced tail length for terrestrial efficiency. Fossil evidence from the Miocene, including genera like Paenemarmota from North American sites, illustrates this transition, with these early ground squirrels showing dental and cranial features suited to herbivorous, burrow-based existence in open habitats. Following the Miocene diversification, ground squirrels underwent further radiation, particularly into Holarctic regions after the Pleistocene glaciations (approximately 2.6 million to 11,700 years ago), when post-glacial warming facilitated northward and eastward expansions across Eurasia and North America.^[5] Molecular phylogenetic studies in the 2000s have refined understanding of their relationships, confirming Marmotini as a monophyletic group closely allied with prairie dogs (Cynomys) and marmots (Marmota), all sharing a common ancestor around 15-10 million years ago. These analyses revealed the traditional genus Spermophilus to be paraphyletic, prompting taxonomic revisions that split it into multiple genera, such as Urocitellus for North American species and Poliocitellus for Eurasian forms like the European souslik, based on mitochondrial and nuclear DNA sequences that highlight distinct evolutionary lineages.

Classification and diversity

Ground squirrels belong to the order Rodentia, family Sciuridae, subfamily Xerinae, and tribe Marmotini, which encompasses marmots, prairie dogs, and true ground squirrels.^[6] The tribe is divided into three subtribes: Marmotina (primarily marmots and close relatives), Spermophilina (true ground squirrels), and Cynomyina (prairie dogs).^[7] Marmotini comprises approximately 95 species across 13 genera, with the highest diversity in North America (over 60 species) and Eurasia (around 30 species).^[8] Major genera include Marmota (marmots, 15 species), Cynomys (prairie dogs, 5 species), Urocitellus (such as the thirteen-lined ground squirrel, 13 species), Ictidomys (thirteen-lined variants, 3 species), and Ammospermophilus (antelope ground squirrels, 3 species). As of 2025, a new species, Urocitellus idahoensis, has been described, contributing to ongoing refinements in genus diversity.^[9] African ground squirrels, such as those in the genera Xerus (5 species) and Euxerus (1 species), fall within the broader subfamily Xerinae but outside Marmotini in the tribe Xerini. Significant nomenclature changes occurred between 2007 and 2009, when the paraphyletic genus Spermophilus was revised into eight monophyletic genera based on analyses of the cytochrome b gene and interphotoreceptor retinoid-binding protein (IRBP) sequences, along with morphological and craniometric data.^[6] These revisions elevated genera like Urocitellus, Ictidomys, and others to recognize distinct evolutionary lineages. Hybridization has been documented among Urocitellus species, involving gene flow that influences their genetic structure, particularly at high latitudes.^[10]

Physical characteristics

Morphology and size

Ground squirrels exhibit a characteristic body plan adapted for terrestrial life, featuring a stocky, cylindrical build with short, sturdy legs and strong, curved claws suited for digging burrows.^[11] Their heads are rounded with small, low-set ears, and they possess internal cheek pouches for storing food, a trait common to all species in the subfamily.^[12] The tail is typically semi-bushy and measures about one-third to one-half the length of the head and body, often held arched over the back during movement.^[13] Size varies significantly across the approximately 68 species of ground squirrels, with head-body lengths ranging from 15 to 60 cm and weights from 100 g to 8 kg.^[12] Smaller species, such as Harris's antelope squirrel (Ammospermophilus harrisii), measure 15-20 cm in head-body length and weigh around 100-150 g, while larger forms like the hoary marmot (Marmota caligata) reach 50-60 cm and up to 8 kg.^[13] Tail lengths generally span 5-25 cm, scaling proportionally with body size; for example, the Arctic ground squirrel (Urocitellus parryii) has a head-body length of 20-30 cm, a tail of 10-15 cm, and weighs 400-850 g.^[14] Sexual dimorphism is prevalent, with males typically 10-20% larger than females in body size across most species, though this difference scales isometrically and does not strongly correlate with sociality or overall body size.^[3] For instance, in the thirteen-lined ground squirrel (Ictidomys tridecemlineatus), adult males average 20-25 cm in head-body length and 150-200 g, compared to females at 18-22 cm and 120-170 g.^[15] Pelage coloration serves primarily for camouflage and varies by habitat, ranging from uniform gray-brown in forested-edge species to mottled or boldly striped patterns in open-country forms.^[16] Species like the thirteen-lined ground squirrel display distinctive alternating dark and light stripes—13 pale yellow-white lines on a brownish background—for blending into grasslands.^[17] Hibernating species often undergo seasonal molts, shifting to paler coats in summer for better concealment in dry environments.^[18]

Adaptations to terrestrial life

Ground squirrels exhibit several skeletal adaptations that facilitate their burrowing lifestyle in terrestrial environments. Their forelimbs are robust and compact, with strong muscles and oval-shaped cross-sections in the limb bones that provide reinforcement during excavation activities. These limbs are equipped with curved claws that enable efficient scratch digging to construct burrows extending up to 1-2 meters in depth. Additionally, the skull is relatively flattened, aiding in soil displacement as the animal pushes through loose earth during tunneling.^[19]^[20]^[21] In terms of sensory adaptations, ground squirrels possess large eyes with a cone-dominant retina, which supports sharp diurnal vision essential for detecting predators and navigating open habitats above ground. Sensitive vibrissae, or whiskers, assist in tactile navigation within dark burrow tunnels, allowing the animals to sense walls and obstacles without relying on sight. Their acute hearing is particularly attuned to seismic vibrations transmitted through the ground, enabling early detection of approaching predators such as snakes or mammals.^[22]^[23]^[24] Physiologically, ground squirrels demonstrate high metabolic flexibility, entering states of torpor during periods of environmental stress or food scarcity, where body temperature and metabolic rate drop dramatically to conserve energy in their burrow systems. Sebaceous oil glands produce secretions that help waterproof the fur, protecting against moisture during rainy seasons or while foraging in damp soils. Expandable cheek pouches, formed by internal skin folds, can hold significant amounts of food—up to approximately 20 grams—allowing efficient transport of seeds and vegetation back to burrows without multiple trips.^[25]^[26]^[27] Dentally, ground squirrels have hypsodont molars with high crowns that resist wear from grinding abrasive vegetation, such as grasses and roots, which form a staple of their diet. Their incisors are chisel-like for clipping plant stems and exhibit continuous growth throughout life, at rates sufficient to counteract constant abrasion during foraging and burrowing.^[28]^[29] Species variations in adaptations reflect environmental demands; for instance, the Mohave ground squirrel, inhabiting hot desert regions, employs estivation—a form of torpor during summer heat—while maintaining body temperatures only slightly elevated above ambient levels to minimize water loss. Its pale, reflective fur aids in deflecting solar radiation, and nasal passages facilitate countercurrent heat exchange to cool inhaled air and retain moisture during respiration in arid conditions.^[30]^[31]^[32]

Distribution and habitat

Geographic range

Ground squirrels, belonging to the subfamily Xerinae, exhibit a predominantly Holarctic distribution, with the greatest diversity concentrated in North America and Eurasia. In North America, over 40 species are recognized, ranging from the Arctic tundra of Alaska to the arid regions of northern Mexico. For instance, the Arctic ground squirrel (Urocitellus parryii) inhabits northern Alaska and Canada, while the Mexican ground squirrel (Ictidomys mexicanus) occurs in northern Mexico and adjacent southwestern United States. Richardson's ground squirrel (Urocitellus richardsonii) exemplifies prairie-dwelling species in the grasslands of central Canada and the northern Great Plains of the United States.^[11]^[33]^[34] In Eurasia, ground squirrels extend from the steppes of Europe across Siberia to northeastern China, encompassing a broad Palearctic range. The European souslik (Spermophilus citellus) is characteristic of open grasslands in Central and Southeastern Europe, while the Daurian ground squirrel (Spermophilus dauricus) inhabits northeastern China, Mongolia, and adjacent Russian territories. The long-tailed ground squirrel (Urocitellus undulatus) occupies steppe and forest-steppe zones in Siberia and parts of Central Asia.^[35]^[36]^[37] Altitudinally, ground squirrels occupy elevations from sea level to over 5,000 meters, adapting to varied mountainous terrains. In Europe, the alpine marmot (Marmota marmota) thrives between 800 and 3,200 meters in the Alps and Carpathians. In Asia, the Himalayan marmot (Marmota himalayana) extends up to 5,000 meters on the Tibetan Plateau.^[38]^[39] Climate change is driving recent distributional shifts, particularly northward expansions in some North American species. For the Mohave ground squirrel (Xerospermophilus mohavensis), models indicate a likely northward shift in suitable habitat due to warming temperatures and altered precipitation patterns. As of 2024, studies on arctic ground squirrels have observed shifts in hibernation cycles, with females emerging earlier due to warmer spring temperatures. High endemism characterizes isolated regions like the Baja California Peninsula, where subspecies such as the Espíritu Santo antelope squirrel (Ammospermophilus leucurus insularis) are restricted to specific Gulf of California islands.^[40]^[41]^[42]

Ecological niches

Ground squirrels occupy a variety of open habitats, including grasslands, deserts, meadows, and forest edges, while generally avoiding dense forests and wetlands due to limited visibility and burrowing challenges.^[43] For instance, black-tailed prairie dogs thrive in shortgrass prairies characterized by level to gently rolling topography and arid conditions.^[43] Similarly, antelope ground squirrels, such as the white-tailed species, prefer arid scrublands, desert washes, and succulent shrub habitats with sparse vegetation.^[44] Townsend's ground squirrels select areas with well-drained soils in sagebrush steppe, often favoring abandoned farmlands, canals, and low-elevation shrublands with vegetation heights typically under 30 cm to enhance predator detection.^[45] Their burrow systems form complex underground networks tailored to survival needs, featuring multiple chambers for nesting, food storage, and hibernation or estivation, with tunnels often 0.7–1.5 m deep and 10–11 cm in diameter.^[46] Entrance plugs made of soil and vegetation help seal burrows against flooding, extreme heat, or predators, and systems expand annually with use.^[47] Colonies vary from solitary individuals to groups exceeding 100, depending on species and resource availability, with larger aggregations common in open prairies.^[48] Microhabitat selection emphasizes loose, well-drained soils for easy excavation and proximity to escape cover like rocks or shrubs, balanced with open sightlines for vigilance against predators.^[49] Ground squirrels often position burrows near vegetative edges but avoid dense understory, prioritizing sites with short grasses and forbs that allow rapid detection of threats.^[50] These rodents tolerate climates ranging from temperate zones to arid deserts, employing hibernation for 6–9 months in colder regions to endure low temperatures and food scarcity.^[51] In hot deserts, species like round-tailed and Mohave ground squirrels enter estivation during peak summer heat, remaining dormant in burrows to conserve energy and avoid desiccation.^[31] As ecosystem engineers, their burrows enhance biodiversity by providing shelter for species such as burrowing owls, which nest in abandoned tunnels, and increasing soil aeration that benefits plant communities.^[52]

Behavior and ecology

Diet and foraging strategies

Ground squirrels are omnivorous, with a diet dominated by herbivorous components that typically comprise 70–90% of their intake, including grasses, seeds, nuts, forbs, and roots. Opportunistic insectivory accounts for 5–20% of consumption, featuring items such as beetles, ants, and other arthropods, while carnivory is rare and limited to small vertebrates, eggs, or carrion in certain species like the California ground squirrel (Otospermophilus beecheyi).^[53]^[54]^[55] Seasonal variations in diet reflect availability and physiological demands; emerging from hibernation in spring, ground squirrels prioritize green vegetation and forbs for rapid nutrient intake, shifting to seeds and drier plant matter in summer, and focusing on high-energy caching in fall to amass stores for overwinter survival. For instance, female Belding's ground squirrels (Urocitellus beldingi) substantially increase insect consumption during lactation to support elevated protein requirements for nursing young.^[56]^[57] Foraging occurs diurnally, primarily above ground through clipping vegetation or digging for buried items, with food transported using expandable cheek pouches; strategies include scatter-hoarding, where seeds are buried in dispersed caches to reduce pilferage risk, or larder-hoarding within burrows for safer storage, as seen in species like the Piute ground squirrel (Urocitellus mollis). In social species such as prairie dogs (Cynomys spp.), foraging involves collective above-ground activity. Nutritional adaptations feature hindgut cecal fermentation, enabling efficient breakdown of fibrous plant material via microbial activity to extract energy from cellulose.^[58]^[59]^[60] Due to their preference for nutrient-rich vegetation, ground squirrels often damage agricultural crops, particularly alfalfa fields and grain stores, leading to their classification as pests in farming regions.^[61] Ground squirrels display a broad spectrum of social organization, from solitary lifestyles in species like Harris's antelope squirrels (Ammospermophilus harrisii), which live alone and only interact during breeding, to highly colonial systems in black-tailed prairie dogs (Cynomys ludovicianus), where groups form expansive towns comprising thousands of individuals subdivided into wards and family units called coteries.^[62]^[63] In intermediate cases, such as round-tailed ground squirrels (Xerospermophilus tereticaudus), individuals form small colonies with overlapping ranges but maintain individual burrows.^[13] This variation reflects adaptations to environmental pressures, including predation risk and resource distribution, with more social species often inhabiting open habitats that favor collective defense.^[64] Social groups in many ground squirrel species are kin-based, characterized by female philopatry—where daughters remain near their natal territories—and male-biased dispersal, promoting matrilineal structures. For instance, in Richardson's ground squirrels (Urocitellus richardsonii), females typically stay on or adjacent to their mother's range, forming stable kin clusters that enhance inclusive fitness through nepotistic behaviors.^[65]^[66] Hierarchies emerge in more social taxa like yellow-bellied marmots (Marmota flaviventris), where dominant breeding pairs control access to resources and mating opportunities within family groups, while subordinates delay reproduction to assist kin.^[67] These dynamics foster cooperation, such as shared territorial defense in colonies, where kin groups collectively repel intruders to protect burrows and foraging areas.^[68] Communication plays a central role in maintaining social bonds and coordinating group activities, primarily through vocalizations, visual signals, and chemical cues. Ground squirrels produce distinct alarm chirps that vary by predator type—higher-pitched for aerial threats and lower for terrestrial ones—to convey specific risks to group members.^[69] Tail-flagging, a rapid waving of the tail, accompanies these calls to amplify urgency, while scent-marking via oral glands on burrow entrances and vegetation reinforces territorial boundaries and kin recognition within groups.^[70] In species like Arctic ground squirrels (Urocitellus parryii), individuals share vigilance duties, with kin alerting others to dangers, thereby reducing per capita predation risk without direct allomothering of young.^[71] Social variations across taxa highlight regional adaptations; European ground squirrels (Spermophilus citellus) form family groups of 10–20 individuals, typically including one breeding male, multiple related females, and their offspring, centered around shared burrow systems.^[72] These patterns underscore how ecological niches shape the balance between solitary independence and group benefits in ground squirrel societies.^[73]

Reproduction and life history

Ground squirrels typically exhibit seasonal polyestry, producing one to two litters per year depending on species and climate, with breeding occurring in spring shortly after emergence from hibernation. In most hibernating species, such as Columbian and European ground squirrels, females produce a single litter annually, while non-hibernating or milder-climate species like California ground squirrels may have two litters in favorable conditions. Gestation periods range from 21 to 30 days; for instance, Columbian ground squirrels have a gestation of about 22 days, and European ground squirrels approximately 29 days. Litter sizes vary widely from 3 to 14 young, with averages of 6-8 in Richardson's ground squirrels and 3.3-3.5 in Columbian ground squirrels.^[74]^[75]^[76]^[77] Mating systems are generally promiscuous, with males engaging in scramble competition or dominance contests to access multiple females, though prairie dogs display harem-polygyny where a dominant male monopolizes breeding within a social group. Reproductive timing is closely integrated with hibernation, as cues for breeding are linked to post-torpor fat reserves; for example, yellow-bellied marmots initiate breeding after emergence, with success determined by spring body mass accumulated during the previous active season.^[78]^[79]^[80] Offspring are altricial at birth, emerging blind and hairless, and receive intensive maternal care, including lactation in natal burrows. Weaning occurs at 4-6 weeks, when young emerge and become independent; for Richardson's ground squirrels, pups reach about 81 g at burrow emergence, representing significant maternal investment during lactation. Infanticide is rare but documented, particularly by intruding males or conspecifics in species like California and Columbian ground squirrels, potentially to redirect female reproductive effort.^[81]^[77]^[82]^[83] In the wild, ground squirrels have a lifespan of 2-5 years, influenced by high juvenile mortality rates of 50-70%, with only 40-50% of female juveniles surviving to one year in species like Richardson's ground squirrels. Captive individuals can live up to 10 years, as seen in California ground squirrels.^[21]^[84]

Antipredator behaviors

Ground squirrels exhibit a range of antipredator behaviors to detect, evade, and deter predators, which include raptors such as hawks, mammals like foxes and badgers, and reptiles including snakes, contributing to annual mortality rates from predation of 40-60% in many populations.^[85] Vigilance is a primary strategy, involving bipedal scanning of the environment for threats; in colonial species like Columbian ground squirrels, individuals allocate up to 30% of their active time budget to this behavior, especially in larger groups where collective detection enhances safety.^[86] Alarm calls serve as acoustic signals that prompt conspecifics to flee, with Belding's ground squirrels (Urocitellus beldingi) producing calls more frequently in the presence of kin, reflecting kin selection as callers assume greater personal risk to benefit relatives. Evasion tactics include rapid dashes toward bolt-holes for cover and tail-waving or flagging, which distracts predators and signals the squirrel's alertness, reducing strike success in encounters with snakes.^[87] In some species, such as California ground squirrels (Otospermophilus beecheyi), chemical defenses involve biting intruders and releasing blood containing protease inhibitors that counteract venom, though this primarily deters reptilian predators; related serum properties may broadly impair predator attacks.^[88] Group living amplifies these behaviors through the dilution effect, where larger colonies reduce per-individual predation risk by spreading vigilance across members, allowing more time for foraging.^[86] Additionally, squirrels engage in mobbing, collectively harassing intruders like snakes by kicking dirt and approaching closely to drive them away, particularly when defending young.^[89] These tactics integrate briefly with broader communication signals in social contexts but focus on immediate threat responses.^[69]

Conservation status

Population threats

Ground squirrel populations face significant declines due to habitat loss from agricultural expansion, urbanization, and overgrazing by livestock, which fragments grasslands essential for their burrowing and foraging. For instance, black-tailed prairie dog (Cynomys ludovicianus) colonies have experienced up to 98% reduction in historical range primarily from conversion to cropland and urban development, alongside intensive grazing that degrades vegetation cover.^[90]^[91] Persecution through poisoning and shooting, often viewing ground squirrels as agricultural pests, exacerbates these declines by directly reducing colony sizes. In the western United States, ongoing control efforts including rodenticides and recreational shooting target prairie dogs, contributing to localized extirpations and hindering population recovery.^[92] Diseases such as sylvatic plague (Yersinia pestis), transmitted by invasive fleas, pose a severe threat, causing near-total colony mortality during outbreaks. Black-tailed prairie dog populations can lose 90-100% of individuals in affected areas, with plague persisting as an endemic issue since its introduction in the early 20th century, further compounded by tularemia in some regions.^[93]^[90] Climate change intensifies these pressures by altering hibernation patterns, increasing drought frequency, and reducing forage availability through shifts in precipitation and temperature. For the Mohave ground squirrel (Xerospermophilus mohavensis), these factors have led to absence from over 40% of its historical range, with models predicting further contraction and northward habitat shifts due to warming deserts.^[94]^[95] Approximately 20% of ground squirrel species are classified as vulnerable or threatened on the IUCN Red List, reflecting cumulative impacts of these threats. Notable examples include the endangered Mexican prairie dog (Cynomys mexicanus), restricted to fragmented habitats in northern Mexico due to agricultural conversion; the Vancouver Island marmot (Marmota vancouverensis), which was critically endangered in the 2000s from habitat loss and predation before partial recovery efforts; and the speckled ground squirrel (Spermophilus suslicus), reassessed as critically endangered in 2024 due to a 99% population decline over the past 30 years from habitat loss and persecution.^[96]^[97]^[98]

Conservation measures

Conservation measures for ground squirrels encompass a range of legal protections, habitat management, and research initiatives aimed at stabilizing populations of various species within the family Sciuridae. Several species benefit from designation in protected areas, such as black-tailed prairie dogs (Cynomys ludovicianus) in Badlands National Park, where management plans support natural population fluctuations while addressing threats like sylvatic plague through monitoring and vaccination efforts.^[99] Reintroduction programs have been implemented for marmots, a type of ground squirrel; for instance, the Vancouver Island marmot (Marmota vancouverensis) has seen successful translocations from captive breeding facilities to wild habitats since the early 2000s, contributing to population recovery.^[100] Under international and national laws, certain ground squirrels receive formal protections. Some species, including the Mexican prairie dog (Cynomys mexicanus) and specific marmots like Marmota caudata, are listed in Appendix II of the Convention on International Trade in Endangered Species (CITES), regulating trade to prevent overexploitation.^[101] In the United States, the Endangered Species Act (ESA) safeguards taxa such as the Idaho ground squirrel (Urocitellus brunneus), listed as threatened since 2000, while prairie dog conservation is integral to the recovery of the endangered black-footed ferret (Mustela nigripes), which relies on prairie dog colonies for prey and habitat.^[102]^[103] Habitat management techniques include controlled burns to maintain grassland ecosystems suitable for species like the northern Idaho ground squirrel, promoting forb and grass diversity essential for foraging.^[104] Ongoing field trials for oral sylvatic plague vaccines, developed by the U.S. Geological Survey, have been conducted on prairie dogs from 2023 to 2025, showing promise in reducing mortality rates during outbreaks by eliciting immune responses in treated colonies.^[105] Captive breeding programs support reintroductions, notably for the European souslik (Spermophilus citellus) in European zoos under the European Association of Zoos and Aquaria, where breeding pairs produce juveniles for release into restored habitats.^[106] Research post-2020 has focused on genomic adaptations for resilience, such as studies identifying genetic variants in prairie dogs that confer resistance to plague, informing targeted conservation breeding.^[107] Community education initiatives, led by organizations like the Prairie Dog Coalition, promote awareness of ground squirrels' ecological roles as keystone species, reducing human-wildlife conflicts and persecution through public outreach and non-lethal management workshops.^[108] A notable success is the Vancouver Island marmot, whose wild population increased from approximately 30 individuals in 2003 to over 300 by 2025, largely due to translocation and habitat protection efforts.^[109]

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Dec 7, 2013 · This could be regarded as evidence that the incisors of the animals studied continued growing throughout hibernation, including the period ...
[29]
Effect of environmental temperature on body temperature and ...
Jul 15, 2002 · When exposed to an air temperature (Tair) of 15°C, the body temperature of this species ranges between 32 and 33.4°C. By lowering TB by only 1.4 ...
[30]
Small Mammals in Hot Deserts: Some Generalizations Revisited
The mammals that enter dormancy at perhaps the highest environmental temperature are those that estivate, including the Mojave ground squirrel (Spermophilus ...
[31]
Countercurrent heat exchange in desert animals - spatial experiments
Sep 16, 2016 · Thus minimising water and heat loss through breathing is the reason for countercurrent heat exchange in their nasal passages. As warm air ...Missing: Mohave ground squirrel adaptations reflective
[32]
Spermophilus mexicanus (Mexican ground squirrel) | INFORMATION
The Mexican Ground Squirrel ranges from Northern Mexico to along the Gulf coast of Texas, extending to western and central Texas and into southeastern New ...
[33]
Thirteen-Lined Ground Squirrels
The 13-lined ground squirrel (Spermophilus tridecemlineatus) is 1 of 40 species of ground squirrels in North America. They are largely a species of the ...
[34]
Distribution, Population Size, and Habitat Characteristics of ... - MDPI
The European ground squirrel (Spermophilus citellus) is an endangered species, endemic to Central and Southeastern Europe, inhabiting burrow colonies in ...
[35]
Spermophilus dauricus (Daurian ground squirrel) | INFORMATION
Daurian ground squirrels currently occupy three countries: China, Mongolia, and the Russian Federation. Within China, they occupy northeastern China as far ...Missing: Siberia | Show results with:Siberia
[36]
Concepts and records of range dynamics in ground squirrels and ...
Mar 10, 2019 · Interspecific competition and isolating geographical barriers are considered as the principal factors that define species range boundaries. The ...
[37]
Xerus erythropus (striped ground squirrel) - Animal Diversity Web
Savanas of eastern Sudan and southwestern Kenya, southwestern Morocco, southern Mauritania and Senegal are the native homes of Geoffrey's ground squirrels.
[38]
Xerus rutilus (unstriped ground squirrel) - Animal Diversity Web
They are native to Djibouti, Eritrea, Ethiopia, Kenya, Somalia, Sudan, Tanzania, and Uganda. Considered the most common ground squirrel of eastern Ethiopia, ...
[39]
Altitudinal Distribution of Alpine Marmot (Marmota marmota) in the ...
May 3, 2018 · The alpine marmot occupies areas ranging in altitude from 1300 to 2800 m in the Pyrenees, although 67% of the colonies are found between 1800 ...
[40]
Hypoxic and Cold Adaptation Insights from the Himalayan Marmot ...
Dec 20, 2018 · The Himalayan marmot (Marmota himalayana), a large squirrel of the genus Marmota, is widely distributed at elevations of 1,900–5,000 m around ...
[41]
Northern palm squirrel | Exotic pest animal species | Biosecurity
Aug 21, 2025 · The northern palm squirrel is not native to Australia and if given the opportunity could establish and breed in Victoria. They have the ...
[42]
Demographic and environmental correlates of home ranges and ...
Oct 27, 2022 · Mohave ground squirrels responded strongly to climate variation, and global climate change will likely result in a northward shift in suitable ...
[43]
Insular Antelope Squirrel - Ammospermophilus leucurus insularis
Sep 20, 2025 · It is endemic to Mexico, where it is known only from the island of Espíritu Santo in the Gulf of California.
[44]
Cynomys ludovicianus - USDA Forest Service
Black-tailed prairie dogs are native to grassland habitats in North America. They inhabit shortgrass prairie [26,53,70,77,91,99], mixed-grass prairie.
[45]
White-tailed Antelope Squirrel (Ammospermophilus leucurus)
Of all Ammospermophilus , white-tailed antelope squirrels are the most widespread in North America; their general range is the Great Basin to Baja California. ( ...
[46]
Spermophilus townsendii (Townsend's ground squirrel)
They prefer well-drained soils, and their habitats of choice include abandoned farmland, canals, and railroad embankments. Their habitat selection can be ...
[47]
The structure of California ground squirrel burrows - ResearchGate
... Burrows of O. douglasii from northern California were 10.9 cm in diameter, and 1.5-0.7 m in length, with most burrows 0.76-1.20 m below ...
[48]
[PDF] the structure of california ground squirrel burrows: control ...
Marsh (1985) stated that ground squirrel burrow systems tend to be expanded in size each successive year, and this could explain the differences between ...
[49]
Rise and fall: Results of a multidisciplinary study and 5-year long ...
Jun 17, 2022 · Anthropogenic effects on the population ecology of European ground squirrels (Spermophilus citellus) at the periphery of their geographic range.
[50]
Relationship between habitat characteristics and densities of ...
Mar 18, 2013 · Habitats are heterogeneous in the range of the southern Idaho ground squirrel, with constantly varying aspect, slope, soils, and vegetation. At ...
[51]
[PDF] Habitat suitability model for California Ground Squirrel
Jun 3, 1995 · Swihart et al. (1988) reported a home range size of 0.17 ha (0.4 ac). California ground squirrels may live singly, or in small, dispersed ...
[52]
Hibernation behavior of a federally threatened ground squirrel
Apr 13, 2021 · Abstract. Hibernation is an adaptation to survive periods of stress, from food limitation or harsh thermal conditions.
[53]
Burrowing Owls Require Mutualist Species and Ample Interior ...
Sep 19, 2024 · Burrows used by non-breeding burrowing owls in fall were also associated with higher densities of ground squirrel burrow systems. The densities ...
[54]
Urocitellus | INFORMATION - Animal Diversity Web
They are primarily herbivorous, eating seeds, grasses, and other available forage (Howell, 1938). In some cases, arthropods are also part of their foraging, ...Missing: strategies | Show results with:strategies
[55]
Belding's Ground Squirrel - Sierra Nevada Aquatic Research ...
While mainly eating seeds, flowers, and plants, their diet occasionally consists of small vertebrates, insects, and carrion. You can spot the Belding' Ground ...
[56]
UC Davis study finds never-before-seen carnivorous squirrels
Dec 19, 2024 · But a new study provides the first evidence that California ground squirrels also hunt, kill and eat voles. The study, led by the University ...Missing: insectivory carnivory percentages
[57]
[PDF] Ground Squirrels - Los Angeles - Lacounty
The ground squirrel's diet varies depending on the time of year. After emerging from hibernation they feed primarily on green grasses and herbaceous plants ...
[58]
[PDF] Spermophilus beldingi - - Clark Science Center
Apr 27, 1984 · Belding's ground squirrels are primarily herbivorous, although insects, other vertebrates, carrion, and conspecifics also are eaten. (Morton, ...
[59]
[PDF] Controlling Piute Ground Squirrels in Southwest Utah
Feb 1, 2020 · Ground squirrels are primarily herbivorous, and their diet changes with the season. ... Ground squirrels are accustomed to foraging above ground ...Missing: strategies | Show results with:strategies
[60]
[PDF] Belding's, California, and Rock Ground Squirrels
Using their cheek pouches for carrying food items, the California and rock ground squirrels are highly prone to hoarding and caching food. The. Belding is ...
[61]
Contributions of Microbes in Vertebrate Gastrointestinal Tract to ...
This review discusses the contributions of gut microorganisms common to all vertebrates, the numerous digestive strategies that allow herbivores to maximize ...<|control11|><|separator|>
[62]
California Ground Squirrels / Citrus / Agriculture - UC IPM
Because ground squirrels feed almost exclusively on green vegetation early in the season, poisoned grain baits are generally not effective until late spring or ...Missing: diet | Show results with:diet
[63]
Ammospermophilus harrisii (Harris's antelope squirrel)
Oct 6, 2014 · These squirrels are never found in groups, they remain alone, dispersed far from their conspecifics. Adult squirrels are only found together ...Physical Description · Reproduction · BehaviorMissing: social organization
[64]
Coloniality - The Prairie Dog Project
Black-tailed prairie dogs (BTPDs) for example, can be found in colonies in the thousands, with many wards and coteries (family groups dominated by one or two ...
[65]
Sociality as a life-history tactic of ground squirrels | Oecologia
Sociality in these species may have evolved through retention of daughters within the maternal home range as a means of continuing reproductive investment ...
[66]
Richardson's ground squirrel offspring and neighbours are resilient ...
Sep 4, 2019 · Thus, we conclude that Richardson's ground squirrels may have evolved resilience to the changing social landscape and are, at least as far as ...
[67]
Behavioural Ecology of Columbian Ground Squirrels
Kin-based social behavior. The species is organized in so-called matrilineal societies, where females are philopatric and kin female overlap both in space ...
[68]
Society formation and maintenance in yellow-bellied marmots
Yellow-bellied marmots are facultatively social and at times live in societies. Societies form when adult females recruit their daughters.
[69]
Belding's Ground Squirrel - Holekamp Lab
Gestation lasts 24-25 days, and the lactation interval is 25-28 days. Young ... Why do female Belding's ground squirrels disperse away from food resources?
[70]
Behaviors associated with vocal communication of squirrels - Diggins
Jun 10, 2021 · Additionally, since vocalizations are usually accompanied by visual signals (e.g., tail flagging), body posturing may indicate how the call ...
[71]
ground squirrel tail flagging in the absence of snakes signals vigilance
Oct 9, 2014 · Squirrels tail flagged most when interacting with a snake. Squirrels also signaled in areas of recent snake encounters, and in this context, ...Missing: vocalizations scent-
[72]
Press release: group squirrel vigilance - Hobson Lab
Nov 4, 2021 · Ground squirrels have few natural defenses against predators, so they rely on an early warning system to identify threats and alert others ...
[73]
European ground squirrel - Spermophilus citellus - Donau-Auen
The European ground squirrel has a slender build and grows to a length of approximately 20cm with a 6cm-long furry tail. A fully-grown specimen may weigh from ...Missing: size | Show results with:size
[74]
Home range, social behavior, and dominance relationships in the ...
Ground squirrels lived alone or in small groups in isolated burrow systems and had broadly overlapping home ranges. They were neither territorial or colonial.
[75]
Social organization in a North African ground squirrel
Anecdotal accounts on Barbary ground squirrels' social organization suggested that they were either solitary or gregarious, or live in small family groups.Missing: review | Show results with:review
[76]
[PDF] MULTIPLE LITTERS IN THE CALIFORNIA GROUND SQUIRREL ...
Reproductive information was collected for two breeding seasons. In the 1977-1978 breeding season both males and females were studied. Males were already ...
[77]
Testing the reproductive and somatic trade‐off in female Columbian ...
In ground squirrels, females in good body condition (i.e., high body mass) allocate more resources to reproduction in the form of larger or heavier litters ...Missing: sources | Show results with:sources
[78]
Explaining the seasonal decline in litter size in European ground ...
Aug 6, 2025 · ... European ground squirrels give birth to only one litter per season, and early reproduction may reduce the time constraints for lactation and ...<|control11|><|separator|>
[79]
Reproductive effort during gestation and lactation by Richardson's ...
On average, litters weighed 16.3% (48 g) of maternal mass at birth and 157.5% (578 g) at emergence from the natal burrow. Compared with other hibernating ...Missing: scientific sources
[80]
The Mating System - The Prairie Dog Project
As part of their genus-wide template, prairie dogs exhibit a harem-polygynous mating system, wherein a single dominant male has exclusive access to a group of ...
[81]
Scramble Competition Polygyny in Thirteen-Lined Ground Squirrels
The mating system of Belding's ground squirrel has been classified as dominance polygyny and/or as a resource-based lek (Sherman and Morton 1984); victory ...
[82]
The timing of reproduction is responding plastically, not genetically ...
Dec 6, 2023 · They have a 4‐month active season, from late‐April/early‐May to late‐September, during which they need to reproduce and accumulate fat reserves ...
[83]
Thirteen-lined Ground Squirrel Species Account
The gestation period is 27–28 days. The young vary in number from 2 to 13; yearling females produce the smallest litters. The young are blind, hairless, and ...
[84]
[PDF] The functional significance of infanticide in a population of California ...
This paper presents data from a four-year study of naturally-occurring infanticide in free-living California ground squirrels. Although Linsdale (1946) and ...Missing: altricial | Show results with:altricial
[85]
[PDF] Parental investment in the Columbian ground squirrel: empirical - HAL
High incidence of infanticide by lactating females in a population of. 796. Columbian ground squirrels (Spermophilus columbianus). Canadian Journal of Zoology.Missing: altricial | Show results with:altricial
[86]
Spermophilus beecheyi (California ground squirrel) | INFORMATION
Lifespan/Longevity The lifespan of a California ground squirrel can be up to 6 years in the wild. They have lived as long as 10 years in captivity.Missing: juvenile mortality semelparity
[87]
[PDF] Functional semelparity drives population dynamics and endangers a ...
Other core red squirrel populations show an increase in life expectancy from age 0, as do many core populations of other sciurids such as Sciurus and Nearctic ...
[88]
[PDF] Life history account for Belding's Ground Squirrel
Feeding: This herbivore feeds on a variety of grasses and forbs, eating leaves, stems, seeds, bulbs, and fruits. Also eats some insects, and occasionally may ...
[89]
Mechanisms of the group-size effect on vigilance in Columbian ...
Columbian ground squirrels showed the expected group-size effect on vigilance. Ground squirrels changed their vigilance according to the number of squirrels ...
[90]
Ground squirrel tail-flag displays alter both predatory strike and ...
Jul 11, 2012 · We found that tail-flagging deterred snakes from striking squirrels, most likely by advertising squirrel vigilance (ie readiness to dodge a snake strike).
[91]
California Ground Squirrel (Spermophilus beecheyi) Defenses ...
Feb 26, 2006 · Effects of Douglas ground squirrel plasma on venom activity are shown in Figure 1. The two populations differed in their ability to inhibit ...
[92]
Ground squirrels heat their tails to discourage rattlesnake attack
Squirrels signal their presence and harass snakes by kicking dirt and pebbles in their faces (9). They piloerect and flag their tails from side to side.
[93]
Prairie Dog | Defenders of Wildlife
Sylvatic plague and habitat loss have contributed to an estimated 98% population decline in prairie dog numbers. Sylvatic plague is an introduced wildlife ...
[94]
Living with Prairie Dogs - Colorado Parks and Wildlife
The biggest threat to prairie dog populations is habitat loss primarily due to development around population centers on the Front Range. New commercial and ...
[95]
The surprising role prairie dogs play in saving ecosystems
Prairie dogs continue to face threats such as poisonings and shootings, habitat loss and plague. If prairie dog populations decline further, wildlife experts ...
[96]
Prairie Dog Habitat Loss in Colorado - Facebook
Mar 25, 2025 · Some of the problems are shooting, poison campaigns, and plague., not to mention agricultural develment, cattle grazing, energy development and ...
[97]
Disease Limits Populations: Plague and Black-Tailed Prairie Dogs
Plague is an exotic vector-borne disease caused by the bacterium Yersinia pestis that causes mortality rates approaching 100% in black-tailed prairie dogs ...
[98]
Conservationists Seek Federal Protection for the Mohave Ground ...
Dec 13, 2023 · The species no longer exists in over 40% of its historical range – mainly due to development expansion and exacerbated by climate change.Missing: shift | Show results with:shift
[99]
Mohave Ground Squirrel 5-Year Species Review – How You Can Help
Aug 23, 2023 · Threats include range contraction due to habitat loss, habitat degradation and fragmentation, and climate change, including increased severity ...
[100]
Species Profile for Mexican prairie dog(Cynomys mexicanus) - ECOS
Mexican prairie dog (Cynomys mexicanus) · Taxonomy: · Listing Status: Endangered · General Information · » Range Information · US Counties in which the Mexican ...
[101]
Vancouver Island Marmot Assessment & Status Report 2019
Dec 6, 2019 · Vancouver Island Marmot was assessed as endangered by the IUCN. Two protected areas have been established specifically to protect marmot habitat ...
[102]
Prairie Dogs: Pipsqueaks of the Prairie - National Park Service
Nov 10, 2020 · In Badlands National Park, wildlife biologists attempt to prevent plague outbreaks by feeding our prairie dogs an oral vaccine. After testing ...Missing: conservation | Show results with:conservation
[103]
Current Status - Marmot Recovery Foundation
The Vancouver Island Marmot (Marmota vancouverensis) is listed as Endangered under the federal Species At Risk Act (SARA) and by the Committee on the Status of ...
[104]
Appendices | CITES
Ground squirrels, tree squirrels. Cynomys mexicanus. Marmota caudata (India). Marmota himalayana (India). Ratufa spp. Order. Scandentia. Tree Shrews. Scandentia ...
[105]
Idaho Ground Squirrel (Urocitellus brunneus) | U.S. Fish & Wildlife ...
It has a short, narrow tail, tan feet and ears, grey-brown throat, and a creamy white eye ring. This rare squirrel needs large quantities of grass seed, stems ...
[106]
[PDF] Black-footed Ferret Recovery Plan - U.S. Fish and Wildlife Service
Although prairie dogs have their own intrinsic value, black-footed ferret and prairie dog management must be separated. Protection of those existing.
[107]
[PDF] Recovery Plan for the Northern Idaho Ground Squirrel - ECOS
2.1 Prescribed burning. As with the restoration of habitat, prescribed low-intensity burns will be utilized to ensure the appropriate grass/forb component ...
[108]
Sylvatic Plague | U.S. Geological Survey - USGS.gov
USGS scientists are working with partners to conduct field trials of an oral sylvatic plague vaccine for prairie dogs. ... 2025, 2024, 2023, 2022, 2021, 2020 ...
[109]
[PDF] EUROPEAN ASSOCIATION OF ZOOS AND AQUARIA - EAZA
Nature Conservation Agency of the Czech Republic | Establishment of breeding sites for the European souslik. Hluboká Zoo, Nordens Ark, Opel-Zoo, Brno Zoo,.
[110]
Prairie dog genes reveal secrets of plague survival - Phys.org
Jul 8, 2025 · A study of the genetic basis of plague immunity in prairie dogs has broad implications for conservation.
[111]
About Us - Prairie Dog Coalition
The Prairie Dog Coalition empowers organizations and individuals by providing conservation tools that protect prairie dogs, restore their ecosystems, and reduce ...
[112]
Vancouver Island Marmot Conservation | The Wilder Institute
By 2003, approximately 30 individuals remained in the wild. ... Thanks to our combined efforts, the wild Vancouver Island marmot population has grown to over 200.