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Gray squirrel

The eastern gray squirrel (Sciurus carolinensis) is a medium-sized tree squirrel native to the deciduous forests of eastern North America, including parts of southern Canada and the eastern and central United States. The species is classified as Least Concern on the IUCN Red List due to its wide distribution and stable populations in its native range.^[1] It is characterized by its soft gray fur, white underbelly, and prominent bushy tail that aids in balance and signaling. Adults typically measure 16 to 20 inches in total length, weigh up to 1.5 pounds, and exhibit color variations including black, white, or blond morphs, with the tail featuring silvery-tipped hairs for camouflage and communication.^[2] Highly adaptable, it thrives in diverse environments from rural woodlands to urban parks, where it constructs nests called dreys from leaves and twigs high in trees or occupies natural cavities.^[3] Its diet is primarily herbivorous, consisting of nuts (such as acorns and hickory nuts), seeds, berries, buds, and fungi, though it opportunistically consumes insects, bird eggs, and small vertebrates during scarcity, and caches food stores for winter survival.^[2] Diurnal and active year-round, gray squirrels are agile climbers capable of speeds up to 15 miles per hour on the ground and use vocalizations like barks and chatters to warn of predators such as hawks, owls, and foxes.^[4] Breeding occurs twice annually, from late winter to early spring and again in summer, with litters of 2 to 6 young after a 40- to 45-day gestation; females reach sexual maturity at 6 to 8 months, males at 9 to 11 months, and offspring are weaned after about 50 days.^[2] In the wild, they typically live 3 to 6 years, though some survive up to 12 years in protected areas, facing threats from habitat loss, vehicles, and predation.^[5] Socially tolerant, they share nests during cold weather but defend food caches aggressively, contributing to their role in forest ecosystems through seed dispersal despite occasional crop damage in agricultural settings.^[6] Introduced to the United Kingdom in the 19th century as an ornamental species, the gray squirrel has become invasive, with populations estimated at around 2.7 million as of 2024 and expanding across most of England, Wales, and parts of Scotland.^[7] There, it outcompetes the native Eurasian red squirrel (Sciurus vulgaris) for food resources like acorns and tree seeds, while carrying squirrelpox virus—a disease lethal to reds but asymptomatic in grays—leading to local extinctions of the red species in overlapping ranges.^[7] Additionally, gray squirrels damage timber by stripping bark from broadleaf trees, reducing regeneration in woodlands, and efforts like culling and habitat management are employed to mitigate these impacts.^[7] Similar introductions have occurred in parts of Canada and continental Europe, underscoring its status as a successful but ecologically disruptive non-native species.^[8]

Taxonomy and nomenclature

Taxonomy

The eastern gray squirrel (Sciurus carolinensis) belongs to the family Sciuridae within the order Rodentia and is classified as follows: Kingdom Animalia, Phylum Chordata, Class Mammalia, Order Rodentia, Family Sciuridae, Genus Sciurus, Species S. carolinensis Gmelin, 1788.^[9] This classification reflects its position as a tree-dwelling rodent adapted to arboreal lifestyles shared across the genus Sciurus.^[10] Phylogenetic analyses based on cytochrome b gene sequences place S. carolinensis within the New World clade of the genus Sciurus, where it forms a close sister group with the fox squirrel (S. niger) and other North American tree squirrels such as S. aberti.^[11] The New World Sciurus lineage diverged from Old World species, including the Eurasian red squirrel (S. vulgaris), with genetic distances indicating earlier diversification in New World populations compared to their Eurasian counterparts.^[11] Five subspecies of S. carolinensis are currently recognized, each adapted to regional variations in climate and habitat across their native range in eastern North America; these differ primarily in pelage coloration, with northern forms often exhibiting grayer or darker fur for camouflage in mixed forests, while southern populations show lighter, more variable tones.^[12]

Subspecies	Geographic Distribution	Distinguishing Traits
S. c. carolinensis	Southeastern USA, from SE Kansas and Missouri east to S Ohio and S Virginia, south to Florida and Louisiana	Lighter gray pelage with yellowish tones; smaller size
S. c. fuliginosus	Northeastern USA, from S Ontario and New York south to N Virginia, west to Wisconsin and E Kansas	Darker, sooty-gray fur; more robust build
S. c. hypophaeus	Southern Great Lakes region, including S Wisconsin, N Illinois, N Indiana, and N Ohio	Pale underparts; intermediate gray tones
S. c. pennsylvanicus	Northeastern North America, from S Quebec, S Ontario, New Brunswick, and Nova Scotia south to C New York, Pennsylvania, N West Virginia, and N Ohio	Silvery-gray pelage; adapted to colder climates
S. c. extimus	Florida Keys (likely extinct)	Smallest subspecies; pale, sandy coloration

^[12]^[13] Analyses of genetic diversity in introduced populations of S. carolinensis, such as those in Ireland, indicate low to moderate overall genetic diversity, with evidence of inbreeding in certain localized groups stemming from limited founder effects during 20th-century introductions.^[14] These findings highlight reduced variation compared to native North American populations, potentially increasing vulnerability to environmental stressors in non-native ranges.^[14]

Etymology

The common name "gray squirrel" derives from the species' characteristic grayish fur coloration and has been in use in North American English since the early 18th century.^[15] English explorer and naturalist John Lawson referred to the animal as the "small gray Squirrel" in his 1709 publication A New Voyage to Carolina, providing one of the earliest documented descriptions by European settlers.^[15] To distinguish it from the western gray squirrel (Sciurus griseus), the regional variant "Eastern gray squirrel" emerged in common usage during the 19th century.^[16] The scientific name Sciurus carolinensis consists of two parts with distinct etymological origins. The genus name Sciurus comes from the Ancient Greek words skia (shadow or shade) and oura (tail), referring to the bushy tail that casts a shadow when the squirrel sits with it arched over its back.^[17] The specific epithet carolinensis means "of Carolina" in Latin, honoring the Carolina colony where the species was first recorded by European naturalists; the colony itself was named after King Charles I or II of England (Latin Carolus). The binomial nomenclature Sciurus carolinensis was formally established in 1788 by German naturalist Johann Friedrich Gmelin in the 13th edition of Carl Linnaeus's Systema Naturae, building on earlier informal descriptions like Lawson's.^[18] Although the species name has remained stable, 20th-century taxonomic revisions primarily affected subspecies designations, such as the recognition of S. c. carolinensis for the nominate form, without altering the core nomenclature.

Physical characteristics

Appearance and morphology

The eastern gray squirrel (Sciurus carolinensis) is a medium-sized arboreal rodent, with adults typically measuring 38–53 cm in total length, including a tail of 15–25 cm, and weighing 400–700 g.^[19]^[12] There is no notable sexual dimorphism in size or coloration.^[19] The fur is dense and soft, with the dorsal surface exhibiting a grizzled pattern ranging from pale to dark gray, often with cinnamon tones on the hips, feet, and head; the underparts are white to buff.^[19]^[8] Gray squirrels undergo biannual molts, in spring and late summer, which can result in slightly darker winter pelage due to longer guard hairs.^[20] Color variants include melanistic (all-black) forms, occurring at frequencies generally below 1% across most of the range but exceeding 75% in the northern part of the range, including the Great Lakes region, albinistic (white), and blond (light) morphs, rare erythristic (reddish) morphs, with albinism being particularly rare.^[21]^[19] Key anatomical adaptations include a bushy tail, comprising about half the body length, which aids in balance during leaps and serves as a visual signal.^[19]^[12] The hind legs are muscular and elongated, enabling jumps of up to 3 meters horizontally between trees, while sharp, curved claws on all feet facilitate gripping bark during climbing.^[22]^[18] Prominent vibrissae (whiskers) around the muzzle and limbs provide tactile feedback for navigating branches.^[19] The dental formula is 1/1, 0/0, 2/1, 3/3, totaling 22 teeth, with continuously growing incisors adapted for gnawing.^[18] Sensory adaptations support a diurnal lifestyle, featuring large, forward-facing eyes that provide binocular vision for depth perception in arboreal environments, acute hearing for detecting predators, and a keen sense of smell for locating buried food caches.^[19]^[12]

Growth and lifespan

Newborns are hairless, blind, with closed ears, and weigh 10 to 15 grams at birth.^[23]^[24]^[25]^[26] In the early stages of development, the eyes open around 4 weeks of age, and the young begin venturing outside the nest by 6 weeks. Weaning from milk to solid food occurs between 7 and 10 weeks, marking the transition from infancy to juvenile stages. By 10 to 12 weeks, juveniles achieve independence from the mother, foraging on their own while continuing to grow.^[25]^[24] Juvenile gray squirrels experience rapid physical growth, increasing in weight from their birth mass to adult sizes of 400 to 700 grams by approximately 6 months of age. Skeletal development, including epiphyseal fusion in long bones, completes by around 1 year, coinciding with full physical maturation.^[27]^[28]^[29]^[30] In the wild, the average lifespan from birth is 1 to 2 years due to high juvenile mortality, though adults may live an average of 6 years and up to 12 years under optimal conditions. Predation and disease are primary factors limiting longevity in natural populations. In captivity, where such threats are minimized, gray squirrels can live 15 to 20 years.^[3]^[4]^[31]

Distribution and habitat

Native range

The eastern gray squirrel (Sciurus carolinensis) is native to the deciduous and mixed forests of eastern North America, with its range extending from the Atlantic seaboard westward to the eastern edge of the Great Plains, and from the Gulf Coast of Florida northward to southern Canada, including regions of Ontario and Quebec. This distribution encompasses approximately 2.5 million square kilometers of primarily temperate woodland habitats. The western limit generally aligns with the Mississippi River valley, while the northern boundary reaches latitudes around 50°N in suitable forested areas.^[2]^[32]^[19] Within this native range, the species prefers mature hardwood forests dominated by oak (Quercus spp.) and hickory (Carya spp.) trees, which provide essential mast crops such as acorns and nuts for caching and winter survival; it also occupies mixed coniferous-deciduous woodlands with diverse understory vegetation for cover and foraging. Optimal habitats consist of continuous forest patches exceeding 40 hectares to support territorial needs and reduce predation risk, with population densities reaching 1-3 individuals per hectare in high-quality mast-producing areas. The altitudinal range spans from sea level to elevations up to approximately 1,500 meters in the Appalachian Mountains, though densities decline at higher altitudes due to harsher conditions and reduced food availability.^[19]^[33]^[3] Historically, the gray squirrel's range originated in the southeastern United States, with pre-colonial expansions northward and westward facilitated by abundant nut-bearing forests; accounts from the 18th and 19th centuries describe massive migratory irruptions involving millions of individuals crossing rivers and ravaging crops during mast failures. Pre-1900 population estimates suggest abundances in the tens of millions across the core range, though exact figures are challenging due to fluctuating densities tied to food cycles. In the 20th century, the native range contracted in some areas due to widespread deforestation for agriculture and urbanization, but subsequent reforestation efforts, particularly in the mid-Atlantic and Midwest, enabled population recovery and localized range expansions by the late 20th and early 21st centuries.^[34]^[35] The species is well-adapted to temperate climates with mild winters (average temperatures above -10°C), where black morphs in northern populations exhibit enhanced thermoregulation, including lower heat loss and metabolic rates, to endure cold snaps. These adaptations support survival in zones with annual precipitation of 750-1,500 mm and growing seasons of 150-200 days, though range shifts have occurred in response to habitat alterations rather than direct climate forcing.^[19]^[36]

Fossil record

The fossil record of the eastern gray squirrel (Sciurus carolinensis) extends to the Pleistocene epoch, with the species documented in at least 20 faunal assemblages across eastern North America, primarily from the late Irvingtonian land mammal age onward (approximately 780,000–250,000 years ago). The earliest remains come from sinkhole deposits such as Coleman IIA in Florida, where teeth and postcranial elements indicate a presence contemporaneous with early Pleistocene vertebrates.^[37] These fossils, often recovered from karstic cave and sinkhole sites in states including Florida, Georgia, Tennessee, and Pennsylvania, reveal a consistent arboreal morphology adapted to forested environments during a period of climatic fluctuation.^[37] Key fossil sites from the Rancholabrean land mammal age (late Pleistocene, ~240,000–11,700 years ago) include cave deposits in Florida and Georgia, where S. carolinensis remains are associated with megafaunal species such as mammoths (Mammuthus spp.) and giant ground sloths (Megalonyx spp.), suggesting shared habitats in open woodlands and forests amid glacial advances.^[37] For instance, specimens from Yarbrough Cave in Bartow County, Georgia, dated to the Last Glacial Maximum (~21,000–18,000 years ago), confirm the species' persistence in southern refugia during peak ice age conditions, with no evidence of local extinction.^[38] Evolutionary analyses of these fossils indicate relative stability in form, with only minor body size increases during the Rancholabrean followed by a reduction toward modern dimensions, reflecting adaptation to postglacial forest recovery rather than dramatic shifts.^[37] Phylogeographic studies further support genetic continuity between Pleistocene ancestors and contemporary populations, showing patterns of divergence in southern refugia during glacial isolation, followed by northward expansion after the Last Glacial Maximum without significant barriers to gene flow.^[39]

Introduced populations

The eastern gray squirrel (Sciurus carolinensis) was first introduced to the United Kingdom between 1876 and 1890, with initial shipments from New York aimed at stocking private estates for hunting and ornamental purposes.^[7] These early releases, starting at locations like Henbury Park in Cheshire, were followed by additional imports that facilitated rapid dispersal across the British Isles.^[40] From the UK, the species spread to Ireland in 1911, when approximately 12 individuals were released by the Earl of Granard near Castle Pollard, County Westmeath.^[41] Introductions to continental Europe began in Italy during the 1940s, with two pairs released in the Piedmont region near Turin in 1948 for a research station, followed by a small group in Genoa's Nervi Park in 1966.^[12] In South Africa, the species arrived around 1900, imported by Cecil Rhodes to his Groote Schuur estate in Cape Town as an exotic addition to the landscape.^[42] Established populations now thrive in the United Kingdom, covering most of England, Scotland, and Wales, where the species occupies woodlands, urban parks, and agricultural areas.^[7] In Ireland, gray squirrels have colonized much of the eastern and northern regions since their 1911 introduction.^[41] Northern Italy hosts the primary continental European population, centered in Piedmont and expanding slowly into adjacent provinces like Lombardy. As of 2025, control efforts include rapid eradications of small populations to prevent further spread, with successes in lowland forests.^[43]^[12] A limited population persists in South Africa, confined to the Cape Town area around Rondebosch, with no significant further spread.^[42] Escaped individuals have appeared in other European countries, including Germany and France, but these sightings have not led to viable breeding populations.^[44] An introduction to Adelaide around 1917 resulted in a short-lived population, which was eradicated by 1922 through targeted culling.^[45] No successful establishment occurred in New Zealand, where attempts to introduce the species were either absent or unsuccessful due to stringent biosecurity measures.^[12] The gray squirrel's establishment in non-native ranges stems from its exceptional adaptability to varied environments, including urban green spaces, deciduous woodlands, and even coniferous forests that differ from its North American origins.^[12] This versatility, combined with a generalist diet and high reproductive output—females producing two litters per year with 3–4 young each—has enabled rapid population growth in suitable habitats, often expanding at rates exceeding 10 km per decade in the early stages of invasion.^[46] In the UK and Italy, for instance, introduced groups quickly reached densities of 5–10 individuals per hectare within a few years of release, outpacing native red squirrels through superior foraging efficiency and resource hoarding.^[40] As of 2025, gray squirrel populations continue to expand in northern Italy, with documented sightings advancing into Lombardy and potential incursions toward the Swiss border.^[47] Modeling suggests possible future establishment in Scandinavia if climate conditions warm, though cold winters currently limit viability there.^[47] The European Union monitors these populations under invasive alien species regulations, implementing early detection and control measures to prevent broader continental spread.^[48] These introduced groups have broadly affected native wildlife by competing for resources and introducing diseases, contributing to declines in local squirrel populations across Europe.^[49]

Behavior

Reproduction and breeding

The gray squirrel (Sciurus carolinensis) exhibits a polygynandrous mating system, where females mate with multiple males during estrus and males compete intensely for access to receptive females.^[19] Courtship typically involves a "mating chase" in which 1 to 10 males pursue an estrous female, establishing dominance hierarchies through aggressive interactions and physical combat, with the dominant male securing primary copulation rights.^[50]^[3] Breeding occurs in two distinct seasons annually, with the primary period from late December to February and a secondary one from May to July in northern latitudes, though timing shifts slightly southward.^[51]^[3] Gestation lasts approximately 44 days, resulting in litters born from March to April and July to August; adult females produce 1 to 2 litters per year, with yearlings typically limited to one.^[52]^[3] Litter sizes average 2 to 4 young (range 1 to 7), and some females may produce a third litter in years of mild weather and abundant food resources.^[53] Reproductive success varies, with annual fecundity averaging about 4.5 embryos per female in well-adapted populations; however, juvenile survival from weaning to adulthood is relatively low at 25 to 40%, influenced by predation and environmental factors.^[51]^[54] Young are born altricial—hairless, blind, and weighing around 14 to 15 grams—and reach weaning at 8 to 10 weeks, after which they briefly accompany the female before dispersing.^[3] Parental care is provided exclusively by females, who construct dreys (leafy nests) in tree cavities or forks for birthing and rearing, aggressively defending them against intruders.^[51]^[3] Males offer no involvement in nest-building, lactation, or protection, and lactation persists for up to 10 weeks to support offspring development.^[51] Breeding rates are density-dependent, with higher reproductive output and juvenile recruitment in low-density conditions following mast-abundant years that enhance overwinter survival.^[52]^[36] In mast years, populations experience reduced competition for resources, leading to improved female condition and increased litter production the following season.^[55] Gray squirrels (Sciurus carolinensis) primarily communicate through a combination of vocalizations, visual signals, and olfactory cues, which facilitate interactions in their social and ecological contexts. Vocal communication includes distinct alarm calls tailored to specific threats: "kuks" and "quaas" are more frequently produced in response to terrestrial predators, with kuks occurring at higher rates early in calling bouts and quaas appearing later, while "moans"—high-pitched vocalizations—are exclusively associated with aerial predators such as raptors.^[56] These calls serve to alert conspecifics and may deter predators by drawing attention to the threat. Visual signals complement vocalizations, particularly tail flicking or flagging, which often accompanies moans during aerial threats to enhance signal efficacy in dense foliage.^[57] Olfactory communication involves scent glands near the mouth and cheeks, as well as urine, used for marking territories and signaling dominance; individuals rub these glands on objects or deposit urine at prominent points to assert presence and readiness to defend resources.^[58] Tactile interactions, such as allogrooming, occur in loose social groups, promoting affiliative bonds primarily among related females and reducing tension during shared resting or feeding.^[59] Dominance hierarchies emerge in feeding areas, where larger, older individuals—often males—displace subordinates through aggressive displays, establishing pecking orders that influence access to food without rigid territorial exclusion.^[58] Socially, gray squirrels are largely solitary outside of breeding seasons, with individuals maintaining overlapping home ranges averaging 0.5–5 hectares, though older males may have larger ones up to 10 hectares. In high-density populations, female-biased natal philopatry leads to matrilineal kin clusters, where related females form amicable groups, share communal nests (especially in winter), and cooperatively defend core areas from unrelated intruders.^[60] Males exhibit less kin-based grouping and tolerate greater overlap in ranges, focusing territorial defense on breeding periods. Recent studies indicate variations in communication strategies, with urban populations relying more on visual tail signals than vocalizations compared to rural ones, likely due to increased ambient noise.^[61]

Daily activity patterns

Eastern gray squirrels (Sciurus carolinensis) exhibit strictly diurnal activity patterns, remaining active from dawn until dusk throughout the year. In warmer months, their activity is typically bimodal, with peaks occurring mid-morning and in the late afternoon, allowing them to optimize energy expenditure during optimal foraging conditions. During winter, this shifts to a unimodal pattern centered around midday, as shorter daylight hours and colder temperatures influence their circadian rhythms.^[62]^[63]^[64] Seasonal variations in activity are pronounced, with peak overall activity in September and October driven by intensive food caching behaviors in preparation for winter. In fall, squirrels increase their daily activity levels to store nuts and seeds, often extending their foraging efforts. Winter activity remains year-round but diminishes during extreme cold below -10°C, when individuals enter torpor-like rest periods in dens or dreys to conserve energy, though true hibernation does not occur. Migration is rare, but local movements of up to 5 km can happen, particularly among juveniles seeking new territories.^[65]^[66]^[67] Activity budgets allocate a substantial portion of time to essential behaviors, with foraging and related activities (including feeding and storing) comprising approximately 50-60% of observed time in urban settings, peaking higher in fall due to caching demands. Travel accounts for about 20% of the budget, facilitating movement between food sources and nests, while grooming and resting occupy 10-15%, aiding in maintenance and energy recovery. These proportions vary seasonally, with resting decreasing in fall as foraging intensifies.^[68] Adaptations to environmental cues include entrainment of circadian rhythms to natural light cycles, ensuring synchronized daily activity with photoperiod changes. For energy conservation, especially in winter, gray squirrels employ heterothermy, allowing controlled hypothermia during rest periods to reduce metabolic rates by several degrees Celsius. This is particularly evident in litters, where huddling in nests helps neonates maintain body temperature during cold snaps, enhancing survival without full torpor.^[62]^[69]

Ecology

Diet and foraging

The eastern gray squirrel (Sciurus carolinensis) maintains an opportunistic omnivorous diet, primarily consisting of nuts and seeds, including acorns, hickory nuts, walnuts, and beechnuts as staples.^[70]^[28] Other components include fruits (such as berries, apples, and cherries), fungi (like truffles and mushrooms), and buds. Insects, such as larvae and beetles, along with occasional bird eggs and nestlings, provide protein, though these animal matters form a minor portion overall.^[70]^[28] Foraging involves selective mast predation, where squirrels assess nut quality by weighing and tasting to avoid infested or low-nutrient items, and scatter-hoarding as the primary caching strategy. Individuals bury thousands of food items annually in numerous shallow sites, often one nut per cache, to minimize pilferage risks from conspecifics or other animals; a portion of these caches are recovered by the squirrels, with the remainder benefiting forest regeneration through forgotten caches that sprout.^[71] In urban environments, gray squirrels supplement natural foraging by scavenging human food waste from trash bins, favoring starchy items like bread and fries (76% of observed retrievals), especially during periods of natural scarcity.^[72] Nutritionally, the diet emphasizes high-fat mast to build fat reserves for winter, supporting extended activity in cold conditions, while the diverse intake minimizes vitamin deficiencies. Gut adaptations, including an enlarged cecum and large intestine, enable microbial fermentation of cellulose from fibrous plant material, enhancing digestibility of tough foods like bark and fungi.^[73] Seasonal shifts occur in response to availability: spring foraging increases reliance on fungi and fresh buds, summer incorporates more fruits and insects, fall focuses on mast collection for caching, and winter may involve bark-stripping on trees like maples when cached stores deplete.^[28]^[5]

Predation and predators

The eastern gray squirrel (Sciurus carolinensis) faces predation from a variety of raptors and mammals in its native range across eastern North America. Primary avian predators include red-tailed hawks (Buteo jamaicensis), barred owls (Strix varia), and other hawks and owls, which often target squirrels during foraging or fleeing on the ground.^[74]^[75] Terrestrial mammalian predators consist of foxes (Vulpes vulpes), coyotes (Canis latrans), bobcats (Lynx rufus), and weasels (Mustela nivalis), which ambush squirrels at ground level or near den sites.^[74]^[76] Raccoons (Procyon lotor) pose a significant threat to nests and litters, frequently raiding dreys or tree cavities to consume eggs, neonates, or juveniles, contributing substantially to early-life losses.^[74]^[77] Predation exerts a heavy toll on juvenile gray squirrels, with annual mortality rates averaging 75% in the first year, much of which stems from predator attacks due to the young's inexperience and smaller size.^[78] Adults experience lower vulnerability, with annual mortality around 50%, largely attributed to their agility in evading pursuits through rapid tree climbing and aerial maneuvers.^[78] Nest predation by raccoons and other mammals can result in up to half of a litter being lost in heavily impacted areas, exacerbating recruitment challenges.^[74] To counter these threats, gray squirrels employ several anti-predator defenses, including vocal alarm calls—such as chirps for aerial predators and chucks or quaa calls for terrestrial ones—that alert conspecifics and may reference communication systems briefly observed in social contexts.^[79]^[80] Mobbing behaviors, where multiple squirrels approach and harass a detected predator with calls and tail flicks, help deter attacks and confuse hunters.^[79] Physical escapes involve swift ascents into tree canopies, leveraging their agility to outmaneuver pursuers; cryptic gray coloration aids concealment in leaf litter and bark during ground foraging.^[74] In urban or introduced settings with higher squirrel densities, group vigilance enhances early detection, allowing collective responses to threats.^[12] Introductions of gray squirrels beyond their native range, such as in Europe, have led to altered predation dynamics, with higher survival rates in invaded areas due to fewer specialized predators compared to the diverse raptor and mammal assemblages in North America.^[12]^[81] In native habitats, intense predation pressure maintains population balances, whereas reduced predation in non-native regions contributes to elevated densities and range expansion.^[82]

Role in ecosystems

The eastern gray squirrel (Sciurus carolinensis) serves as a primary disperser of mast seeds from oak (Quercus spp.) and hickory (Carya spp.) trees in its native North American range through scatter-hoarding behavior, where individuals bury nuts individually in shallow soil caches across territories.^[83] This caching promotes forest regeneration by protecting seeds from desiccation and predation, with many caches forgotten and left to germinate, facilitating the establishment of new trees.^[84] Effective dispersal distances typically range from 10 to 100 meters, allowing seeds to colonize gaps in mature deciduous forests and contribute to canopy renewal.^[85] As an omnivore occupying a mid-trophic level, the gray squirrel links primary producers to higher carnivores by consuming plant matter, fungi, and invertebrates, thereby regulating insect populations through predation on larvae and adults.^[32] It also forms a key prey base for mid-level predators such as red foxes (Vulpes vulpes), coyotes (Canis latrans), and various raptors, supporting trophic stability in woodland ecosystems.^[19] In native habitats, gray squirrels enhance plant biodiversity by dispersing seeds to microsites that favor germination and by inadvertently promoting understory diversity through cache site selection in shaded or disturbed areas. They contribute to fungal mutualisms by consuming hypogeous truffles and dispersing ectomycorrhizal spores via scat, aiding the symbiotic associations between fungi and tree roots that improve nutrient uptake and forest health.^[86] However, population booms in high-mast years can increase foraging pressure on understory vegetation, potentially altering herbaceous composition through root disturbance and selective browsing.^[87] Recent 2020s research highlights how gray squirrel caching behaviors support climate-resilient forests by enabling seed dispersal of mast species into novel habitats, facilitating tree range shifts in response to warming temperatures and altered precipitation patterns.^[85] These dynamics underscore the species' role in maintaining adaptive forest structures amid environmental change.^[84]

Health and diseases

Common diseases

Gray squirrels (Sciurus carolinensis) are affected by several viral diseases, including squirrel fibroma, which is caused by a poxvirus in the genus Leporipoxvirus and results in the formation of benign skin tumors known as fibromas. These tumors typically appear as raised, wart-like growths on the head, legs, or body and are transmitted primarily through the bites of insects such as mosquitoes or fleas that act as mechanical vectors.^[88] Another viral illness, rabies, occurs rarely in gray squirrels, with only nine confirmed cases reported in the United States from 1995 to 2010 despite extensive testing of over 21,000 squirrels; however, cases have been documented sporadically in urban settings where squirrels may encounter infected wildlife more readily. Transmission of rabies requires direct contact with infected saliva, usually via bites, and affected squirrels exhibit neurological symptoms like aggression or disorientation.^[89] Bacterial infections represent another category of common diseases in gray squirrels. Tularemia, caused by the bacterium Francisella tularensis, has been identified in both eastern and western gray squirrels, with fifteen cases confirmed in a study of necropsied animals, some showing classic lesions while others were subclinical. Squirrels typically acquire the infection through ingestion of contaminated water, soil, or infected tissues from other animals, leading to symptoms such as lethargy, fever, swollen lymph nodes, and abscess formation in organs like the liver or spleen.^[90] Leptospirosis, resulting from Leptospira species bacteria, is similarly transmitted via contact with urine-contaminated water or environmental sources, with gray squirrels serving as potential reservoirs; clinical signs in infected squirrels include lethargy, jaundice, renal failure, and abscesses, often mirroring the disease's effects in other mammals.^[91] Mange outbreaks, driven by the mite Sarcoptes scabiei, are prevalent in dense gray squirrel populations, particularly in urban or fragmented habitats, where close contact facilitates rapid spread and can result in mortality due to intense itching, hair loss, thickened skin, and secondary bacterial infections leading to debilitation.^[92] Calcium deficiency also contributes to metabolic bone disease in gray squirrels, manifesting as weakened bones, fractures, and impaired mobility from diets low in calcium relative to phosphorus, such as those dominated by seeds and nuts; this nutritional imbalance has been linked to reduced bone mineral density in wild populations and may drive behaviors like bark stripping to access calcium-rich phloem.^[93] These diseases carry zoonotic risks, with tularemia, leptospirosis, and rabies potentially transmissible to humans and pets through bites or contact with infected tissues or fluids, underscoring the need for vigilant monitoring in introduced ranges like Europe where gray squirrels interact more frequently with human environments.^[94]

Parasites and pathogens

Gray squirrels (Sciurus carolinensis) are host to a variety of ectoparasites, including fleas such as Orchopeas howardi, ticks from the genus Ixodes (notably Ixodes scapularis), and sucking lice. These parasites are commonly found on squirrels in both natural and suburban environments, with ticks being the most prevalent, followed by lice and fleas. In a study of eastern gray squirrels in southeastern Georgia, O. howardi fleas showed higher prevalence in woodland compared to urban parkland settings.^[95] In suburban Pennsylvania habitats, I. scapularis ticks were the dominant ectoparasite, often infesting the head and ears.^[96] Endoparasites of gray squirrels include nematodes such as Strongyloides robustus and protozoans like Trypanosoma cruzi, alongside external myiasis caused by warble fly larvae (Cuterebra emasculator). S. robustus is a common gut nematode with prevalence up to 56.6% in invasive populations, while T. cruzi infects approximately 5.3% of eastern gray squirrels in southeastern U.S. regions, serving as a reservoir for Chagas disease. Warble flies induce myiasis through larval infestation under the skin, affecting about 19% of gray squirrels during late summer to fall, with an average of 1.9 larvae per infested host.^[97]^[98]^[99] Ticks like Ixodes spp. transmit the pathogen Borrelia burgdorferi, the causative agent of Lyme disease, to gray squirrels, which act as reservoir hosts; in one suburban study in Pennsylvania, 58.7% of squirrels tested positive for B. burgdorferi antibodies.^[100] Parasite loads, particularly ectoparasites and gastrointestinal helminths, tend to be higher in urban squirrels due to increased population densities facilitating transmission. These infestations can impact squirrel fitness by reducing survival rates and body condition, though specific control measures like anthelmintics face challenges from emerging resistance.^[101]

Human interactions

Invasive status and impacts

The eastern gray squirrel (Sciurus carolinensis) is classified as an invasive alien species of Union concern under EU Regulation 1143/2014, which has been in effect since 2016 and mandates measures to prevent its spread, including prohibitions on imports and keeping within the European Union.^[102] In the United Kingdom, following the regulation's transposition, imports and releases of gray squirrels are illegal, with enforcement actions ongoing to limit their establishment.^[103] The species is also profiled in the IUCN Global Invasive Species Database as one of the world's 100 worst invasive aliens due to its high environmental impacts, including habitat alteration and biodiversity threats in introduced ranges.^[8] Environmentally, gray squirrels cause significant damage through bark-stripping, particularly on broadleaf trees like sycamore (Acer pseudoplatanus), beech (Fagus sylvatica), and oak (Quercus spp.), which exposes cambium layers to pathogens and insects, leading to tree decline and mortality rates of up to 24% in affected sycamore stands.^[104] In non-native European forests, this behavior reduces woodland regeneration and alters ecosystem structure by favoring stressed or dying trees, while their foraging depletes food resources such as nuts and seeds, exacerbating pressures on native flora and indirectly on other wildlife.^[8] Such impacts are most pronounced in the UK and Italy, where introduced populations have expanded into deciduous and mixed woodlands. Economically, gray squirrel damage to forestry in the UK is estimated at £37 million annually in England and Wales as of 2025, including lost timber value from bark-stripping and reduced growth, with control costs contributing significantly.^[105] In Italy, historical agricultural losses from gray squirrels girdling poplar (Populus spp.) and damaging maize seedlings have reached up to €70,000 yearly for replanting, while broader eradication efforts have incurred costs exceeding €900,000 in targeted campaigns; combined European costs have risen beyond previous €10-20 million estimates as of 2017.^[106] Urban populations contribute to nuisance issues, with property damage from garden raiding and structural gnawing totaling £1.9 million annually in the UK alone.^[106] Management strategies primarily rely on trapping and culling to reduce populations and limit damage, with programs emphasizing early-spring interventions using baited live traps followed by humane dispatch, as implemented in UK woodland protection schemes.^[107] In 2025, research advances include fertility control trials using oral contraceptives delivered via bait, showing promising results in bait uptake and development toward non-lethal population management, marking a shift toward non-lethal genetic approaches.^[108] These efforts aim to complement traditional culling while addressing ethical and ecological concerns in invasive control.

Displacement of native species

The eastern gray squirrel (Sciurus carolinensis) has significantly displaced native Eurasian red squirrels (Sciurus vulgaris) in the United Kingdom through a combination of resource competition and disease transmission. Gray squirrels outcompete reds for food resources, particularly acorns and other hard mast, due to their higher digestive efficiency—reds achieve only about 59% efficiency on acorns compared to grays—and ability to consume unripe nuts. ^[109] ^[110] This exploitation competition reduces food availability for reds, especially in broadleaf woodlands. Additionally, grays exhibit interference competition by dominating feeding sites and occasionally displaying aggression toward reds, disrupting their foraging and leading to lower red population recruitment and breeding success. ^[111] ^[112] Grays also transmit squirrelpox virus (SQPV), a disease to which they are largely resistant but which is often fatal to reds, accelerating displacement. ^[113] Since the introduction of grays in the late 19th century, the UK red squirrel population has declined from an estimated 3.5 million to around 287,000 individuals as of 2025, representing over 95% loss, with reds now restricted primarily to Scotland and isolated refugia in England and Wales. ^[114] In Italy, a small gray squirrel population was successfully eradicated in Turin Province in 2025. Grays reproduce more rapidly, typically producing two litters per year with 3–7 young each, compared to reds' one or occasionally two litters of 3–5 young, allowing grays to maintain higher population densities and further pressure red populations. ^[110] ^[112] Recent models predict potential extinction of red squirrels in remaining English strongholds by the mid-21st century without intensified control, though 2025 studies indicate resilience to climate change. ^[115] ^[116] Beyond red squirrels, grays impact other native wildlife, including birds and small mammals. They occasionally raid nests of woodland songbirds, but recent studies indicate grey squirrels play a minimal role in nest predation, with failure rates and population impacts debated; older data suggested up to 27% in some tit species (Parus spp.) and 85% for open-nesting birds in high-density areas. ^[117] ^[118] ^[119] This predation may reduce breeding success for species like great tits (Parus major) and blue tits (Cyanistes caeruleus), though population-level effects remain debated. ^[118] Grays also compete with small mammals for food and habitat, potentially limiting resources for species like dormice (Muscardinus avellanarius) through cache theft and generalist foraging. ^[120] Similar displacement occurs in introduced ranges on mainland Europe, such as Italy, where grays have caused local red squirrel extinctions in 62% of surveyed sites in Piedmont since the 1970s, with complete loss across over 1,150 km². ^[121] ^[122]

Cultural and economic uses

Gray squirrels have been utilized as a food source in various regions, particularly in the traditional cuisine of the U.S. South, where they feature prominently in dishes like Brunswick stew, a stew originating from early 19th-century recipes that combines squirrel meat with vegetables and other game.^[123]^[124] The meat is valued for its nutritional profile, being low in fat at approximately 2.7 grams per 100 grams and high in protein at 18.1 grams per 100 grams, making it a lean alternative to many domesticated meats.^[125] In the United States, gray squirrels are actively hunted for this purpose across states, contributing to regional economies through harvest and related activities.^[19] Historically, gray squirrel pelts have been used for clothing, with squirrel fur trimming considered fashionable in early 19th-century America, as noted in accounts of widespread squirrel migrations that supplied pelts for apparel.^[126] The soft, short fur, often gray-blue in color, was incorporated into garments like coats and linings, a practice with roots in European traditions that extended to North American settlers.^[127] Participation in the pet trade is limited due to the species' status as a wild animal and regulatory restrictions on keeping native wildlife; in most U.S. states, owning a gray squirrel as a pet requires special permits, and it is outright illegal in several without federal USDA approval, reflecting concerns over invasiveness and welfare.^[128]^[129] In Native American folklore, gray squirrels often appear as clever trickster figures, characterized by their noisy, aggressive behavior that spreads gossip and instigates trouble among other animals in traditional stories.^[130] Contemporary perceptions vary, with gray squirrels viewed as beloved park wildlife and subjects of nature observation by enthusiasts, yet also as pests causing property damage in urban and rural settings.^[131] Hunting regulations for gray squirrels differ by state, typically allowing seasons from late summer to winter with daily bag limits of four to eight animals; for example, in Indiana, the season runs from August 15, 2025, to January 31, 2026, with a daily limit of five.^[132] Economically, gray squirrels contribute to ecotourism in their native ranges, ranking as the second-most observed mammal after birds for wildlife watchers, enhancing visitor experiences in parks and forests.^[19] In invaded areas like the United Kingdom, control efforts including culling impose significant costs, estimated at a midpoint of £14 million annually for managing populations and mitigating damage to woodlands.^[133]

References

[1]
Eastern Gray Squirrel - Maryland DNR
Diet: The diet of gray squirrels typically includes an assortment of seeds, nuts and berries such as acorns, hickory nuts, walnuts, beechnuts, pine seeds, maple ...
[2]
Gray Squirrel - SUNY ESF
Gray squirrels feed extensively on fungi, berries, and fruits during the summer, especially the fruit of the black cherry. In the south, this species requires ...
[3]
Eastern Gray Squirrel (Sciurus carolinensis) - NYC.gov
Eastern gray squirrels are tree-dwelling animals, 9-12 inches long, with varied fur colors, that live in tree cavities or dreys, and can run up to 15 mph.Missing: diet | Show results with:diet
[4]
DNR: Fish & Wildlife: Gray Squirrel - IN.gov
Gray squirrels may eat green field corn; but, their principal diet is made up of hard mast, wild berries, and fruits. Gray squirrels do occasionally eat fungi, ...
[5]
Tree Squirrels - Penn State Extension
Jan 1, 1997 · The diet of the gray squirrel dictates its habitat. Gray squirrels can be found in any area that supplies sufficient amounts of nuts and seeds ...<|control11|><|separator|>
[6]
Grey Squirrel (Sciurus carolinensis) - Woodland Trust
The introduction of grey squirrels has had a disastrous impact on the UK's only native squirrel species, the red squirrel. Greys compete with reds for food ...
[7]
https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/animals/mammals/grey-squirrel/
[8]
Sciurus carolinensis - NCBI
THE NCBI Taxonomy database allows browsing of the taxonomy tree, which contains a classification of organisms.
[9]
Phylogeny and Zoogeography of Six Squirrel Species of the Genus ...
From the transversional substitutions at the third codon, the divergence time among the New World Sciurus was estimated to be approximately 9.8–14.4 Myr ago.
[10]
Sciurus carolinensis (grey squirrel) | CABI Compendium
Oct 16, 2025 · Sciurus carolinensis carolinensis Gmelin, 1788; occurs in most of south-eastern USA, from SE Kansas and Missouri east to S Ohio and S Virginia, ...
[11]
Sciurus carolinensis (Eastern Gray Squirrel) - BioLib.cz
subspecies Sciurus carolinensis carolinensis Gmelin, 1788. subspecies Sciurus carolinensis extimus Bangs, 1896. subspecies Sciurus carolinensis fuliginosus ...
[12]
A genetic analysis of grey squirrel (Sciurus carolinensis) populations ...
Apr 10, 2022 · This study analysed the genetic profile of grey squirrel populations in Ireland to gain insight into their introduction, evolutionary history in Ireland,Missing: post- | Show results with:post-
[13]
A New Voyage to Carolina, by John Lawson - Project Gutenberg
Flying-Squirrel. This Squirrel is gray, as well as the others. He is the least of the Three. His Food is much the same with the small gray Squirrels. He has ...
[14]
Eastern Gray Squirrel - Discover Lewis & Clark
The generic name Scuirus is from the Greek skuiros, meaning “shade tail,” in ... Obviously, the common name is an Anglicized version of the Greek name.
[15]
North American gray squirrel | rodent | Britannica
squirrel, (family Sciuridae), generally, any of the 50 genera and 268 species of rodents whose common name is derived from the Greek skiouros, meaning “shade ...
[16]
A species account of the Eastern gray squirrel (Sciurus carolinensis)
DISTRIBUTION. Native distribution includes eastern one-third of state. Introduced at locations to the west of its native range. For example, a thriving ...
[17]
Sciurus carolinensis (eastern gray squirrel) - Animal Diversity Web
Geographic Range. Sciurus carolinensis ranges over the eastern United States to just west of the Mississippi River and north to Canada.
[18]
Sciurus carolinensis - GISD
Oct 17, 2005 · The grey squirrel (Sciurus carolinensis) is native to deciduous forests in the USA and has been introduced to the UK, Ireland, Italy and South Africa.
[19]
Squirrel Fur Colour & Characteristics - Wildlife Online
Colour and appearance of both species may change in accordance with moults. Both Reds and Greys moult biannually -- once in the spring (March to July) and again ...
[20]
Multiple origins of melanism in two species of North American tree ...
11 jul 2019 · Melanism (uniform dark brown or black colouration over the whole body) occurs at low frequency (less than 1%) across most of the range of both ...
[21]
Squirrels - Mass Audubon
They can jump six feet straight up and can launch themselves 10 feet or more from a tree, building, or railing to reach a bird feeder. How to Identify a ...
[22]
Gray Squirrel Management - Alabama Cooperative Extension System -
Oct 20, 2020 · Gray squirrels usually produce two litters of young per year. Breeding peaks in January and June, and gestation normally lasts about 44 days.Life History · Breeding Biology · Gray Squirrel ManagementMissing: infancy | Show results with:infancy
[23]
Gray Squirrel - CT.gov
After a 44-day gestation period, females give birth to a litter of two to seven young. They are blind and helpless at birth but are weaned and somewhat ...Missing: infancy development
[24]
[PDF] found a baby squirrel
They commonly have litters of three or four pups. Babies' eyes open at four weeks. Babies may begin exploring outside the nest by six weeks and are weaned by ...
[25]
[PDF] Gray Squirrel Biology & Management
At birth, the squirrel's eyes and ears are closed and no teeth have erupted through the gums. After 3 weeks, the ears of the young squirrel open, followed by ...Missing: infancy | Show results with:infancy
[26]
Eastern Gray Squirrel - SCDNR - Species
Sexual maturity and litter production generally occur between 10 months to 1 year of age. ... Eastern gray squirrel (Sciurus carolinensis). Section 4.7.1 U.S. ...
[27]
Eastern Gray Squirrel | State of Tennessee Wildlife Resources Agency
Eastern Gray Squirrel, Sciurus carolinensis. Eastern Gray Squirrel. Eastern ... The average age of sexual maturity in females is one year, 11 months for males.
[28]
[PDF] Post Oak Savannah Wildlifer
Apr 1, 2009 · The gray squirrel averages 18 inches in total length with a tail averaging about. 8 inches. Adults weigh between. 11 and 21 ounces. Cat ...<|control11|><|separator|>
[29]
[PDF] age estimation in yellow-bellied marmots - CHAPTER I
Dubock identified four stages of radial-ulnar epiphyseal fusion and the ages at which they occur in the gray squirrel (Table 3). ... previous studies involved ...
[30]
Mammals - De Soto National Memorial (U.S. National Park Service)
Sep 13, 2022 · They weight between 14 to 21oz. Lifespan: In the wild their life expectancy is 1 to 2 years, but they can live to between 6 to 12 years old.
[31]
Gray Squirrel | Sciurus carolinensis - Adirondack Nature
Nov 18, 2020 · There are 5 recognized subspecies. Ours is Sciurus carolinensis pennsylvanicus. Other nonscientific names include Eastern Gray Squirrel, Cat ...
[32]
Eastern Gray Squirrel | NC State Extension Publications
It lives in a variety of forest types but favors areas with mature hardwood trees. Mast-bearing hardwood trees are the most important element of squirrel ...
[33]
[PDF] THE GRAY SQUIRREL-PAST, PRESENT AND FUTURE
Gray squirrel numbers decreased, with habitat destruction and chestnut blight contributing to the decline. Some feared extinction in the early 20th century.
[34]
[PDF] The Urbanization of the Eastern Gray Squirrel in the United States
eth century hinders estimates of the size of historical squirrel populations, which can fluctuate dramatically from year to year depending on food supplies ...
[35]
[PDF] Environmental Factors' Effects on Eastern Gray Squirrel (Sciurus ...
Apr 23, 2020 · The results show two birth peaks for Eastern gray squirrels, with over 60% of annual infants admitted during August and September. There were ...Missing: development | Show results with:development
[36]
None
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[37]
[PDF] BALMNH_No_28_2011.pdf - The University of Alabama
Linnaeus, 1758 - Tree squirrels. Sciurus carolinensis Gmelin, 1788 - Eastern gray squir- rel - First Pleistocene Occurrence. Sciurus niger Linnaeus, 1758 -.
[38]
General lack of phylogeographic structure in two sympatric, forest ...
... last glacial maximum. For S. niger, the genetic structure was much less pronounced, with fewer strongly diverged haplotypes. This finding suggests that ...
[39]
Don't blame grey squirrels: their British invasion had much more to ...
Jan 26, 2016 · Grey squirrels were imported to the UK from the 1890s onwards, and the traditional view is that they spread rapidly across the UK due to their ...
[40]
Controlling the grey squirrel population
Fact: Genetic research has determined that all the grey squirrels in Ireland are related back the original 12 animals brought to the island in 1911. This ...
[41]
Impacts of Rhodes on Biodiversity 1 : Eastern Grey Squirrel - BDI
Aug 22, 2020 · Cecil John Rhodes introducted the Eastern Grey Squirrel to his estate in Cape Town about 1900. This is the story of how this invasive ...
[42]
Grey Squirrel (Sciurus carolinensis) - Columbia University
Mar 2, 2002 · Threat(s): In Europe, Sciurus carolinensis is considered extremely destructive to native trees and the only native squirrel species, Sciurus ...
[43]
The Grey Squirrel Sciurus carolinensis in Adelaide, South Australia
Aug 6, 2025 · The Squirrels, restricted to urban plantings of northern hemisphere trees, were subsequently eradicated and were last recorded in 1922. It is ...
[44]
Predicting the spread of the American grey squirrel (Sciurus ...
In the worst case scenario, the spread will be significantly faster: the species is predicted to reach France in 2026–2031 and Switzerland in 2031–2041.
[45]
Future Range Dynamics Suggest Increasing Threats of Grey ... - MDPI
Jun 2, 2023 · In summary, climate change may induce changes in the ranges of grey squirrels and red squirrels, resulting in shifts in the range overlaps ...Missing: temperate zones deforestation reforestation
[46]
Mostly false: “Squirrels are on the verge of extinction” - eufactcheck.eu
Jul 21, 2025 · The claimed threat for red squirrels could be a future one, as grey squirrels are likely to expand all over Europe in the foreseeable future, ...Missing: gray | Show results with:gray
[47]
a new threat for endemic red squirrel subspecies | Biological Invasions
Mar 25, 2014 · In Italy, grey squirrels were first introduced in 1948 in Turin, a population that is now spreading steadily and leading to red squirrel local ...
[48]
Reproductive behavior of the grey squirrel
A study was made of the reproductive behavior of the grey squirrel (Sciurus carolinensis). The winter mating period was from 25 January to 13 February; ...
[49]
Reproductive Traits of an Invasive Alien Population of Grey Squirrel ...
Apr 24, 2020 · Reproductive traits of an invasive alien population of grey squirrel (Sciurus carolinensis) in Central Italy.
[50]
Eastern Gray Squirrel | Ohio Department of Natural Resources
Habitat & Behavior. Gray squirrels prefer large expanses of wooded areas of hardwood trees. Timber management practices that create stands of middle-aged and ...Missing: diet | Show results with:diet
[51]
Eastern Gray Squirrel - UF/IFAS Extension Sumter County - Blogs
Sep 21, 2020 · Sciurus carolinensis. Identification: The eastern gray squirrel ranges in size between 17 to 20 inches long and weighs about 1 to 1.5 lbs.
[52]
Density‐dependent plasticity in territoriality revealed using social ...
Nov 17, 2022 · Squirrel density is closely linked to white spruce masting events, such that in mast years, density is typically low but recruitment (i.e. ...
[53]
Gray squirrel alarm call composition differs in response to simulated ...
Eastern gray squirrels use three acoustically distinct vocalizations, namely kuks, quaas and moans, in their alarm calling bouts. Although moans are highly ...
[54]
Joint tail and vocal alarm signals of gray squirrels (Sciurus ... - jstor
Apr 2, 2014 · Individuals responded with tail signals (twitches and flags) and vocalizations (kuks, quaas and moans), but only flags and moans are associated ...
[55]
Squirrel Behaviour - Dominance, Aggression & Territoriality
Typically, the larger and older the squirrel, the more dominant it is likely to be and, frequently, the larger its home range. Grey squirrels (Sciurus ...
[56]
The Sociable Gray Squirrel | The Outside Story
Feb 11, 2019 · Gray squirrels are not territorial; they do not exclude others from their home ranges, though nursing females will defend den trees.
[57]
Natal Philopatry, Communal Nesting, and Kinship in Fox Squirrels ...
Aug 6, 2025 · Grey squirrels (Sciurus carolinensis) display a hierarchical social system, with males usually dominant over females, and adults over subadults ...Missing: territoriality | Show results with:territoriality<|control11|><|separator|>
[58]
Multimodal alarm behavior in urban and rural gray squirrels studied ...
We found that the squirrels were more active in the urban habitats and that they responded more to tail flagging in the urban habitats as compared to the rural ...
[59]
Diurnal and seasonal activity of the grey squirrel (Sciurus carolinensis)
The diurnal and seasonal activity of the grey squirrel is quantified. A single midday peak occurs in the winter. This peak is displaced into morning and ...
[60]
Sciurus carolinensis Gmelin, 1788 - GBIF
Sciurus carolinensis possesses a cosmopolitan distribution in Louisiana, being absent from only the southernmost parishes. Since Lowery (1974), a nonvouchered ...Missing: geographic | Show results with:geographic
[61]
https://academic.oup.com/cz/article/56/3/313/5559822
[62]
[PDF] Life history account for Eastern Gray Squirrel
Populations of eastern gray squirrels are found in orchard-vineyard, urban, and possibly valley foothill riparian habitats. SPECIFIC HABITAT REQUIREMENTS.
[63]
Food habits and caching behavior of urban grey squirrels
Food-caching and recovery behaviors show a strong seasonality. Food caching starts with the maturation of husked nuts and terminates with the onset of winter.
[64]
Eastern Gray Squirrel - Wildlife in Winter
Dec 5, 2020 · Gray squirrels do not hibernate and are active all winter except during extreme weather when they remain in a drey or den.Missing: hypothermia | Show results with:hypothermia
[65]
(PDF) Seasonal comparisons of daily activity budgets of gray ...
Aug 7, 2025 · Gray squirrels (Sciurus carolinensis) use trees for various resource needs in urban and nonurban settings; particularly, mast producing ...Missing: traveling | Show results with:traveling
[66]
Do Squirrels Hibernate During Winter | USX Pest Control
Jan 20, 2025 · However, with torpor, the changes last for a few hours, possibly up to 24 hours. After that time, the animal wakes and forages for food.Missing: variations | Show results with:variations<|separator|>
[67]
Eastern Gray Squirrel | NC State Extension Publications
Oct 28, 2019 · In summer they also eat fruits and fungi as well as bird nestlings and insects. ... Urban yards with bird feeders are prime habitat for gray ...
[68]
Effects of competition and food availability on travel time in scatter ...
Audience effects on food caching by grey squirrels (Sciurus carolinensis): evidence for pilferage avoidance strategies. ,. Anim Cogn. ,. 2007. , vol. 10. (pg.Missing: diet | Show results with:diet
[69]
Gray squirrels consume anthropogenic food waste most often during ...
Nov 4, 2022 · The eastern gray squirrel (S. carolinensis) is a medium sized (300–710 g) tree squirrel native throughout eastern North America (Koprowski 1994) ...
[70]
Squirrel Food & Feeding - Diet Composition | Wildlife Online
The result was that these animals developed longer intestines, with particular expansion of the large intestine and cecum. A Grey squirrel (Sciurus carolinensis) ...
[71]
Eastern Gray Squirrel - National Park Service
Feb 8, 2021 · Like many small animals they have several predators. Predatory birds, foxes, coyotes, bobcats, mountain lions, raccoons, domestic cats, and ...
[72]
[PDF] Eastern Gray Squirrel - NC Wildlife
Birds of prey (i.e., red-tailed hawks, barred owls, etc.) are important predators of gray squirrels, as are bobcats, coyotes, foxes, and black rat snakes.Missing: behavior | Show results with:behavior
[73]
Gray Squirrel - Kansas Mammal Atlas - Fort Hays State University
Adults may jump as far as 2.5 meters between trees. Gray squirrels are frequently observed crossing roads or small creeks through the tree canopy.
[74]
[PDF] Northern Raccoon predation on European Starling nestlings in ...
eggs by Eastern Gray Squirrel (Sciurus carolinensis),. Red Squirrel ... Raccoon predation on Ancient Murrelets on. East Limestone Island, British ...
[75]
Gray Squirrel | Vermont Fish & Wildlife Department
A gray squirrel density of one per acre is a reasonable goal in good habitat, with two five per acre possible in the very best habitats.Missing: hectare optimal
[76]
[PDF] Does Gray Squirrel (Sciurus carolinensis) Response to ...
We presented alarm calls to free-ranging eastern gray squirrels (Sciurus carolinensis) and recorded behavioral changes in vigilance and antipredatory response.
[77]
[PDF] A Review of Squirrel Alarm-Calling Behavior: What We Know and ...
The Asian Callosciurus seem to have the most predator-specific alarm vocalizations observed in an arboreal squirrel based on data available to date, but ...
[78]
[PDF] Interactions between native and invasive species - AIR Unimi
Mar 31, 2023 · of pine marten predation on red and grey squirrels. Mamm. Bio. 100 ... squirrel populations may persist in refugia as native predator recovery ...
[79]
Queen's research highlights significance of native predators to ...
Feb 26, 2020 · The research reveals how a native predator, the pine marten, is helping to conserve the UK and Ireland's only native squirrel, ...Missing: gray | Show results with:gray
[80]
[PDF] Oak Dispersal Syndromes: Red vs White Oaks
Detecting the effects of seed hoarders on the distribution of seedlings of tree species: gray squirrels (Sciurus carolinensis) and oaks (Quercus spp.) as a ...
[81]
Squirrel-Seed Interactions: The Evolutionary Strategies and Impact ...
Aug 3, 2020 · However, the frequency of embryo removal is much higher in the WOs and was significantly more evident in higher mast years (Xiao et al., 2010).
[82]
Over the limit: Consequences of gray squirrel personality on the ...
Species are shifting ranges to track suitable conditions in response to climate change (Parmesan and Yohe, 2003), with 59 % of over 26,000 recorded range shifts ...Missing: zones deforestation reforestation
[83]
Redundancy among mammalian fungal dispersers and the ...
Knowing the relative importance of different mammal species as dispersers helps us to understand how this loss in mammal diversity could affect plant-fungi ...
[84]
Squirrel Damage on Trees and Shrubs
Feb 28, 2023 · Eastern gray squirrels feed on a wide variety of plants and can disturb plant roots and shallowly planted bulbs and seedlings while looking ...
[85]
Squirrel pox | | Wisconsin DNR
Squirrel pox, also called squirrel fibroma, is caused by a poxvirus called squirrel fibroma virus, which is related to other poxviruses.Missing: eastern | Show results with:eastern
[86]
Rabies in rodents and lagomorphs in the United States, 1995–2010
Squirrels were the rodent most commonly submitted for rabies testing (21,977/70,682 [31.1%]). However, only 9 (0.04%) squirrels were found to be rabid during ...
[87]
Francisella tularensis infection without lesions in gray tree squirrels ...
Feb 20, 2014 · Fifteen cases of Francisella tularensis infection (tularemia) were identified in western gray (Sciurus griseus) and eastern gray (Sciurus carolinensis) ...
[88]
Leptospirosis in Animals - CDC
Apr 4, 2025 · Just like people, animals can get leptospirosis through contact with contaminated urine or body fluids of an infected animal or contact with ...What To Know · Dogs · Symptoms In Animals
[89]
A review of sarcoptic mange in North American wildlife - ScienceDirect
This review article provides a summary of the current knowledge of mange in wildlife, with a focus on the most common clinically-affected species in North ...<|separator|>
[90]
Regulation of bone mineral density in the grey squirrel, Sciurus ...
Grey squirrels' bone mineral density was lower on a calcium oxalate diet, suggesting they may not effectively utilize it for bone maintenance.Missing: eastern | Show results with:eastern
[91]
About Tularemia - CDC
May 15, 2024 · Symptoms vary depending how the person was infected. Tularemia can be life-threatening, but most infections can be treated successfully with ...
[92]
Ectoparasites of gray squirrels in two different habitats ... - PubMed
Ectoparasites were recovered from anesthetized squirrels and compared between hosts from the 2 habitats.
[93]
Macroparasite Fauna of Alien Grey Squirrels (Sciurus carolinensis)
Feb 5, 2014 · The most common parasites are Nearctic nematodes Strongyloides robustus (prevalence: 56.6%) and Trichostrongylus calcaratus (6.5%), red squirrel ...Missing: Protospirura ascarides Trypanosoma flies myiasis
[94]
Trypanosoma cruzi infection in mammals in Florida: New insight into ...
Eastern gray squirrels are a known T. cruzi reservoir in the southeastern US, and this study is the first report of T. cruzi infected gray squirrels in Florida ...
[95]
Prevalence of Cuterebra emasculator in squirrels in Mississippi
Approximately 19% of the gray and 5% of the fox squirrels were infested with 1.9 and 2.5 larvae per host, respectively. Myiasis was seen between 14 August and ...
[96]
An Invasive Mammal (the Gray Squirrel, Sciurus carolinensis ...
This study examined the role of gray squirrels (Sciurus carolinensis) (n = 679), an invasive species in the United Kingdom, as B. burgdorferi sensu lato hosts.<|control11|><|separator|>
[97]
[PDF] Risk, Habitat Use, and Behavioural Variation in Urban Grey Squirrels.
to be associated with increased gastro-intestinal parasite load (Santicchia et al.,. 2019). ... the urban site contained higher population density of squirrels, ...
[98]
Anthelmintic resistance in soil-transmitted helminths: One-Health ...
Dec 20, 2023 · This review provides an overview of the major human and animal STHs, treatment of the STHs, AR development and drug-related factors contributing towards AR, ...Missing: 2020s | Show results with:2020s
[99]
Eradication and control of grey squirrel
It includes grey squirrel on the list of invasive alien species of Union concern, obliging Member State to eradicate these species within months of their ...Missing: gray UK IUCN
[100]
March 2019 update: Invasive non-native species and grey squirrels
Mar 1, 2019 · These actions will remain illegal under the Invasive Alien Species (Enforcement and Permitting) Order in line with the EU Regulation (1143/2014) ...Missing: IUCN | Show results with:IUCN
[101]
Squirrel Interaction with Humans - Damage to Forestry | Wildlife Online
They mention that the bark stripping “season” typically runs from late April until late July, although can continue into September – most economic damage is ...Missing: gray foraging
[102]
(PDF) Economic damage by invasive grey squirrels in Europe
May 1, 2017 · Invasive alien species (IAS) comprise a global threat to biodiversity and may also cause economic harm by damaging natural resources and ...
[103]
Management of grey squirrels - Forest Research
Grey squirrels are extremely destructive in woodlands, stripping bark from the main stem and branches of trees. Typically beech and sycamore trees are most ...
[104]
Celebrating progress & world first for grey squirrel fertility control ...
Sep 24, 2025 · Positive news for a programme aiming to find a non-lethal option for invasive grey squirrel management. The multi-year research programme being ...
[105]
On the replacement of the red squirrel in Britain - PubMed
Diffusion modelling has shown that conservative demographic traits combined with feeding competition could explain red squirrel replacement by grey ...Missing: mechanisms aggression
[106]
What Do Squirrels Eat? What to Feed Grey Squirrels | Ark Wildlife UK
Squirrels primarily eat plant-based foods, but there are instances where squirrels may show opportunistic behaviour by eating small birds or their eggs, ...<|separator|>
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The Mechanism of Replacement of Red Squirrels by Grey Squirrels
Aug 6, 2025 · We restated the commonly cited Interference Competition Hypothesis (ICH) that grey squirrels interfere with the behaviour of red squirrels in three possible ...
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Alien species and interspecific competition: effects of introduced ...
Jan 6, 2004 · The presence of grey squirrels resulted in a reduction in red squirrel fitness which was evident by lower population summer breeding and a lower recruitment.Missing: divergence | Show results with:divergence
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Disease threats posed by alien species: the role of a poxvirus in the ...
Red squirrels are declining in the United Kingdom. Competition from, and squirrel poxvirus (SQPV) disease carried by, grey squirrels are assumed to be ...
[110]
Red Squirrel Facts: Why Are They Endangered & More
Nov 1, 2018 · Since then, the UK population of reds has dropped from around 3.5 million to between 120,000 to 160,000 individuals (according to different ...
[111]
Squirrels Interaction with Other Species - Native Bird Decline
The researchers found that as many as 27% of total nest failures of tit species (Parus) in Nottingham were attributable to Grey squirrels.
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[PDF] Impacts of Grey Squirrels on Woodland Birds: An Important Predator ...
Nor have we found any published North American study that clearly demonstrates that the Grey Squirrel has had a significant impact on nesting success of a bird ...
[113]
Squirrels in the UK: what they are up to, when and why
Red squirrel numbers have dramatically declined since the introduction of grey squirrels and are now considered endangered in the UK. Their strongholds are in ...
[114]
Interactions between native and invasive species: A systematic ...
We present a systematic review of the literature on competition and interactions between red and gray squirrels.
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Red squirrel populations wiped out in northern Italy - The Guardian
Sep 27, 2012 · Scientists say there are no red squirrels in a 1150 sq km area of Piedmont after invasive greys took hold in the region.Missing: loss | Show results with:loss
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(PDF) Modelling the impact of forest design plans on an endangered ...
Aug 6, 2025 · The Eurasian red squirrel is under threat in the UK from the introduced North American grey squirrel. National measures to save the species ...
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Traditional Brunswick Stew (Appalachian Squirrel Stew)
Rating 4.3 (28) · 1 hr 10 minJan 23, 2025 · Traditional Brunswick stew is made with small game, namely squirrel or opossum. Since they don't generally sell squirrel meat at the grocery store, these days ...
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Squirrel is back on the menu - Fine Dining Lovers
Oct 14, 2020 · The meat of the squirrel was a major source of protein for settlers on the frontier of North America, exemplified by the Brunswick stew, a ...
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Squirrel Nutritional Information - Wild Harvest Table
Calories: 102. Protein (g), 18.1. Fat (g), 2.7. Total saturated fat (g), 0.3. Total Mono-unsaturated fat (g), 1. Total Poly-unsaturated fat (g), 0.79.
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Squirrel Invasion - Southeast Ohio History Center
Jan 19, 2023 · Some local histories report the population exploded in Kentucky and thousands of squirrels swam across the Ohio River to attack the cornfields ...
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Squirrel - Vintage Fashion Guild
Squirrel fur is soft, fluffy, and short, naturally dark gray blue or red, often dyed pale brown. It was used in 14th century Europe, and was relatively ...
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Pet Squirrel Legal States 2025 - World Population Review
| It is illegal to sell or trade squirrels in Ohio without a state permit, and federally illegal to sell or trade squirrels without a USDA permit as well.
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When Squirrels Were One of America's Most Popular Pets
Apr 28, 2017 · While many people captured their pet squirrels from the wild in the 1800s, squirrels were also sold in pet shops, a then-burgeoning industry ...
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Native American Squirrel Mythology
In Native American folktales, squirrels are most noted for their noisy and aggressive behavior. Squirrel characters frequently spread gossip, instigate trouble ...
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Gray Squirrel - NC Wildlife
Gray squirrels are diurnal and active year-round. They typically have grayish-brown fur and a whitish belly with a conspicuously bushy tail; however, some ...
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DNR: Fish & Wildlife: Squirrel Hunting - IN.gov
Fox and gray squirrels are regulated species in Indiana and can be hunted from Aug. 15, 2025 – Jan. 31, 2026. The daily bag limit is five. The possession limit ...Missing: Native folklore trickster cultural significance modern pest park
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[PDF] The cosT of grey squirrel damage To woodland in england and wales
Grey squirrel damage to trees in England and Wales is estimated to cost £37m a year in lost timber value, reduced carbon capture, damage mitigation and trees ...Missing: Italy | Show results with:Italy