Sciurus carolinensis ranges over the eastern United States to just west of the Mississippi River and north to Canada. Introductions have occurred in the western states and some of Canada that was not previously inhabited, as well as in Italy, Scotland, England and Ireland.

Biogeographic Regions: nearctic (Introduced , Native ); palearctic (Introduced )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Eastern U.S. and adjacent southern Canada; southern Quebec to Manitoba, south to eastern Texas and Florida. Range has been extended through introductions into Quebec, Ontario, New Brunswick, Manitoba, Saskatchewan, British Columbia, Nova Scotia, California, Oregon, Washington, and Montana (Teaford 1986, Koprowski 1994). Introduced also in the British Isles, Italy, South Africa, and Australia (extirpated by 1973) (see Koprowski 1994).

Sciurus carolinensis is a medium sized tree squirrel with no sexual dimorphism in size or coloration. The dorsal surface ranges from grizzled dark to pale grey and may have cinnamon tones. The ears are pale grey to white and its tail is white to pale grey. Underparts are grey to buff. Melanism is common in the northern portions of the range and albinism is rare in all areas. There are a total of 22 teeth in the adults with a dental formula of i (1/1), c (0/0), p (2/1/), m (3/3). The total length of these squirrels ranges from 380 to 525 mm, tail length ranges from 150 to 250 mm, ear length ranges from 25 to 33mm, and hind foot length ranges from 54 to 76mm.

Range mass: 338 to 750 g.

Average mass: 540.33 g.

Range length: 380.0 to 525.0 mm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: sexes alike

Average basal metabolic rate: 2.062 W.

Length: 50 cm

Weight: 710 grams

• Terrestrial

Sciurus carolinensis prefers habitats of mature continuous woodlands of greater than 40 hectares with diverse understory vegetation. Densities are highest in forests with trees that produce foods that last through winter storage such as oaks (Quercus) and walnuts (Juglans).

Habitat Regions: temperate

Terrestrial Biomes: forest

Other Habitat Features: urban ; suburban

Comments: Prefers mature deciduous and mixed forests with abundant supplies of mast (e.g., acorns, hickory nuts). A diversity of nut trees is needed to support high densities. Also uses city parks and floodplains. Seldom far from permanent open water. In southern Alabama, narrow bands of hardwoods along ephemeral streams were an important component of the habitat in even-aged pine and mixed pine-hardwood stands (Fischer and Holler 1991). Rests in tree cavity or leaf nest; leaf nests apparently are made primarily by dispersing juveniles 18-19 weeks old. Nests in tree cavities or in leaf nests, usually 25 feet or more above ground. Most winter-spring litters are born in tree cavities, most spring-summer litters in leaf nests (Teaford 1986). Cavities suitable for nesting are dry, 15-25 cm in diameter, 40-50 cm deep, with an entrance hole about 8 cm in diameter (Teaford 1986). Females may move young from tree cavity nest to leaf nest, possibly to escape fleas.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Massive movements may occur in some years.

Sciurus carolinensis feeds mostly on nuts, flowers and buds of more than 24 species of oaks, 10 species of hickory, pecan, walnut and beech tree species. Maple, mulberry, hackberry, elm, bucky and horse chestnut fruits, seeds, bulbs or flowers are also eaten along with wild cherry, dogwood, hawthorn, black gum, hazelnut, hop hornbeam and gingko tree fruits, seeds, bulbs and/or flowers. The seeds and catkins of gymnosperms such as cedar, hemlock, pine, and spruce are another food source along with a variety of herbaceous plants and fungi. Crops, such as corn and wheat, are eaten, especially in the winter. Insects are eaten in the summer and are probably especially important for juveniles. Cannibalism has been reported, and squirrels may also eat bones, bird eggs and nestlings, and frogs. They bury food in winter caches using a method called scatter hoarding and locate these caches using both memory and smell.

Animal Foods: birds; mammals; amphibians; eggs; carrion ; insects

Plant Foods: leaves; seeds, grains, and nuts; fruit

Other Foods: fungus

Foraging Behavior: stores or caches food

Primary Diet: omnivore

Comments: Diet consists of seeds, fruits, nuts, fungi, occasional insects and small vertebrates (e.g., bird eggs). Scatterhoarder; buries nuts and acorn in fall for later consumption (winter-spring).

Eastern grey squirrels are important predators of seeds and other animals in the ecosystems in which they live. Their seed-caching activities may help disperse tree seeds. They may help to distribute truffle fungal spores when they eat truffles. Eastern grey squirrels are also prey animals themselves and are hosts for parasites such as ticks, fleas, lice, and roundworms. They are important and ubiquitous members of the forest ecosystems in which they live.

Eastern grey squirrels are important members of the forest ecosystems in which they live. They eat a lot of seeds. Their seed-caching activities may help disperse tree seeds. They may help to distribute truffle fungal spores when they eat truffles. They also prey on other animals in the ecosystem where they live. And of course eastern grey squirrels are also prey animals themselves! They are hosts for parasites such as ticks, fleas, lice, and roundworms.

Eastern grey squirrels are preyed on by many predators, including American mink, other weasels, red foxes, bobcats, grey wolves, coyotes, lynx, and birds of prey, such as red-tailed hawks. They emit warning calls to warn neighboring squirrels of the presence of predators. Their extreme agility in the trees makes them difficult to capture.

Known Predators:

• American minks (Neovison vison)
• weasels (Mustela)
• red foxes (Vulpes vulpes)
• bobcats (Lynx rufus)
• grey wolves (Canis lupus)
• Canada lynx (Lynx canadensis)
• coyotes (Canis latrans)
• birds of prey (Falconiformes)
• red-tailed hawks (Buteo jamaicensis)

Fall density generally ranges from 0.5 to 14/ha, but 3.2/ha generally is considered high for extensive forested tracts; densities of 21/ha or more may occur in city parks; populations tend to increase after bumper mast crops, decrease if mast crop fails (Teaford 1986). May aggregate at abundant food sources.

Home range averages 0.5-10 ha, with older males tending to have the largest ranges (Teaford 1986); usually home range is less than 5 ha (see Koprowski 1994). Not territorial, home range overlap is extensive; social system is characterized by a linear dominance hierarchy.

Disperses up to a few kilometers from natal area upon approaching sexual maturity. Large-scale one-way emigrations have been observed, generally coinciding with high population density and mast crop failure.

Taken by many predators, but predation does not appear to limit populations (Teaford 1986). Mean annual mortality reported for adults is 42-57% (Koprowski 1994).

Eastern grey squirrels communicate among themselves with a variety of vocalizations and postures, such as tail flicking. They also have a keen sense of smell and can determine much about their neighbors in this way, including levels of stress and reproductive condition.

Eastern grey squirrels communicate among themselves with a variety of vocalizations and postures, such as tail flicking. They also have a keen sense of smell. They use their sense of smell to determine many things about their neighbors. Some of the things they can determine are levels of stress and reproductive condition.

Communication Channels: visual ; tactile ; acoustic ; chemical

Perception Channels: visual ; acoustic

Comments: Active during the day, particularly in the morning and late afternoon, though unimodal activity may occur in winter. May be inactive for a day or two during extremely cold, snowy weather.

The maximum longevity is 12.5 years in the wild but a captive female lived to be more than 20 years of age.

Range lifespan

Status: wild: 12.5 (high) years.

Average lifespan

Status: wild: 12.5 years.

Average lifespan

Status: captivity: 23.5 years.

Average lifespan

Status: wild: 23.5 years.

Average lifespan

Status: wild: 23.6 years.

Average lifespan

Status: captivity: 12.0 years.

Males compete among themselves for the ability to mate with female eastern grey squirrels. Females may mate with more than one male as well.

Mating System: polygynandrous (promiscuous)

Males start following females 5 days before estrus and may come from as far away as 500 meters. Estrus in the female is indicated by an enlarged pink vulva, a condition which usually lasts less than 8 hours. The vagina is closed in prepubescent and anestrous females. Copulation lasts less than thirty seconds. After ejaculation, a gelatinous white vaginal plug forms, preventing further sperm entry.

Breeding occurs in December-February and May-June and is slightly delayed in more northern latitudes. Gestation lasts 44 days. Most females begin their reproductive life at 1.25 years but can bear young as early as 5.5 months. Females may bear young twice a year for more than 8 years. Males usually are sexually mature by 11 months but maturity can be delayed by as much as two years if the young males are housed with a dominant adult male. Inactive testes weigh 1g, whereas active testes weight 6-7g. This cycle of testicular recrudescence and regression occurs twice a year.

Newborns are naked with the exception of their vibrissae and they weigh from 13-18g. Young are altricial. Weaning begins in the seventh week and is completed by the tenth. At this point, the juvenile pelage is lost. Adult size and mass are reached at 9 months. Two litters are born each year in late winter and midsummer with generally 2-4 young per litter (up to 8 young are possible).

Breeding interval: Eastern grey squirrels breed twice in a year, typically.

Breeding season: Breeding occurs in December-February and May-June and is slightly delayed in more northern latitudes.

Range number of offspring: 2.0 to 8.0.

Average number of offspring: 3.0.

Average gestation period: 44.0 days.

Average weaning age: 3.0 weeks.

Range age at sexual or reproductive maturity (female): 5.5 (low) months.

Average age at sexual or reproductive maturity (female): 15 months.

Range age at sexual or reproductive maturity (male): 5.5 (low) months.

Average age at sexual or reproductive maturity (male): 15 months.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization ; viviparous

Average birth mass: 15 g.

Average gestation period: 44 days.

Average number of offspring: 4.

Newborns are naked with the exception of their vibrissae. Vibrissae are small hairs around the nose and mouth that are used for touch, much like the whiskers of a cat. The newborns weigh from 13g to 18g. Young are altricial. They are cared for in the nest by their mother until they reach independence. Weaning begins in the seventh week and is completed by the tenth. At this point, the juvenile hair is lost. Adult size and mass are reached at 9 months old.

Parental Investment: no parental involvement; altricial ; pre-fertilization (Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)

In Illinois, most breeding occurs in December-February and May-June; slightly later in more northern latitudes (see Koprowski 1994). One or two litters/year. First litter is produced mostly in February-March, sometimes as early as January in some areas; second litter, July or August. Gestation lasts 44 days. Litter size most often is 2-3. Young are tended by female. Weaning is completed at about 10-12 weeks (in spring and/or late summer-early fall). Most breed as yearlings, sometimes sooner (as early as 5 months) or later. Reproductive output, including the percentage of adults that produce young and the number of litters/year, is positively correlated with mast abundance. Maximum reproductive longevity is about a decade.

Sciurus carolinensis is not threatened.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Management Requirements: See Williamson (no date) for information on habitat management. An area can function as a gray squirrel management unit as long as it is 15-30 m wide and 2-4 ha in extent; a reasonable goal for managing a population for hunting in an extensive area is 1.2-2.5 squirrels/ha; 5-12 squirrels/ha may be suitable and possible where squirrels are managed for nonconsumptive recreation on smaller sites; 12-30 tree cavities/ha is a reasonable management goal (Teaford 1986, which see for further recommendations).

See Teaford (1986) for specifications for the construction and placement of wooden nest boxes and rubber tire shelters.

See also Nixon and Hansen (1987).

In Great Britain, Sciurus carolinensis is considered very destructive to property and is ranked second in negative impact only to the Norway rat (Rattus norvegicus).

Negative Impacts: crop pest; household pest

Eastern grey squirrels provided food for Native Americans and colonists and are still eaten by some people today. They have economic importance in some states, such as Mississippi where 2.5 million are harvested each year with an economic impact of 12.5 million dollars.

Squirrels are ranked second to birds in value to nature watchers.

Positive Impacts: food ; ecotourism

Comments: Popular game species, with many millions harvested annually.

Comments: Individuals inhabiting the Mississippi River floodplain and delta region are smaller than individuals from adjacent areas; allozyme analyses revealed that there are differences among eastern and western populations as defined by their geographic location relative to the present channel of the lower Mississippi River (Moncrief 1993).