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Lifespan, longevity, and ageing

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Maximum longevity: 23.6 years (captivity)
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Benefits

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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

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Lawniczak, M. 2002. "Sciurus carolinensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_carolinensis.html
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Mara Katharine Lawniczak, University of Michigan-Ann Arbor
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Associations

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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)
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Lawniczak, M. 2002. "Sciurus carolinensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_carolinensis.html
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Mara Katharine Lawniczak, University of Michigan-Ann Arbor
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Morphology

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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.

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Lawniczak, M. 2002. "Sciurus carolinensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_carolinensis.html
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Mara Katharine Lawniczak, University of Michigan-Ann Arbor
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Life Expectancy

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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.

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Lawniczak, M. 2002. "Sciurus carolinensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_carolinensis.html
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Habitat

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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

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Lawniczak, M. 2002. "Sciurus carolinensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_carolinensis.html
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Mara Katharine Lawniczak, University of Michigan-Ann Arbor
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Distribution

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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 )

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Lawniczak, M. 2002. "Sciurus carolinensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_carolinensis.html
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Mara Katharine Lawniczak, University of Michigan-Ann Arbor
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Trophic Strategy

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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

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Lawniczak, M. 2002. "Sciurus carolinensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_carolinensis.html
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Mara Katharine Lawniczak, University of Michigan-Ann Arbor
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Associations

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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.

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Lawniczak, M. 2002. "Sciurus carolinensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_carolinensis.html
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Mara Katharine Lawniczak, University of Michigan-Ann Arbor
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Benefits

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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

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Lawniczak, M. 2002. "Sciurus carolinensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_carolinensis.html
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Mara Katharine Lawniczak, University of Michigan-Ann Arbor
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Conservation Status

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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

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Lawniczak, M. 2002. "Sciurus carolinensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_carolinensis.html
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Mara Katharine Lawniczak, University of Michigan-Ann Arbor
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Behavior

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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 ; tactile ; acoustic ; chemical

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Lawniczak, M. 2002. "Sciurus carolinensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_carolinensis.html
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Mara Katharine Lawniczak, University of Michigan-Ann Arbor
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Untitled

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Some interesting clines occur in both skull size and coat color. There is a decreasing cline southward in skull size, though toothrows and mandible sizes remain the same (possibly due to stabilizing selection on those characters involved in mastication). Also, more black-coated squirrels occur in the north. Studies have shown that black animals have 18% lower heat loss in temperatures below -10 degrees Celcius, along wth a 20% lower basal metabolic rate, and a nonshivering thermogenesis capacity 11% higher than grey morphs.

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Lawniczak, M. 2002. "Sciurus carolinensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_carolinensis.html
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Reproduction

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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); sexual ; 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)

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Lawniczak, M. 2002. "Sciurus carolinensis" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_carolinensis.html
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Mara Katharine Lawniczak, University of Michigan-Ann Arbor
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Biology

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Grey squirrels are active during the day (6); they feed on seeds, nuts, buds, insects, bird eggs (6) and fungi, depending on the time of year (3), and are well-known for their habit of hoarding food in autumn to see them through the harsh winter months (3). Seeds, cones or nuts are hidden in small scrapes scattered over the ground and buried (3). The general area is remembered, and then the cache is re-found by smell over fairly short distances (3). Breeding takes place in December to February, and again in March to May. During this time, a number of males may follow a female when she is about to come into oestrus; during this 'following phase' the female may occasionally turn on the male and rebuff his advances by lunging at him aggressively. The day the female comes into oestrus, a number of males chase the female, making 'buzzing' noises; this is known as the 'mating chase', and the female can respond aggressively to males. Through much male-male chasing, dominant males are able to get closer to the female; when she is ready she crouches on the ground, and the first male to reach her mates with her (3). Gestation takes up to 44 days, during which time females are solitary, and nest in a 'drey' of twigs and leaves (1). If conditions are good (6), two litters are produced each year, consisting of one to eight young (6). The young are usually weaned by ten weeks (1), and reach sexual maturity at 10 to 12 months of age (6). The average lifespan is eight to nine years (6).
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Conservation

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No conservation measures are in place for this introduced and now common species. Grey squirrels are controlled to protect trees and in areas where red squirrels persist (6). The eradication of grey squirrels for conservation reasons is unlikely; the costs involved would be enormous, and the species is very popular with the public (6).
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Description

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Although a familiar mammal in many parts of Great Britain, the grey squirrel is non-native, having been first introduced from the eastern USA in 1876 (3). It is responsible for the decline in populations of our native red squirrel (Sciurus vulgaris) (3). The introduced species is larger than the red squirrel, has largely grey fur with touches of russet-brown, and white underparts (2). Unlike the red squirrel, this species never has ear tufts (2). The sexes are similar in appearance (1).
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Habitat

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A very adaptable species, the grey squirrel prefers mature broadleaved woodlands with a rich understorey layer (1). It also occurs in conifer woodlands, urban areas where there are mature trees, as well as gardens and parks (6).
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Range

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Introductions of this species to the UK continued up until 1915. Between 1930 and 1945 it underwent a huge expansion in range; it is now common throughout central and southern England, Wales and the central lowlands of Scotland (3), and is still increasing in terms of range and numbers (6). The grey squirrel has also been introduced to South Africa, Australia (3) and Italy (4). In Italy the species has extended its range into the Alps and Piedmont, and it seems likely that it will now spread throughout much of Europe (4). Its native range extends throughout the eastern USA reaching as far north as Canada, and south to the Mississippi River (1).
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Status

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Introduced invasive species (3). No conservation status.
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Threats

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This species is a serious pest in Britain, and its habit of removing tree bark is extremely damaging. In addition to out-competing red squirrels, it also carries a disease called parapox virus, which affects the native species (5).
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Associations

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Fungus / feeder
Sciurus carolinensis feeds on fruitbody of Russula
Other: minor host/prey

In Great Britain and/or Ireland:
Fungus / feeder
Sciurus carolinensis feeds on fruit of Corylus avellana

Fungus / feeder
Sciurus carolinensis feeds on fruit of Fagus sylvatica

Fungus / feeder
Sciurus carolinensis feeds on subterranean ascoma of Elaphomyces granulatus

Animal / dung saprobe
gregarious perithecium of Sordaria fimicola is saprobic in/on dung or excretions of dung of Sciurus carolinensis

Animal / dung saprobe
apothecium of Thelebolus nanus is saprobic in/on dung or excretions of dung of Sciurus carolinensis

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Eastern gray squirrel

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The eastern gray squirrel (Sciurus carolinensis), also known, particularly outside of North America, as simply the grey squirrel, is a tree squirrel in the genus Sciurus. It is native to eastern North America, where it is the most prodigious and ecologically essential natural forest regenerator.[4][5] Widely introduced to certain places around the world, the eastern gray squirrel in Europe, in particular, is regarded as an invasive species.

In Europe, Sciurus carolinensis is included since 2016 in the list of Invasive Alien Species of Union concern (the Union list).[6] This implies that this species cannot be imported, bred, transported, commercialized, or intentionally released into the environment in the whole of the European Union.[7]

Distribution

Sciurus carolinensis is native to the eastern and midwestern United States, and to the southerly portions of the central provinces of Canada. The native range of the eastern gray squirrel overlaps with that of the fox squirrel (Sciurus niger), with which it is sometimes confused, although the core of the fox squirrel's range is slightly more to the west. The eastern gray squirrel is found from New Brunswick, through southwestern Quebec and throughout southern Ontario plus in southern Manitoba, south to East Texas and Florida.[2] Breeding eastern gray squirrels are found in Nova Scotia, but whether this population was introduced or came from natural range expansion is not known.[8]

A prolific and adaptable species, the eastern gray squirrel has also been introduced to, and thrives in, several regions of the western United States and in 1966, this squirrel was introduced onto Vancouver Island in Western Canada in the area of Metchosin, and has spread widely from there. They are considered highly invasive and a threat to both the local ecosystem and the native squirrel, the American red squirrel.[9]

Overseas, Eastern gray squirrels in Europe are a concern because they have displaced some of the native squirrels there. They have been introduced into Ireland,[10] Britain, Italy, South Africa, and Australia (where it was extirpated by 1973).[2]

In Ireland, the native squirrel – also colored red – the Eurasian red squirrel S. vulgaris – has been displaced in several eastern counties, though it still remains common in the south and west of the country.[11] The gray squirrel is also an invasive species in Britain; it has spread across the country and has largely displaced the red squirrel. That such a displacement might happen in Italy is of concern, as gray squirrels might spread to other parts of mainland Europe.[12]

A brown morph of the gray squirrel in Union Square, NYC.

Etymology

The generic name, Sciurus, is derived from two Greek words, skia, meaning shadow, and oura, meaning tail. This name alludes to the squirrel sitting in the shadow of its tail.[13] The specific epithet, carolinensis, refers to the Carolinas, where the species was first recorded and where the animal is still extremely common. In the United Kingdom and Canada, it is simply referred to as the "grey squirrel". In the US, "eastern" is used to differentiate the species from the western gray squirrel (Sciurus griseus).

Description

Bounding tracks in concrete
Leucistic eastern gray squirrel
Alert eastern gray squirrel
Melanistic eastern gray squirrel carrying a peanut

The eastern gray squirrel has predominantly gray fur, but it can have a brownish color. It has a usual white underside as compared to the typical brownish-orange underside of the fox squirrel.[14] It has a large bushy tail. Particularly in urban situations where the risk of predation is reduced, both white[15] – and black-colored individuals are quite often found. The melanistic form, which is almost entirely black, is predominant in certain populations and in certain geographic areas, such as in large parts of southeastern Canada. Melanistic squirrels appear to exhibit a higher cold tolerance than the common gray morph; when exposed to −10 °C, black squirrels showed an 18% reduction in heat loss, a 20% reduction in basal metabolic rate, and an 11% increase to non-shivering thermogenesis capacity when compared to the common gray morph.[16] The black coloration is caused by an incomplete dominant mutation of MC1R, where E+/E+ is a wild type squirrel, E+/EB is brown-black, and EB/EB is black.[17]

The head and body length is from 23 to 30 cm (9.1 to 11.8 in), the tail from 19 to 25 cm (7.5 to 9.8 in), and the adult weight varies between 400 and 600 g (14 and 21 oz).[18][19] They do not display sexual dimorphism, meaning there is no gender difference in size or coloration.[20]

The tracks of an eastern gray squirrel are difficult to distinguish from the related fox squirrel and Abert's squirrel, though the latter's range is almost entirely different from the gray's. Like all squirrels, the eastern gray shows four toes on the front feet and five on the hind feet. The hind foot-pad is often not visible in the track. When bounding or moving at speed, the front foot tracks will be behind the hind foot tracks. The bounding stride can be two to three feet long.[21]

The dental formula of the eastern gray squirrel is 1023/1013 (upper teeth/lower teeth).[16]

1.0.2.31.0.1.3 × 2 = 22 total teeth.

Incisors exhibit indeterminate growth, meaning they grow consistently throughout life, and their cheek teeth exhibit brachydont (low-crowned teeth) and bunodont (having tubercles on crowns) structures.[16]

Behavior

Reaching out for food on a garden bird feeder, this squirrel can rotate its hind feet, allowing it to descend a tree head-first.

Like many members of the family Sciuridae, the eastern gray squirrel is a scatter-hoarder; it hoards food in numerous small caches for later recovery.[2] Some caches are quite temporary, especially those made near the site of a sudden abundance of food which can be retrieved within hours or days for reburial in a more secure site. Others are more permanent and are not retrieved until months later. Each squirrel is estimated to make several thousand caches each season. The squirrels have very accurate spatial memory for the locations of these caches, using distant and nearby landmarks to retrieve them. Smell is used partly to uncover food caches, and also to find food in other squirrels' caches. Scent can be unreliable when the ground is too dry or covered in snow.[22]

Squirrels sometimes use deceptive behavior to prevent other animals from retrieving cached food. For example, they will pretend to bury the object if they feel that they are being watched. They do this by preparing the spot as usual, for instance, digging a hole or widening a crack, miming the placement of the food, while actually concealing it in their mouths, and then covering up the "cache" as if they had deposited the object. They also hide behind vegetation while burying food or hide it high up in trees (if their rival is not arboreal). Such a complex repertoire suggests that the behaviours are not innate, and imply theory of mind thinking.[23][24]

The eastern gray squirrel is one of very few mammalian species that can descend a tree head-first. It does this by turning its feet so the claws of its hind paws are backward-pointing and can grip the tree bark.[25][26]

Eastern gray squirrels build a type of nest, known as a drey, in the forks of trees, consisting mainly of dry leaves and twigs. The dreys are roughly spherical, about 30 to 60 cm in diameter and are usually insulated with moss, thistledown, dried grass, and feathers to reduce heat loss.[20] Males and females may share the same nest for short times during the breeding season, and during cold winter spells. Squirrels may share a drey to stay warm. They may also nest in the attic or exterior walls of a house, where they may be regarded as pests, as well as fire hazards due to their habit of gnawing on electrical cables. [27] In addition, squirrels may inhabit a permanent tree den hollowed out in the trunk or a large branch of a tree.[28]

Eastern gray squirrels are crepuscular,[19] or more active during the early and late hours of the day, and tend to avoid the heat in the middle of a summer day.[28] They do not hibernate.[29]

Eastern gray squirrels are born hairless with their eyes closed.

Eastern gray squirrels can breed twice a year, but younger and less experienced mothers normally have a single litter per year in the spring. Depending on forage availability, older and more experienced females may breed again in summer.[30] In a year of abundant food, 36% of females bear two litters, but none will do so in a year of poor food.[16] Their breeding seasons are December to February and May to June, though this is slightly delayed in more northern latitudes.[19][28] The first litter is born in February or March, the second in June or July, though, again, bearing may be advanced or delayed by a few weeks depending on climate, temperature, and forage availability. In any given breeding season, an average of 61 – 66% of females bear young.[16] If a female fails to conceive or loses her young to unusually cold weather or predation, she re-enters estrus and has a later litter. Five days before a female enters estrus, she may attract up to 34 males from up to 500 meters away. Eastern gray squirrels exhibit a form of polyandry, in which the competing males will form a hierarchy of dominance, and the female will mate with multiple males depending on the hierarchy established.[16]

Eastern gray squirrel drey

Normally, one to four young are born in each litter, but the largest possible litter size is eight.[16] The gestation period is about 44 days.[16] The young are weaned around 10 weeks, though some may wean up to six weeks later in the wild. They begin to leave the nest after 12 weeks, with autumn born young often wintering with their mother. Only one in four squirrel kits survives to one year of age, with mortality around 55% for the following year. Mortality rates then decrease to around 30% for following years until they increase sharply at eight years of age.[16]

Melanistic eastern gray squirrel
Melanistic eastern gray squirrel

Rarely, eastern gray females can enter estrus as early as five and a half months old,[28] but females are not normally fertile until at least one year of age. Their mean age of first estrus is 1.25 years.[16] The presence of a fertile male will induce ovulation in a female going through estrus.[16] Male eastern grays are sexually mature between one and two years of age.[31] Reproductive longevity for females appears to be over 8 years, with 12.5 years documented in North Carolina.[16] These squirrels can live to be 20 years old in captivity, but in the wild live much shorter lives due to predation and the challenges of their habitat. At birth, their life expectancy is 1–2 years, an adult typically can live to be six, with exceptional individuals making it to 12 years.

Growth and ontogeny

Juvenile eastern gray squirrel developing fur

Newborn gray squirrels weigh 13–18 grams and are entirely hairless and pink, although vibrissae are present at birth. 7–10 days postpartum, the skin begins to darken, just before the juvenile pelage grows in. Lower incisors erupt 19–21 days postpartum, while upper incisors erupt after 4 weeks. Cheek teeth erupt during week 6. Eyes open after 21–42 days, and ears open 3–4 weeks postpartum. Weaning is initiated around 7 weeks postpartum, and is usually finished by week 10, followed by the loss of the juvenile pelage. Full adult body mass is achieved by 8–9 months after birth.[16]

Communication

Calls recorded in Surrey, England

As in most other mammals, communication among eastern gray squirrel individuals involves both vocalizations and posturing. The species has a quite varied repertoire of vocalizations, including a squeak similar to that of a mouse, a low-pitched noise, a chatter, and a raspy "mehr mehr mehr". Other methods of communication include tail-flicking and other gestures, including facial expressions. Tail flicking and the "kuk" or "quaa" call are used to ward off and warn other squirrels about predators, as well as to announce when a predator is leaving the area.[32] Squirrels also make an affectionate coo-purring sound that biologists call the "muk-muk" sound. This is used as a contact sound between a mother and her kits and in adulthood, by the male when he courts the female during mating season.[32]

The use of vocal and visual communication has been shown to vary by location, based on elements such as noise pollution and the amount of open space. For instance, populations living in large cities generally rely more on the visual signals, due to the generally louder environment with more areas without much visual restriction. However, in heavily wooded areas, vocal signals are used more often due to the relatively lower noise levels and a dense canopy restricting visual range.[33]

Diet

Hazelnuts gnawed by gray squirrel; the curved cut marks left by the sharp incisors are visible around the holes

Eastern gray squirrels eat a range of foods, such as tree bark, tree buds, flowers,[34] berries, many types of seeds and acorns, walnuts, and other nuts, like hazelnuts (see picture) and some types of fungi found in the forests, including fly agaric mushrooms (Amanita muscaria).[35] They can cause damage to trees by tearing the bark and eating the soft cambial tissue underneath. In Europe, sycamore (Acer pseudoplatanus L.) and beech (Fagus sylvatica L.) suffer the greatest damage.[36] The seeds and catkins of gymnosperms cedar, hemlock, pine, and spruce are another food source,[34] as well as those of angiosperms such as hickory, oak, and walnut, and truffles. Mast-bearing hardwood trees are also very important to their diet. These trees help store food like acorns, beechnuts, and hickory nuts, which are important foods for them during the spring and fall months. Red oak acorns are found in the spring, winter and fall. White oak acorns are found in the fall and winter. Hickory and beechnuts are found in spring, winter and fall. Walnuts are found in fall and winter. Buds and flowers are found in spring and summer. Fleshy fruits and berries are found in summer. Fungi mushrooms are found in spring, summer, and fall. Yellow poplar seeds are found in summer, fall and winter.[37] The squirrels also raid gardens for wheat,[34] tomatoes, corn, strawberries, and other garden crops.[38] Sometimes they eat the tomato seeds and discard the rest. On occasion, eastern gray squirrels also prey upon insects, frogs, small rodents including other squirrels, and small birds, their eggs, and young.[2][28] They also gnaw on bones, antlers, and turtle shells – likely as a source of minerals scarce in their normal diet.[35] In urban and suburban areas, these squirrels scavenge for food in trash bins. However, these foods aren't safe for them to digest because they include sugar, fat, as well as additives that can make them sick. Eastern gray squirrels are thought to be herbivores, but they are Omnivores.[39]

Eastern Gray Squirrel eating a cicada

Eastern gray squirrels have a high enough tolerance for humans to inhabit residential neighborhoods and raid bird feeders for millet, corn, and sunflower seeds. Some people who feed and watch birds for entertainment also intentionally feed seeds and nuts to the squirrels for the same reason.[40] However, in the UK eastern gray squirrels can take a significant proportion of supplementary food from feeders, preventing access and reducing use by wild birds.[41] Attraction to supplementary feeders can increase local bird nest predation, as eastern gray squirrels are more likely to forage near feeders, resulting in increased likelihood of finding nests, eggs and nestlings of small passerines.[42]

Predation

Eastern gray squirrels predators include hawks, weasels, raccoons, bobcats, foxes, domestic and feral cats, snakes, owls, and dogs.[28] Their primary predators are hawks, owls, and snakes.[43] Raccoons and weasels may consume a squirrel depending on where it lives in the United States.[44] Rattlesnakes eat squirrels in California as they are searching for food in a heavy forest.[44] The squirrel is susceptible to be eaten by a fox in the eastern region of the United States.[44]

In its introduced range in South Africa, it has been preyed on by African harrier-hawks.[45] When a predator is approaching the Eastern Gray Squirrel, other squirrels will inform the squirrel of the predator by sending a signal to let the squirrel know. The speed of a squirrel makes it hard for it to be captured by the predators.[46]

Diseases

Diseases such as Typhus, Plague, and Tularemia are spread by Eastern Gray Squirrels. If not properly treated, these diseases have the potential to kill squirrels. When bitten or exposed to bodily fluids, humans can contract these diseases. Also carried by Eastern Grey Squirrels are parasites such as ringworm, fleas, lice, mites, and ticks which can kill their squirrel host. Their skin may become rough, blotchy, and prone to hair loss due to the mite parasite during the chilly winter months. The parasites are not transferred to people when these squirrels reside in attics or homes.[47] A frequent illness spread by ticks is Lyme disease.[48] Ticks can also spread Rocky Mountain Spotted Fever. It can result in damage to internal organs including the heart and kidney if not properly treated.[49] An eastern gray squirrel is susceptible to illness. They are susceptible to diseases including fibromatosis and squirrel box. A squirrel with fibromatosis, a virus-induced illness, may grow massive skin tumors all over the body. Blindness could result from a tumor that is discovered close to a squirrels mouth or eye.[50]

Habitat

Eastern gray squirrel staying in a birdhouse

In the wild, eastern gray squirrels can be found inhabiting large areas of mature, dense woodland ecosystems, generally covering 100 acres (40 hectares) of land.[28] These forests usually contain large mast-producing trees such as oaks and hickories, providing ample food sources. Oak-hickory hardwood forests are generally preferred over coniferous forests due to the greater abundance of mast forage.[19] This is why they are found only in parts of eastern Canada which do not contain boreal forest (i.e. they are found in some parts of New Brunswick, in southwestern Quebec, throughout southern Ontario and in southern Manitoba).

Eastern gray squirrels generally prefer constructing their dens upon large tree branches and within the hollow trunks of trees. They also have been known to take shelter within abandoned bird nests. The dens are usually lined with moss plants, thistledown, dried grass, and feathers. These perhaps provide and assist in the insulation of the den, used to reduce heat loss. A cover to the den is usually built afterwards.[51]

Eastern grays squirrels also use dens for protection from prey and helps them look after their young. Young survive 40 percent less if they lived in a leaf nest compared to a den. Squirrels tend to claim 2-3 dens at the same time. Canopy and midstory Trees are used by squirrels to hide from predators such as hawks and owls. The typical squirrel ranges over 1.5 to 8 acres (0.61 to 3.24 ha) and tend to be smaller where more of them are found.[37]

Close to human settlements, eastern gray squirrels are found in parks and back yards of houses within urban environments and in the farmlands of rural environments.[52]

Introductions

The eastern gray squirrel is considered an invasive species in the UK (Bunhill Fields, London)

The eastern gray squirrel is an introduced species in a variety of locations in western North America: in western Canada, to the southwest corner of British Columbia and to the city of Calgary, Alberta;[13] in the United States, to the states of Washington and Oregon and, in California, to the city of San Francisco and the San Francisco Peninsula area in San Mateo and Santa Clara Counties, south of the city. It has become the most common squirrel in many urban and suburban habitats in western North America, from north of central California to southwest British Columbia.

By the turn of the 20th century, breeding populations of the eastern gray squirrel had been introduced into South Africa, Ireland, Italy, Australia (extirpated by 1973), and the United Kingdom.[53]

In South Africa, though exotic, it is not usually considered an invasive species owing to its small range (only found in the extreme southwestern part of the Western Cape, going north as far as the small farming town of Franschhoek), as well because it inhabits urban areas and places greatly affected by humans, such as agricultural areas and exotic pine plantations. Here, it mostly eats acorns and pine seeds, although it will take indigenous and commercial fruit, as well.[54] Even so, it is unable to use the natural vegetation (fynbos) found in the area, a factor which has helped to limit its spread.[55] It does not come into contact with native squirrels due to geographic isolation (a native tree squirrel, Paraxerus cepapi, is found only in the savanna regions in the northeast of the country)[56] and different habitats.

Gray squirrels were first introduced to Britain in the 1870s, as fashionable additions to estates.[57] In 1921 it was reported in The Times that the Zoological Society of London had released Eastern Greys to breed at liberty in Regents Park:

A dozen years ago the Zoological Society of London obtained a number from a private collection in Bedfordshire for the purpose of inducing them to breed at liberty in the Gardens in Regent’s Park. They were first kept in a large enclosure from which, when they had become used to visitors, they were allowed to pass in and out by a rope bridge to a tree. It was hoped that they would spread from the Gardens to the Park. After two or three years in which they seemed to be disappearing, they suddenly became ubiquitous...The grey squirrels are plainly happy and plainly give happiness to Londoners...On the other hand, grey squirrels, whether by taking advantage of tubes and buses, or by deliberate human connivance, have spread from London and are invading the country over very wide areas. They are said to drive out the red squirrel, to raid gardens, and to add to the anxieties of the pheasant breeder. We hope that fuller inquiry will not sustain these charges.[58]

They spread rapidly across England, and then became established in both Wales and parts of southern Scotland. On mainland Britain, they have almost entirely displaced native red squirrels. Larger than red squirrels and capable of storing up to four times more fat, gray squirrels are better able to survive winter conditions. They produce more young and can live at higher densities. Gray squirrels also carry the squirrelpox virus, to which red squirrels have no immunity. When an infected gray squirrel introduces squirrelpox to a red squirrel population, its decline is 17–25 times greater than through competition alone.[57]

In Ireland, the displacement of red squirrels has not been as rapid because only a single introduction occurred, in County Longford. Schemes have been introduced to control the population of gray squirrels in Ireland to encourage the native red squirrels. Eastern gray squirrels have also been introduced to Italy, and the European Union has expressed concern that they will similarly displace the red squirrel from parts of the European continent.

An Eastern Gray Squirrel and a Red Squirrel eating seeds

Displacement of red squirrels

In Britain and Ireland, the eastern gray squirrel is not regulated by natural predators,[59] other than the European pine marten, which is generally absent from England and Wales.[60] This has aided its rapid population growth and has led to the species being classed as a pest. Measures are being devised to reduce its numbers, including a campaign starting in 2006 named “Save Our Squirrels” using the slogan "Save a red, eat a grey!" which attempted to re-introduce squirrel meat in to the local market, with celebrity chefs promoting the idea,[61] cookbooks introducing recipes containing squirrel and the Forestry Commission providing a regular supply of squirrel meat to British restaurants, factories and butchers.[62] In areas where relict populations of red squirrels survive, such as the islands of Anglesey, Brownsea and the Isle of Wight, programs exist to eradicate gray squirrels and prevent them from reaching these areas in order to allow red squirrel populations to recover and grow.[63]

Although complex and controversial, the main factor in the eastern gray squirrel's displacement of the red squirrel is thought to be its greater fitness, hence a competitive advantage over the red squirrel on all measures.[64] Within 15 years of the grey squirrel's introduction to a red squirrel habitat, red squirrel populations are extinct.[65] The eastern gray squirrel tends to be larger and stronger than the red squirrel and has been shown to have a greater ability to store fat for winter. Due to the lack of trees in their native Ireland for them to reside in, red squirrels are the only species being harmed by the invasion of grey squirrels.[65] The squirrel can, therefore, compete more effectively for a larger share of the available food, resulting in relatively lower survival and breeding rates among the red squirrel. Parapoxvirus may also be a strongly contributing factor; red squirrels have long been fatally affected by the disease, while the eastern gray squirrels are unaffected, but thought to be carriers – although how the virus is transmitted has yet to be determined. Red squirrel extinction rates can be 20–25 times greater in areas with confirmed cases of squirrel pox than they are in areas without the disease.[65] his competitive action done between these two squirrels is reasoned to qualify the eastern gray squirrel as a keystone species because since the eastern gray squirrel is coming and wiping out the red squirrels, there would be a reduced chance of competition hence more eastern gray squirrels will come in to Ireland.[66] However, several cases of red squirrels surviving have been reported, as they have developed an immunity – although their population is still being massively affected. The red squirrel is also less tolerant of habitat destruction and fragmentation, which has led to its population decline, while the more adaptable eastern gray squirrel has taken advantage and expanded. Methods done to control this competition between these squirrels are that red squirrels should remain in their original habitats, such as Ireland, while the grey squirrels should be kept out of these places entirely as a means of controlling this squirrel competition.[65]

Similar factors appear to have been at play in the Pacific region of North America, where the native American red squirrel has been largely displaced by the eastern gray squirrel in parks and forests throughout much of the region.

Ironically, "fears" for the future of the eastern gray squirrel arose in 2008, as the melanistic form (black) began to spread through the southern British population.[67] In the UK, if a "grey squirrel" (eastern gray squirrel) is trapped, under the Wildlife and Countryside Act 1981, it is illegal to release it or to allow it to escape into the wild; instead, it is legally required be "humanely dispatched".[68]

In the late 1990s, Italy's National Wildlife Institute and University of Turin launched an eradication attempt to halt the spread of gray squirrels in northwest Italy, but court action by animal rights groups blocked this. Hence gray squirrels are expected to cross the Alps into France and Switzerland in the next few decades.[69][70]

Ecosystem

Eastern Grey Squirrels are important to the ecosystem by eating a lot of seeds. By caching seeds, they help in the spread of tree seeds. Also, by eating truffles, they contribute to the spread of fungal spores. In addition, they are essential to the environment because they transport parasites.[71] The ecology is influenced by the contribution of squirrels to nature. They support the environment by gathering seeds. While being gathered, the seeds are scattered in certain places. Even though the seeds are not helpful to the squirrels because they can't remember where they were hidden, they are still growing in nature. These seeds increase the diversity of trees by bringing additional trees into the environment.[72] They are an important key to the forest ecosystem that they belong to.[73]

Fossil record of the eastern gray squirrel

Twenty different Pleistocene fauna specimens contain S. carolinensis, found in Florida and dated to be as early as the late Irvingtonian period.[16] Body size seems to have increased during the early to middle Holocene and then decreased to the present size seen today.

As food

Gray squirrels were eaten in earlier times by Native Americans and their meat is still popular with hunters across most of their range in North America. Today, it is still available for human consumption and is occasionally sold in the United Kingdom.[74] However, physicians in the United States have warned that squirrel brains should not be eaten, because of the risk that they may carry Creutzfeldt–Jakob disease.[75]

See also

References

  1. ^ Thorington, R.W., Jr.; Hoffman, R.S. (2005). "Family Sciuridae". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. p. 760. ISBN 978-0-8018-8221-0. OCLC 62265494.
  2. ^ a b c d e Cassola, F. (2016). "Sciurus carolinensis". IUCN Red List of Threatened Species. 2016: e.T42462A22245728. doi:10.2305/IUCN.UK.2016-2.RLTS.T42462A22245728.en. Retrieved 19 November 2021.
  3. ^ De Abreu-Jr, Edson Fiedler; Pavan, Silvia E.; Tsuchiya, Mirian T. N.; Wilson, Don E.; Percequillo, Alexandre R.; Maldonado, Jesús E. (2020). "Museomics of tree squirrels: A dense taxon sampling of mitogenomes reveals hidden diversity, phenotypic convergence, and the need of a taxonomic overhaul". BMC Evolutionary Biology. 20 (1): 77. doi:10.1186/s12862-020-01639-y. PMC 7320592. PMID 32590930. S2CID 220071854.
  4. ^ Goheen, Jacob R.; Swihart, Robert K. (2003). "Food-hoarding behavior of gray squirrels and North American red squirrels in the central hardwoods region: Implications for forest regeneration". Canadian Journal of Zoology. 81 (9): 1636–1639. doi:10.1139/z03-143.
  5. ^ Steele, M. A.; Hadj-Chikh, L. Z.; Hazeltine, J. (1996). "Caching and Feeding Decisions by Sciurus carolinensis: Responses to Weevil-Infested Acorns". Journal of Mammalogy. 77 (2): 305–314. doi:10.2307/1382802. JSTOR 1382802.
  6. ^ "List of Invasive Alien Species of Union concern - Environment - European Commission". ec.europa.eu. Retrieved 27 July 2021.
  7. ^ "REGULATION (EU) No 1143/2014 of the European parliament and of the council of 22 October 2014 on the prevention and management of the introduction and spread of invasive alien species". Archived from the original on 3 March 2017.
  8. ^ Huynh H.; Williams G.; McAlpine D.; Thorington R. (2010). "Establishment of the Eastern Gray Squirrel (Sciurus carolinensis) in Nova Scotia, Canada". Northeastern Naturalist. 17 (4): 673–677. doi:10.1656/045.017.0414. S2CID 84649999.
  9. ^ "Alien Species Alert" (PDF). Retrieved 8 March 2017.
  10. ^ McGoldrick, M.; Rochford, J. (2009). "Recent range expansion by the Grey Squirrel (Sciurus carolinensis Gmelin 1788". Irish Naturalists' Journal. 30: 24–28. JSTOR 20764520.
  11. ^ Carey, M., Hamilton, G., Poole, A., and Lawton, C. (2007) The Irish Squirrel Survey 2007. COFORD, Dublin, ISBN 1902696603
  12. ^ "Summary (of Bertolino S., Lurz. P.W.W., Rushton S.P. 2006, DIVAPRA Entomology & Zoology)". Europeansquirrelinitiative.org. Archived from the original on 20 January 2011. Retrieved 10 June 2010.
  13. ^ a b Hamilton, H. (1990). Smith, D. (ed.). Eastern Grey Squirrel. Hinterland Who's Who. ISBN 978-0-660-13634-9. Archived from the original on 23 December 2014. Retrieved 18 November 2008.
  14. ^ "New York's Wildlife Resources" (PDF). Department of Natural Resources at Cornell University. p. 2. Archived from the original (PDF) on 15 July 2007. Retrieved 28 September 2013.
  15. ^ Nelson, Rob. "White and Albino Squirrel Research Initiative". UntamedScience.com. Retrieved 23 March 2015.
  16. ^ a b c d e f g h i j k l m n Koprowski, John L. (1994). "Sciurus carolinensis" (PDF). Mammalian Species (480): 1–9. doi:10.2307/3504224. JSTOR 3504224. Archived from the original (PDF) on 27 March 2014. Retrieved 26 March 2014.
  17. ^ McRobie, H.; Thomas, A.; Kelly, J. (2009). "The Genetic Basis of Melanism in the Gray Squirrel (Sciurus carolinensis)". Journal of Heredity. 100 (6): 709–714. doi:10.1093/jhered/esp059. PMID 19643815.
  18. ^ BBC: Science and Nature, "Grey squirrel: Sciurus carolinensis"
  19. ^ a b c d "Red & Gray Squirrels in Massachusetts". MassWildlife. Massachusetts Division of Fisheries and Wildlife. Archived from the original on 17 May 2013. Retrieved 3 April 2012.
  20. ^ a b "Basic information about squirrels". ICSRS. Interactive Centre for Scientific Research about Squirrels. 17 November 2015. Retrieved 14 April 2017.
  21. ^ Murie, Olaus Johan and Elbroch, Mark (2005). Peterson Field Guide to Animal Tracks, Houghton Mifflin Harcourt, p. 79, ISBN 061851743X.
  22. ^ McCracken, Brian. "DO SQUIRRELS REALLY KNOW WHERE THEY BURY THEIR FOOD?". Animals – mom.me.
  23. ^ Grant, Steve (21 October 2004). "The Squirrel's Bag Of Tricks: They Can't Get Out Of The Way Of Cars, But Other Behaviors Demonstrate Advanced Thinking (for A Rodent)", The Hartford Courant.
  24. ^ "Smart squirrels fool food thieves", BBC, 17 January 2008.
  25. ^ Alexander, R. McNeill (2003). Principles of animal locomotion. Princeton University Press. p. 162. ISBN 978-0691086781.
  26. ^ Nations, Johnathan A.; Link, Olson. "Scansoriality in Mammals". Animal Diversity Web.
  27. ^ "Eastern Grey Squirrel - WildlifeNYC". www.nyc.gov. Retrieved 3 November 2022.
  28. ^ a b c d e f g Lawniczak, M. (2002). "Sciurus carolinensis". Animal Diversity Web. Retrieved 10 July 2008.
  29. ^ "The Grey Squirrel (Sciurus carolinensis)" (PDF). Grey squirrel Advisory. Archived from the original (PDF) on 7 February 2006. Retrieved 10 July 2008.
  30. ^ Curtis, Paul D. and Sullivan, Kristi L. (2001) Tree Squirrels, Wildlife Damage Management Fact Sheet Series, Cornell Cooperative Extension, Ithaca, N.Y.
  31. ^ Webley, G. E.; Pope, G. S.; Johnson, E (1985). "Seasonal changes in the testes and accessory reproductive organs and seasonal and circadian changes in plasma testosterone concentrations in the male grey squirrel (Sciurus carolinensis)". General and Comparative Endocrinology. 59 (1): 15–23. doi:10.1016/0016-6480(85)90414-9. PMID 4018551.
  32. ^ a b Kelly, John (9 April 2012). "Learn to speak squirrel in four easy lessons". Washington Post. Retrieved 7 March 2014.
  33. ^ Partan, Sarah R. (2010). "Multimodal alarm behavior in urban and rural gray squirrels studied by means of observation and a mechanical robot" (PDF). Current Zoology. 56 (3): 313–326. doi:10.1093/czoolo/56.3.313.
  34. ^ a b c Lawniczak, Mara Katharine. "Sciurus carolinensis (eastern gray squirrel)". Animal Diversity Web.
  35. ^ a b Long, Kim (September 1995). Squirrels: a wildlife handbook. Big Earth Publishing. p. 95. ISBN 978-1-55566-152-6.
  36. ^ Butler, F. and Kelleher, C. (eds) 2012. All-Ireland Mammal Symposium 2009. Irish Naturalists' Journal, Belfast, ISBN 978-0-9569704-1-1
  37. ^ a b "Eastern Gray Squirrel | NC State Extension Publications". content.ces.ncsu.edu. Retrieved 19 November 2022.
  38. ^ "How to Manage Pests – Tree Squirrels". University of California. Retrieved 23 May 2014.
  39. ^ Warner, Monique (28 June 2022). "Are Squirrels Omnivores, Herbivores Or Carnivores?". Retrieved 21 November 2022.
  40. ^ Long, Kim (1995), Squirrels: A Wildlife Handbook, Johnson Books, pp. 144–146, ISBN 9781555661526.
  41. ^ Hanmer, Hugh J.; Thomas, Rebecca L.; Fellowes, Mark D. E. (2018). "Introduced Grey Squirrels subvert supplementary feeding of suburban wild birds" (PDF). Landscape and Urban Planning. 177: 10–18. doi:10.1016/j.landurbplan.2018.04.004. S2CID 90663919.
  42. ^ Hanmer, Hugh J.; Thomas, Rebecca L.; Fellowes, Mark D. E. (2017). "Provision of supplementary food for wild birds may increase the risk of local nest predation" (PDF). Ibis. 159 (1): 158–167. doi:10.1111/ibi.12432.
  43. ^ Watson, Jessica (9 August 2022). "What Impact Does The Eastern Gray Squirrel Have Economic ? Find Out Here Squirrel Arena". www.squirrelarena.com. Retrieved 21 November 2022.
  44. ^ a b c "All of the Types of Squirrels". Sciencing. Retrieved 20 November 2022.
  45. ^ "Polyboroides typus (African harrier-hawk, Gymnogene)". Archived from the original on 3 November 2013. Retrieved 29 June 2013.
  46. ^ "Eastern Gray Squirrel". Chesapeake Bay. Retrieved 11 October 2022.
  47. ^ "Eastern Gray Squirrel | Mid-Atlantic Wildlife Control". Best Animal Removal Services - Mid-Atlantic Wildlife Control. Retrieved 3 November 2022.
  48. ^ "Lyme disease - Symptoms and causes". Mayo Clinic. Retrieved 3 November 2022.
  49. ^ "Rocky Mountain spotted fever - Symptoms and causes". Mayo Clinic. Retrieved 3 November 2022.
  50. ^ anirudh (29 June 2011). "Eastern Gray Squirrel - Facts, Diet, Habitat, Behavior and Pictures". Animal Spot. Retrieved 3 November 2022.
  51. ^ "Eastern Gray Squirrel". Project Noah. Retrieved 11 October 2022.
  52. ^ "The Leading America Zoo Site on the Net". americazoo.com. Retrieved 30 October 2011.
  53. ^ Long, J. L. (2003). Introduced Mammals of the World: Their History, Distribution and Influence. Csiro Publishing, Collingwood, Australia. ISBN 9780643099166
  54. ^ "The Grey Squirrel – Sciurus carolinensis of Southern Africa". Home.intekom.com. Retrieved 10 June 2010.
  55. ^ "Sciurus carolinensis (Grey Squirrel)". Biodiversityexplorer.org. Retrieved 10 June 2010.
  56. ^ "Tree Squirrel | Rodent | Southern Africa". Krugerpark.co.za. Retrieved 10 June 2010.
  57. ^ a b "History of grey squirrels in UK". Daily Telegraph (UK). 28 August 2018. Archived from the original on 12 January 2022. Retrieved 1 September 2018.
  58. ^ Anon (20 December 1921). "The success of grey squirrels". The Times. Times Newspapers Limited.
  59. ^ The grey squirrel policy and action statement. forestry.gov.uk
  60. ^ Sheehy, Emma; Lawton, Colin (March 2014). "Population crash in an invasive species following the recovery of a native predator: the case of the American grey squirrel and the European pine marten in Ireland". Biodiversity and Conservation. 23 (3): 753–774. doi:10.1007/s10531-014-0632-7. S2CID 10449048.
  61. ^ "Jamie 'must back squirrel-eating'". BBC News. 23 March 2006. Retrieved 22 August 2007.
  62. ^ Spieler, Marlena (6 January 2009). "Saving a Squirrel by Eating One". The New York Times. ISSN 0362-4331. Retrieved 13 December 2021.
  63. ^ "Red squirrel conservation, squirrel ecology and grey squirrel management". The Friends of the Anglesey Red Squirrels. Retrieved 22 August 2007.
  64. ^ Wauters, L. A.; Gurnell, J.; Martinoli, A. & Tosi, G. (2002). "Interspecific competition between native Eurasian red squirrels and alien grey squirrels: does resource partitioning occur?". Behavioral Ecology and Sociobiology. 52 (4): 332–341. doi:10.1007/s00265-002-0516-9. S2CID 44051537.
  65. ^ a b c d "Controlling the grey squirrel population | Department of Agriculture, Environment and Rural Affairs". DAERA. 24 August 2015. Retrieved 19 November 2022.
  66. ^ Molles, Manuel C., Jr. (2019). Ecology : concepts and applications. Anna Sher (Eighth ed.). New York, NY. ISBN 978-1-259-88005-6. OCLC 1010579815.
  67. ^ "Black squirrels set to dominate". BBC News. 20 January 2009. Retrieved 30 October 2011.
  68. ^ "Defra Rural Development Service Technical Advice Note 09" (PDF). Archived from the original (PDF) on 1 July 2007.
  69. ^ Bertolino, Sandro; Genovesi, Piero (2003). "Spread and attempted eradication of the grey squirrel (Sciurus carolinensis) in Italy, and consequences for the red squirrel (Sciurus vulgaris) in Eurasia" (PDF). Biological Conservation. 109 (3): 351–358. doi:10.1016/S0006-3207(02)00161-1.
  70. ^ United Nations Environment Programme World Conservation Monitoring Centre (2010) Review of the Grey Squirrel Sciurus carolinensis. UNEP-WCMC, Cambridge
  71. ^ Lawniczak, Mara Katharine. "Sciurus carolinensis (eastern gray squirrel)". Animal Diversity Web. Retrieved 3 November 2022.
  72. ^ "Why should you love squirrels? Here are six reasons". news.ufl.edu. Retrieved 3 November 2022.
  73. ^ Lawniczak, Mara Katharine. "Sciurus carolinensis (eastern gray squirrel)". Animal Diversity Web. Retrieved 20 November 2022.
  74. ^ "Wild meat: Squirrel nutcase". The Economist, Vol. 402 Number 8772 (3 March 2012).
  75. ^ Blakeslee, Sandra (27 August 1997). "Kentucky Doctors Warn Against a Regional Dish: Squirrels' Brains". The New York Times. Retrieved 15 February 2017.

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Eastern gray squirrel: Brief Summary

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The eastern gray squirrel (Sciurus carolinensis), also known, particularly outside of North America, as simply the grey squirrel, is a tree squirrel in the genus Sciurus. It is native to eastern North America, where it is the most prodigious and ecologically essential natural forest regenerator. Widely introduced to certain places around the world, the eastern gray squirrel in Europe, in particular, is regarded as an invasive species.

In Europe, Sciurus carolinensis is included since 2016 in the list of Invasive Alien Species of Union concern (the Union list). This implies that this species cannot be imported, bred, transported, commercialized, or intentionally released into the environment in the whole of the European Union.

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