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Species
Sciurus carolinensis Gmelin 1788
IUCN
NCBI
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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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Rights holder/Author | ©1995-2013, The Regents of the University of Michigan and its licensors |
Source | http://animaldiversity.ummz.umich.edu/accounts/Sciurus_carolinensis/ |
Some interesting clines, or geographic changes, occur in both skull size and coat color. Going from north to south, skull sizes decrease, even though toothrows and mandible sizes remain the same. Also, more black-coated squirrels occur in the north. It may be that being black gives these squirrels some advantages over grey colored squirrels in colder northern climates.
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | ©1995-2012, The Regents of the University of Michigan and its licensors |
Source | http://www.biokids.umich.edu/critters/Sciurus_carolinensis/ |
Eastern grey squirrels are found throughout the eastern United States to just west of the Mississippi River and north into Canada. They have been introduced into some part of the western United states and some areas of Canada where they were not previously found. They have also been introduced into Italy, Scotland, England, and Ireland. In these places eastern grey squirrels are considered a pest species. They compete with native European red squirrels. In some areas, the native squirrels are becoming threatened and endangered as a result of this competition.
Biogeographic Regions: nearctic (Introduced , Native ); palearctic (Introduced )
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Rights holder/Author | ©1995-2012, The Regents of the University of Michigan and its licensors |
Source | http://www.biokids.umich.edu/critters/Sciurus_carolinensis/ |
Eastern gray squirrels feed mostly on nuts, seeds, flowers and buds of various trees. These trees include maple, mulberry, hackberry, elm, and dogwood. The seeds they eat usually come from cedar, hemlock, pine, and spruce. They also eat a variety of herbaceous plants and fungi. Crops, such as corn and wheat, are also eaten, especially in the winter. Insecta are eaten in the summer and are especially important for young squirrels. Cannibalism has been reported, and squirrels may also eat bones, Aves eggs and nestlings, and Anura. They bury food in winter caches using a method called scatter hoarding. They later locate these caches using both memory and smell.
Female eastern grey squirrels need extra protein and minerals from their foods when they are pregnant and nursing young. They may get these from insects, meat, and bones. They also need extra water during nursing. Squirrels can get some moisture from the foods they eat but generally need to drink standing water, which they can get from streams, ponds, puddles, or from small pools of water that collect in tree holes during rains.
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
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | ©1995-2012, The Regents of the University of Michigan and its licensors |
Source | http://www.biokids.umich.edu/critters/Sciurus_carolinensis/ |
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.
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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Rights holder/Author | ©1995-2013, The Regents of the University of Michigan and its licensors |
Source | http://animaldiversity.ummz.umich.edu/accounts/Sciurus_carolinensis/ |
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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Rights holder/Author | Copyright Wildscreen 2003-2008 |
Source | http://www.arkive.org/grey-squirrel/sciurus-carolinensis/ |
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.
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | ©1995-2013, The Regents of the University of Michigan and its licensors |
Source | http://animaldiversity.ummz.umich.edu/accounts/Sciurus_carolinensis/ |
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)
Pregnancy lasts 44 days. Most females begin their reproductive life at 1.25 years old 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. 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)
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | ©1995-2012, The Regents of the University of Michigan and its licensors |
Source | http://www.biokids.umich.edu/critters/Sciurus_carolinensis/ |
Comments: Popular game species, with many millions harvested annually.
License | http://creativecommons.org/licenses/by-nc/3.0/ |
Rights holder/Author | NatureServe |
Source | http://explorer.natureserve.org/servlet/NatureServe?searchName=Sciurus+carolinensis |