The eastern gray squirrel (Sciurus carolinensis), also known as the grey squirrel depending on region, 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.
Sciurus carolinensis is native to the eastern and midwestern United States, and to the southerly portions of the eastern 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 to Manitoba, south to East Texas and Florida. Breeding eastern gray squirrels are found in Nova Scotia, but whether this population was introduced or came from natural range expansion is not known. It has also been introduced into Ireland, Britain, Italy, South Africa, and Australia (where it was extirpated by 1973). Eastern gray squirrels in Europe are a concern because they have displaced some of the native squirrels there. In 1966, this squirrel was also introduced to 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 red squirrel.
A prolific and adaptable species, the eastern gray squirrel has also been introduced to, and thrives in, several regions of the western United States. The gray squirrel is an invasive species in Britain; it has spread across the country and has largely displaced the native red squirrel, S. vulgaris. In Ireland, the red squirrel has been displaced in several eastern counties, though it still remains common in the south and west of the country. That such a displacement might happen in Italy is of concern, as gray squirrels might spread to other parts of mainland Europe.
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. 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).
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. It has a large bushy tail. Particularly in urban situations where the risk of predation is reduced, both white – 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. Genetic variations within these include individuals with black tails and black-colored squirrels with white tails. (See tree squirrel for more information on these color variations.)
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). They do not display sexual dimorphism, meaning there is no gender difference in size or coloration.
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.
The dental formula of the eastern gray squirrel is 1023/1013 (Upper teeth/Lower Teeth).
220.127.116.11 × 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.
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. 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, and use 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.
Squirrels sometimes use deceptive behavior to prevent other animals from retrieving cached food. 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 behaviors are not innate, and imply theory of mind thinking.
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.
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 30~60 cm in diameter and are usually insulated with moss, thistledown, dried grass, and feathers to reduce heat loss. 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. In addition, squirrels may inhabit a permanent tree den hollowed out in the trunk or a large branch of a tree.
Predators include humans, hawks, weasels, raccoons, foxes, domestic and feral cats, snakes, owls, and dogs. In its introduced range in South Africa, it has been preyed on by African harrier-hawks.
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. In a year of abundant food, 36% of females bear two litters, but none will do so in a year of poor food. Their breeding seasons are December to February and May to June, though this is slightly delayed in more northern latitudes. 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. 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 polygyny, in which the competing males will form a hierarchy of dominance, and the female will mate with multiple males depending on the hierarchy established.
Normally, one to four young are born in each litter, but the largest possible litter size is eight. The gestation period is about 44 days. 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.
Rarely, eastern gray females can enter estrus as early as five and a half months old, but females are not normally fertile until at least one year of age. Their mean age of first estrus is 1.25 years. The presence of a fertile male will induce ovulation in a female going through estrus. Male eastern grays are sexually mature between one and two years of age. Reproductive longevity for females appears to be over 8 years, with 12.5 years documented in North Carolina. 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.
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.
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. 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.
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.
Eastern gray squirrels eat a range of foods, such as tree bark, tree buds, 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). 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. The squirrels also raid gardens for tomatoes, corn, strawberries, and other garden crops. 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. They also gnaw on bones, antlers, and turtle shells – likely as a source of minerals scarce in their normal diet.
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. 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. 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.
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. These forests usually contain large amounts of dense understory vegetation that provides them sufficient amount of food sources and favorable shelters. Oak-hickory hardwood forests are preferred over coniferous forests.
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.
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.
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; 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. At the turn of the 20th century, the eastern gray squirrel was introduced into South Africa, Ireland, Hawaii, Bermuda, Madeira Island, the Azores, the Canary Islands, Cape Verde, Italy and the United Kingdom.
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. Even so, it is unable to use the natural vegetation (fynbos) found in the area, a factor which has helped to limit its spread. 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) and different habitats.
Gray squirrels were first introduced to Britain in the 1870s, as fashionable additions to estates. 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.
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.
In Britain and Ireland, the eastern gray squirrel is not regulated by natural predators, other than the European pine marten, which is generally absent from England and Wales. 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 one plan for celebrity television chefs to promote the idea of eating the squirrels. In areas where relict populations of red squirrels survive, such as the islands of Anglesey and Brownsea, programs exist to eradicate gray squirrels in an effort to allow red squirrel populations to recover.
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. 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. 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. 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.
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. 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 should be humanely destroyed.
Twenty different Pleistocene fauna specimens contain S. carolinensis, found in Florida and dated to be as early as the late Irvingtonian period. Body size seems to have increased during the early to middle Holocene and then decreased to the present size seen today.
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. 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.
The black squirrel occurs as a melanistic subgroup of both the eastern gray squirrel and the fox squirrel. Their habitat extends throughout the Midwestern United States, in some areas of the Northeastern United States, Eastern Canada, and also in the United Kingdom. The overall population of black squirrels is small when compared to that of the gray squirrel. The rarity of the black squirrel has caused many people to admire them, and the black squirrels enjoy great affection in some places as mascots.Clove Lakes Park
Clove Lakes Park is a public park located in the New York City borough of Staten Island, in the neighborhood of Sunnyside.With valuable ecological assets, Clove Lakes Park has a rich natural history and a few remnants of the past. Chief among them are the park's lakes and ponds, outcroppings of serpentine rocks, and Staten Island's largest living thing, a 119-foot-tall (36 m) tulip tree. Clove Lakes Park is home to many species of indigenous wildlife. Visitors can see fish such as black crappie, brown bullhead, bluegill, emerald shiner, pumpkinseed, largemouth bass, and carp; birds such as red-tailed hawk, belted kingfisher, double-crested cormorant, red-winged blackbird, Canada goose, and mallard: as well as reptiles and amphibians, like the common snapping turtle, eastern painted turtle, red-eared slider, and occasionally even the red-backed salamander. The park is also home to mammals such as eastern gray squirrel, muskrat, eastern cottontail, and eastern chipmunk.
Interstate 278, built in 1964, goes through the cleft inside the park to connect the roadway to major interchanges at the then-newly built Verrazano-Narrows Bridge to the East and the Goethals Bridge to the West. When first proposed, the expressway was to be named the Clove Lake Expressway.
The park is known for its cozy picnic accommodations and boating. Besides strolling down trails and paddling on its bodies of water to appreciate its beauty, visitors can also experience the park as a more modern recreation zone. Several baseball diamonds, a soccer field, basketball court, playgrounds, and football field dot the park's landscape. The Staten Island World War II Veteran's Memorial Ice Skating Rink is an outdoor rink located in what could be called the "active" part of the park, close to its other fields and courts.
The park consists of three lakes; the main one is Clove Lake, which run offs to Martling Lake, and then to Brooks Lake.Eastern grey squirrels in Europe
Europe's grey squirrels (Sciurus carolinensis) originated in North America, where they are known as eastern gray squirrels (to differentiate from western gray squirrels). They eat large seeds, flowers, buds, fruits, fungi, some insects and occasionally bird eggs. The eastern grey squirrel was introduced to Continental Europe in 1948 and has quickly taken advantage of Europe's food sources, habitats and lack of predators for grey squirrels. They were first introduced into England, in a concerted way, in 1876, and through rapidly growing population and further introductions they spread to the rest of Britain by the early-to-mid 20th century. The native squirrel in Europe is the red squirrel (Sciurus vulgaris). Both species have similar diets, use similar locations of the environment and have similar activity patterns; however, there is no evidence of noticeable aggression between the two species. These eastern grey squirrels are considered an invasive species in Europe because of their presence contributing to the displacement of the red squirrels.
The invasion of the grey squirrel in the United Kingdom can be classified as a Disease Mediated Invasion (DMI). More specifically, the invasion of the grey squirrels and displacement of the red squirrels can be described by "spillover DMI", which is defined as a non-native species bringing diseases with them into the new area that will infect the native species. Spillover is especially an issue of when the invading species is morphologically similar to the native one. This can have devastating effects.Gray squirrel
Gray squirrel or grey squirrel may refer to several species of squirrel indigenous to North America:
The eastern gray squirrel (Sciurus carolinensis), from the eastern United States and southeastern Canada; introduced into Britain, Ireland, western North America, Italy, and South Africa
The western gray squirrel (Sciurus griseus), from the western United States
The Arizona gray squirrel (Sciurus arizonensis), from the southwestern United States and adjacent Mexico
The Mexican gray squirrel (Sciurus aureogaster), from southern Mexico and Guatemala; introduced into the Florida KeysJapanese squirrel
The Japanese squirrel (Sciurus lis) is a tree squirrel in the genus Sciurus endemic to Japan. The Japanese squirrel's range includes the islands of Honshū, Shikoku, and Kyūshū. Recently, populations on south-western Honshū and Shikoku decreased, and those on Kyūshū disappeared. One of the factors affecting the local extinction of this species seems to be forest fragmentation by humans.Jock's Copse
Jock's Copse is a local nature reserve in Priestwood, Berkshire, England. The nature reserve is owned and managed by Bracknell Forest Borough Council. Along with Temple Copse & Tinkers Copse it forms part of what is known locally as The Three Copses.Mearns's squirrel
Mearns's squirrel (Tamiasciurus mearnsi) is a species of squirrel native to Mexico. It is an endangered species which occurs in low densities and is threatened by habitat loss. It is possibly also threatened by competition from the eastern gray squirrel, which was introduced to the range of Mearns's squirrel in 1946, but may not be present anymore. It is closely related to the Douglas squirrel, but far less is known about its behavior, which was first studied in detail in 2004-2005. It is named for the nineteenth century American naturalist Edgar Mearns.Pennsylvania State Game Lands Number 256
State Game Lands No. 256 consists of 1,254 acres, located in Perry County east of New Bloomfield, Pennsylvania, United States. The terrain is gently rolling woodland broken by numerous small drainages. The most common game species found here are deer, wild turkey, grouse, and eastern gray squirrel.Pine squirrel
Pine squirrels are squirrels of the genus Tamiasciurus, in the Sciurini tribe, of the large family Sciuridae.Sciurinae
Sciurinae is a subfamily of squirrels in the (family Sciuridae), uniting the flying squirrels with certain related tree squirrels. Older sources place the flying squirrels in a separate subfamily (Pteromyinae) and unite all remaining sciurids into the subfamily Sciurinae, but this has been strongly refuted by genetic studies.Sciurini
Sciurini is a tribe that includes about forty species of squirrels, mostly from the Americas. It includes five living genera—the American dwarf squirrels, Microsciurus; the Bornean Rheithrosciurus; the widespread American and Eurasian tree squirrels of the genus Sciurus, which includes some of the best known squirrel species; the Central American Syntheosciurus; and the American pine squirrels, Tamiasciurus. Like other arboreal squirrels, they are sometimes referred to as tree squirrels.Sciurus
The genus Sciurus contains most of the common, bushy-tailed squirrels in North America, Europe, temperate Asia, Central America and South America.Sleepy Creek Wildlife Management Area
Sleepy Creek Wildlife Management Area is located in Morgan and Berkeley Counties in West Virginia's Eastern Panhandle. It encompasses 22,928 acres (92.79 km2), mostly covered with mixed oak and pine forest, although about 3,500 acres (14 km2) are covered with mixed hardwoods. The 205-acre (83 ha) Sleepy Creek Lake is located entirely within the WMA.Temple Copse
Temple Copse is a local nature reserve in Priestwood, Berkshire, England. The nature reserve is owned and managed by Bracknell Forest Borough Council. Along with Jock's Copse & Tinkers Copse it forms part of what is known locally as The Three Copses.Tinkers Copse
Tinkers Copse is a local nature reserve in Priestwood, Berkshire, England. The nature reserve is owned and managed by Bracknell Forest Borough Council. Along with Jock's Copse & Temple Copse it forms part of what is known locally as The Three Copses.Tommy Tucker (squirrel)
Tommy Tucker (before/in 1942 – 25 June 1949) was a male Eastern gray squirrel who became a celebrity in the United States, touring the country wearing women's fashions while performing tricks, entertaining children, and selling war bonds. A Washington Post columnist called him "the most famous squirrel ever to come from Washington."Tree squirrel
Tree squirrels are the members of the squirrel family (Sciuridae) commonly just referred to as "squirrels". They include over a hundred arboreal species native to all continents except Antarctica and Oceania. They do not form a single natural, or monophyletic group; they are related to others in the squirrel family, including ground squirrels, flying squirrels, marmots, and chipmunks. The defining characteristic used to determine which species of Sciuridae are tree squirrels is dependent on their habitat rather than their physiology. Tree squirrels live mostly among trees, as opposed to those that live in burrows in the ground or among rocks. An exception is the flying squirrel that also makes its home in trees, but has a physiological distinction separating it from its tree squirrel cousins: special flaps of skin called patagia, acting as glider wings, which allows gliding flight.
The best known genus of tree squirrels is Sciurus, which includes the Eastern gray squirrel of North America (introduced to Great Britain in 1876), the red squirrel of Eurasia, and the North American fox squirrel, among many others. Many tree squirrel species have adapted to human-altered environments such as rural farms, suburban backyards and urban parks; and because they are diurnal (active during the daytime) they have become perhaps the most familiar wildlife to most humans.Western gray squirrel
The western gray squirrel (Sciurus griseus) is an arboreal rodent found along the western coast of the United States and Mexico. It is a tree squirrel.
In some places, this species has also been known as the silver-gray squirrel, the California gray squirrel, the Oregon gray squirrel, the Columbian gray squirrel and the banner-tail. There are three geographical subspecies: Sciurus griseus griseus (central Washington to the western Sierra Nevada in central California); S. g. nigripes (from south of San Francisco Bay to San Luis Obispo County, California); and S. g. anthonyi (which ranges from San Luis Obispo to northern Baja California).
Game animals and shooting in North America