Eastern Grey Squirrels

SCIENTIFIC NAME: Sciurus Carolinensis

DESCRIPTION: The grey squirrel weighs approximately 275g, has a body height of approximately 25cm and a tail length of approximately 20cm. Both sexes appear to be gray in color. However, their hair is actually a mix of black, white, and brown banding on each individual strand. Their underside is white with some cinnamon color flanks on the face and sides just behind the front shoulder. Each of the tail hairs is tipped with white and often lighter gray than its body.

The Western Red Squirrel (Tamiasciurus hudsonicus) is approximately half the size of the Grey’s. The Grey Squirrels’ shear size allows them to dominate and extirpate the Red’s from their traditional territory.

DISTRIBUTION: Eastern grey squirrels are native to central and eastern North America,
from southern Canada as far west as Manitoba to the Gulf of Mexico. They have been introduced to western North America, Europe South Africa and Australia. Grey squirrels were first introduced to Stanley Park in Vancouver, British Columbia sometime before 1914. This population has now spread through the lower Fraser Valley and south into the United States. There are also scattered populations in British Columbia and Alberta. Grey squirrels were introduced to southern Vancouver Island in 1966 and are now found as far north as Nanaimo.

THREATS:

Impacts on Garry Oak and associated ecosystems
Eastern grey squirrels cache acorns in the ground and can be effective dispersers of some species of oak. However, they frequently bite out the tips of the acorns of some oaks, including Garry oaks, and may negatively affect oak regeneration. Grey squirrels also disperse the seeds of other plants. Grey squirrels can damage and kill trees, especially young oaks, by stripping the bark. Squirrels may also eat native lily bulbs such as camas (Camassia spp.) in Garry oak ecosystems. Squirrels eat birds’ eggs and nestlings and compete with birds for tree cavities. Grey squirrels eat large numbers of acorns and may compete with other species that depend on this food. In Europe, eastern grey squirrels have displaced European red squirrels (Sciurus vulgaris). The Grey Squirrel has made it to the Invasive Species Specialist Group of the World Conservation Union’s list of “100 of the World’s Worst Invasive Alien Species.” British and Italian environmental groups have ranked the Grey Squirrel as second in negative impact only to the Norway rat (Rattus norvegicus). The most damaging food item enjoyed by the Grey Squirrel is tree bark. In winter when food is scarce, the Grey Squirrel can strip maples, pines, hemlocks and others of their protective bark, leaving the tree vulnerable to disease.

Impacts on Urban Centres
The most serious damage in urban areas arises where the squirrel enters the roof spaces of houses by climbing the walls or jumping from nearby trees. Once inside, they chew woodwork, ceilings, and insulation on electrical wiring or tear up the loft insulation to form a drey. The noise nuisance from a litter of squirrels can cause many sleepless nights. They are also a pest in the garden—they raid fruit crops, bird feeders and can cause damage to trees by stripping the bark, which often results in the weakening of young shoots and a misshapen tree.

Impacts on Nut Growers and Farmers
In the rural areas such as the Sannich Peninsula where Nut Growers are inundated with Grey Squirrels, farmers are facing massive losses of nut crops. Fruit Growers in the Southern USA are also experiencing loss due to squirrels biting and damaging or eating the fruit.

In British Columbia, grey squirrels can reach higher densities than native red squirrels (Tamiasciurus hudsonicus) and may outnumber and eventually displace them, especially in highly fragmented and mixed oak/conifer forests where their habitats may overlap. Grey squirrels may be carriers of parapoxvirus, which may infect North American red squirrels.

INTRODUCED SPECIES: are a most serious threat to biodiversity, second only to habitat degradation. The eastern gray squirrel (Sciurus carolinensis) is native to eastern North America, but has been introduced to several countries outside its natural range. In Europe, it has been introduced to Britain, Ireland, and Italy, and in all 3 countries it has spread and replaced the native European red squirrel (S. vulgaris). There are several possible explanations for the replacement of the European red squirrel by eastern gray squirrels, but the main hypotheses involve exploitation competition between the 2 species, although a disease that is fatal to red squirrels and possibly spread by the gray squirrel also may have contributed. Gray squirrels cause economic damage to forests by removing bark from trees, particularly broadleafed types such as oak and beech, and have the potential to suppress natural forest regeneration.

FEEDING HABITS: Gray squirrels are most active for two hours after sunrise and for two to five hours before sunset. During this time, squirrels tend to move more along the ground using their sense of smell to find food. The gray squirrel’s feeding habits are seasonal. During the winter months, they prefer acorns, nuts, and other seeds of a variety of hardwood and pine species. In the spring and summer months, they may eat a variety of plant buds, insects, agricultural crops, or bone.

LIFE HISTORY: The eastern gray squirrel has two breeding periods per year – one around December to February and the other around May to June. During these months, this animal is a promiscuous breeder. Essentially, both sexes breed with multiple partners. Competition is the tool used to determine which males will mate. Once female gray squirrels are bred, they have a 42 to 46 day gestation period. At the end of this time, the female gives birth to a litter of two to four altricial young in a nest made of leaves and twigs about 30 to 45 feet above the ground or in a tree den. Altricial young are helpless and dependant upon maternal care. They are hairless except for whisker-like hair around their nose and mouth. These hairs are used as feelers. Newborn gray squirrels weigh about one-half ounce. Females start to wean their young at about seven weeks of age and the weaning process is usually completed by the tenth week of life. Young squirrels reach physical and sexual maturity at about nine and 14 months of age.