The Eastern Grey Squirrel is an introduced species in British Columbia, and is native to eastern North America. It has spread since its arrival in the province and is now found in the lower Fraser Valley, the Okanagan and southern Vancouver Island. In spite of concerns, according to Nagorsen (pers. comm.2012, there is no evidence that this species is impacting the native Douglas Squirrel. Read more below.
The native range of the Eastern Grey Squirrel is the eastern United States and adjacent southern Canada; New Brunswick to Manitoba, south to eastern Texas and Florida. However, it has been introduced to other parts of North America and to Europe. It was introduced to the British Isles, Italy, South Africa, and Australia (extirpated by 1973). On mainland Britain, it has almost entirely displaced the populations of native Red Squirrels. It was also introduced to a variety of locations on the west coast of North America, including British Columbia and the states of Washington and Oregon and, in California, to the city of San Francisco and the peninsula area of San Mateo and Santa Clara counties, south of the city. It has become the most common squirrel in many urban and suburban habitats in the western United States north of central California.
In British Columbia, the Eastern Grey Squirrel is found in the lower Fraser Valley, the Okanagan, and southern Vancouver Island. There were two separate introductions of the species in the province, one in Stanley Park around 1914 (an intentional introduction), and one in southeastern Vancouver Island in the late 1960's (three squirrels escaped from a farm). It is now well established in the lower Fraser Valley (east to Chilliwack and south to Boundary Bay), with reports from 100 Mile House and Quesnel. In 2009, it was first reported in the Okanagan (Nagorsen pers. comm. 2012). On Vancouver Island it is found west to Sooke, and north to Duncan.
Carl and Guiget (1958) provide the following information on its first arrival in BC:: "Gray Squirrels were introduced to Stanley Park at Vancouver shortly before 1914. Three or four pairs were released from stock believed to have been obtained in Ontario. They had become established by 1920."
Five subspecies of the Eastern Gray Squirrel are recognized. The BC populations are thought to be derived from Ontario populations, which are Sciurus carolinensis pennsylvanicus
Conservation Note :
Displacement of the native Douglas Squirrel and Red Squirrel in BC by this introduced species has been a concern of naturalists and the provincial Ministry of the Environment. Nonetheless, any declines or range loss in the two native squirrel species is more likely the result of the loss of coniferous forest habitat from urbanization on SE Vancouver Island and the lower mainland rather than displacement by the Eastern Grey Squirrel. In eastern North America, Red Squirrels and Eastern Grey Squirrels co-exist but use different habitats. A preliminary study done by a student from the University of Saskatchewan in Stanley Park and Pacific Spirit Park in the lower mainland (see Hwang and Larivière 2006) found little evidence for a decline in the native Douglas Squirrel despite populations of Eastern Grey Squirrels in the parks. However, impact on Garry oak savannas on southeastern Vancouver Island may be a concern, as Eastern Grey Squirrels may kill some acorns before burying them. More research is need to determine the impact of the Eastern Grey squirrel on our native flora and fauna.
Conservation Note Author: David Nagorsen