E-Fauna BC: Electronic Atlas of the Wildlife of British Columbia

Tamiasciurus douglasii (Bachman, 1839)
Douglas Squirrel
Family: Sciuridae

© Les Leighton  Email the photographer   (Photo ID #8978)


Distribution of Tamiasciurus douglasii in British Columbia.
Source: Map courtesy of David Nagorsen

Introduction


Douglas Squirrel is a small species of diurnal, conifer-associated pine squirrel that is found in the southwestern corner of British Columbia, along the coast and on a handful of islands in Howe Sound and Desolation Sound. It is similar to the Red Squirrel--a species that is more widely spread in the province and in Canada, but is not found in the southwestern coastal areas of the province where the Douglas Squirrel is found. Because the Douglas Squirrel is dependent on old growth and mature forests, it is often displaced in its BC range by urban development and removal of required forest habitat. In some locations in BC, it can co-occur with the introduced Eastern Grey Squirrel. In spite of concerns that the Eastern Grey Squirrel displaces the native Douglas Squirrel, there is no evidence of this (Gonzales et al. 2008). Two well-known examples of co-occurrences in BC are in Stanley Park, where the two species have co-occurred for more than 90 years (Gonzales 2001), and in the forested portions of the Richmond Nature Park (Davis and Klinkenberg 2008).

Read the paper by Gonzales et al. (2008) for more details on the relationship between native and non-native squirrels.

Species Information

Douglas Squirrels are about 33 cm in length (including its tail, which is about 13 cm long), and weigh between 150 and 300 grams. Their appearance varies according to the season. In the summer, they are a grayish or almost greenish brown on their backs, and pale orange on the chest and belly, while legs and feet appear brown. In the winter, the coat is browner and the underside is grayer; also, the ears appear even tuftier than they do in summer. Like many squirrels, Douglas Squirrels have a white eye ring. A noticeable black band run along the sides.

Biology


Douglas Squirrels are active by day, throughout the year. In summer nights, they sleep in ball-shaped nests that they make in the trees, but in the winter they use holes in trees as nests. They are territorial; in winter, each squirrel occupies a territory of about 10,000 square metres, but during the breeding season a mated pair will defend a single territory together. Groups of squirrels seen together during the summer are likely to be juveniles from a single litter.
Reproduction

Mating can occur as early as February. Gestation is about four weeks, and the young (which are altricial) are weaned at about eight weeks of age. There may be up to six kits in a litter, though four is more usual. In the southern and lower parts of their range they produce two litters each year.
Diet

Douglas Squirrels mostly eat seeds of coniferous trees such as Douglas Fir, Sitka Spruce and Shore Pine, though they do also eat acorns, berries, mushrooms, the eggs of birds such as Yellow Warblers, and some fruit. Unlike many other types of tree squirrel, they lack cheek pouches in which to hold food. They are scatter hoarders, burying pine cones (which they cut from the trees while green) during the autumn. They often use a single place, called a midden, for peeling the scales off cones to get at the seeds. The discarded scales may accumulate for years, into piles more than a meter across as the same site is used by generations of squirrels.
Behaviour

Douglas Squirrels are active by day, throughout the year, often chattering noisily at intruders. In summer nights, they sleep in ball-shaped nests that they make in the trees, but in the winter they use holes in trees as nests. They are territorial; in winter, each squirrel occupies a territory of about 10,000 square metres, but during the breeding season a mated pair will defend a single territory together. Groups of squirrels seen together during the summer are likely to be juveniles from a single litter.
Predators

Predators include American Martens, Bobcats, domestic cats, Northern Goshawks, and owls.

Habitat


Douglas Squirrels live in coniferous forests, from the Sierra Nevada mountains of California northwards to coastal British Columbia, from sea level to approx. 1800 m. They prefer old-growth or mature second-growth forest, and some authors regard them as dependent on its presence.

Distribution

Global Range

This species of pine squirrel is found in the Pacific coastal states and provinces of North America.
Distribution in British Columbia

In British Columbia, the Douglas Squirrel is found along the coast and in the coast mountains in the southwestern corner of the proviince, as far east as Pemberton. It is reported from six coastal islands (Bowen and Gambier Islands in Howe Sound and four islands in Desolation Sound.

Conservation


BC populations of this species are not of conservation concern.

Taxonomy


Little genetic difference between Douglas Squirrel and Red Squirrel has been found, and reports of hybrids between the two species have not been, so far, supported by genetic studies. Four subspecies of Douglas Squirrel are presently recognized, with one subspecies found in BC: Tamiasciurus douglasii mollipilosus (a small coastal form).

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)
COSEWIC
NativeS4S5YellowNot Listed
BC Ministry of Environment: BC Species and Ecosystems Explorer--the authoritative source for conservation information in British Columbia.

Additional Photo Sources

Species References

Nagorsen, David W. 2005. Rodents and Lagomorphs of British Columbia. Royal BC Museum Handbook. Royal BC Museum, Victoria.

General References


Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2019. E-Fauna BC: Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. [Accessed: 23/10/2019 10:46:29 AM]
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