Eastern Gray Squirrel (Sciurus carolinensis)

KINGDOM Animalia
PHYLUM Chordata
CLASS Mammalia
ORDER Rodentia
FAMILY Sciuridae


This bushy-tailed arboreal rodent is gray with rusty tinges on the face, sides, and legs, and white underparts. With tail, it averages about 45 cm in length. It is one of the most familiar mammals of the Pacific Northwest, but that was not the case a century ago. It has been widely introduced into the region from its native range in the forests of eastern North America, the first introduction in Seattle in 1925. And, it should be added, the introductions have been widely successful. The deciduous trees it prefers as habitat and food sources are widely planted in Northwest cities, if not native there.

The presence of Eastern Gray Squirrels is easily detected by their prominent “nests” of leaves high in trees. These are sleeping nests, less preferred than a tree hollow, especially as a permanent den where the young are born. Mating takes place during the winter, and two or three young are born to reproducing females during early spring. They stay in the nest and nurse for 8–9 weeks, when they are weaned and abandoned by their mother. Some females have a second litter, mating in summer and giving birth in early fall.

These squirrels live only about a year, on average, but a few (not only the oldest but presumably the wisest) have survived as much as ten years. Their preferred foods include nuts of all kinds, for example acorns and beech nuts in their native range, but include other seeds, leaf buds, flowers, and the cambium layer of tree bark. They spend much time hunting for fungi, including some that are poisonous to humans. Eastern Gray Squirrel populations wax and wane with the abundance of nut crops in their native range, but this is less evident in the Northwest.

Many members of the squirrel family cache seeds for later recovery, and this one is no exception. Give one a succession of peanuts and watch what it does with them. Caching behavior is well developed only in certain mammals and birds, in which it increases the odds of winter survival. The squirrels push the peanuts into the ground and later find them by smell.

Many home owners consider these squirrels a nuisance when they are attracted to bird feeders, but in fact they furnish the opportunity to watch the behavior of a small mammal at length. The native Western Gray Squirrel has disappeared from much of its former range around Puget Sound, presumably because of habitat changes and intolerance of development, and native Douglas Squirrels and Townsend’s Chipmunks have become rare in most cities, so the presence of a survivor such as this may be what we have to accept as a substitute. We know of no deleterious effect it has on any native species.