Pine squirrel, Chickaree, Douglas’s squirrel
The Douglas squirrel (Tamiasciurus douglasii) is a pine squirrel found in the Pacific Northwest of North America. It is sometimes known as the chickaree or Pine squirrel, although these names are also used for the American red squirrel. The Native Americans of Kings River also called the Douglas squirrel the "Pillillooeet", in imitation of its characteristic alarm call.
Douglas squirrels are distinguished by their orange-colored front teeth that never stop growing. Hence, they constantly control the length of their teeth so they don't overgrow. Their appearance varies according to the season. In the summer, they are greyish or almost greenish-brown on their backs, pale orange on the chest and belly, while their legs and feet appear brown. In the winter, the coat is browner and the underside is grayer; the ears also appear even tuftier than in summer. Like many squirrels, Douglas squirrels have a white eye ring.
Endemic to the Pacific coast of North America, the Douglas squirrels occur in northern California, west and central Oregon, western Washington, and southwestern British Columbia (Canada). The preferred habitat of this species is coniferous forest.
Douglas squirrels are active throughout the year, although they usually spend cold winters and storms in their nests. During the summer months, they construct their nests in the forks of limbs of trees. During the winter months, they nest in tree crevices, holes from deserted woodpecker nests as well as under their underground food stores. Douglas squirrels may also use empty nests, abandoned by birds. Individuals are usually solitary except with mothers and their young. In addition, mature squirrels socialize during the mating season. As scansorial animals, Douglas squirrels are excellent climbers and jumpers. When moving in trees, the powerful claws allow them to grip tree bark, whereas the tail helps them keep balance. They spend the greater part of their time climbing, watching after predators, and looking for food. In spite of their solitary habits, these squirrels are very noisy animals, particularly when they defend their territories or give out an alarm call.
Douglas squirrels are herbivores (granivores) and primarily feed on pine seeds. However, their diet usually varies depending on the season of the year. Overall, they consume fungi, cambium of conifers, twigs, sap, leaves, buds, nuts such as acorns, mushrooms, fruits, and berries, supplementing this diet with occasional nestlings, eggs of birds as well as various arthropods.
Douglas squirrels have a monogamous mating system in which one male mates with one female exclusively. Breeding season occurs in March-June but sometimes can last from February to August. Females usually yield a single litter per year. However, sometimes they may produce another litter by the end of the breeding season, in August-September. The gestation period lasts for 31-35 days, yielding 4-6 young, which are blind and lack fur. The young gain their fur at 18 days old, opening their eyes at 26-36 days of age. After a while, they leave the nest but continue to closely associate with their mother. The weaning process takes around 6 to 9 weeks. Becoming independent, young squirrels remain with the family until 4-7 months of age and become reproductively mature when they are 8-9 months old.
Along with many other species of their range, the Douglas squirrels suffer from toxins that are present in their habitat due to human activities. On the other hand, these animals are threatened by the destruction of their natural habitat, including the critically endangered temperate rainforests.
According to IUCN, the Douglas squirrel is common throughout its range but no overall population estimate is available. Today, this species’ numbers are stable and it is classified as Least Concern (LC) on the IUCN Red List.
On one hand, the Douglas squirrels disperse seeds from conifer trees by carrying cones to their food stores. On the other hand, due to consuming fruiting bodies of fungi, these rodents serve as key distributors of fungi's spores, doing it through their feces. Subsequently, fungi spores develop mycorrhizal relationships with the roots of conifer trees.
