Pine squirrel, Chickaree, Douglas’s squirrel, Douglas’ squirrel
The Douglas squirrel is a rodent, native to British Columbia. This species is otherwise called 'the pine squirrel' and 'chickaree'. The Douglas squirrels are distinguished by their orange colored front teeth that never stop growing. Hence, they constantly control the length of their teeth so that they don't overgrow. Within their range, the Douglas squirrels compete with the introduced species of the Eastern grey squirrel.
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 conifer forest or at least one, having some conifer trees.
These diurnal animals are active throughout the year, although they usually spend cold winters and storms in their nests. During the summer months, these animals 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. The Douglas squirrels are also known to 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.
As granivorous animals, these squirrels primarily feed upon pine seeds. However, their diet usually varies depending on 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 are monogamous, which means that 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. Gestation period lasts for 31 - 35 days, yielding 4 - 6 young, which are blind and lack fur. A newborn baby of this species is very tiny, weighing only 13 - 18 g. Young gain their fur at 18 days old, opening their eyes at 26 - 36 days of age. After a while, the young leave the nest, but continue to closely associate with their mother. Weaning process takes around 3 months, occurring from 6 to 9 weeks old. Becoming independent, young squirrels remain with the family until 4 - 7 months old. The age of sexual maturity is 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 destruction of their natural habitat, including the critically endangered temperate rainforests.
According to IUCN, the Douglas squirrel is common and widespread 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 of conifer tree by carrying cones to their food stores. On the other hand, due to consuming fruiting bodies of fungi, these rodents serve as key distributers of fungi's spores, doing it through their feces. Subsequently, fungi's spores develop mycorrhizal relationships with roots of conifer tree.