Douglas Squirrel

## Description

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.

## Distribution

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.

## Behavior

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.

## Diet

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.

## Reproduction

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.

## Population

### Threats

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.

### Number

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.

### Ecological niche

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.

## Fun Facts

This rodent is known for its lively and noisy behavior. Moreover, it doesn't fear humans. The Native Americans of Kings River called the Douglas squirrel the ‘Pillillooeet’ - this is how the alarm call of this animal sounds like.

Douglas squirrel is a highly vocal species. This animal communicates with conspecifics through a system of calls, including low 'chir' and 'burr' sounds as well as a loud ‘bauf, bauf bauf’ call. Douglas squirrels typically give out these vocalizations during courtship period, defending their territory or as an alarm call.

Douglas squirrels possess well-developed senses of hearing and smell as well as excellent eyesight. In addition, whiskers, growing on their noses, chins and around the eyes, help them sense their environment.

The tail of squirrel is multifunctional. Firstly, it allows the animal keep balance while climbing up and down trees or moving between trees. To compare, the tail of this animal acts like a stick that we hold sideways in order to balance on a beam. Furthermore, their tails may act as 'umbrellas', protecting them from sunlight or rain. Moreover, when the weather gets cold, these animals use their tails as 'warm blankets'. And finally, they communicate with conspecifics, using their tails as 'flags'.

Teeth of these animals have a very high growth rate. Hence, squirrels constantly sharpen and wear down their teeth. They usually do it by chewing on solid things, including twigs that no only sharpen, but also clean and trim their teeth. Meanwhile, those living in urban areas, chew on electrical wires and hoses.