What do they look like?

Red squirrels are 280 to 350 mm in length, 95 to 150 mm of which is the tail. They weigh between 140 and 250 g (average 194.5 g). Fur color is highly variable across their range. Color also changes seasonally. The fur on their back is usually brownish or olive-red in color. Their belly is white or cream color. During the summer, a black stripe runs along their side, between their back and belly. Their tail is often edged with white. There are white bands encircling their large, black eyes. The tail is not as thick or bushy as other North American tree squirrels. Red squirrels are well adapted for climbing and running through the trees with compact, muscled bodies, strong claws, and powerful hind limbs.

Red squirrels might be confused with young fox squirrels or eastern grey squirrels. Red squirrels have a distinct white eye ring, which other squirrel species lack. Red squirrels are also distinguished by their extreme speed and agility; they dart around trees and bushes, often while chattering loudly. The grey/red fur on their back as well as the white fur on their belly also helps distinguish red squirrels from other tree squirrels.

Where in the world do they live?

Red squirrels have one of the widest distributions of all North American squirrels. They are found in Alaska, through Canada and the northeast United States and south through the Appalachian states. They also occur throughout the Rocky Mountains.

What kind of habitat do they need?

Red squirrels are found in a variety of forested habitats, including coniferous, deciduous, and mixed forests. They can be found in suburban settings where there are large stands of mature trees.

How do they reproduce?

In warmer climates red squirrels have two breeding seasons, in the late winter and mid-summer. In colder climates, there is only one breeding season, which begins at the spring thaw, from mid-January to mid-February. After a 33 to 35 day pregnancy, females gives birth to up to 8 young. Litter size is typically 2 to 5 individuals. They usually give birth in a lined den or a tree hollow. Young develop very quickly are weaned 7 to 8 weeks after birth. At 40 days of age they leave the nest. Because juveniles are more susceptible to predation from animals like owls, hawks, and martens, they are less likely to survive than adults. About 25% of juveniles survive past their first year.

Females care for and nurse their young in the nest for 40 days. In the fall following their birth, young red squirrels disperse from their mother's home range.

How long do they live?

Red squirrels can live up to 7 years in the wild, though most die before they are 1 year old.

How do they behave?

Red squirrels are solitary, diurnal animals that are active throughout the year. They are most active at dawn and in the late afternoon. They make dens in old woodpecker holes, tree hollows, and other small crevices. Red squirrels in the northern part of their range often spend the winter in a system of underground tunnels. Red squirrels often migrate if their local food supply runs low. During these migrations they often cross water; they are good swimmers.

Home Range

The home range of red squirrels generally range between 1 and 2.4 ha in area.

How do they communicate with each other?

Red squirrels have keen senses of smell, sight, and hearing. They are very vocal and loudly scold intruders in their home range. Vocalizations consist of rattles, screeches, growls, buzzes, and chirps.

What do they eat?

Red squirrels eat a variety of foods, including seeds, fruit, nuts, bark, buds, shed antlers, reptiles, insects, tree sap, pine cones, fungi (including mushrooms that are poisonous to humans), eggs, young birds, mice, and young rabbits. However, red squirrels primarily eat the seeds of conifer trees. They may eat up to 2/3 of the pine seed crop in an area each year. Red squirrels store seeds and nuts underground, in piles, or under rocks for the winter. They are able to relocate these buried seeds 30 cm underground and 4 meters below snow by using their tremendous sense of smell. Many seed stockpiles are not recovered, however, making red squirrels a key tree planter and seed disperser.

What eats them and how do they avoid being eaten?

Red squirrels are quick and agile and can escape predators by taking refuge in thick vegetation or in the trees. Red squirrels are also fairly aggressive small animals and defend themselves if cornered. Common predators include owls, hawks, weasels, snakes, red foxes, bobcats, Canada lynx, and American martens.

What roles do they have in the ecosystem?

Red squirrels have a large impact on tree populations in two ways. They can severely limit the regrowth of conifer trees because they eat so many seeds. However, they often drop seeds or forget the stockpiles of their seeds. They thus are seed dispersers. They also distribute the spores of beneficial fungi that help trees to acquire nutrients and grow. Red squirrels are also important prey animals for many small predators because of their abundance.

Do they cause problems?

Red squirrels can severely damage young trees in plantations and crops in storage. They may also gnaw on many household items and can become a nuisance if they nest in homes.

How do they interact with us?

Red squirrels are beneficial because they disperse tree seeds and the spores of fungi required by many trees for successful growth. About 1 to 3 million red squirrels are harvested annually for their fur in Canada, bringing in about 1 million dollars. They are a major prey item for other economically important species such as martens, bobcats, and lynx.

Are they endangered?

Red squirrels are common and not currently threatened throughout most of their range. Numbers of a subspecies in southeastern Arizona, Mt. Graham red squirrels (Tamiasciurus hudsonicus grahamensis), have been reduced to 150 individuals, and they are listed as endangered. New buildings, campgrounds, and continued logging threatens its last habitat.

Contributors

Tanya Dewey (author), Animal Diversity Web, University of Michigan Museum of Zoology. George Hammond (editor), University of Michigan, Animal Diversity Web staff. Gail McCormick (editor), University of Michigan.

Eric J. Ellis (author), University of Michigan.

References

The Smithsonian Book of North American Mammals