Meet the pine squirrels

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Raise your paw if you love, love, love pines! Pine squirrels sure do. Meet the Douglas, American Red and Mearns’s. They’re strongly associated with all things pine — they live and nest in pine forests and depend on pine seeds for food.

Douglas Squirrel. (Steve Voght / Flickr; cc by 2.0)

The DOUGLAS SQUIRREL (Tamiasciurus douglasii), sometimes called a Chickaree, inhabits West Coast pine forests from California north into Canada and Alaska. Douglas Squirrels are only about a foot long, including their tail. Very active and noisy, naturalist John Muir called them the “squirrel of squirrels” because they possess “every attribute peculiarly squirrelish enthusiastically concentrated.” They have distinct summer and winter coats. In summer, they’re reddish-brown to grayish-brown on the topside. In winter, they’re more grayish overall and may have noticeable ear tufts.

Douglas Squirrel midden. (hthrd / Flickr; CC BY-NC 2.0)

They feed on available foods, such as acorns, fruit, mushrooms, buds and sap, and will visit bird feeders for nuts. But conifer seeds are their main diet. In fall, they bury pine cones for eating later. Sometimes they store mushrooms in the fork of trees. The squirrels often use the same spot year after year for peeling scales off pine cones to get at the seeds. These refuse piles are called middens. Generations of squirrels may use one, with it growing several feet high and wide. In summer, Douglas Squirrels build nests of twigs, mosses, shredded bark and lichens on tree limbs or in tree forks. In winter, they nest in tree cavities or in underground burrows. The squirrels are solitary except during mating season, which is late-February to April. Babies are born about one month later. They’ll stay with their mother up to a year, so if you see a group of them it’s probably a mother and her offspring. They’re named after David Douglas (1799-1834), a Scottish botanist who spent some years traveling in North America.

AMERICAN RED SQUIRRELS (Tamiasciurus hudsonicus) are the most widely distributed of the pine squirrels, ranging from Alaska and Canada to the Great Lakes region, and south and east along the Rocky Mountains. They inhabit conifer forests, but occasionally mixed forests, too.

American Red Squirrel mother and babies. (Gilles Gonthier / Flickr; CC BY 2.0)

 Red squirrels are recognizable by their deep reddish color and small body — only about 6 to 7 inches long, plus a 6-inch tail. Red squirrel females are receptive to mating for only one day in about February and sometimes for one day in about August. On those single days, they often mate with several males. Four to five (usually) babies are born 35 to 40 days later. Juveniles have a high mortality in their first year. If they survive it, they may live up to 10 years. An isolated group of red squirrels in southeast Arizona is different enough to be considered a sub-species. Named the Mt. Graham Pine Squirrel (T. hudsonicus grahamenis), they became stranded there when the area around them became desert during the last glacial times (22,000 to 12,500 years ago). There are 24 more recognized red squirrel subspecies, with the main difference between them being where they live. The American Red Squirrel shouldn’t be confused with the Eurasian Red Squirrel — they’re in a different genus (Sciurus vulgaris).

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Mearns’s Squirrels. (© Nicolas Ramos-Lara)

MEARNS’S SQUIRRELS (Tamiasciurus mearnsi) live in isolation in the open, dry pine and fir forests of the Sierra de San Pedro Mártir mountain range in Baja California, Mexico. The heaviest of the pine squirrels, genetic evidence suggests they evolved from Douglas’s Squirrels and became separated from them about 12,000 years ago. They’ve made unique adaptations to their rugged habitat. For instance, other squirrels are willing to use leaf nests and burrows for nesting, but the Mearns’s will use only tree cavities and only in large diameter trees. This means that suitable live trees and snags are vital to their survival. Another difference is their jaw strength. The Douglas and Red squirrels can carry pine cones in their mouth, but the Mearns’s can carry big ones. Also, unlike the other pine squirrels, they don’t build and defend middens.

Mearns’s babies. (© Melissa Merrick)

These baby Mearns’s are lying at the base of a tree. They were under attack by vicious ants when researcher Melissa Merrick heard their intense cries. Ordinarily they wouldn’t be out in the open like this, but their mother was moving them from an old nest to a new one. Melissa removed all the ants, which had already caused wounds, and left the pups on a large piece of bark on the ground. She waited nearby and watched as their mother returned and safely carried them all up the tree to a new nest. A happy ending! Mearns’s are named for Edgar Alexander Mearns (1856-1916), a naturalist and surgeon in the U.S. Army who served for some years in Mexico. They’re now federally listed as threatened in Mexico due to their low population and isolation. The IUCN¹ lists them as endangered. You can learn more about the Mearns’s from Nicolas Ramos-Lara’s study, The Ecology of the Endemic Mearns’s Squirrel.

¹International Union for Conservation of Nature
*Top photo: (Steve Voght / Flickr; cc by 2.0)

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