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Summer 2006 - Act•ionLine

by Donald S. Heintzelman | Summer 2006

Spotlight on Squirrels

Donald S. Heintzelman is a professional ornithologist with a special interest in raptors, and is the author of 21 published books. He has more than 50 years field experience studying raptors, Tundra Swans, and other wildlife throughout the world. He lives in the rural countryside in southeastern Pennsylvania.

Depending upon one’s perspective, squirrels are fascinating or controversial animals. Let’s look at them more closely.

There are, according to The Smithsonian Book of North American Mammals,1 273 species classified within the Family Sciuridae—the squirrel family—and 66 species of them live in parts of North America. These include chipmunks, marmots, woodchucks, antelope squirrels, ground squirrels, prairie dogs, fox squirrels and the more familiar squirrels.

Two common species are the Eastern Gray Squirrel (Sciurus carolinensis) and the Red Squirrel (Tamiasciurus hudsonicus).

Deciduous forests

These forests are comprised of trees with leaves that fall off or are shed seasonally to avoid adverse weather conditions such as cold or drought. Most deciduous plants lose their leaves in autumn. Examples are maple, ash, and cherry trees.

The Eastern Gray Squirrel is common in most of the eastern United States and parts of the eastern half of extreme southern Canada. Members of this species live in hardwood and deciduous-coniferous forests, especially with large, old trees. They can also be spotted in rural and suburban areas, city parks, tree-lined streets and backyards. Black (melanistic) and rarer white (albino) color morphs have been spotted—the former in Washington, DC, and the latter in Olney, Illinois.

Tree cavities and large leaf nests provide housing for squirrels. They have a varied diet that can include acorns, nuts, leaf buds, flowers, fungi and mushrooms, as well as tree bark, insects, bird eggs, and sunflower seeds.

Ask an ecologist about Gray Squirrels and the likely reply will be that they are among nature’s most important natural foresters—mammals responsible for inadvertently planting innumerable trees and shrubs in woodlands and forests when they hide acorns, nuts, conifer seeds and other seeds for consumption later.

But Gray Squirrels also are popular targets for hunters during autumn and many thousands are shot every year. Hunters have not learned to live in harmony with some wildlife. Indeed, in Michigan in February, a man wearing camouflage clothing was shot by another hunter who mistook the man’s exposed elbow for a squirrel.

Coniferous forests

Coniferous forests are made up of trees belonging to the order Coniferae. They have resinous sap, and bear cones, rather than fruits, as their method of dispersing seeds. Leaves are usually needles, scales, or narrow and linear in shape. The names of these cone-bearing trees include pine, fir, spruce, hemlock and cedar. Most conifers are evergreens, and do not lose all their needle-like leaves at once like deciduous hardwood trees do. But some conifers are deciduous, such as the larch tree or the bald cypress.

Many backyard birdwatchers also dislike Gray Squirrels because they commonly raid birdfeeders to eat the delicious (but expensive) sunflower seeds meant to attract native birds. In fact, Gray Squirrels are known to be among the most creative of all backyard wildlife in inventing ways to reach birdfeeders and their sunflower seed treasures.

Many people, however, enjoy having Gray Squirrels feeding on sunflower seeds. For example, Priscilla Feral, president of Friends of Animals, enthusiastically tells folks about three orphaned Gray Squirrels she received from a rehabilitator. Released on her suburban Connecticut property, they occupied an owl nest box in a maple tree, and enjoyed daily meals of sunflower seeds and fruit (and occasionally some peanuts)—plus a bowl of fresh water—on the ground below the maple tree. Gray Squirrels are fascinating, treasured, and welcome guests on Priscilla’s property. Those living there now are likely the offspring of the first group, as the life span of most Gray Squirrels is a year or less.

Red Squirrels are native to the southern two-thirds of Canada and Alaska, and sizeable northern portions of the contiguous United States. Their barks and chatters are heard often coniferous forests, and sometimes in deciduous-coniferous forests. They inhabit tree cavities, round nests constructed of twigs, leaves, grass, and lichens, or even underground burrows.

Conifer cone seeds are basic Red Squirrel food. As a squirrel strips seeds from cones, the discarded parts fall to the ground forming piles (middens). Squirrels then store more pine cones with seeds in the middens; some are used for decades by generations of squirrels. Additional food includes mushrooms and bird eggs. Squirrels eat some fresh mushrooms which would be poisonous to people; excess mushrooms are cached on tree branches for later use.

Red Squirrels might eat about two thirds of a forest’s pine cone crop, causing a loss of tree regeneration; but their feeding activities spread fungi spores needed by some conifers. Thus, a symbiotic relationship exists between Red Squirrels and coniferous trees.

Squirrels are fascinating and important members of the North American habitats, wildlife communities and ecosystems in which they live.

  • 1. Don E. Wilson and Sue Ruff, eds., Smithsonian Institution Press (1999).
Donald S. Heintzelman

Act•ionLine Summer 2006

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