by Cameron Douglas
They’re cute, lively and downright entertaining: chattering between each other, scampering across tree branches, darting along the ground, and occasionally testing your reflexes behind the wheel. Squirrels are the quintessential lovable rodent, endearing themselves to humans with just a twitch of their tails.
Squirrels are part of the family Sciuridae, a large group that includes tree squirrels, ground squirrels, chipmunks (including woodchucks), flying squirrels, and prairie dogs. The earliest squirrels go back to the Eocene Period, and are most closely related to the mountain beaver and dormouse. More than 200 species of squirrels live in every continent on Earth with the exceptions of Australia and Antarctica.
The word “squirrel” was first specified in 1327. It came from the Anglo-Norman esquirel from the Old French escurel. Going farther back, the Latin word sciurus was borrowed from the ancient Greek sciouros, meaning “shadow-tailed,” a reference to the specie’s characteristic appendage.
Ground and tree squirrels are diurnal, while most flying squirrels are nocturnal. Ground squirrels are social while tree squirrels are more the loner type, interacting mostly with mates. The eastern gray squirrel is one of few mammals that can descend a tree head first. They do this by turning the rear paws to face backward — the same as raccoons do. All squirrels have claws that are well suited to climbing and clinging to branches. The tail acts as a rudder to hold course or swerve as needed.
Tree squirrels typically live in the hollows of trees, or in nests they construct of leaves, twigs and grass that are laid into the crooks of tree branches. The occupants may remain in their homes for several days during cold weather.
Squirrels breed once or twice a year, birthing from two to eight offspring. Babies are born naked, toothless and blind. The mother will generally care for them, weaning after six to ten weeks. A squirrel lives five to ten years. Most urban squirrels never see their first birthday, due to their inexperience and poor judgment regarding the speed of oncoming automobiles. Nevertheless, squirrel populations are robust.
Squirrels are unable to digest cellulose. Because of this, they mostly depend on a diet of protein, carbohydrates and fats. Nuts are of course a favorite squirrel snack. In temperate zones, springtime is difficult for squirrels because buried nuts begin to sprout and therefore are not available for eating, while new food sources aren’t ready yet. During these times, squirrels may depend on the buds of trees. Their diet also includes seeds, conifer cones, fruit, fungi, and some green vegetation. Faced with hunger, squirrels will consume meat from various sources.
The thirteen-lined ground squirrel will actually hunt. In the 1920’s, a researcher named Bailey observed a thirteen-lined squirrel preying on a chicken. Others have been seen consuming freshly killed snakes. Birds, lizards and smaller rodents are occasionally at risk from a marauding squirrel.
Squirrels themselves are prey to a wide variety of predators, with little in the way of defenses other than flight. Groups of ground squirrels sometimes warn each other of danger with a whistling call.
Like other rodents, squirrels have four front teeth that never stop growing. This works well because squirrels never stop gnawing on things. Their chisel-shaped front teeth can cut into the shells of nuts. Holding the nut in its front paws, the squirrel either gnaws the nut or, keeping its jaws still, twirls the nut against its teeth.
Any wild animal can carry infectious diseases. Last July, part of the Table Mountain campground in the Angeles National Forest closed after a squirrel that had been trapped tested positive for the plague (usually referred to as bubonic plague). There were no reports of human infection. Human cases of the plague are rare and treatable with antibiotics.
Here at home, Pacific Grove Animal Control Officer Liz Conti-Yeo reports some of our local squirrels have had mild diseases in the past such as mange, but the population currently appears healthy.
Squirrels face another danger that has a subsequent impact on human existence — they can cause electrical power outages. It happens when a hapless squirrel touches an energized component, such as the cylindrical transformer at the top of a pole, and a grounded piece of equipment. The ensuing squirrel flambé can knock out power for a few seconds or several hours. Electrical grids are usually able to handle a brief short-circuit like this if the poor creature is thrown clear. If not, then it’s lights out. Last April in Tampa, a “squirrelectrocution” cut service to 700 people. Jon Mooallem, a New York Times columnist, has tracked these events and counts 24 such instances since Memorial Day. Fifteen hundred people went without power in Mason City, Iowa; another 1500 lost electricity in Roanoke, Virginia. Also 5,000 customers in Clackamas County, Oregon. And a total of 10,000 Kentuckians in two instances just a few days apart. Mooallem adds that in 1987 a squirrel shut down the NASDAQ for 82 minutes.
As with any wild animal, if you observe a squirrel in distress, contact the SPCA or your local animal control officer.
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