Thursday, January 8, 2009 9:52 PM CST
In battle of wits, squirrels usually win
By ESTHER LUTZ
If we had to pick a Public Enemy N0. 1 in the backyards of Illinois, it would have to be that confounded little busybody, the gray squirrel. Although highly entertaining at times with their acrobatic prowess and bushy-tailed errant ways, these cunning little mammals continue to exasperate and test the mettle of human endurance when it comes to feeding the backyard birds.
Sometimes it reaches the level of an all-out war of wits between rodent and man.
Why do they exasperate us so? Perhaps because there is something about being challenged by a gray, furry, one-pound, four-footed beast with big front teeth that sparks an automatic fight response in otherwise level-headed and peace-loving human beings. The quest to find the perfect squirrel-proof bird feeder is what drives us to attempt to outwit, outthink, outmaneuver and outperform the craftiest of those aggressive bushytails. And yet they continue to overcome the most expensive, complicated, and inventive anti-squirrel systems that we can dream up.
A little about the squirrel — Sciurus carolinensis.
Common in the eastern half of the U.S., the eastern gray squirrel is frequently seen conspicuously out in the open, in the trees and scampering about in the yards and parks of east-central Illinois. A member of the rodent family, it typically weighs from one to one and a quarter pounds with a length of 17 1/4 to 18 1/4 inches. The fur is gray on the back with mixed dark and light hairs in the coat (“salt and pepper” pattern), and white to light gray on the belly. A distinctive feature is the long, bushy tail used for warmth, balance and shade, and as a means of communication with other squirrels. Melanistic (black) individuals can be found in populations near Mahomet and Gibson City, and an albinistic (white) population resides in Olney, which is nationally known as the “Home of the White Squirrels.”
One of the best known mammals in much of its range, these animals are active by day and survive quite well in suburbs and parks, on college campuses and wherever there are good-sized trees and larger areas of forest, especially oak and hickory trees. The diet is quite varied and includes many acorns and nuts, buds, bark and fungi. They will eat flowers, insects, bird eggs and carrion, and they often chew on bones and deer antlers for calcium. Fruits, berries and succulent plant materials are eaten in summer, and corn and cultivated fruits are taken when available. Nuts and acorns are frequently cached in tree hollows and in the ground for later use, a practice also known as “scatter hoarding.” Most food is carried away from gathering sites to be eaten or buried. As many people have learned, this species of squirrel is also quite adept at raiding bird feeders.
Two mating seasons per year with two litters are common. The gestation period is 44 to 46 days, with the births of three babies in the spring between February and April, and another litter in August or September. Two basic types of natural dens are used to rear the young — tree cavities and leaf nests constructed with a frame of sticks filled with dry leaves and lined with strips of bark, corn husks, leaves or other natural materials. The babies are hairless and blind, and their ears are closed at birth. They will begin to explore outside the nest about the time they are weaned at 10 to 12 weeks when they are about half their adult weight. Breeding for the first time will occur at about one year of age and generally only once during the first breeding year.
The senses of a squirrel are very acute — the sense of smell is uncanny. They may not always remember where they buried their last cache of nuts, but they can surely smell a pile of them buried under several inches of leaves or snow. Their hearing enables them to be aware of changes in normal forest sounds, the footsteps of a predator, a door being opened or feeders being filled. The sense of sight is remarkably powerful, and they can distinguish fine detail — a useful trait when leaping from tree to tree. Because the eyes are on opposite sides, the squirrel has a wide range of vision without turning its head. Squirrels are a good food source for hawks, owls, raccoons, foxes, coyotes, bobcats and tree-climbing snakes. Typically, about half the squirrels in a population will die each year, with those reaching four years of age in the wild quite rare. Predation seems to have little effect on squirrel populations, but they are vulnerable to numerous parasites and diseases. Their role as a prey species makes them an important part of the food web, and they play a vital ecological role in forest regeneration, as well. Their survival instinct of burying tree seeds and nuts in caches to use later in the season is quite useful, but they don’t always return for all that they bury. In fact, most of the nuts that a squirrel recovers will not be the ones that it has hidden. Because so many of the buried nuts remain undisturbed, some of the acorns and seeds will undoubtedly sprout later and grow into trees. As a result, the forest continually regenerates and replenishes over time.
While tree squirrels do not hibernate, they will spend more time in their nests in the colder months. During severe weather conditions, they have been known to spend several days there, coming out to hunt for buried nuts, acorns and seeds when the temperature becomes tolerable again.
So, what can we do when squirrels become an annoying menace? Is there an end to the nightmare of the human-birdfeeder-squirrel triangle? We’re bigger and stronger than they are, but can we win the backyard war?
Don’t be discouraged. There is hope. Tune in next month and we’ll explore some practical defensive options.
Esther Lutz is east -central Illinois master naturalist for University of Illinois Extension in Coles County.
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