|Fox (sciurus niger) and gray (sciurus carolinensis) squirrels are both considered tree squirrels, even though fox squirrels spend most of their time on the ground. When the first settlers arrived in Wisconsin, they
|Fox (sciurus niger) and gray (sciurus carolinensis) squirrels are both considered tree squirrels, even though fox squirrels spend most of their time on the ground. When the first settlers arrived in Wisconsin, they found a huge population of squirrels, and in fact some communities actually paid bounties for them to save crop damage. During this time there were enormous squirrel migrations, and in 1842, a gray squirrel migration lasted four weeks and involved, according to one observer, nearly half a billion squirrels. As forests were burned or cleared for agriculture, squirrel population quickly declined.
The fox squirrel is the larger of the two species, measuring 20-22 inches in total length, including 8-10 inches of tail, and weighing 24-32 ounces. Grays are 18-21 inches long and weigh 16-28 ounces. There is no real size or color difference between males and females of either species. Gray squirrels, normally gray in color, have some tawny coloration in summer, a white chin, throat and belly, and bushy tails bordered with white-tipped hairs. In some areas, black (melanistic) gray squirrels are common. Fox squirrels appear more grizzled looking, their fur being rusty brown with a pale yellow to orange belly and tawny-tipped hairs bordering their bushy tails. Tree squirrels, like all rodents, have incisor teeth that continuously grow allowing them to feed on hard nuts and seeds. Squirrels have very keen eyesight, and have adapted well to life among the trees. Special tactile hairs enhance their sense of touch to help them find their way in dark tree holes and cavities. Tracks are normally evenly spaced, and the claw marks are quite visible. The hind feet often strike the ground ahead of or on top of the front footprints, and clusters of tracks can be 10 inches to 5 feet apart depending on the speed of the animal.
Squirrels mate from late January through February and again during a second season in May though early July. The male selects a female, chases her until they mate, and then chooses another. While males may mate with several females, they will vigorously defend these mates against other males. After breeding, the female seeks a nest, which may be the winter den in a tree cavity or hollow log that she has lined with shredded bark and plant fibers. If an existing den is not available, she will build a round leaf nest in the crotch of a tree, at least 25 feet above ground for a gray squirrel and 30 feet up for a fox squirrel. These nests have small hidden entrances on the sides and will be abandoned after one or two years. The young are born after 40-44 days, and litter sizes range from 2-5 for grays and 1-6 for foxes. Young squirrels weigh only 1/2 ounce when born, their skin is without fur and pinkish, and their eyes and ears are closed. Development is slow with eyes not opening for 4-5 weeks and ears taking 6 weeks to open. Hair covering starts at about six weeks, and by two months the little ones are weaned and furry. The first litter stays with the female for about three months or until she has the second litter. The second litter stays throughout the winter. Females normally do not breed the first year, but tree squirrels are sexually mature after 10-11 months.
Squirrels have a great diversity in their diets. Gray squirrels eat many kinds of nuts, acorns, seeds, fruits of plants like maple, elm, hickory, beech, cherry, oak and thornapple. They also feed regularly on fungus, inner tree bark, sap, and occasionally corn, grain and the underground fleshy parts of plants, and have even been known to eat insect pupae and cocoons and to rob bird's nests of eggs and nestlings. Fox squirrels are a little more particular and eat walnuts, hickory nuts, acorns, hazelnuts, fruits, and when nuts are not available, seeds and buds. Fox squirrels seldom bother bird nests. Both species will gnaw on bones to get mineral matter and sharpen their incisors. They bury nuts and acorns in single holes for later meals, but many of these buried treasures are never recovered and end up becoming trees.
Gray squirrels are primarily forest dwellers, preferring mature hardwoods with bushy undergrowth and nearby streams and lakes. They frequently inhabit wooded parks and residential neighborhoods in small woodlots. Fox squirrels are most often found in open agricultural areas with oak and hickory woodlots, often traveling along fencerows, and hardly ever in city parks. Both species seem to stay close to home. The gray squirrel normally stays within 1,000 feet, and many times less than 400-500 feet, of its nest. Home ranges for fox squirrels are typically less than 40 acres and often around 10 acres. Tree squirrels nest in either hollow tree dens or leaf nests, with grays preferring hollow tree dens in the winter and leaf nests at other times, and foxes always opting for leaf nests even while tree dens are abundant. Squirrels are considered diurnal (daytime) animals, most active during the day with peak activity in late afternoon and early evening. Fox squirrels are the most strictly diurnal with very little activity before 8 a.m. or after 5 p.m. Both species are most active in the fall storing nuts, and sometimes it is at this time that young born in the spring will disperse to 