Squirrels have been a familiar part of the lives of North Americans since we were first settled. Squirrels were an important source of food for settlers, and many revolutionary war and civil war soldiers gained their shooting skills through squirrel hunting. Squirrel tails also serve as a source of fly-tying materials for fisherman.

Early settlers recorded migrations of large numbers of squirrels which traveled across long distances. Thousands of animals could be seen moving across fields, wooded areas and even rivers. These migrations may have been caused by large populations and food shortages but no one is certain.

Squirrels are a source of both amusement and frustration. It is amusing to watch a squirrel burying a full ear of corn under a pile of fallen leaves. We find their antics and playful tumbling amusing, until they empty our bird feeders in the process. Bird watchers spend both time and money on various inventions to keep squirrels out of bird feeders. Squirrels jumping out of trees onto roofs and sliding down rainspouts can be fun to watch. However, that same squirrel may anger us when it uses our garage or attic for a winter home.

Squirrels belong to the animal order Rodentia. Like all rodents, they have two upper and two lower incisors. These are flat, open rooted front teeth, used for gnawing. These front teeth grow continuously and are worn down by the squirrels' constant gnawing.

DESCRIPTION

The Sciuridae family has several identifying characteristics. They have 4 toes on their front feet and 5 on their back feet. The squirrel family name comes from the Greek word skiouros. This means shade tail--a most appropriate name for an animal with a bushy tail that keeps it warm during cold nights. Most squirrel species are active during daylight hours (diurnal), except flying squirrels which are active at night (nocturnal).

Fox Squirrel (Sciurus niger). Its head and body average 10-15 inches in length and its tail may be 9-14 inches long. These squirrels weight from 1 1/2 to 3 pounds. Fox squirrels have a cylinder shaped body, square head, and short, rounded ears. Its fur is rusty or yellow colored with an orange belly. The tail is beige with dark tipped hair.

Eastern Gray Squirrel (Sciurus carolinensis). This squirrel's head and body is 8-10 inches long with a 7-10 inch tail. Gray squirrels weigh from 1/2 - 1 1/2 pounds. They have a slender, long body, round head and pominent ears.

Their fur is solid gray while their tail fur may have white tips. White tufts appear on the ears in winter. The "Black squirrels" found in the midwest are actually gray squirrels with melanistic coloration.

HABITAT, DISTRIBUTION, POPULATION SIZE

The eastern gray squirrel and fox squirrel live in two different types of habitat. Fox and gray squirrels thrive in mature trees. The fox squirrel does best in small woodlots of mature trees while the gray does best in widespread forests of mature trees.

Fox squirrels prefer forest edges, mature hedge rows, and small, open woodlots and can adapt to a variety of tree species. As forests were cleared for agriculture and timber, fox squirrels expanded their range into the remaining woodlots. Shrubby fence rows became ideal travel routes between woodlots.

In good habitat a fox squirrel needs about five acres to meet its year-around survival needs including nesting locations, shelter and food. Good habitat for a fox squirrel would include woodlots and hedgerows with trees of mixed ages and species. Oak, walnut, hickory and beech trees are the best nut producing trees for squirrels.

FOOD PREFERENCES

Eastern gray squirrels and fox squirrels are omnivorous. This means they will eat anything available. Both species take advantage of seasonal food sources. Both species eat summer fruit such as strawberries, grapes, apples, thornapples, serviceberries, raspberries, and cherries. Other summer foods include green corn, green nuts and maple seeds. Spring foods include elm seeds, tree buds, corn, insects, mushrooms and other fungi, and any stored nuts they can find. Squirrels will eat bird eggs, fledglings or even adult birds if they have the chance.

Squirrels and other rodents will chew on bones such as shed deer antlers or skeletal remains. They gain calcium and other minerals from these sources.

The annual fall mast (all fruits, seeds and nuts produced in a forest) production is vital as fall and winter food for all wildlife. Fall is the season squirrels consume large amounts of mast in order to add layers of body fat for warmth and energy.

Squirrels also store food for the winter. Some major nut producing trees are oaks, hickories, butternuts, walnuts, beech and hazelnuts. Both the fox and gray squirrel store the nuts by lodging them in crevices in trees and burying them in the ground. They use their strong sense of smell to dig them out from under snow drifts during the winter. Squirrels do not find all the nuts they bury. As a result, many new trees sprout from nuts buried by squirrels.

LIFE HISTORY

Breeding. Squirrels breed from January through September. The female is receptive (capable of being fertilized) for only 10-14 days during a breeding cycle. The mature male's testicles drop into the scrotum during breeding seasons starting at 18 months of age. During the non-breeding season of the year, the testicles are pulled up into the abdominal cavity. This has given rise to the common belief that the smaller red squirrels castrate fox and gray squirrels. Courtship involves the males chasing receptive females. It is a noisy time with much purring, barking, and sucking noises among both males and females. Male squirrels do not spend any time with the pregnant female and do not help in raising the young.

Gestation/Birth. The average gestation period (pregnancy) for a fox squirrel is 44 days. The female then gives birth to 3 or 4 young. The number of squirrels in a litter depends on available food supplies.

Female squirrels may use holes in trees or even leaf nests for nesting purposes. The female lines her nesting den with feathers, moss, shredded bark and other soft plant materials. The first litter is born in mid March and the second litter is born in July. The young are born completely hairless with closed eyes and ears, a large head, and have large feet with claws.

Hair appears on the back at about age 7 days. The ears open and the first teeth appear at 25 days. Tail hair appears and the eyes open at 35 days. The young may begin exploring outside the nest around 55 days, staying very close to their home. The female will move her young if she feels the current nest is in danger. After 90 days, young squirrels are independent. Young squirrels begin building their own leaf nests around eighteen weeks of age.

Squirrels one year old as well as older adults produce the first litters of the year. Normally, only females 2 years or more old will produce second litters. Females producing two litters raise an average of 6 young each year. During the fall, 40% of the fall squirrel populations are usually yearlings or older. About 60% are young produced that year.

Nests. Winter nests are elaborate twig and leaf nests built in the fork of tree branches. They are very compact, almost circular in shape and waterproof. Soft plant materials and feathers may line the nest. Summer nests are less elaborate and may have a saucer shaped platform on top. The nests may be built either in deciduous (lose leaves during the winter) or evergreen (stay green year-around) trees. Both summer and winter nests are easily seen in the winter when the deciduous trees have dropped their leaves.

Squirrels may also use natural cavities in trees. These are formed by rot and weather damage or they may be old woodpecker nests. Squirrels will occasionally claim holes in the ground for nesting purposes.

Feeding. Squirrels may forage (seek food) either in the tree tops or on the ground. When eating on the ground, they carry their food to a tree stump or other perch so they can watch for predators while eating. This practice accounts for the piles of nut shells or seed husks sometimes found on top of a tree stump. These piles are called middens.

Other Behavior. Fox and gray squirrels have a social hierarchy to determine which squirrels get the best foods, nests and mates. Each squirrel in the population has a rank--ranging from the dominant male and female squirrels to the newborn. High ranking squirrels, usually adult males, dominate most females and younger males and have first preference for food, den sites, and mates.

eIf food supplies are abundant, squirrels may feed together during severe winter weather. Some even share a winter den which means they can share body warmth. Normally, they gather in groups only during mating season. Females exhibit territorial behavior immediately around their nest site.

Squirrels interact with each other by making various barking like calls. Their calls serve as invitations during mating season, while others warn of danger.