Fox squirrels, the largest native tree squirrel species in North America, display a flexible diet that allows them to thrive in various environments. Their scientific name, Sciurus niger, reflects their shaded tail and, in some regional color phases, their dark coloration. Understanding their dietary habits is crucial to appreciating their ecological role and adaptability.
Physical Characteristics and Adaptations
Fox squirrels exhibit three primary color phases: gray in the north, black in the south, and rusty-brown in the west, including Ohio. A few albinos have also been observed. Their upper side is grizzled rusty yellow to gray-brown, while their underside, eye-rings, cheeks, and feet are pale orange to rusty brown. The bottoms of their feet are black. Their bushy tails, bordered with tawny-tipped hairs, serve multiple purposes: an umbrella, a blanket, a rudder, and a parachute. The tail also aids in balance when navigating branches or wires and acts as a counterbalance during high-speed turns. A fox squirrel’s tail ranges from 7 to 14 inches long.
Their eyes are set high on the sides of their head, providing a wide field of vision, and they possess good eyesight even in dim light. Their ears, rounded and about three-quarters of an inch to 1.25 inches high, give them a keen sense of hearing. Numerous prominent whiskers (vibrissae) further enhance their sensory perception.
Habitat and Distribution
Fox squirrels prefer open hardwood forests with large trees, such as oak and hickory in the north, and coniferous forests in the south, interspersed with cleared areas. They also inhabit suburban trees and golf courses. Found in the eastern and central United States, extending west to the Rocky Mountains, their populations declined in the northeast with European settlement but increased in the Midwest as settlers cleared the land.
These solitary creatures maintain territories spanning 10-50 acres, with a single hectare potentially supporting one to seven squirrels.
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Primary Food Sources
Fox squirrels primarily consume hickory nuts, oak acorns, black walnuts, butternuts, beech nuts, American hazelnuts, and pine cones. These items constitute a significant portion of their diet, providing essential nutrients and energy.
Secondary Food Sources
In addition to nuts and seeds, fox squirrels also eat maple and yellow poplar seeds, osage-oranges, flowering dogwood berries, buds and flowers, pawpaw, wild black cherry fruit, fungi, and tree bark. These supplemental food sources contribute to a well-rounded diet, especially when primary sources are scarce.
Animal Matter Consumption
Fox squirrels occasionally consume animal matter, including insects, insect eggs, bird eggs, and nestling birds. This opportunistic behavior provides them with protein and other nutrients not readily available in plant-based foods.
Interactions with Humans
Fox squirrels often raid backyard birdfeeders, competing with birds for seeds and overcoming anti-squirrel devices. They may also enter cornfields, damaging crops by removing cobs and eating kernels. These interactions sometimes lead to them being considered a nuisance.
Foraging Behavior
Fox squirrels may travel far from their trees in search of food, especially in the fall. They often forage on the ground, primarily during the day and even on moonlit nights. Typically, they carry food to a favorite perch-a low branch, log, or stump-for consumption.
Read also: What Eastern Gray Squirrels Eat
Food Storage and Retrieval
Fox squirrels are scatter hoarders, burying nuts and acorns individually or storing them in large piles inside hollow trees. They later locate these buried caches through smell, with an impressive 99% retrieval rate. Those not retrieved may germinate, contributing to new tree growth, although some nuts have their germinating ends nipped to prevent sprouting.
Communication
Fox squirrels communicate using various barks, coughs, grunts, and churrs. They emit a series of barks and chatters when alarmed or distressed, sounding like "chuck-chuck-chuck" or "que-que-que." During courtship, they may emit whines and screams.
Nesting Habits
Fox squirrels prefer nesting in tree cavities, particularly those made by pileated woodpeckers. An ideal area may have one to two tree cavities per acre. They also build nests on tree branches and crotches, using twigs, grasses, leaves, moss, and other plant materials. These nests have an outside diameter of about 12-24 inches and an inside diameter of about 6-8 inches, with one entrance. During the summer, they may also construct smaller, flat nesting platforms. Both sexes participate in nest building, favoring white oaks and American chestnuts for nesting trees, typically located at least 30 feet above the ground. They often use between three and six different nests.
Reproduction and Development
Depending on the latitude, the breeding season usually occurs from December to February and May to July. During this time, several males may pursue a single receptive female for several days. Gestation lasts about 44 to 46 days, with each litter containing one to seven young. Females often move their young to different nests to avoid bad weather, predators, and parasites. Pups are born blind and hairless, with pink and purplish skin, measuring about 5 inches long and weighing about half an ounce to three-quarters of an ounce. Fur develops after two weeks, eyes open after four to five weeks, and weaning occurs after eight weeks. By 10-12 weeks, they may begin to wander from the nest.
Health and Longevity
Fox squirrels can suffer from external parasites, such as chiggers, fleas, lice, ticks, bot flies, and sarcoptes mites, as well as internal parasites, including pinworms, roundworms, tapeworms, and protozoans. The average lifespan is about 6 years, but they can live up to 10 years.
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Subspecies and Regional Variations
Southeastern Fox Squirrel (Sciurus niger niger)
The Southeastern Fox Squirrel, one of four subspecies in Virginia, requires mature pine and mixed pine forests, particularly longleaf pines with tree cavities for nesting. Their diet includes herbaceous and woody plant parts like pine cones, fruits, sap, roots, and tubers. They also opportunistically consume bird eggs, nestlings, and adult birds. Like other squirrels, they store food, such as acorns, in ground caches. Nesting occurs in summer and fall, typically in May, June, September, and October, with females producing one or two litters of one to six young.
Southern Fox Squirrel (Sciurus niger shermani)
The southern fox squirrel, previously classified as Sherman's fox squirrel, is a large rodent found throughout peninsular Florida and up to central Georgia. It can reach a length of 27.6 inches (70 centimeters) and weigh between one to three pounds (0.46-1.4 kilograms). This species varies in color from black to brown, with a black head, white ears, and a white snout. They typically have two breeding seasons each year: winter (October to February) and summer (April to August). Nests are made of Spanish moss, pine needles, twigs, and leaves, or within tree cavities. Females average one litter per year with about 2.3 offspring per litter. Young are weaned at 90 days and reach sexual maturity at about nine months. They inhabit open, fire-maintained longleaf pine, turkey oak, sandhills, and flatwoods. Habitat destruction is the main threat, with only 10-20% of their original habitat remaining.
Delmarva Fox Squirrel (Sciurus niger cinereus)
The Delmarva fox squirrel, once found throughout the Delmarva Peninsula, southeastern Pennsylvania, and southern New Jersey, is now primarily located on the eastern shore of Maryland and Virginia. It has a silver-gray coat, short rounded ears, and whitish feet, growing up to 30 inches long and weighing up to 3 pounds, with a bushy tail reaching 15 inches. They live in mature forest stands along streams and bays, and in small woodlots next to agricultural fields. Their habitat includes mature loblolly pine stands near marshes and tidal streams. They prefer forests with an open understory, a high percentage of mature mixed hardwoods and pines, relatively closed canopies, and a high proportion of forest edge. Their diet includes nuts, seeds, and acorns from oak, pine, maple, and hickory trees, as well as fruit, fungi, insects, and immature green pinecones. They mate in late winter, with females giving birth to a litter of 1-4 young from February through April. Loss of habitat is the major reason for their decline, but conservation efforts have led to a recovery in their population.
Dietary Preferences: A Case Study
A study conducted at the UCLA botanical garden examined the food preferences of fox squirrels (Sciurus niger). Researchers presented a variety of nuts and seeds to a group of twelve fox squirrels over six days, recording the number of each food type consumed. The results indicated that walnuts were the favorite food, followed closely by peanuts and hazelnuts. Sunflower seeds were the least preferred. This information can help inform what types of squirrel snacks to fill feeders with. These food preferences may be unique to the fox squirrels living in this area, as California ground squirrels and Western grey squirrels living at another field site have very different food preferences.
Behavioral Traits and Intelligence
Fox squirrels are known for their intelligence. Squirrels are also highly intelligent creatures. They are also highly intelligent creatures. They exhibit complex problem-solving skills, particularly in accessing food sources. The four front teeth of the Eastern fox squirrel grow continuously throughout its life.
Conservation Status and Threats
The Eastern fox squirrel is abundant and widely distributed, according to the IUCN. However, no overall population estimate is available. Currently, this species is threatened by the loss of its natural habitat which results in a sharp population decline. Thus, the population in certain parts of Florida suffers from excessive logging of their pine forest habitat as well as development such as urbanization. On the other hand, their habitat is now becoming less favorable due to the prevention of fires, which cause an overgrowth of understory vegetation. The main threat to the southern fox squirrel population is the destruction of their habitats. Habitat loss has been significant as it is estimated that only 10-20% of original southern fox squirrel native habitat is still intact, most of it having been logged, converted to pasture, degraded by lack of fire, or used for agriculture, commercial and residential development.
Ecological Impact
Feeding on a wide variety of seeds, the Eastern fox squirrels have a huge impact on the ecosystem of their range, helping many plants survive. This is largely due to their habit of storing food items: burying seeds underground, they often forget them. As a result, many of these seeds consequently sprout.