Squirrel information on tree squirrels are divided into 2 groups: large tree squirrels (fox and gray squirrels), pine squirrels (red squirrels). Flying squirrel information can be found here. Eastern gray squirrels typically are gray but have some variation in color. Some animals have a distinct reddish cast to their gray coat. Black individuals are common in some areas. Local populations of white gray squirrels are found in upstate New York. Though not albino, white squirrels have gray on the back of their heads, necks, or shoulders. Several color variations can occur in a single population.
Fox squirrels are larger than eastern gray squirrels. They can vary in color from a deep orange-rust color to more reddish color with yellow undersides.
Red squirrels are red-brown above with white underparts. They have small ear tufts and often have a black stripe separating the dark upper color from the light belly.
Large tree squirrels include fox squirrels that measure 18 to 27 inches from nose to tip of the tail. They weigh about 1¾ to 2¼ pounds. Eastern gray squirrels (Figure 1) measure 16 to 20 inches. They weigh 1¼ to 1¾ pounds. Red squirrels are considerably smaller. They are 10 to 15 inches long and weigh 1/3 to 2/3 pounds. Southern flying squirrels are 8 to 10 inches long and weigh 1½ -2 ½ ounces.
Voice and Sounds
Squirrels emit a variety of sounds including churrs, barks, and squeals. Churrs express anger, barks act as warnings, and squeals occur when a squirrel is terrorized or in pain.
Squirrel Information on Mating and Reproduction
Fox and gray squirrels first breed when they are about a year old. Gray squirrels breed in mid-December or early January, and a small percentage breeds again in June. Fox squirrels breed in January. Young squirrels may breed only once in their first year. The gestation period is 40 to 45 days with young born in February-March. During the breeding season, noisy mating chases take place when 1 or more males pursue a female through the trees. Tree squirrels have about 3 young per litter. At birth, they are hairless, blind, and their ears are closed. Young weigh about ½ ounce at birth and 3 to 4 ounces at 5 weeks. At weaning, they are about half of their adult weight. Young begin to explore outside the nest about the time they are weaned at 10 to 12 weeks. After the young are weaned, they usually do not remain with their parents. However, young female gray squirrels may stay with their mother for several months, although they don’t necessarily remain near the nest site.
Typically, about half of the squirrels in a population die each year. In the wild, squirrels over 4 years old are rare, while individuals may live 10 years in captivity.
Red squirrels breed in late winter and the gestation period is the same as gray and fox squirrels. The litter size is 3 to 6 young.
Squirrels are cavity dwellers, preferring hollow trees and buildings (Figure 3a). Large leafy nests (Figure 3b), called dreys, are constructed with a frame of sticks filled with dry leaves and lined with leaves, strips of bark, corn husks, or other materials, are constructed particularly in the summer, as they are cooler. Squirrels will also den in rock crevices, burrows, brush piles, chimney flues, attics, and barns. Survival of young in cavities is higher than in leaf nests, making cavities preferred sites for nests.
Red squirrels prefer old woodpecker nest holes and hollow tree limbs.
Individual home ranges vary from 1 to 100 acres, depending on the season and availability of food. Squirrels move within their range according to the availability of food. They often seek mast-bearing forests and cornfields in the fall and tender buds of maple trees are favored in the spring. During fall, squirrels may travel 50 miles or more in search of better habitat. Populations of squirrels fluctuate regularly. When population numbers are high, squirrels, especially gray squirrels, may go on mass emigrations where many individuals die.
Gray squirrels are the most common and adaptable squirrel species. They can inhabit just about any habitat and are often found in great numbers in cities, especially in and around parks. The fox squirrel has the most limited distribution of all the squirrels and found mainly in NY. They are found only in pockets in the most western part of the state. The presence of mature hardwoods often is important to all species of squirrels. Gray and fox squirrels prefer hardwood forests (fox squirrels like the forest edge); red squirrels prefer softwood forests or mixed hardwoods and conifers.
It is important to distinguish the types of food storage used by squirrels. Large squirrels, such as gray and fox squirrels, scatter cache, which means they store individual acorns or other seeds (mast) in different areas around their home range. Smaller squirrels, such as red squirrels, store food in 1 place. It is not uncommon to find trash-bag-sized piles of pine cones inside attics or gutters, brought there by red squirrels.
Fox and gray squirrels have similar food habits. They eat a variety of native foods and adapt quickly to unusual sources of food. Typically, they feed on mast (wild tree fruits and nuts) in fall and early winter. Acorns, hickory nuts and walnuts are favorite fall foods. Fox squirrels feed heavily on pine cones; gray squirrels will as well in spring. Nuts often are cached for later use. In late winter and early spring, both species prefer tree buds. In summer, they eat fruits, berries, and succulent plant materials. Fungi, corn, and cultivated fruits are taken when available. Squirrels chew bark from a variety of trees.
Damage to Structures
Squirrels, being rodents, are known for their gnawing. The size of holes made by squirrels can be generalized. Fox and gray squirrels use holes the size of a baseball (Figure 4a). Red squirrels use holes the size of a golf ball. Flying squirrels use holes the size of a quarter.
Squirrels often travel power lines and short-out transformers. They gnaw on wires, enter buildings, and build nests in attics. They may chew holes through tubing used in maple syrup production. Feces of flying squirrels mixed with urine can cause stains.
Damage to Livestock and Pets
Squirrels do not pose a threat to pets but will consume bird eggs and nestlings. Flying squirrels are small enough to enter most birdhouses and are likely to eat nestling birds.
Damage to Landscapes
Squirrels occasionally damage trees by chewing and stripping bark from branches and trunks. Red squirrels damage pine trees and paper birch.
Tree squirrels may eat pine cones and nip twigs to the extent that they interfere with the natural reseeding of important forest trees. In forest seed orchards, squirrel damage interferes with commercial seed production.
In nut orchards, squirrels can severely curtail production by eating nuts prematurely and by carrying off mature nuts. In fruit orchards, squirrels may eat cherry blossoms and destroy ripe pears. Red, gray, and fox squirrels may chew the bark of various orchard trees.
Squirrels may damage lawns by burying or digging up nuts. They chew bark and clip twigs on ornamental trees or shrubbery planted in yards. Squirrels often take food at feeders intended for birds. Sometimes they chew to enlarge openings of birdhouses and then enter to eat nestling songbirds. Squirrels may eat planted seeds, mature fruits, corn, and grains.
Health and Safety Concerns
Squirrels chew on electrical lines, leading to fires. If left long enough, their gnawing can weaken rafters.
Fox and gray squirrels are vulnerable to several parasites and diseases. Ticks, mange, fleas, and internal parasites are common. Squirrel hunters often notice bot fly larvae, called “wolves” or “warbles,” protruding from the skin, especially before frosts. The larvae do not impair the quality of the meat for eating and they are not known for harboring diseases dangerous to humans. The droppings of flying squirrels have been associated with murine typhus.
Overview of Damage Prevention and Control Methods
- Remove bird feeders
- Cut down or trim trees back at least 6 feet from buildings
- Install sheet metal bands on isolated trees to prevent damage to developing nuts
- Install chimney caps and seal any gaps in the chimney flashing
- Close external openings to buildings; do not seal animals inside the home
- Plastic tubes on non-electrical service wires may prevent access to buildings
- Strobe lights- especially good for attics
Other Control Methods
- One-way doors
- Squirrels may be captured by hand using leather gloves, nets, and snake tong