Gray Squirrels of different shades

Often thought of as a good example of industrious behavior, the Eastern Gray Squirrel (Sciurus carolinensis) is a native species common to Frederick County. In our area, coloring of gray squirrels can vary from light gray, gray with a reddish or brownish tinge, to black. Normal gray squirrels have 2 normal genes that produce the gray color. The actual hairs on a squirrel with normal color have bands of black, white and brown, which give the squirrel it gray appearance.

Black squirrels have a melanistic (from the word melanin, originating with the Greek word for color) mutation in which the hairs have more black and less white and brown. A black squirrel can have either 1 normal color gene and 1 black color gene, or 2 black color genes. Where there are larger populations of black squirrels, mixed color litters can be common. Squirrels with 2 black color genes are very black, and those with 1 black and one normal color gene appear a brown-black. Historically, a reproducing population of black squirrels was found in Ontario, Canada. Some of these were imported into the US and have created populations of black squirrels. For example, 18 Canadian black squirrels were released at the National Zoo in Washington, DC, around the turn of the 20th century. The proportion of black squirrels has increased over the last century, with approximately half the squirrels in several areas of DC now possessing black coloration. Some studies show that black squirrels out-compete the normal gray colored ones. Although other studies show that since the black squirrels are more unique as well as easier to see, they are preferentially fed more often by humans than normally colored gray squirrels.

Each gray squirrel can store thousands nuts, seeds and fruits by burying them or hiding them in many different locations. While squirrels have a good memory of their areas, their sense of smell helps them home in on the stored food. Even so, much of their hidden food is not eaten, and the acorns, hickory nuts and other seeds they bury help grow new trees and plants.

Both male and females are approximately the same size, about 9 to 12 inches body length with a tail an inch or 2 shorter than the body. A mature squirrel weighs about a pound. Very few mammals can descend a tree headfirst, as does the Eastern Gray squirrel. It is able to do this by being able to rotate its feet so that the claws are facing backwards to grip the tree on the way down. Nests are typically built of dry leaves and sticks in tree forks, or in hollow trees, about 40 feet above ground, with the males and females sharing the nest during their twice a year breeding periods and in cold weather. Litters of about 2 to 4 young are born in late winter and in early summer, after a 44 day gestation period. Squirrels start breeding at about 1 year of age and can live the wild to about 12 years. Predators include hawks, owls, foxes, bobcats and raccoons, as well as domestic animals.

In our area Eastern Gray Squirrels exist in similar forest habitat with the smaller Southern Flying Squirrel. While gray squirrels are more active in the morning and late afternoon hours, flying squirrels are less commonly seen since they are more nocturnal. They do not actually fly, but glide using a membrane called the patagium which stretches from wrist to ankle. The glides are controlled by the squirrels by changing positions of the arms and legs and using the tail as an airbrake. The Southern Flying Squirrel breeds twice a year at times similar to the grey squirrel and generally lives in hollow tree cavities about 15 to 20 feet above ground.

Because they are very adaptable and tolerant of humans, gray squirrels have become invasive in areas like California, Ireland and Britain where they were not a native species. They outcompete the native Douglas red squirrels on the West Coast and the Eurasian red squirrels in the British Isles. American red squirrels are a different species (Tamiasciurus hudsonicus) native to Maryland and to Frederick County. The American Red Squirrel is about 3/4ths the size of the more common gray squirrel and generally produces one litter per year. Its diet is also similar to the gray squirrel. In Maryland, Fall and Winter small game hunting is allowed by the Department of Natural Resources for both the Red and Gray Squirrels, but not for the flying squirrel. Communicable diseases in squirrels are rare, although rabies can occur. The DNR recommends avoiding contact with a squirrel that appears aggressive, lethargic or has trouble moving.

Article by FCFCDB

Nature Notes for 6/23/23