Except for gardeners having to replace bulbs and seedlings, and homeowners having to repair roofs, insulation, ceilings, and foundations, most people like having cute little squirrels of all kinds around. When squirrels become a pest, however, knowing the different types of squirrels is essential for choosing the rodent removal methods that will work. And even when the desire is encouraging squirrels to visit a park or woodland, understanding the different types of squirrels is necessary for protecting squirrels from predators, disease and knowing how to get rid of squirrels.
The most common squirrel in North America is the red squirrel. It is so common, in fact, that the nomenclature for red squirrels gets more than a little confusing. Sciurus niger, its Latin zoological name, literally means “black squirrel” (Tesky, Julie L has wrote a paper on them). Red squirrels are also known as fox squirrels, stump-eared squirrels, raccoon squirrels, and monkey-faced squirrels. They are often mistaken for Eastern gray squirrels, despite the fact that the “red” squirrel has a reddish coat on its back, red and black on its tail, and rust-colored fur on its legs.
Red squirrels are found throughout North America east of the Rocky Mountains, except in Canada’s maritime provinces and in New England. They were once also the most common squirrel in the United Kingdom and Europe, although in many locations the red squirrel has been nearly wiped out by diseases brought by the imported gray squirrel.
From its nose to the tip of its tail, the red squirrel may be as much as a meter (39 inches) long. The body of an adult red squirrel ranges from 45 to 70 cm (18 to 28 inches) long and the tail from 20 to 35 cm (8 to 14 inches) long. Adults weigh between 500 and 1000 grams (1.1 to 2.2 pounds), with little difference in the sizes of male and female adults.
Red squirrels are omnivores (Nature Works gives a very good description of omnivores). They prefer nuts and seeds, but they will also eat the eggs of nesting birds, small lizards, and small snakes. Pet red squirrels may live as long as 18 years, but the overwhelming majority of red squirrels in the wild are consumed by predators before they reach maturity at the age of one year.
The the gray squirrel, Sciurus carolinensis , is the predominant species of squirrel on the Atlantic seaboard of the United States and Canada. In Canada and the UK it is usually referred to as the “grey” squirrel. It ranges across the southern United States to west Texas and is also found in the American Midwest.
The gray squirrel has a grayish-brown coat on its back and white fur on its belly. In urban areas where gray squirrels have few predators, however, some individual gray squirrels will grow red or even white fur on their backs. Most gray squirrels in Canada have black fur on their backs, and some gray squirrels in New England have white tails and black fur on their backs or black tails and white fur on their backs. Gray squirrels are a little smaller than red squirrels, just 23 to 30 cm (9 to 12 inches) from head to tail with tails 20 to 25 cm (8 to 10 inches) long. They weigh usually about half as much red squirrels, 400 to 600 grams (about 3/4 to 1-1/4 pounds).
The gray squirrel eats nuts and seeds almost exclusively. It is a scatter-hoarder, burying nuts and seeds randomly but densely enough that it does not have to remember where it laid in its winter supplies. When the time comes to rely on stored food, the squirrel simply starts digging until it finds a nut or seed. When nuts are scarce, however, the gray squirrel can remember the location of food from visual landmarks, and it can smell caches of nuts from about 2 cm (1″) away. Individual squirrels make thousands of caches of food every season. Unlike other kinds of squirrels, they can descend from trees head first.
Gray squirrels were introduced into the UK and Ireland in the nineteenth century. They have been much more successful than the native red squirrels in the British Isles and across most of Western Europe (the ADW will give you more info about their habitat).
The gray squirrel is the natural reservoir for an infectious disease known as squirrelpox. The virus that causes squirrelpox is in the same family of viruses that cause chickenpox, cowpox, prairie dog pox, and smallpox. The infection causes painful blistering and scarring of the skin of squirrels, although it is not known to be transmitted to humans. Death in squirrels is usually caused not by the infection itself but rather by starvation and dehydration due to an inability to leave the nest.
Gray squirrels usually recover from squirrelpox, but any red squirrels they infect usually die of it. Epidemiologists believe that the reason red squirrels are dying out in places as far apart as Scotland and the Yukon territory of Canada is the spread of this viral infection. If you are concerned about the health of red squirrels in the wild, don’t trap and release gray squirrels into their territory.
Millions of Americans first became familiar with flying squirrels through the cartoon characters Rocky and Bullwinkle, Rocky an intrepid flying squirrel usually wearing an aviator’s helmet with goggles, and Bullwinkle a less than mindful Minnesota moose constantly pursued by sinister foreign agents Boris and Natasha. Although there are no specimens in the wild that wear aviator’s helmets and goggles, the flying squirrels, identified by zoologists as Petaurisini or Pteromyini, actually can glide up to 90 meters between trees with the help of the patagium, a parachute-like membrane that supports them in the air.
Flying squirrels are found over most the temperate regions of the Northern Hemisphere, from Finland to Japan, India, and Indonesia, and from Canada through the United States to Mexico and Central America. Flying squirrels are almost never a household pest, but the Southern flying squirrel that ranges from Eastern Canada to Florida sometimes carries the fleas that spread a serious and potentially fatal infectious disease called sylvatic (or woodland) epidemic typhus.
In the United States, outbreaks of epidemic typhus most commonly occur in wilderness camps where one or more hikers or campers come into physical contact with a flying squirrel. The medical journal Emerging Infectious Diseases reported a case of study of a cluster of cases of typhus at a wilderness camp in western Pennsylvania. Animal experts later learned that over 70% of flying squirrels in that woods carried the microorganism that causes the disease.
It’s essentially impossible for homeowners to control flying squirrels. Up to 50 individuals will share up to 50 nests, each adult flying squirrel having a range of 4 to 6 hectares (10 to 15 acres). It’s far more important to handle flying squirrels with care if they are encountered dead or injured, being especially sure not to be bitten by fleas or ticks.
The California ground squirrel, Spermophilus beecheyi, is a colorful squirrel with an especially bushy tail. The fur on its back and head is mottled with brown, yellowish, and gray hairs, with white fur around the eyes and black hair on the ears. Although the tail has thick hair, it is just 15 cm (6 inches) long, the squirrel’s length from the head to the tip of the tail about twice as long, approximately 30 cm (12 inches). The Nature Mapping Foundation has a good photo of one and shows you on a map where they are predominately located.
While ground squirrels learn to beg from picnickers, they prefer to eat nuts, seeds, and young plants and trees. Ground squirrels do not damage roofs and attics, but burrows that cause the collapse of piers and beams can cause serious damage to a house. Mowing lawns and maintaining walkways becomes difficult where California ground squirrels dig their tunnels, and gardeners and landscapers often find they repeatedly have to replace plants due to predation by the ground squirrels
Ground squirrels carry and are susceptible to bubonic plague. Infection with plague can wipe out entire colonies of California ground squirrels, and it is transmissible to humans. It is important not to handle dead California ground squirrels. Note the location of the carcass and call local public health officials for removal.
Western grey squirrels (Sciurus griseus) are found throughout forested areas in California in the USA. Their presence is easy to recognize by the stripping of bark off oak trees. Douglas squirrels (Tamiasciurus douglasii), which are sometimes called chickarees, live closer to the coast, and are also recognized by the peeling of bark off trees.
Both squirrels are a problem for professional tree growers, but they seldom approach houses, apartments, or storage buildings. The problem with these squirrels is the infections they carry. Douglas squirrels can carry squirrelpox and endanger other species. Western grey squirrels can carry the ticks that can infect people with Lyme disease.
The thirteen-lined ground squirrel (Spermophilus tridecemlineatus) is native to the American Midwest. As its name suggests, it is easily recognized by the 13 stripes on its back. This squirrel spends about half the year foraging for nuts and seeds and about half the year in hibernation. It only lives where snakes also hibernate during the winter.
Thirteen-lined ground squirrels are solitary. They only meet to mate, unless there is an abundant source of food. When gardeners can tolerate the damage this species does in the garden, chances are they would be better off simply to allow it to return to its burrow when it has eaten its fill. Capturing one squirrel from a burrow 1 meter (3 feet) below the ground that is 10 to 20 meters (30 to 60 feet) long with multiple side entrances is a time-consuming and frustrating proposition.
These seven species, of squirrels, are only the types of squirrels most likely to be encountered in the English-speaking world. There are pygmy squirrels in western Africa that weigh less than 15 grams (1/2 ounce) whose hearts beat 500 times per minute. There are burrowing squirrels in Kazakhstan that grow larger than many dogs, up to 8 kilos (18 pounds), whose hearts beat only 18 times per minute during hibernation. There are squirrels that eat nuts, squirrels that eat bugs, squirrels that eat birds, and squirrels that eat pizza when it is available.
Each type of squirrel relates to the human world in a different way. Being able to identify the squirrel, however, is the first step in a happy relationship with the world’s most popular and sometimes most pestiferous rodent.