Squirrels are small, agile diurnal mammals. More than 300 species inhabit a wide range of environments, including deserts, woodlands and urban parks. Squirrels live on all continents except Australia. They are divided into three groups: tree squirrels, ground squirrels and flying squirrels.
Many tree squirrels live in nests called dreys, large piles of twigs and leaves high in the fork of a tree. Other species live in tree cavities. Ground squirrels live in burrows underground.
Squirrels mate in late winter or early spring. During mating, females will lead males on wild chases, leaping from branch to branch at high speeds.
Baby squirrels are born naked and blind, weighing no more than one or two ounces. The mother nurses them for about two months. Many species have two litters each year, while others have only one.
In captivity squirrels can live up to 20 years. Wild squirrels rarely live more than eight years. Mortality is highest in the first year of life.
Predators include domestic and wild cats, coyotes and hawks. Flight is the squirrel’s primary defense mechanism. Some species chatter or whistle an alarm call. In urban and suburban environments, cars cause many squirrel deaths.
Squirrels eat a wide variety of nuts, seeds and fruits. Occasionally they will eat eggs and insects. In urban areas, they also eat human leftovers, including bread and pizza.