Squirrels are a diverse group of rodents found across the globe, inhabiting a wide array of environments. These adaptable creatures have developed distinct living strategies, from constructing elaborate nests high in trees to digging complex underground burrow systems. Their ability to thrive in varied settings highlights their ecological flexibility.
Diverse Squirrel Habitats
Squirrels are broadly categorized into tree squirrels, ground squirrels, and flying squirrels, each preferring specific habitats.
Tree squirrels, such as the eastern gray squirrel, live in mature forests, including deciduous, mixed, and coniferous woodlands, especially where nut-producing trees like oak, hickory, walnut, and maple are abundant. These arboreal species utilize the canopy for shelter and food. Red squirrels, for instance, are commonly found in coniferous and mixed forests.
Ground squirrels favor open landscapes. Their preferred habitats encompass fields, pastures, grasslands, rocky outcrops, and even semi-arid deserts. Species like the California ground squirrel inhabit open areas with dry, rocky soils, while thirteen-lined ground squirrels thrive in short grasslands and prairies. They dig extensive tunnel systems.
Flying squirrels live in dense, mature forests with tall trees that facilitate their gliding movements. They are found in both deciduous and coniferous forests and woodlands. The northern flying squirrel, for example, inhabits coniferous and mixed forests across North America.
Squirrel Homes and Shelters
Squirrels construct or utilize various structures for shelter, protection, and raising their young.
Tree squirrels build nests called dreys, which are spherical structures made from interwoven twigs, leaves, and bark. These dreys are commonly situated in the forks of trees or close to the main trunk, providing stability and concealment. While summer dreys may be lighter and more open, winter dreys are larger and more insulated.
Tree squirrels and flying squirrels also use natural tree cavities, such as hollows or abandoned woodpecker holes, as dens. These tree cavities offer increased protection from predators and harsh weather, making them particularly favored for winter shelter and for birthing and raising offspring. Flying squirrels, being nocturnal, often den in tree cavities, snags, or even rock crevices.
In contrast, ground squirrels create underground burrows. These burrows can be extensive and feature multiple entrances for escape routes. They serve as secure spaces for shelter, hibernation, and raising young.
Global Reach and Urban Adaptations
Squirrels exhibit a wide geographical distribution, inhabiting nearly every continent, including the Americas, Eurasia, and Africa. They are found in diverse natural habitats, ranging from boreal and coniferous forests to tropical rainforests and savannas. However, squirrels are generally absent from the driest deserts and the high polar regions. While not native to Australia, some species, such as the eastern gray squirrel, have been introduced to new regions, including parts of Europe.
Beyond natural environments, squirrels have adapted to human-dominated landscapes. They are common in urban and suburban areas, utilizing parks, backyards, and human structures for shelter and resources. Urban squirrels make nests in attics, chimneys, walls, and basements. Their ability to navigate and exploit these environments, including using utility lines as pathways, demonstrates their flexibility. This adaptability allows them to thrive in close proximity to human activity, often relying on human-provided food sources like discarded items or bird feeders.