Flying squirrels are nocturnal rodents that glide between trees using a membrane of skin. This adaptation allows them to navigate arboreal environments with agility.
Global Distribution of Flying Squirrel Species
The distribution of flying squirrel species spans a wide geographical range, primarily across the Northern Hemisphere. In North America, two primary species exist: the Northern flying squirrel (Glaucomys sabrinus) and the Southern flying squirrel (Glaucomys volans). The Southern flying squirrel is found throughout the eastern United States, extending from Maine south to Florida and west from Minnesota to Texas, also reaching southeastern Canada, Mexico, and Central America. Its range encompasses urban areas as well as forests, from lowlands to elevations of up to 5,000 feet.
The Northern flying squirrel has a more extensive, though often patchier, distribution across North America. This species inhabits coniferous and mixed coniferous forests across much of Canada, from Alaska to Nova Scotia, and extends south into the mountains of North Carolina and west to Utah in the United States. Specific subspecies, like the Carolina and West Virginia northern flying squirrels, inhabit the Appalachian Mountains. Humboldt’s flying squirrel, once considered part of the Northern species, is distinct and found in British Columbia, northern California, Washington, and Oregon.
Beyond North America, a diverse array of flying squirrel species are found throughout Asia, with some extending into parts of Europe. They are found across South Asia, Southeast Asia, and central and southern China. For instance, Indian giant flying squirrels have a wide but patchy distribution in India, particularly in the Himalayan Mountains, and across the mainland of Southeast Asia, excluding the Malay Peninsula.
Specific Asian species include the Japanese giant flying squirrel, found in Japan on islands like Honshu, Kyushu, and Shikoku. The Red giant flying squirrel is distributed from Afghanistan, through northern India and Pakistan, to Java, Taiwan, Sri Lanka, and parts of Borneo and Peninsular Malaysia. The Siberian flying squirrel’s range extends into parts of northeast Europe, including Russia, Finland, and Estonia.
Ecological Preferences and Specific Habitats
Flying squirrels inhabit forest ecosystems. Mature deciduous or mixed forests provide structure for gliding and abundant food.
Suitable nesting sites are essential. Flying squirrels use natural tree cavities, such as hollows in mature tree trunks, or abandoned woodpecker holes. These dens are typically lined with soft materials like leaves, moss, bark, and pine needles. Old-growth forests with large trees and snags are important, providing numerous suitable cavities.
The forest canopy provides an elevated platform for launching glides and offering protection from predators. A closed canopy with closely spaced trees facilitates gliding. They also require water sources and a consistent supply of food within their home range, which includes nuts, seeds, fungi, and insects.
Environmental Influences on Their Range
Environmental factors shape flying squirrel ranges and habitats. Climate, including temperature and precipitation, directly influences the types of forests that can thrive in a region. For instance, Northern flying squirrels are associated with colder, boreal, or coniferous forests, while Southern flying squirrels are found in warmer, temperate deciduous forests.
Food sources like nuts, seeds, fungi, and lichens, linked to specific tree species, also dictate their presence. Northern flying squirrels, for example, rely on fungi and lichens common in moist, older forests. Elevation can also influence their distribution, with some species or subspecies, like the Carolina northern flying squirrel, restricted to high-elevation “sky-islands” in mountain ranges. These conditions define the boundaries of their natural range.
Conservation Concerns for Flying Squirrel Habitats
Flying squirrel populations face conservation challenges due to habitat degradation and loss. Deforestation, urbanization, and agricultural expansion lead to habitat loss. Habitat fragmentation, where continuous forests are divided, restricts movement and reduces genetic flow.
Climate change is another threat, altering forest ecosystems and pushing species ranges northward or to higher elevations. This can lead to a reduction in suitable habitat. Rising temperatures allow Southern flying squirrels to expand their range northward, potentially displacing Northern flying squirrels. Invasive insects, like woolly adelgid beetles affecting spruce-fir forests, also threaten preferred tree species for some Northern flying squirrel subspecies. Maintaining healthy, connected forest ecosystems is crucial for their long-term survival.