The question of whether flying squirrels are endangered is complex, requiring a distinction between widespread species and isolated subspecies. All North American flying squirrels belong to the genus Glaucomys, a group of nocturnal mammals found across the continent. While often described as “flying,” these creatures are expert gliders, using a furred membrane called the patagium to steer and slow their descent after launching from trees. Their conservation status varies based on their specific geographic location and genetic identity.
Defining North American Flying Squirrels
North America is home to two species: the Southern Flying Squirrel (Glaucomys volans) and the Northern Flying Squirrel (Glaucomys sabrinus). They are distinguished by size and fur coloration. The Southern species is smaller, measuring eight to ten inches long, and possesses entirely white belly fur.
The Northern Flying Squirrel is larger, reaching ten to twelve inches in length, and its underbelly fur has a slate-gray base beneath the white tips. The Southern species is the most widespread, inhabiting deciduous and mixed forests across the eastern United States. The Northern species has a more fragmented range, preferring cooler, higher-elevation coniferous forests in the Appalachian Mountains, the Northeast, and the western mountains.
The General Status of Common Species
For most flying squirrel populations, the answer to the endangerment question is “no.” Both the Southern Flying Squirrel and the overall Northern Flying Squirrel population are classified by the International Union for Conservation of Nature (IUCN) as species of “Least Concern.” Their populations are considered stable and widespread across their respective ranges.
The Southern Flying Squirrel demonstrates adaptability, thriving in various forest types and suburban woodlands. The Northern species, while preferring colder climates, is also common across its extensive boreal and high-elevation habitats. Their success is due to their nocturnal habits and their ability to use tree cavities and abandoned woodpecker holes for nesting.
Specific Subspecies Facing Extinction
A different reality faces certain genetically isolated populations, particularly the Carolina Northern Flying Squirrel (Glaucomys sabrinus coloratus). This subspecies is federally listed as Endangered under the Endangered Species Act (ESA). Its habitat is limited to the high-elevation spruce-fir forests of the Southern Appalachian Mountains, a region often referred to as “sky islands.” These habitats, found only in parts of North Carolina, Tennessee, and Virginia, are vulnerable to environmental change.
The primary threats are habitat fragmentation, destruction, and climate change. The spruce-fir ecosystem is being destroyed by invasive pests, such as the balsam woolly adelgid, which kills the Fraser fir trees essential to the squirrel’s survival. Warmer temperatures allow the Southern Flying Squirrel to expand its range, introducing a parasitic nematode. Because the Carolina Northern Flying Squirrel lacks immunity, this leads to illness and death.
Ongoing Recovery and Protection Efforts
Conservation efforts focus on restoring the high-elevation habitats the endangered subspecies depend on. Much of the remaining habitat is under public protection, including National Forests and National Parks, which serves as a foundation for recovery. Scientists actively monitor populations using specialized tools, such as ultrasound detectors, to track the squirrels’ vocalizations without disturbing them.
The Southern Appalachian Spruce Restoration Initiative (SASRI) focuses on planting nursery-raised red spruce trees to rebuild damaged forests. This restoration requires a balance, as managers must control competing vegetation, like yellow birch, that can stunt the growth of young spruce but also provides shelter for the squirrels. Protecting the remaining habitat from invasive pests, such as the balsam woolly adelgid, remains a challenge to ensure the long-term survival of this isolated and vulnerable animal.