The scratching in the attic that homeowners usually blame on mice is, in a surprising number of wooded suburbs, coming from something else entirely: a flying squirrel colony that moved into the space between the roof deck and the insulation months ago and has been coming and going through a gap under the fascia board every night since. Southern flying squirrels are common across most of the eastern half of the country and parts of the Pacific Northwest hosts the larger northern flying squirrel, yet both species are so completely nocturnal that a household can share a yard with them for years without a single daytime sighting.
Gliding, Not Flying
Neither species actually flies. A fold of skin called the patagium stretches from wrist to ankle on each side, and when the animal leaps from a trunk and spreads all four limbs, that skin catches the air like a small kite. A flattened, feather-like tail acts as a rudder, and small adjustments in limb tension let the squirrel bank around branches mid-glide. A single leap from height can cover well over 100 feet, ending with an upward swoop at the last moment that converts forward speed into lift and lets the animal land on a trunk feet-first instead of crashing into it.
That braking maneuver is the reason flying squirrels favor mature trees with tall, branch-free trunks; a glide path needs both a high enough launch point and open space to cover real distance, which is one reason clearing understory trees while leaving canopy trees standing tends to suit them better than a densely packed young woodlot.
A Schedule Built Around Owls and Bats
Activity typically starts thirty to sixty minutes after sunset and continues in bursts through much of the night, tapering well before dawn. That window overlaps heavily with both the hours owls hunt and the hours bats are on the wing, and flying squirrels are a documented part of the diet of barred owls and great horned owls in particular. Diet itself runs toward hickory nuts and acorns cached individually in scattered spots rather than one central larder, supplemented by tree sap, fungi (including underground truffles, which the squirrels locate by scent and which depend on the squirrels to spread their spores through droppings), and, opportunistically, insects, bird eggs, and nestlings.
Confusable Sounds in the Attic
Flying squirrels, gray squirrels, roof rats, and bats can all produce scratching sounds in a wall or attic cavity, and the timing is often the clearest clue: gray squirrels are active at dawn and again toward dusk, while sounds continuing steadily well into the middle of the night point more toward flying squirrels, rats, or bats. Because flying squirrel colonies den communally, an attic infestation is often a family group rather than a single animal, and exclusion work is best timed outside of the spring and summer months when young are present and unable to leave through a one-way door on their own.
Unlike most tree squirrels, flying squirrels den in groups during cold weather. A dozen or more individuals, sometimes from more than one family line, will crowd into a single insulated cavity and huddle together overnight, cutting individual heat loss substantially compared to denning alone. The group scatters back into separate summer territories once nightly temperatures climb.
Making a Yard More Attractive Without Inviting Them Indoors
- Leave standing dead trees where it is safe to do so — snags provide the natural cavities flying squirrels prefer over roof spaces
- Add a nest box with a 1.25-inch round entrance — mounted 15 to 20 feet up on a trunk, well away from the house itself
- Keep a mix of mature nut and mast trees — hickories, oaks, and beeches supply both food and gliding launch points
- Seal obvious attic entry points — gaps under fascia boards and at roof-wall junctions are the usual access routes
Two Species, Different Ranges
The southern flying squirrel is the one most likely sharing a suburban lot east of the Mississippi and south of the Great Lakes, adapted to mixed hardwood forest and comfortable in fragmented, tree-dotted neighborhoods. The northern flying squirrel favors cooler, coniferous and mixed forest further north and at higher elevation, and runs somewhat larger with a greyer coat than the southern species' warmer brown. A separated mountain population, the Carolina northern flying squirrel, is federally listed due to its extremely limited high-elevation range in the southern Appalachians, a reminder that even a genus most people never see includes at least one population under genuine conservation pressure alongside otherwise common, everyday backyard residents.
Compared to the daytime tree squirrels most households already recognize on sight, flying squirrels are a near-invisible neighbor: smaller, quieter in daylight, and organized around a completely different clock. A nest box placed with that clock in mind gives them a den option that does not run through anyone's roof.