A wild neighbour almost nobody notices.

The Southern flying squirrel is common and widespread across northern New Jersey — far more common than most people realise. But its strictly nocturnal habits mean most residents only ever learn one lives nearby from noises in the attic after dark.

What they look like

Southern flying squirrels are small, just eight to ten inches long and weighing only two to three and a half ounces, with soft grey-brown fur on top and a creamy white belly. Their most distinctive features are oversized dark eyes, built for night vision, and the patagium — a loose fold of furred skin stretching from wrist to ankle on each side, which looks like a spare flap of skin at rest but becomes a gliding surface the instant the limbs spread wide.

Not flight — gliding

Despite the name, flying squirrels don’t fly. They glide. Launching from a high branch, a flying squirrel spreads all four limbs to stretch the patagium taut, turning its body into a shallow parachute. It steers with small adjustments of its limbs and uses its flattened tail as a rudder and brake, landing lower than where it started every time.

A typical glide covers 20 to 30 feet, though individuals have been recorded gliding well over 100 feet between trees.

Family life

Flying squirrels don’t pair off. Males compete for access to a receptive female, and neither sex sticks with one partner. That’s a contrast with their habits the rest of the year, when — unusually for squirrels — they’re happy to den together in groups.

They breed twice a year, in late winter and again in summer, after a gestation of about 40 days. Litters bring two to seven young, born blind and hairless, dependent on their mother for roughly two months.

Outside breeding season they’re highly social. It’s common for many individuals — sometimes a dozen or more — to den together in the same tree cavity or nest box, huddling for warmth, especially in winter. Adults maintain several nests and will move litters between them if one becomes disturbed or infested with fleas.

Daily habits

Flying squirrels are the most nocturnal of all New Jersey’s squirrel species, rarely active before full dark and almost never seen on the ground, since they travel almost entirely by climbing and gliding between trees.

They’re omnivores with a broader diet than most tree squirrels: nuts, seeds, berries, mushrooms, and flower blossoms, but also bird eggs, insects, and occasionally small vertebrates.

When feeding on hickory nuts and acorns, a flying squirrel neatly cuts a hole in one end to extract the meat rather than cracking the shell. A cache of hollowed nutshells is a good clue that flying squirrels rather than gray squirrels have been at work.

Territory and range

Home ranges are fairly small, typically one to five acres of mature woodland with plenty of cavity-bearing trees. Males’ ranges overlap broadly with each other and with females, while females keep more exclusive territories, especially while raising young. Because flying squirrels depend on tree cavities for both nesting and travel corridors, older trees and connected canopy are especially important habitat.