Most squirrels are not active at night, so if you’re hearing noises in your attic after dark, the culprit is either flying squirrels or something else entirely. Gray squirrels and fox squirrels, the ones you see running around your yard, are active at dawn and dusk and sleep through the night. Flying squirrels, their smaller and less familiar cousins, are fully nocturnal and one of the most common sources of unexplained nighttime attic noise.
Gray Squirrels vs. Flying Squirrels
Gray squirrels are the species most people picture when they think of attic squirrels. They’re early risers. You’ll hear the most movement in the early morning and again around sundown, and they typically leave the attic during the warmer parts of the day. If your attic noises happen strictly at night, gray squirrels are almost certainly not responsible.
Flying squirrels operate on the opposite schedule. They leave the attic shortly after sundown to forage and return before sunrise. They have large, dark eyes built for night vision, and because they’re nocturnal, most homeowners have never actually seen one. They’re surprisingly common, though. Southern flying squirrels live across the entire eastern half of the United States, and they frequently colonize attics in groups. A single flying squirrel is rarely alone. If you have one, you likely have several.
What Flying Squirrels Sound Like
Flying squirrels are small, roughly the size of a chipmunk, so they don’t produce the heavy thumping you’d expect from a raccoon. What you’ll hear instead is fast, light scurrying that crosses the ceiling quickly. They move faster than bats and cover more ground. You may also hear grinding or gnawing sounds, especially at night, as they chew on wood, wiring, or other materials. Because they’re rodents, their teeth grow continuously, and they chew constantly to keep them worn down.
The timing is the biggest clue. If the activity starts after sunset and quiets down before dawn, flying squirrels are a strong possibility.
Other Animals That Make Noise at Night
Several other animals share that nocturnal schedule, and telling them apart matters because removal strategies differ.
- Mice and rats are nocturnal and tend to become most active after you go to bed. They produce soft, quick skittering and gnawing sounds. Mice are lighter and quieter than flying squirrels, while rats can sound similar in weight. Both are highly attuned to your household routine and wait for quiet before moving around.
- Raccoons are much heavier. A single adult raccoon sounds like a person walking in the attic. If a mother has denned with kits, you may hear soft mewing early on that gives way to thumping, wrestling, and snarling as the young grow.
- Bats are generally very quiet. They make a soft scratching sound as they crawl but move awkwardly and slowly compared to rodents. You won’t hear gnawing, but you may notice high-pitched, fast chirping that sounds metallic and cricket-like.
Signs of Flying Squirrels in Your Attic
Sound alone won’t give you a definitive answer. If you can safely inspect your attic, look for a few things. Flying squirrel droppings are small and dark, similar to mouse droppings, so size alone won’t distinguish them. But nesting material is a giveaway: flying squirrels build nests from shredded insulation, gnawed wood, leaves, and fur. You may also notice a persistent bad smell from accumulated urine and feces, especially if the colony has been there for a while.
Check the exterior of your home for entry points. Flying squirrels can squeeze through holes as small as 1.5 inches in diameter. Common entry points include gaps around roof vents, soffit intersections, and where utility lines enter the house. Any hole roughly the size of a quarter or larger is big enough.
Why Attic Squirrels Are a Serious Problem
Whether it’s a gray squirrel nesting during the day or flying squirrels active at night, the damage profile is the same. Squirrels chew electrical wiring, which creates a genuine fire hazard. Some estimates attribute up to 20% of house fires of undetermined origin to rodent damage to wiring. They also tear apart insulation for nesting material, reducing your home’s energy efficiency, and can damage HVAC ductwork. Over time, urine and feces contaminate insulation to the point where it needs full replacement.
Getting Them Out Safely
The standard approach is exclusion: letting the animals leave on their own while blocking them from returning. This typically involves installing a one-way door over the main entry point so squirrels can exit but not re-enter. Every other gap, crack, or hole large enough for entry needs to be sealed at the same time, using hardware cloth, wire mesh, or metal flashing. Foam and caulk alone won’t hold; squirrels chew right through them.
Timing matters. Flying squirrels breed twice a year, with litters born roughly between February and April and again between June and August. Babies are born helpless, with their eyes closed for the first three to four weeks, and they nurse for about 65 days. If you seal entry points while flightless young are still inside, they’ll die in the attic, creating odor problems and potentially drawing insects. Late fall and early winter, after the summer litters have matured but before the spring breeding season, tend to be the safest window for exclusion work.
For flying squirrels in particular, the colonial nature of the problem makes professional removal worth considering. A single family of gray squirrels is one thing; a group of ten or more flying squirrels using multiple entry points is considerably harder to manage with a single one-way door. Sealing every potential entry point on a roofline requires careful inspection, often from a ladder, and missing even one gap means the colony simply relocates to a new opening on the same house.