The noises heard moving through an attic or within wall voids between dusk and dawn are almost certainly not caused by a squirrel. Most common squirrel species, such as the Eastern gray squirrel, are strictly diurnal, meaning their activity cycle is confined to daylight hours. Consistent movement or vocalizations after sunset should immediately shift suspicion away from squirrels and toward other nocturnal wildlife. The time of day a noise occurs is the most reliable clue in identifying a mystery animal living within a home’s structure. Determining the true identity of the intruder requires careful analysis of the sounds and the animal’s typical behavior patterns.
Squirrels: Diurnal Habits and Daytime Sounds
Eastern gray and fox squirrels follow a diurnal pattern, typically emerging from their nests shortly after sunrise and retreating before dusk. Their activity peaks often occur in a bimodal pattern, with high energy in the early morning and again in the late afternoon, resting during the hottest part of the day. During the night, squirrels sleep, and any noise from them would be brief and infrequent, like a momentary stir rather than sustained movement.
When squirrels are active during the day, their movements create distinct sounds that can be heard inside a home. They produce loud, rapid scurrying and scampering noises as they run across surfaces, which can sound like a fast, light pitter-patter. Squirrels gnaw on wood and wiring to maintain their constantly growing incisors, resulting in grinding sounds. Their vocalizations include a sharp chattering or barking sound, often described as a “kuk” or “qua,” used to signal alarm.
Common Nocturnal Intruders Making Noise
If sustained noise begins after sunset and continues into the night, the source is likely one of several common nocturnal species that seek shelter inside structures. Raccoons are frequent intruders, often gaining access through chimneys or damaged soffits. Their large body size, which can exceed 20 pounds, means their movements translate into loud thumps, slow dragging, and heavy walking sounds across ceiling joists.
Mice and rats, both highly nocturnal rodents, are responsible for much night noise, particularly in wall cavities and ceilings. These smaller animals create subtle, fast-paced noises like light scratching and scurrying, as well as the sound of gnawing on wood or drywall. Bats are another common nocturnal resident; they produce very soft, almost indiscernible scratching or rustling sounds as they crawl inside wall voids, along with high-pitched chirping or squeaking vocalizations. Opossums are also nocturnal and can cause surprisingly loud thumping noises, though their movements are typically slow and deliberate.
Sound Sleuth: Differentiating Nocturnal Noises
Analyzing the characteristics of the sound can help pinpoint the specific nocturnal intruder, starting with the volume. Loud, heavy thumps or the sound of something being dragged are usually caused by larger animals like raccoons or opossums. Raccoons, due to their weight and deliberate movement, create a distinctly heavy thud, particularly noticeable when they jump from a rafter or crawl across the attic floor.
In contrast, the noises made by smaller rodents and bats are much lighter and quicker. Mice and rats produce fast, light scratching sounds, often accompanied by consistent chewing. If the noise is a soft, fluttering sound or a faint, high-pitched chirp coming from within a wall or near a chimney, bats are a strong possibility. The timing of the noise can also be diagnostic; mice are often most active in the middle of the night, while larger animals like raccoons are frequently heard around dusk and dawn as they leave and return to the den.
The location of the sound offers another clue, as animals gravitate toward different parts of a structure. Noises consistently heard from deep within wall cavities or around the roofline suggest smaller animals like bats or mice. If the sounds are clearly coming from the open space of the attic, especially if they involve heavy walking, a raccoon is the more likely suspect. Observing the pace can distinguish between the two largest suspects, as raccoons tend to move in a more casual, lumbering fashion compared to the slower, more labored movement of an opossum.