Cooler Nights, More Attic Calls: Raccoons and Squirrels in Colorado This Fall

Why fall brings both animals indoors

As Front Range nights turn colder through September and October, both raccoons and squirrels shift into shelter-seeking mode. Raccoons and squirrels are both responding to the same seasonal change, but their reasons for wanting into a warm, dry attic differ enough that it is worth understanding both before deciding what you are dealing with.

Raccoons do not hibernate the way some mammals do, but they do become far less active during the coldest stretches of winter and rely on a den to ride out bad weather. According to Colorado Parks and Wildlife, adult raccoons weigh eight to 22 pounds and are heaviest in autumn, which reflects exactly the seasonal bulking and shelter-seeking that drives them toward an attic, chimney, or soffit gap once temperatures start dropping. A warm, dry cavity beats a hollow tree or a rock crevice for riding out winter, which makes an occupied Denver-area home an attractive option this time of year.

Squirrels are working on a different timeline. Fox squirrels, the species most commonly found in Front Range attics, spend late summer and early fall caching food for winter. Colorado Parks and Wildlife notes that fox squirrels bury nuts to retrieve later in the cold months, a habit efficient enough that the squirrels that forget where they buried them end up planting trees by accident. That same caching instinct extends to nest-building: an attic gap, chewed just slightly larger than it needs to be, gives a squirrel a secure, insulated nesting cavity that beats a leaf nest in a tree during a hard winter. Once one squirrel finds a workable opening, it is common for the same entry point to see repeated activity as the animal returns to the same nest night after night, or as more than one animal uses the same space.

Telling the two apart before you call anyone

Sound and timing are the two most reliable clues a homeowner can use before a technician ever sets foot in the attic. Squirrel activity clusters around dawn and dusk, when the animal is naturally most active, and sounds like quick scratching, light rolling, or the patter of small, fast movement. Raccoon activity is heavier and slower, more of a deliberate thump or drag, and happens overnight rather than at first light.

Droppings differ too. Squirrel droppings are small, barrel-shaped pellets with rounded ends. Raccoon droppings are noticeably larger, often tubular, and tend to collect in one repeated spot, called a latrine, rather than being scattered. That latrine habit is actually useful information: if you are finding droppings concentrated in a single corner of the attic rather than spread throughout, that is a raccoon pattern, not a squirrel one.

Entry points also tend to differ by size and location. Squirrels can exploit gaps as small as a couple of inches and often chew a roofline vent, fascia board, or eave return to make an opening large enough to pass through repeatedly. Raccoons need a considerably larger opening, commonly a damaged roof vent, a gap where a chimney chase meets the roofline, or a soffit corner that has already started to separate, and they will actively enlarge a weak spot rather than just use an existing hole.

The health side of the comparison

Raccoon latrines carry a specific risk worth taking seriously. The CDC describes Baylisascaris procyonis, a roundworm commonly carried by raccoons, as capable of causing severe illness in people, particularly children, if eggs from contaminated soil or droppings are accidentally ingested. That is why a raccoon latrine in an attic or on a deck should be treated as a job for someone trained in safe removal and decontamination, not a weekend cleanup project.

Squirrel-related health risks tend to be more indirect. The animals themselves carry a lower direct disease profile for humans, but an active nest brings fleas, ticks, and mites into the structure, and chewed wiring introduces a real fire risk that has nothing to do with the animal's biology at all. Both risks, the parasite exposure from raccoons and the wiring damage from squirrels, are reasons to address either animal promptly rather than waiting to see if it moves on.

A few things homeowners get wrong about fall denning

One common misconception is that a raccoon or squirrel in the attic is "just passing through" and will leave on its own once the weather warms up slightly. In practice, once either animal has committed to a den or nest site ahead of winter, it tends to stay put unless something forces it out, cold snaps included. A brief warm spell in October or November does not undo the decision an animal already made to settle in.

Another misconception is that noise alone tells you how many animals are present. A single raccoon can sound like more than one animal as it repositions itself or drags nesting material, and a squirrel nest can house more than one individual well before any young are born, especially as multiple squirrels seek shelter from the same cold snap. An inspection that identifies actual entry and exit patterns, rather than guessing from sound alone, gives a far more accurate picture of what is actually in the space.

What removal looks like for each, and why it is not a same-day fix

For both species, exclusion, not a same-day seal, is the approach that avoids the pitfalls of DIY trapping: daily trap checks, relocation-distance rules, and the risk of separating a mother from young that cannot fend for themselves. A technician first confirms which animal is present and whether young are likely in the space, since a den or nest with dependent offspring changes the timeline. One-way doors are then installed at the confirmed entry points so the adult, and any older young capable of leaving, can exit but not return. Secondary gaps are sealed at the same time to prevent the animal from simply finding a second opening.

Once monitoring confirms the space is empty, the technician returns to remove the one-way devices, permanently seal every opening, and, if needed, address contaminated insulation or a raccoon latrine as a separate cleanup step. Homes in Arvada, Westminster, and similar established Denver-metro suburbs often have original roofline vents and soffit returns that have degraded over the years, so they carry more of these vulnerable points than newer construction. Fall inspections in those neighborhoods regularly turn up more than one active or recently used entry point.

Frequently asked questions

Related reading

• Raccoon Removal in Colorado
• Squirrels in the Attic: Damage and Removal