Autumn Critters

Squirrels are out in full force and busy in the autumn months, preparing for the coming winter by searching for and storing nuts, cones, mushrooms, and more. They often store their stash in one area or split it up, depending on the species. Unfortunately, they often target attics as overwintering spots, so they create their nest and store their food there. The red squirrel’s coat turns a brighter orange-red color upon the arrival of colder weather, and in autumn, they may get covered in pine sap from spending time gathering food. 

For bats, autumn usually means mating and preparing for hibernation. After the second of two breeding seasons of the year (the first being spring/summer), many bat pups are born in autumn, so bats are quite active during these months. Most bats will leave naturally by the end of late fall in order to migrate, but until then, they may still be in your attic or chimney and can cause serious damage in a short amount of time. The little brown bat, Northern long-eared bat, and big brown bat hibernate in mines and caves across the state (and unfortunately, sometimes your home). Other species, like the silver-haired bat, the Eastern red bat, hoary bat and evening bat all migrate south during the winter.

Unlike some other critters on this list, rodents don’t hibernate. However, upon cooler weather that autumn brings, mice are more likely to find their way into your home via unsecured holes in your foundation, cracks in the roof, etc. Mice are very active in fall months, busy searching for food stuffs they can gather for their nests so they do not have to traverse out in the cold to find food in winter. Areas of your home like walls and attics look most attractive to mice, offering them a cozy and warm place to nest for the coming winter.

During autumn, raccoons’ fur coat gets thicker to accommodate the colder temperatures. They stuff themselves with food to prepare for winter. These fierce creatures prefer to remain in a state of partial hibernation for the majority of the winter. They will come out to look for food during warmer days, but for the most part they are in a state of torpor (something bats also do), which is a minor form of hibernation. Ideal den locations for raccoons include your attic, chimney, and/or outbuildings/sheds—comfortable and low-traffic areas.

Colloquially known as field mice, voles are small rodents that are very prominent in the state. We have a number of vole species in the state, including the red-backed vole, the meadow vole, rock vole and the heather vole. They look like small brown mice and they can live outdoors in conditions as low as freezing, if there’s enough insulation from snow. As such, voles are not as likely to be in your home as other rodents might, but they do occasionally still get into your home.

Autumn is among the most active seasons for brown rats, because the temperature drops and the weather is rainier. They use the autumn months to search for appropriate nesting areas to stay warm and nest during winter, often destroying things like insulation, boxes and sometimes books to construct their nests. They seek out places to nest like your attic or walls. Rats are notorious for reproducing quickly, and are able to have several litters per year. Like raccoons, rats do not properly hibernate in autumn, but they do focus primarily on food gathering in the autumn months to stockpile in their nest so they don’t have to venture out in the snow and cold weather.

As their name suggests, chimney swifts are most commonly found in chimneys. This common bird almost exclusively nests in the dark and protected structures in groups, and it’s even been reported that up to a thousand birds have roosted in a single chimney before. Luckily, chimney swifts migrate south during winter, but if you are using your fireplace before they migrate, they could be injured.

Cold-blooded snakes are often seen taking advantage of the last dependably warm days in autumn before they go into hibernation for winter. Unfortunately, the colors of the falling leaves help camouflage snakes. Most snakes in Minnesota are nonvenomous, but can still strike if they feel threatened.

Like most of wildlife animals, opossums don’t love winter and want to be as warm and comfortable as possible during these months. Autumn brings opossums trying to find suitable locations. They spend most of their time in these still-warm months searching for food, although they do not truly “hibernate”. Opossums are quite transient during spring and summer months, but in the fall and winter they can be found in the same spot for a longer period.

For flying squirrels, autumn slows down, and their main focus is securing food for the impending winter. Flying squirrels hibernate. They take advantage of nut and cone-bearing trees. These rodents often forget where they bury the nuts and seeds, so in a roundabout way, flying squirrels are helping to repopulate forests. Flying squirrels molt to prepare for winter (they actually use their discarded fur to help supplement their nest), and their winter coat is thicker.

In autumn, chipmunks are preparing for the winter months, like many other rodents, by searching for food. Some chipmunks spread their food caches throughout different areas (known as scatter hoarding) and some store it all in one place, a process known as larder hoarding. These small striped rodents are partial hibernators that will wake for a few days to eat (a process known as torpor). They can also get into your home to hibernate, which is a rude awakening if you don’t know they’re there until it’s too late and they’ve already caused damage.

Birds are another critter busy prepping for winter in the autumn months. Many birds are seen beginning the migration process to warmer areas for the winter, but birds like cardinals, woodpeckers, sparrows, finches, chickadees, nuthatches and more overwinter in the state.

These critters are active throughout the whole year, but in autumn, they’re working on their complex tunnels. As the weather gets cold and the soil starts to freeze, moles will dig even further into the ground and stick it out through winter.

Known simply as “gophers”, pocket gophers are also active in fall, as the moisture level in the soil is adequate for digging. They measure between 7 and 10 inches and can weigh between one and two pounds. They don’t usually get inside homes, but much like moles, their damage is present in yards outside.

Many insects are still fairly prominent in the still-warm autumn months—especially stinging insects. Insects like bees, wasps and hornets, ants, spiders, beetles, centipedes and more may still infest your home, requiring immediate removal. Once it gets cooler in fall, this is a sign to insects that it’s time to find a warm place—which unfortunately, is often your home.

Though they’re not necessarily hazardous to your health, ants can be incredibly frustrating in places like your kitchen and bathroom looking for food in winter. Some carpenter ants can build nests inside your home during the colder winter months.

For the most part, bees are non-aggressive and vital to the environment. Sometimes, though, if bees construct their nest inside your home or in a high traffic area for you and your loved ones, they become an issue. Bees continue to forage through the autumn months if it is relatively warm, and they gather food for the hive through winter.

Much like wasps, hornets are also active in the fall months, for the same reasons. Stinging insect colonies have reached their yearly peak number in autumn and are always searching for comfortable warm areas—like your home. Hornets, wasps and yellow jackets all switch from a primarily insect-based protein-heavy diet to a diet of sweet items in the fall, such as fruit drinks, sodas and more.

Bad news for homeowners, especially those who are frightened of stinging insects, in autumn. Wasps are out and about in this season looking for food. They construct nests around lighting, furniture and decks, making their close proximity even more dangerous. Wasps have more time to forage for their preferred food sources and are consequently out more during the day, which equates to more human interaction—and more chances to get stung.

Another stinging insect that is active in fall is the yellow jacket. As their food sources begin to dwindle later in the autumn months, yellow jackets (like many of us!) get frustrated and angry that they aren’t able to find enough food.