Bats in Winter in Utah

Most Utah bats migrate or hibernate once insects disappear, but a bat can still turn up in your living room in January. Here is what Utah DWR and DHHS say to do, and why winter is for inspection rather than sealing.

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Where Utah’s bats go in winter

Utah has 18 confirmed bat species. In a July 14, 2026 news release, the Utah Division of Wildlife Resources (DWR) explained that when insects aren’t available in winter, many of the state’s bats either migrate or hibernate, some do a combination of both, and others stay active year-round. Five species migrate, leaving from late August through October and returning in April and May. KSL.com, reporting on DWR’s white-nose syndrome work, put the number of hibernating Utah species at 13.

Utah’s hibernating bats don’t look like the famous eastern caves packed with thousands of bats. DWR Mammal Conservation Coordinator Kimberly Hersey says bats here usually hibernate alone or in small groups in caves, mines and cliff crevices, and DWR’s white-nose syndrome page says the winter locations of most western bat populations are still unknown. Wild Aware Utah, a wildlife-conflict education site run out of Utah’s Hogle Zoo, adds that most Utah species are year-round residents that hibernate, and that hibernating species usually breed in the fall.

Why a bat turns up indoors in November–February

A lone bat in a living room in December usually didn’t fly in from outside. More often it was already roosting in the building, in an attic, wall void, or behind a chimney chase, and something woke it. Wildlife agencies in other states (Wisconsin DNR and New Hampshire Fish and Game, for example) single out the big brown bat as the species most likely to hibernate inside buildings, in small groups or alone. DWR describes the big brown bat as common in Utah. A warm spell, a furnace running, or attic work can rouse a torpid bat, and it may follow warm air or light into the living space.

Bats do not chew their way in. Wild Aware Utah says they use existing gaps as small as about ¼ inch, plus open doors, windows, and torn screens. A winter bat is a sign there is an opening somewhere that will matter again in spring.

What to do if you find a bat inside in winter

Don’t touch it. Utah DHHS and DWR both say never to handle a bat with bare hands.
Decide whether anyone had contact. Per Utah DHHS, a bat that bit or scratched someone, touched a pet, or was found in a room where someone was sleeping (or with an unattended child or impaired adult) must be captured and tested. Bites can be too small to see or feel. Call your local health department right away, and don’t release the bat.
If no contact is possible, confine the bat to one room. Utah DHHS suggests closing interior doors and opening one to the outside. In freezing weather, though, a bat pushed outdoors may not survive; New Hampshire Fish and Game advises releasing winter bats only during the warmest part of the day, and not in below-freezing temperatures, high wind, or heavy rain.
If it can’t go outside safely, wear heavy leather gloves, cover the bat with a small box or can, slide cardboard underneath (DWR’s method), and call your city’s animal control or the DWR regional office for guidance rather than leaving it in the container.
Bat on the ground or on the snow? Utah DHHS says not to touch it and to report it to animal control, DWR, or your local health department.

DWR regional offices

Northern Region (Ogden): 801-476-2740
Central Region (Springville): 801-491-5678
Salt Lake office: 801-538-4700
Northeastern Region (Vernal): 435-781-9453
Southeastern Region (Price): 435-613-3700
Southern Region (Cedar City): 435-865-6100

Rabies risk in the off-season

Utah’s rabies season is mostly a warm-weather event. The DHHS annual reports say most rabid animals are detected from June through October. In 2025 the first positive came on May 28 and the last on October 8; in 2024 the dates were May 17 and October 4. In 2025, 24 animals tested positive statewide and all 24 were bats. Of 240 bats tested, the most ever submitted in one year, 10.0% were positive, and they exposed at least 19 people and 26 pets.

A low winter count is not a reason to skip the call. The only rabies variant known in Utah is the bat variant, and Utah DHHS recommends testing whenever contact can’t be ruled out. Testing a captured bat can rule out the need for post-exposure shots.

White-nose syndrome has reached Utah

White-nose syndrome is a fungal disease of hibernating bats that has spread to more than 40 states since it was detected in New York. The National Park Service announced in September 2024 that the fungus, Pseudogymnoascus destructans, had been found at Canyonlands National Park, on a Townsend’s big-eared bat in a mine and in a sample from the mine floor. That was the first detection in Utah. The NPS said there was no evidence of the disease or of bat deaths in Utah at the time.

The fungus makes hibernating bats wake more often, so they burn through fat reserves and may leave their roosts early in search of food. DWR says the big brown bat and little brown bat, both common in Utah, have been infected elsewhere. DWR asks the public to report dead or sick bats found between January and April to the Division, and to stay out of caves and mines used by bats. White-nose syndrome does not infect people, but a sick or dead bat should still never be handled bare-handed.

Winter is for inspection, not exclusion

DWR’s guidance is to seal openings in fall, when bats are leaving their roosts, and never from May through August while pups depend on their mothers. Winter brings a different problem. If bats are hibernating in the attic or walls, sealing the openings traps them inside, where they die or find their way into the living space. Agencies such as the University of Arizona Cooperative Extension and Maryland DNR advise postponing winter exclusion until spring unless it’s certain no bats are hibernating in the building.

That makes winter a good season for the groundwork:

Look for guano along the foundation, under eaves, and in the attic. Wild Aware Utah describes it as crumbly and full of insect parts. Wear a respirator and gloves near droppings.
Map gaps at ridge vents, gable vents, chimney chases, fascia boards, and siding joints, so the job is ready when bats are active again.
Seal openings that clearly aren’t in use, such as interior gaps around attic hatches, pipes, and light fixtures, to keep a waking bat out of the living space.
Book one-way exclusion for the next safe window: spring, after bats are active again but before females settle in to give birth in May or June, or the following fall after August.

Our fall bat swarming guide covers the September migration, and the maternity season guide explains why summer exclusion is off-limits.

Common questions

Do bats hibernate in Utah?

Yes. Utah DWR says that when insects disappear in winter, many Utah bats either migrate or hibernate, some do a combination of both, and a few stay active year-round. Wild Aware Utah says most Utah species are year-round residents that hibernate. DWR notes Utah bats usually hibernate alone or in small groups in caves, mines and cliff crevices.

Why is there a bat in my house in winter?

A bat found indoors in winter has often been roosting somewhere in the building. Wildlife agencies note that the big brown bat, which DWR calls common in Utah, is the species most likely to overwinter in buildings, and warm spells or household heat can rouse it.

Can I put a bat outside in the snow?

Avoid it if no one had contact. Bats released into freezing weather may not survive. Contain it without touching it and call your local animal control or the DWR regional office for advice. If anyone may have had contact, do not release it at all: call your local health department so it can be tested.

Do bats carry rabies in winter?

Utah’s rabid bats are mostly detected from June through October. In 2025 the first and last positives were May 28 and October 8. That does not make a winter bat safe: Utah DHHS says any bat that bit or scratched someone, touched a pet, or was found where someone was sleeping should be captured and tested.

Can bats be sealed out of a Utah attic in winter?

Not if bats are hibernating inside, because sealing would trap them. DWR names fall as the best time to seal openings, and it does not allow sealing from May through August while pups are present. In winter, have the attic inspected and the openings mapped, then schedule exclusion for the next safe window.

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