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bats — where they go in a New Hampshire winter
Winter: OFF
Daniel Brady · NH-Licensed Pesticide Applicator · License #782664
Reviewed by Daniel Brady

Where Do Bats Go In The Winter?

Winter genuinely ends the household issue — for most species
For once, the popular belief is correct: bats really do hibernate. Four of New Hampshire's five cave-hibernating bat species fly out of state to a mine or cave with stable cold, humid air, so if bats summered in your attic, the household issue is genuinely over for the winter. The exception is the big brown bat, which can hibernate right inside a building — meaning a colony you had in August may still be there, dormant, in January. All of New Hampshire's bats are protected, and white-nose syndrome has devastated their numbers, so no bat work here is ever a kill service.

At a glance

  • Winter’s effect: Winter genuinely ends the household issue — for most species
  • Where they go: A hibernaculum
  • How far: Gone
The honest answer

The short of it

The verdict
Winter genuinely ends the household issue — for most species

This is the one time the myth is true: bats really do hibernate. Which is exactly why you leave them alone — most have already flown out of state, and every one that's here is protected.

The one question nobody else answers

Does winter actually help you?

Every reader assumes the answer is yes — that winter is a break. For the pests that matter most in a New Hampshire home, it is the opposite. Here is where this one lands.

The winter switch
Winter genuinely ends the household issue — for most species

This is the one time the myth is true: bats really do hibernate. Which is exactly why you leave them alone — most have already flown out of state, and every one that's here is protected.

Does winter help you?

For Bats, the winter switch is OFF — winter ends it.

Most people assume

That bats "kind of" hibernate, vaguely — sleeping through winter somewhere without much precision about where or how.

What actually happens

Bats are the genuine true hibernators of this entire twenty-page hub. New Hampshire has five cave- and mine-hibernating species (little brown, big brown, northern long-eared, eastern small-footed, and tricolored bats), and because the state lacks enough naturally suitable mines and caves, most fly out of state — to Vermont, New York, or Massachusetts — to hibernate in a stable, cold, humid hibernaculum. Three other species (eastern red, hoary, and silver-haired bats) migrate south entirely instead of hibernating locally. The one exception that matters to a homeowner is the big brown bat, which is documented hibernating inside buildings rather than traveling to a hibernaculum — and may occasionally appear flying on an unusually warm winter day.

Not one animal — not one answer
  • OFF

    Cave/mine-hibernating species that leave New Hampshire (little brown, northern long-eared, eastern small-footed, tricolored bats)

    Flown to an out-of-state hibernaculum at roughly 40°F and 90%+ humidity. If these summered in your attic, the household issue genuinely ends until spring — and the popular 'they hibernate' belief is exactly correct for them.

  • ON

    Big brown bat

    The one species documented hibernating inside New Hampshire buildings rather than traveling to a hibernaculum. A colony present in summer may still be there, dormant, in January — and may occasionally be seen flying on a mild winter day. This is the bat you can still have in your structure in the dead of winter.

  • OFF

    Migratory tree bats (eastern red, hoary, silver-haired bats)

    These species migrate south entirely rather than hibernating in place — flown, not dormant, but the outcome for a homeowner is the same: gone until spring.

The line

This is the one time the myth is true: bats really do hibernate. Which is exactly why you leave them alone — most have already flown out of state, and the ones in New Hampshire are protected.

So — does winter help you?
Yes, honestly, for most species — a summer attic colony is genuinely gone until spring. But winter is precisely when you must NOT seal a suspected big-brown-bat roost, because doing so can entomb hibernating bats still inside.
What to do in January
For most households, do nothing — do not disturb a suspected roost, and do not attempt any exclusion work until the correct seasonal window. If a single bat turns up flying in living space, treat it as a potential rabies exposure and contact NH DHHS; do not seal entry points in winter if bats may be hibernating inside. Real exclusion work is timed and performed by a licensed wildlife-control specialist, never as a winter job.
The literal question

Where they actually go

A hibernaculum

an out-of-state mine or cave holding a stable 40°F and 90%-plus humidity — except the big brown bat, which may hibernate right inside your attic, wall void, or barn instead

How far from you
  1. Inside your house
  2. On your structure
  3. In your yard
  4. Nearby outdoors
  5. Gone

They are gone.

What the place actually is

Hibernating bats need a site that stays cold and humid enough, all winter, to avoid the fatal extremes of freezing or drying out — and New Hampshire simply doesn't have enough natural mines and caves that fit, so most of the state's bats leave entirely. Big brown bats are the exception: buildings can offer a comparable cold, stable void, which is why this is the one species that can genuinely be hibernating inside your structure right now rather than hundreds of miles away.

Can you see them?
Usually not, and that's the point — a hibernating bat must not be disturbed. The one exception is a lone big brown bat that rouses and appears flying on an unusually mild winter day; that's a documented, if uncommon, part of its pattern, though it can also signal a bat forced out of hibernation by disease.
Where the myths die

How they actually survive it

The survival mechanism

True hibernation

True hibernation — the only genuine one in this entire hub

Is it hibernation? Yes — true hibernation
Bats are the only animal in this entire hub where 'hibernation' is the correct word, and it's worth being precise about why: this is a multi-month, profound metabolic shutdown, categorically different from the torpor raccoons use, the year-round full activity of squirrels and opossums, or the shallow overnight dip a chickadee uses. Do not let the correct bat answer bleed into any other animal in this cluster — none of the rest hibernate.
How it works

Hibernating bats enter a profound, multi-month metabolic suppression on stored fat, punctuated by periodic, costly arousals. That arousal cost is exactly why white-nose syndrome — caused by the fungus Pseudogymnoascus destructans, which grows on bats in the same cold, humid conditions hibernation requires — is so lethal: it rouses hibernating bats more often than normal, burning through fat reserves before spring arrives and leaving many unable to survive the season.

The winter myth

What everyone gets wrong

The myth

"Bats hibernate in my attic all winter, so leaving them alone until spring is the simplest option" — or, just as often, the opposite conclusion: "they're just sleeping, so I can clear them out now."

Why people believe it

The underlying fact — bats hibernate — is actually correct, which is what makes both misreadings so understandable. People reasonably assume that correct biology translates directly into a simple homeowner decision, when it doesn't.

The correction

Most of New Hampshire's bats aren't even in the attic to begin with come winter — they've flown to an out-of-state hibernaculum. But if the colony includes big brown bats, they may genuinely be hibernating inside the structure right now, and disturbing or sealing that space in winter is both illegal for a protected species and lethal to the animals trapped inside.

Why it matters
A well-intentioned winter 'clean-out' can kill protected, white-nose-devastated bats outright, or trap dying animals inside a wall where they decompose. Correct action is timed exclusion during the legal window outside both hibernation and the maternity season — not a decision made casually in either direction.
Actually — this one holds
Yes — genuinely, for once. Bats really are the one true hibernator in this hub. The mistake isn't the biology; it's assuming that fact makes either 'ignore it' or 'clear them out now' a safe conclusion. Neither is.
What you would actually see

The signs in January

What you would actually see
4
  • Usually none at all — a summer colony that used a hibernaculum is simply gone
  • A single bat flying outdoors on an unusually mild winter day (most likely a big brown bat, occasionally a sign of white-nose disturbance)
  • Staining or a build-up of guano near a roost entry point, left over from the warm season
  • A bat found inside living space, most often a disoriented big brown bat
What it means
No winter activity at all is the expected, good-news outcome for most species. A bat seen flying in the cold is the unusual case and should be left alone, not investigated or handled.
Easily confused with
A bat flying outdoors on a mild winter day can look like normal foraging behavior, but it may instead be a white-nose-affected animal that has left its hibernaculum prematurely and is unlikely to survive — not a sign that all is well.
What to do about it

The honest winter action

What genuinely works right now, and — at equal weight — what does not. This is where we decline the work there is no honest reason to do in January.

The honest verdict
Wait for spring
What works now

Nothing lethal, ever, under any circumstance. The only appropriate winter action is documenting a suspected roost and planning proper exclusion for the correct legal window later in the year.

What does not work now

Winter sealing of any suspected entry point — this can entomb hibernating big brown bats inside the void. Any DIY removal or kill approach is both illegal for a protected species and ineffective at solving the underlying access issue.

Do not
  • Don't seal a suspected bat entry point in winter — it can entomb hibernating bats
  • Don't attempt DIY bat removal or handling at any time of year
  • Don't assume a 'sleeping' colony means it's safe to disturb, and don't assume it means you should leave a genuine indoor bat problem unaddressed forever either — the answer is a properly timed specialist, not a decision made alone
Our honest lane

This is explicitly not an Anchor job. Bats are protected wildlife under New Hampshire law, and any exclusion work belongs to a licensed wildlife-control specialist working within NH Fish & Game guidance — timed outside both the mid-May-to-mid-August maternity period and the winter hibernation season, most often in late summer. Anchor does not perform bat removal, does not treat a bat roost as a pest-control job, and will always route a genuine bat concern to the correct specialist rather than attempt it.

State-listed as Endangered, Threatened, or Special Concern (NH Fish & Game); the northern long-eared bat is additionally federally Endangered under the U.S. Endangered Species Act, effective March 31, 2023 (USFWS)All bat species native to New Hampshire (little brown, big brown, northern long-eared, eastern small-footed, tricolored, eastern red, hoary, and silver-haired bats)

No lethal control, ever, for any bat species. Any structural bat issue must be handled through exclusion only — one-way doors that let bats leave but not return — performed by a licensed wildlife-control operator working within NH Fish & Game guidance.

Timing constraint
Never exclude bats mid-May through mid-August (the maternity period) — non-volant pups left behind in a sealed roost will starve. Never seal a suspected entry point during winter hibernation, particularly for big brown bats known to overwinter in buildings — sealing then can entomb hibernating animals. The generally correct window for exclusion is late summer, once young can fly and before hibernation begins.

Authority: NH Fish & Game — Homeowners and Bats; UNH Cooperative Extension — Bats in New Hampshire

The health angle

Named, proportionate — and routed to a doctor

Rabies — bats are the most commonly reported source of human rabies exposure in the United States

See a doctor
Who is at risk
  • Anyone who wakes to find a bat in a bedroom
  • A sleeping child, or anyone impaired, in a room where a bat is found
  • Anyone who touches or handles a bat directly
Precautions
  • Never handle a bat with bare hands
  • If a bat is found in a room with a sleeping or impaired person, treat it as a potential exposure even without a visible bite — a bat's bite can be too small to notice
  • Safely confine the bat in the room, without touching it, if it can be done without risk, so it can be tested
When to seek care

Contact NH DHHS's Bureau of Infectious Disease Control and seek prompt medical evaluation any time a bat is found in a room with a sleeping person, a child, or someone impaired — this counts as a potential rabies exposure under CDC guidance regardless of whether a bite is visible.

Emergency: 911Poison Control: 1-800-222-1222

Health guidance from: CDC — Preventing Rabies from Bats

In depth

The full picture

01

The one myth in this entire hub that's actually true

Every other page in this cluster exists to correct "they hibernate." This one exists to confirm it. Bats really do hibernate — a genuine, profound, multi-month metabolic shutdown, not the loose waking dormancy of a raccoon or the full winter activity of a squirrel or opossum. It's the one time in this entire hub where the popular belief and the biology line up exactly.

The reason this page still needs care isn't the biology. It's that a correct fact gets misapplied into two opposite bad conclusions: 'they're asleep, so ignore it forever' and 'they're just sleeping, so I can clear them out right now.' Both are wrong, and for the same underlying reason — hibernation doesn't make a bat problem simple, it makes the timing of any response a legal and biological constraint rather than a homeowner's convenience.

02

Where New Hampshire's bats actually spend the winter

New Hampshire has five cave- and mine-hibernating bat species — little brown, big brown, northern long-eared, eastern small-footed, and tricolored bats — that need a hibernaculum holding a stable cold temperature around 40°F and humidity above 90%. The state simply doesn't have enough naturally suitable mines and caves, so most of these bats fly out of state entirely, to Vermont, New York, or Massachusetts, to hibernate. Three additional species — eastern red, hoary, and silver-haired bats — don't hibernate locally at all; they migrate south for the winter the way many birds do.

The genuine exception, and the fact most worth knowing if you've had bats in a building, is the big brown bat. It's documented hibernating inside structures — attics, wall voids, barns — rather than traveling to a hibernaculum, which means a colony present in August can still be there, dormant, in January.

03

True hibernation, precisely — and why white-nose syndrome is so devastating

Hibernation, done properly, is a profound metabolic suppression sustained for months, interrupted by periodic arousals that cost the animal real energy each time. That arousal cost is exactly what makes white-nose syndrome so lethal: the fungus behind it, Pseudogymnoascus destructans, thrives in the same cold, humid conditions hibernating bats need, and it disturbs them into rousing far more often than normal — burning through fat reserves meant to last until spring.

The scale of the resulting decline is documented and severe: one surveyed New Hampshire hibernation site held 3,135 little brown bats in 2008 and a single bat by 2018 (Vermont Center for Ecostudies, citing NH Fish & Game biologist Emily Preston). That collapse is the direct reason four of New Hampshire's five hibernating species are now state-listed, and it's the entire context for why this page treats 'just clear them out' as the wrong instinct rather than a convenience.

04

The one page in the hub where 'leave it alone' is a legal rule

New Hampshire's bats are protected, and that status isn't decorative. Exclusion — one-way doors that let bats leave a roost but not return — is the only legal method, performed by a licensed wildlife-control specialist, and it can only happen during a specific window: after young bats can fly (ruling out the mid-May-to-mid-August maternity period, when sealing a roost would starve non-volant pups) and before hibernation begins (ruling out winter, when sealing would entomb hibernating big brown bats). That generally leaves late summer as the correct season, which is exactly why 'clear them out in winter because they're just sleeping' is not simply bad advice here — it's the one action in this entire hub that's actually illegal to perform.

05

The population split that matters most

The single most useful fact on this page is that 'bats' isn't one answer. If your attic held bats that leave for a hibernaculum — little brown, northern long-eared, eastern small-footed, or tricolored bats — winter genuinely ends the household issue, and the summer colony is simply gone until spring. If it held big brown bats, the colony may still be there right now, dormant, which changes both what you'll see (occasionally, a bat flying on a mild day) and what you should do (nothing, until the correct exclusion window arrives). Getting this distinction right is worth more than any generic 'bats hibernate' answer, because it tells you whether winter has already solved your problem or whether it's simply paused.

Key takeaways
6 points
  • Bats are the only genuine true hibernator among all twenty animals in this hub — the popular belief is correct for them, uniquely.
  • Most of New Hampshire's bats fly out of state to a hibernaculum because the state lacks enough natural caves and mines.
  • Big brown bats are the exception — they can hibernate inside buildings, meaning a summer colony may still be present, dormant, in January.
  • White-nose syndrome has caused catastrophic declines — one NH site fell from 3,135 little brown bats to a single bat in a decade.
  • All NH bat species are protected; exclusion is the only legal method, and it must avoid both the maternity season and winter hibernation.
  • Bats are the leading source of human rabies exposure in the US — a bat found near a sleeping or impaired person always warrants medical evaluation.
New Hampshire context

What this looks like in a New Hampshire house

Manchester's first hard frost lands around October 19 to 29 in a typical year (NOAA), by which point most of New Hampshire's hibernating bats have already left for an out-of-state hibernaculum. If a colony that used your attic or barn over the summer included big brown bats, though, some of that colony may genuinely still be there, hibernating in place, through the coldest months.

Because New Hampshire's own hibernation sites have been so severely affected by white-nose syndrome, the honest framing for a homeowner isn't 'get rid of the bats.' It's documenting what you have and scheduling exclusion, if it's genuinely needed, for the correct late-summer window with a specialist who works within NH Fish & Game guidance — never a winter call, and never a kill service.

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ManchesterNashuaConcordDerryBedfordSalemHudsonAmherst
The other half of this question

Want the full 12-month picture for bats?

This page answers where they go in winter, and whether winter helps you at all. The timing guide answers the other question — when they are active, month by month, across the whole New Hampshire year.

See the 12-month timing guide

We don't do bat work. Neither should anyone, in winter.

Bats are NH-protected wildlife, and winter is exactly when they must not be disturbed. If you have a genuine bat concern, we'll point you to a licensed wildlife-exclusion specialist and the correct season for the work.

Get a Free Inspection(603) 785-0118
Follow-up questions

Frequently asked

Sources & citations(8)
  1. NH Fish & Game — White-nose Syndrome

    Five NH cave-hibernating species; white-nose syndrome fungus and its impact on hibernating populations

    govverified 2026-07-16
  2. NH Fish & Game — Little Brown Bat species profile

    Hibernation in mines/caves at ~40°F and 90%+ humidity; most NH bats leave the state to hibernate; state-endangered status

    govverified 2026-07-16
  3. NH Fish & Game — Bats of New Hampshire

    Big brown bats documented hibernating inside buildings rather than at a hibernaculum

    govverified 2026-07-16
  4. NH Fish & Game — Homeowners and Bats

    Exclusion timing, one-way doors, migratory vs. hibernating species, rabies contact guidance

    govverified 2026-07-16
  5. UNH Cooperative Extension — Bats in New Hampshire

    Do not exclude bats mid-May through mid-August (maternity period); five hibernating species; rabies guidance

    extensionverified 2026-07-16
  6. Vermont Center for Ecostudies — Results of New Hampshire Bat Hibernacula Surveys Dismal

    Little brown bat hibernacula count fell from 3,135 (2008) to 1 (2018) at a surveyed NH site

    academicverified 2026-07-16
  7. CDC — Preventing Rabies from Bats

    Bats as the most commonly reported source of human rabies exposure; bat-in-room exposure guidance

    govverified 2026-07-16
  8. NOAA National Weather Service, Gray/Portland ME (GYX) — Concord, NH Seasonal Climatology (1991–2020 normals)

    Concord, NH (nearest NWS GYX first-order station to Manchester) First Fall Freeze normal, i.e. first hard frost typically ~Oct 19-29

    govverified 2026-07-16

Written & reviewed by

Verified

Daniel Brady

NH-Licensed Pesticide Applicator · License #782664 (NHDAMF, RSA 430)

Daniel Brady is the New Hampshire–licensed applicator behind Anchor Pest Services, a family-owned pest control company serving the Manchester area since 2017.

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Last updated Jul 2026

Honest pest help for New Hampshire homes

Bats Are Protected — We'll Tell You Who To Call Instead

Bats are NH-protected wildlife, devastated by white-nose syndrome, and Anchor Pest Services does not perform bat removal at any time of year. What we can do is help you correctly identify a wildlife issue and route a genuine bat concern to a licensed exclusion specialist working within NH Fish & Game timing rules. Where Anchor genuinely helps in winter is rodent and general wildlife exclusion — not bats. Family-owned since 2017, NH license #782664, serving Manchester, Nashua, Concord and nearby towns.

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