How do I get bats out of my attic legally?

Install a one-way exclusion valve — a screen tacked at the top and sides, open at the bottom — after mid-August, once pups can fly. Watch at dusk for a few nights to confirm no bats are re-entering, then seal the opening permanently and consider offering a bat house nearby. NH Fish & Game recommends this timed approach; installing it during maternity season traps flightless pups inside.

When is it illegal to exclude bats in New Hampshire?

From mid-May through mid-August, NH's bat maternity/pup season. Excluding bats during this window seals flightless pups inside, where they die — both an animal-welfare and a legal problem, since all NH bat species are protected and four cave-hibernating species are state-endangered. UNH Cooperative Extension and NH Fish & Game both flag this window explicitly; confirm exact dates with NH Fish & Game before a specific job.

Are bats in New Hampshire protected by law?

Yes, all NH bat species are legally protected, and the four cave-hibernating species — little brown, northern long-eared, eastern small-footed, and tricolored bat — carry state-endangered status due to white-nose syndrome. Population counts at some monitored New Hampshire mines fell from 3,230 little brown bats in 2009 to just 16 by 2011. This history is exactly why exclusion timing and method matter so much here.

Which birds can I legally exclude or remove from my property?

Only pigeons (rock doves), European starlings, and house sparrows are exempt from the federal Migratory Bird Treaty Act. Nearly every other bird you'll see nesting on a New Hampshire home — sparrows' native look-alikes, swallows, wrens, and more — is protected, and disturbing an active nest without a federal permit is illegal regardless of the mess or noise it's causing.

What's the most effective way to keep birds off a ledge or roofline?

Netting is considered the gold standard because it fully excludes birds from a space rather than just discouraging landing. Spikes and sloped ledge panels work well on larger birds like pigeons but are less effective against small birds, which can nest in the gaps between spike rows. Combine any barrier with sealing soffit and vent openings for a durable fix that doesn't just push the birds to a nearby ledge instead.

Can I remove a bird nest myself if it's in my way?

Only if you can confirm it belongs to an unprotected species — pigeon, European starling, or house sparrow — and even then, check for eggs or chicks first. Removing an active nest of any protected native species without a federal permit is illegal under the Migratory Bird Treaty Act, no matter how inconvenient its location. When in doubt, get the species confirmed before touching a nest.

Is bat exclusion something I can do myself?

Technically the mechanics are simple, but in practice this is close to pro-only work: it requires correctly identifying the species, timing the job to a narrow legal window, doing height work on rooflines and fascia, and handling guano safely with respiratory protection. Given the rabies risk and legal exposure for getting the timing wrong, most NH homeowners are better served by a licensed wildlife technician.

What happens if bats are excluded during maternity season?

Flightless pups left behind when adults are sealed out will die inside the structure, creating odor, insect, and possible structural cleanup problems, in addition to being both inhumane and against the guidance from NH Fish & Game and UNH Cooperative Extension. If you discover bats in the maternity window, wait until mid-August or later, or call a wildlife professional to assess the situation safely.

Do bats and birds get in through the same spots on NH homes?

Often, yes — chimneys, gable and ridge vents, soffits, and fascia gaps on older New Hampshire homes serve as entry points for both bats and unprotected nesting birds. Sealing these openings after confirming a space is empty is the durable, shared fix, which is why exclusion for one often prompts a broader look at the whole roofline for the other rather than treating them as separate jobs.

Mechanical & PhysicalUrban Pest Birds & Bats

Mechanical Bird & Bat Control: Legal Exclusion in NH

TL;DR

One-way exclusion valves reliably evict bats without harming them — rated HIGH — but NH and federal law forbid excluding bats from mid-May through mid-August, when flightless pups would be trapped and die inside. Native birds are protected under the Migratory Bird Treaty Act; only pigeons, European starlings, and house sparrows can legally be excluded or removed. This is timed, legally constrained work best handled by a licensed pro.

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NH License #782664Family-owned since 2017Updated Jul 2026

Bat exclusion blackout window
Mid-May through mid-August (NH maternity/pup season)
NH Fish & Game; UNH Cooperative Extension
How a one-way bat valve works
A screen tacked at the top and sides, open at the bottom, so bats crawl out but can't climb back in
NH Fish & Game
Protected bird species
Nearly all native NH birds — only pigeons, European starlings, and house sparrows are exempt
Migratory Bird Treaty Act, Federal Register 2020
NH bat population collapse
Little brown bat counts fell from 3,230 to 16 across four monitored mines, 2009–2011
White-nose syndrome; UNH Extension / Taking Action for Wildlife

The honest verdict

Does this actually work?

HIGH when the method and timing are legally correct — a one-way bat valve installed after mid-August works reliably, and netting fully excludes unprotected birds — but the legal window and species rules make DIY error-prone.

Works — High

Evidence: NH Fish & Game recommends one-way doors specifically "to make sure the bats are out before you seal," and UNH Cooperative Extension states exclusion must not happen mid-May through mid-August "when babies cannot fly and will get trapped in the space." The Migratory Bird Treaty Act exempts only pigeons, starlings, and house sparrows from protection, making most other bird exclusion contingent on confirming an empty or unprotected nest first.

Works when

A one-way bat valve is installed after mid-August, once pups can fly
Dusk exits are confirmed stopped before the opening is permanently sealed
Bird barriers (netting, spikes, ledge slopes) target confirmed unprotected species or empty sites
Entry points are sealed only after the space is verified empty

Fails when

Exclusion is attempted during the mid-May–mid-August bat maternity season
An opening is sealed before bats are confirmed out, trapping the colony
A native bird's active nest is disturbed without a federal permit
Spikes are used against small birds that simply nest between the rows

At a glance

Bat exclusion works — but only inside a narrow legal window

How it works

Pro-only

For bats, a timed one-way valve lets the colony leave at dusk to feed but blocks re-entry, so the space can be permanently sealed once it's confirmed empty. For birds, physical barriers like netting, spikes, and sloped ledges deny landing and nesting sites without touching a live animal. Both approaches remove the pest without chemicals, but both carry legal limits — bat timing and native-bird nest protections — that make much of this job pro-only.

Vital stats

Time: Bat exclusion is bounded to mid-August through fall; bird barrier installs can happen any time except around an active protected nest
Best for: Little and big brown bats roosting in attics, chimneys, and behind fascia; pigeons, European starlings, and house sparrows nesting or roosting on ledges, eaves, and rooflines.
Cost: Low materials cost for small bird barriers; bat exclusion and roofline height work are typically licensed-pro jobs

Search "how to get bats out of my attic" and most results skip the part that matters most in New Hampshire: timing is the law, not a suggestion. A one-way exclusion valve genuinely works — bats crawl out at dusk to feed and can't find their way back in — but installing one during the mid-May to mid-August maternity season traps flightless pups inside, where they die and decompose. That's illegal and inhumane, and it's the single most common DIY bat-exclusion mistake.

Birds carry their own legal ceiling: nearly every native species you'll see on a NH roofline is federally protected, and disturbing an active nest without a permit is against the law regardless of how much of a nuisance it is. Only pigeons, European starlings, and house sparrows can be legally excluded or removed outright. This page walks through what mechanical exclusion actually looks like for both — and is honest that, between the biology, the height work, and the legal exposure, most of this job belongs to a licensed pro.

Step by step

How to do it

Identify the species and the entry point
Watch the suspected roost at dusk for a few evenings in July to confirm whether it's bats, and identify any nesting birds before doing anything else.
Caution: Do not proceed with any exclusion or nest removal until you've confirmed the species — the legal rules differ sharply between them.
Confirm you're inside the legal window
For bats, wait until mid-August or later, after pups can fly. For birds, confirm the nest belongs to an unprotected species (pigeon, European starling, house sparrow) or is inactive.
Caution: Excluding bats mid-May through mid-August, or disturbing an active protected bird nest, is both inhumane and illegal.
Install a one-way exclusion valve for bats
Hang a screen over the opening, tacked at the top and sides and left open at the bottom, so bats can crawl out at dusk to feed but can't climb back in.
Tip: Watch for several consecutive nights to confirm no bats are re-entering before you seal anything.
Seal the opening once confirmed empty
Once no bats have re-entered for several nights, permanently seal the gap with caulk and flashing, and consider mounting a bat house nearby as an alternative roost.
Tip: Offering a bat house nearby helps keep a beneficial, insect-eating colony on the property without letting it back into the structure.
Install physical barriers for unprotected birds
Clean droppings with PPE first, then install netting for full exclusion or spikes/sloped panels on ledges, and seal any openings into soffits or vents the birds were using.
Caution: Never disturb an active nest of a protected species — confirm the species and nest status before any physical removal.

What you need

Tools & materials

Bat one-way exclusion valve or screen
Lets bats leave at dusk while blocking re-entry
Tack top and sides only; leave the bottom open
Caulk and flashing
Permanently seals confirmed-empty entry points
Use after several nights of no re-entry
Bat house
Offers displaced bats an alternative roost nearby
Mount away from human living space
Bird netting
Full physical exclusion from ledges, eaves, and rooflines
Considered the most complete barrier for unprotected species
Bird spikes or ledge slope panels
Deters landing on ledges and flat surfaces
Less effective against small birds, which can nest between spikes
PPE / N95-or-better respirator
Protects against guano and droppings during cleanup
Essential before any droppings cleanup

Stay safe

Safety first

General
High risk
Bats are a rabies-vector species — never handle one with bare hands, and treat any bite or scratch as a medical situation requiring prompt evaluation.
Applicator
Caution
Accumulated bat or bird guano can carry respiratory hazards; wear an N95-or-better respirator and gloves during any cleanup, and treat roofline and fascia work as height work requiring proper fall protection.
General
Caution
Excluding bats during maternity season or disturbing an active protected-bird nest carries real legal exposure under state and federal wildlife law, in addition to being inhumane.

Avoid these

Common mistakes

Why this method fails in practice.

Excluding bats during the mid-May–mid-August pup season, trapping flightless young inside
Sealing an opening before confirming bats have actually stopped re-entering
Disturbing or removing an active nest of a protected native bird species
Using spikes against small birds that simply nest in the gaps between them
Attempting roofline or fascia exclusion without proper fall protection

New Hampshire context

Bird and bat exclusion law in New Hampshire

New Hampshire's bat colonies have been hit hard by white-nose syndrome since it was first documented in the state in the winter of 2008–09, so exclusion timing here isn't just a legal formality — it protects populations that have already collapsed by nearly 99% in some monitored hibernacula. The practical exclusion window is mid-August through fall, after pups can fly and before bats seek winter hibernation sites. Older Manchester, Nashua, and Concord homes with fascia gaps, chimneys, and gable vents are common bat and bird entry points and often need height work that's genuinely pro-only.

Peak season

Mid-August through fall — the only legal window to exclude bats

Bat exclusion is prohibited mid-May through mid-August (NH maternity season); nearly all native NH birds are protected under the federal Migratory Bird Treaty Act, and disturbing an active nest without a permit is illegal.

UNH Cooperative Extension advises against excluding bats from mid-May through mid-August "when babies cannot fly and will get trapped in the space," and documents the severe NH bat population declines from white-nose syndrome.

This method targets

Pests this applies to

When to call a pro

Bird Control / Wildlife with Anchor

Between species identification, legal timing, height work, and guano handling, most bird and bat exclusion in New Hampshire is better handled by a licensed technician than a weekend DIY project. Anchor's team works within NH Fish & Game and federal Migratory Bird Treaty Act rules to exclude and seal correctly the first time.

Call us when…

Any bat colony in an attic, wall void, or chimney
A protected native bird nesting somewhere that conflicts with the property
Any exclusion job requiring ladder or roofline height work
Guano cleanup in an attic or wall space
Uncertainty about whether a species is legally protected before taking action

Bird Control / Wildlife

free inspection; same-day service across southern and central New Hampshire.

Get a free inspection Learn about the service

Keep them out

Screen chimneys, gable vents, and soffits before bats or birds establish a roost
Schedule any bat exclusion for mid-August or later, never during maternity season
Confirm species before removing any nest, and default to calling a pro when unsure

Common questions

Frequently asked

Sources & further reading(7)

[1]
NH Fish & Game — Homeowners and Bats
One-way bat valve method, maternity-season exclusion timing
govverified 2026-07-13
[2]
UNH Cooperative Extension — Bats in New Hampshire
Mid-May–mid-August exclusion blackout, protected/endangered status, white-nose syndrome population decline
extensionverified 2026-07-13
[3]
Taking Action for Wildlife — Winter Surveys of NH Bats
Little brown bat population decline in monitored NH mines (3,230 to 16)
academicverified 2026-07-13
[4]
Federal Register — Migratory Bird Treaty Act, Regulations Governing Take (2020)
Which species the Migratory Bird Treaty Act protects and exempts
govverified 2026-07-13
[5]
All About Birds — What Is the Migratory Bird Treaty Act?
Plain-language explanation of protected-nest law
encyclopediaverified 2026-07-13
[6]
OvoControl — Spikes, Wires, and Nets Compared
Netting as the most complete bird exclusion barrier
industryverified 2026-07-13
[7]
Bird B Gone — Bird Spikes
Spikes less effective against small birds nesting between rows
industryverified 2026-07-13

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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Anchor Pest Services

When urban pest birds & bats won't quit, we will.

Same-day service across Southern New Hampshire. NH-licensed #782664. Family-owned since 2017. We diagnose the pest, then treat it the right way — with a satisfaction guarantee.

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Keep Exploring

Mechanical Bird & Bat Control: Legal Exclusion in NH

Works when

Fails when

Bat exclusion works — but only inside a narrow legal window

How it works

How to do it

Identify the species and the entry point

Confirm you're inside the legal window

Install a one-way exclusion valve for bats

Seal the opening once confirmed empty

Install physical barriers for unprotected birds

Tools & materials

Bat one-way exclusion valve or screen

Caulk and flashing

Bat house

Bird netting

Bird spikes or ledge slope panels

PPE / N95-or-better respirator