Big brown bat
Eptesicus fuscus
- Identification
- Larger than the little brown bat, with a broad nose; hardy and tolerant of cooler roosts.
- Lifecycle & behavior
- Maternity colonies in summer; more likely than other bats to overwinter in buildings rather than migrate.
- When it's active in Central NY
- Common in CNY structures and, because it can overwinter indoors, sometimes found flying inside in winter. Protected and beneficial.
- Risk & damage
- Rabies risk on contact and histoplasmosis risk from guano; overwintering individuals may appear in living space.
- Why DIY falls short
- Same legal maternity-season restriction applies; single-bat handling raises rabies-exposure questions.
- How we treat it
- Humane exclusion outside the restricted window, sealing, cleanup, and safe handling of any bat in living space.
Big brown bat or little brown bat?
Big brown bats are the larger of the two, with a wingspan near thirteen inches and heavier build. Little brown bats are smaller and glossier. For a homeowner the practical difference is seasonal: big brown bats are considerably more tolerant of cold and are the species most often found overwintering inside buildings here, which is why a bat appearing indoors in January is usually this one.
Big brown bats in Central New York
Big brown bats are now the bat most commonly encountered in buildings in this region, having fared better through white-nose syndrome than little brown bats. They roost in attics, soffits, behind shutters and siding, and in wall voids, and they can overwinter in a heated structure rather than migrating to a hibernaculum.
That overwintering habit is why big brown bats turn up in living space in the middle of winter — a bat roosting in a wall void wakes and moves the wrong direction. Exclusion is still subject to New York's maternity-season timing restrictions.
As with any bat, one found in a bedroom or with a child or impaired person should be contained for testing rather than released.
Dealing with big brown bat?
Our bat removal & exclusion handles it — guaranteed, family-owned, and local.
Big brown bat — common questions
Why did a bat appear in my house in the middle of winter?
Most likely a big brown bat overwintering in a wall void or attic that woke and moved into living space instead of out. Unlike little brown bats, they commonly overwinter inside heated structures here rather than migrating. It usually indicates a roost in the building.