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5 brown bats flying against a black background
This great photo is five shots of the same bat merged into one. Photo: stuart anthony, flickr

All bats in the Northeast are insect-eaters, making them environmentally and economically important. In other words, they are good to have around.

9 brown bats huddled together on a cave wall
Big brown bats resting on a cave wall. Photo: U.S. Department of Agriculture, flickr

There are two types of bats in the Northeast. Some species live largely solitary lives primarily in tree canopies and cavities and, like many birds, migrate south for the winter. Bats in the second group are communal and typically overwinter in caves and mines. These species, especially little brown bats and big brown bats, are most likely to be found in buildings.

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What do bats look like?

Batman got it right—you’re most likely to see bat silhouettes in the sky at dawn and dusk. Most bats that will use buildings in the Northeast look surprisingly small hanging from the rafters, but actually have 9 to 12 inch wingspans.

brown bat with wings extended clinging to a tree trunk
Little Brown Bat on a tree trunk. Photo: J. N. Stuart, flickr

You may also notice their poop, aka guano, which piles up beneath their hang-out spots and entry holes.

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Why Should I Worry About Bats?

Bats are one of those creatures that instill fear in people. (Thanks, Hollywood.) But many of those fears are overblown. Don’t take offense if a bat swoops at you outside—it’s not going after you like some birds do if you get too close to its nest. Instead, that bat is hungrily catching flying insects, including pesky mosquitos. And don’t worry about it getting stuck in your hair. Their use of precise echolocation helps find those small insects and prevents collisions with larger objects like you.

longish, brown feces piled up on an overturned rug in an attic
Bat droppings can be about the same size and shape as mouse droppings. However, they are often found in piles, created by roosting bats. Photo: NYSIPM

If you find a bat in your room, it’s probably as shocked as you are. Sometimes the young get lost when learning to fly in late summer. If a bat gets trapped indoors or you find it on the ground, call a professional wildlife control operator. Always be cautious about the potential for rabies, especially if there is a possibility of direct contact with a person or pet.

Also of concern, bat guano can grow mold. One, histoplasma, can cause respiratory problems due to histoplasmosis. Wear a protective mask when in places where bats have resided indoors.

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Why Do I Have Bats in My Attic?

Beginning in the spring and into the fall, both species have “maternal roosts” consisting of females and the young-of-the-year congregating in the warm upper sections of buildings. Bats can get through crevices as small as ¼” wide by 1 ½” long or holes ½” by ½”. At night they’re mainly on the wing and hunting, but now and then they relax a bit under your porch or breezeway.

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How Do I Manage Bats?

If bats are in your belfry, call a professional . They’ll work with you at the right times of the year to close up crevices and holes that let bats in. Closing up entry holes in the summer could trap baby bats inside. Sources for assistance in locating professionals include your state’s wildlife agency, the National Wildlife Control Operators Association (, and in New York State, the NYS Wildlife Management Association (

Bat-proofing of a building is best done with the use of checkvalves (one-way door devices), either home-made or commercial .

light brown bat curled up clinging to cave wall with white powder on nose
Little brown bat with white-nose syndrome. Photo: Al Hicks, NYS DEC, U.S. Fish and Wildlife Service flickr

The legal status of bats varies from state to state. In New York, two species, the Indiana bat and the northern long-eared bat, are protected. However, the conservation of all bats is encouraged. This is particularly important since the populations of some bat species, especially the little brown bat, have been decimated by an introduced fungal disease, whitenose syndrome.

Due to the biocontrol benefits of bats, you may be interested in promoting bat habitat on your property by building bat boxes.

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