Bat resting on a chimney
Bat resting on a chimney

Learn how to evict bats safely or live with them using MassWildlife's Homeowner's Guide to Bats pdf format of Homeowner's Guide to Bats
. This publication contains tips on handling a bat in the house, designs for one-way doors, bat house plans, and a key to identifying the nine bat species in Massachusetts. 

Report Bat Colonies

Due to recent catastrophic mortalities of bats from White Nose Syndrome (WNS), MassWildlife biologists would like reports of summer bat colony locations. If you see a colony of bats (10 or more bats is a colony), please let us know. We study bat colonies in Massachusetts to see how many have survived after the onset of White-nose Syndrome. Our monitoring also leads to advances in conservation and management for endangered bat species, ensuring protection and security of the colonies. Please email Jennifer Longsdorf ( to report bat colonies. Include the address, type of location—type of structure (house, building) or tree—and roughly how many bats are in the colony. Your help is greatly appreciated!

White-nose Syndrome in Massachusetts

Since the onset of White-nose Syndrome in Massachusetts, the state’s population of bats has dwindled to less than 1% of what it was. In one abandoned mine, almost every bat hibernating over the 2008/2009 winter died from White-nose Syndrome. 10,000 bats dropped to just 14 in the span of a single season. White-nose Syndrome is caused by a fungus that grows on cave-hibernating bats during the winter. The growing fungus rouses the bats, causing them to use precious fat stores before fully waking in the spring, leading to starvation. As a result of the drastic mortality from White-nose Syndrome, all species of cave bats are Endangered in Massachusetts.

Two species of bats have summer colonies in Massachusetts houses. These are the Little Brown Bat and the Big Brown Bat. The Little Brown Bat also hibernates in caves during the winter, where it can contract White-nose Syndrome. Before White-nose Syndrome in Massachusetts, the Little Brown Bat was the most common bat species in the state. We are especially interested in how this species is doing post White-nose Syndrome, including knowing the size and location of their colonies. This summer, we will be banding Little Brown Bats, and also tagging all females with radio transmitters to help us locate maternal colonies. We will also be doing surveys, site visits to bat colonies, and monitoring  any newly discovered maternity colonies to determine colony size, site ownership, and security. Monitoring long-term population changes will greatly help us understand the survival of Little Brown Bats post White-nose Syndrome. This work will be also be used in future recovery efforts. Learn more about White-nose Syndrome on our website.

Bats in Your Home

In summertime, with hot, humid weather, some homeowners may discover bats residing in their home. Attics are the most common portion of a house in which bat roost and raise their young. After a few very hot summer days, an attic may become too warm for the bats, forcing them out and sometimes into people's living quarters as they search for cooler places to roost. Inexperienced young bats may fall down a chimney, fly in open windows, or fly down attic stairs. 

What You Can Do

Fortunately, a single bat flying in a room can usually be dealt with quite easily. Open an outside window or door in the room containing the bat and close off the rest of the room from the house. It's usually only a matter of a few minutes of circling before the bat locates the open window and leaves the house. Bats do not attack people or fly into people's hair.

If a bat has landed, it can be assisted out of a house in several ways. For a bat on a curtain, place a jar, coffee can or small box over the bat, carefully working the animal into the container, and cover it. A bat on the floor can be covered with a towel. Another method is to put on leather gloves and simply pick up the bat and release it outdoors-don't use cotton gloves or handle a bat with bare hands. Whatever method is used, don't worry when the bat squeaks loudly when handled. Take the bat outdoors and release it.

If anyone has had direct contact with a bat or if a bat is found in a room with a sleeping person, the bat should be safely captured and not released. Contact local health officials for assistance in evaluating potential rabies risk and submitting the bat to the Department of Public Health for rabies testing.

Little Brown Bats and Big Brown Bats are the most likely bat species to be found in buildings like houses. In some cases, with small numbers of bats, people don't mind their presence and concentrate on blocking holes and cracks leading into the human living quarters.

Where there is a large colony in house walls, biologists recommend that homeowners wait to initiate eviction proceedings until the first week of August through November. Waiting to evict the colony allows time for any young bats to mature and leave the house on their own.

Learn how to evict bats safely or live with them using MassWildlife's Homeowners Guide to Bats pdf format of Homeowner's Guide to Bats
. This publication contains tips on handling a bat in the house, designs for one-way doors, bat house plans, and a key to identifying the nine bat species in Massachusetts. 

Homeowners who wish to hire someone to safely evict a bat colony can find a list of licensed Problem Animal Control agents.

Endangered Bats in Massachusetts

Northern Long-eared Bat

Due to severe population declines, the U.S. Fish & Wildlife Service listed the Northern Long-eared Bat in April 2015. To assist project proponents in complying with the 4(d) rule, the NHESP is providing a map for known locations of winter hibernacula and maternity roost trees. 

Need information on endangered bats in Massachusetts? The following fact sheets focus on bats listed on the Massachusetts Endangered Species Act (MESA) list.