Cover photo credit: Ann Froschauer/USFWS



“Endangered” means the species lives in the wild in Ontario but is facing imminent extinction or extirpation.

Date added to the Species at Risk in Ontario List

January 24, 2013.

Read the Assessment Report

What it looks like

Little brown bats have glossy brown fur and usually weigh between four and 11 grams – about as much as a Canadian loonie or toonie.

They are typically four or five centimetres long, with a wingspan of 22 to 27 centimetres. Little brown bats look similar to northern long-eared bats.

They can be distinguished by the fleshy projection that covers the entrance to the ear. In little brown bats, the projection is long and thin, but rounded at the tip.

Little brown bats eat insects. They feed at night and are most active in the two or three hours after sunset. The female little brown bat usually gives birth to only one young, which is able to fly and obtain its own food when just three weeks old.

Where it lives

Bats are nocturnal. During the day they roost in trees and buildings. They often select attics, abandoned buildings and barns for summer colonies where they can raise their young.

Bats can squeeze through very tiny spaces (as small as six millimetres across) and this is how they access many roosting areas.

Little brown bats hibernate from October or November to March or April, most often in caves or abandoned mines that are humid and remain above freezing.

Where it’s been found in Ontario

The little brown bat is widespread in southern Ontario and found as far north as Moose Factory and Favourable Lake.

Outside Ontario, this bat is found across Canada (except in Nunavut) and most of the United States.

What threatens it

Little brown bats are threatened by a disease known as white nose syndrome, caused by a fungus which is believed to have been inadvertently brought from Europe to North America.

The fungus grows in humid cold environments, such as the caves and mines where little brown bats hibernate.

The syndrome affects bats by disrupting their hibernation cycle, so that they use up body fat supplies before the spring when they can once again find food sources.

It is also thought that the fungus affects the wing membrane, which helps to maintain water balance in bats. Because of this, thirst may wake bats up from hibernation, which may be why those infected with white nose syndrome can be seen flying outside caves and mines during the winter.

Bats at more than three quarters of Ontario’s hibernation sites are at high risk of disappearing due to white nose syndrome. Mass die-offs mean that there are no individuals left to reproduce.

Action we are taking

Endangered Species and their general habitat are automatically protected.

Recovery strategy

A recovery strategy advises the ministry on ways to ensure healthy numbers of the species return to Ontario.

Read the executive summary and the full document (December 5, 2019).

Government response statement

A government response statement outlines the actions the government intends to take or support to help recover the species.

Read the government response statement (September 8, 2020)

Habitat protection

General Habitat Protection - January 24, 2013

What you can do

Report a sighting

  • Report a sighting of an endangered animal or plant to the Natural Heritage Information Centre. Photographs with specific locations or mapping coordinates are always helpful.
  • Report any unusual bat behaviour or deaths to the Canadian Cooperative Wildlife Health Centre at 1-866-673-4781 or the Natural Resources Information Support Centre at 1-800-667-1940.


Volunteer with your local nature club or provincial park to participate in surveys or stewardship work focused on species at risk.

Be a good steward

  • private land owners have a very important role to play in species recovery; if you find Little Brown Bat on your land, you may be eligible for stewardship programs that support the protection and recovery of species at risk and their habitats
  • don’t enter non-commercial caves and abandoned mines where bats may be present; avoid visiting caves and abandoned mines where white nose syndrome has been identified
  • consider building a bat box for your property, learn more about how to build one and where to set it up

Report illegal activity

Report any illegal activity related to plants and wildlife to 1-877-TIP-SMNR (847-7667).

Quick facts

  • little brown bats are one of only two bat species in Ontario that are known to use human structures as summer maternity colony habitat
  • bats are the only mammals that can fly; their wings are folds of skin stretched between elongated finger bones, the sides of the body, the hind limbs and the tail
  • although they usually live six or seven years, one little brown in Ontario was documented at 31 years old