Little Brown Myotis | NWT Species at Risk

Little Brown Myotis

Myotis lucifugus

NWT List of Species at Risk:

Special Concern

NWT SARC Assessment:

Special Concern

Federal Species at Risk Act list:

Endangered

COSEWIC Assessment:

Endangered

NWT General Status Rank:

At Risk

Description:

The Little Brown Myotis is a medium-sized bat. Fur on its back ranges from yellowish-brown to dark brown-black and is often glossy. Fur on its underside is lighter and goes from light brown to tan. The tragus (fleshy projection which covers the entrance of the ear) is short and blunt. Females are slightly larger than males and usually only have one young (called a pup) per year.

Wingspan: 22 to 27 cm (9 to 11 in), Weight: 7 to 14 g (0.3 to 0.5 oz).

Report Little Brown Myotis sightings to WildlifeOBS@gov.nt.ca.

There are eight bat species in the NWT - seven confirmed and one suspected. Check out the Bats of the Northwest Territories poster with activities and brochure.

Distribution

The Little Brown Myotis is found throughout much of Canada south of the treeline. In the NWT, it has been found north and south of Great Slave Lake, in the Dehcho, and occasionally in the Sahtu.

Range map information

Habitat and biology

Little Brown Myotis is an insect-eating bat that hunts flying insects in a variety of habitats, often over water. A Little Brown Myotis can eat as many as 600 mosqito-sized insects in one hour.

Summer roosts can include man-made structures (like attics), tree cavities, under the bark of trees, rock crevices and caves.

Winter hibernation sites (also called hibernacula) are usually in caves or mines. Approximately 3,000 bats overwinter in one NWT cave, making it the largest known hibernation site in western Canada. Nahanni National Park Reserve is the northernmost bat hibernation area documented in North America.

Population size and trends

Since 2006, this bat has been dying in significant numbers in the eastern United States and Canada from a disease called white-nose syndrome. The fungus that causes white-nose syndrome grows in humid cold environments typical of the caves where bats hibernate. It is estimated that at the current rate of spread, the fungus will severely impact the entire Canadian population of Little Brown Myotis within the next two decades.

Threats

A fungal disease called white-nose syndrome occurs elsewhere in Canada but has not yet been reported in the NWT. It could eventually spread north. A map of its spread is available at www.whitenosesyndrome.org. Bats with white-nose syndrome show loss of body fat and unusual behaviour during winter, including flying outside in the day. Bats with white-nose syndrome very often die of the disease.

Human activities at hibernation sites, such as caves and mines, can have significant negative impacts on bat populations. Removing or renovating buildings that are used by bats, or blocking their entry/exit points, can kill large numbers of bats at once. To help the Little Brown Myotis, avoid entering caves and abandoned mines where bats may be hibernating, and use bat-friendly practices to deal with bats in buildings.

Protection and recovery

In 2013, COSEWIC assessed Little Brown Myotis as Endangered in Canada because of population declines due to white-nose syndrome. Little Brown Myotis was listed as Endangered under the federal Species at Risk Act (SARA) in 2014. A national recovery strategy is available on the federal Species at Risk Public Registry and includes critical habitat identification.

In 2017, the NWT Species at Risk Committee assessed Little Brown Myotis as a species of Special Concern in the Northwest Territories because of its high vulnerability to white-nose syndrome. In 2018, Little Brown Myotis was listed as Special Concern in the NWT under the Species at Risk (NWT) Act. An NWT Bats Management Plan is available here.

Area:

Dehcho, Sahtú, South Slave, North Slave / Tłı̨chǫ