Little Brown Myotis

Nicole DollEducation

Little brown myotis
  • Scientific NameMyotis lucifugus 
  • SARA Status: Endangered
  • COSEWIC Status: Endangered 
  • COSEWIC Range: Yukon, Northwest Territories, British Columbia, Alberta, Saskatchewan, Manitoba, Ontario,Québec, New Brunswick, Prince Edward Island, Nova Scotia, Newfoundland and Labrador 

At one time, the little brown myotis, also known as the little brown bat, was the most common bat species in Canada. However, their populations are declining at an alarming rate due to a spreading disease called white-nose syndrome.  

Photo by Jason Corbett courtesy of Bat Conservation International 

As its name suggests, the little brown bat is small, weighing only 7-9 grams with a wingspan of 25-27 cm. They live relatively long, with some individuals recorded to even live past 30. They are active during the night, feeding on many different kinds of insects using echolocation. A single bat can eat over 1000 insects per night! By consuming such large amounts of insects, many pest species such as mosquitoes are kept under control.  

The little brown bat is widespread across North America and has been observed in every province and territory in Canada except for Nunavut. Their preferred habitat is areas that are close to lakes, wetlands, and streams due to increased food availability, however, they are observed in a variety of other ecosystems as well. The little brown bat is one of only two species of bats that use human structures like buildings to roost during the day.  

Bats are the only mammals that are capable of true flight. This is important for the little brown bats, as they’re known to migrate short distances between their summer and winter roosts. While the distance of the migration varies depending on where the bats are, they have been observed to travel up to 1000 km to hibernating areas.

It is common for these bats to return to the same winter and summer roosting areas each year. The hibernating areas are typically in caves or abandoned mines where it is humid and the temperature remains stable without freezing. These hibernating areas are referred to as hibernacula. 

These bats are true hibernators, meaning that they are able to slow down their metabolism and heart rate, but still wake up intermittently to drink and eliminate wastes. However, they do not eat during this time and instead rely on fat deposits that were collected over the summer months.  

Threats: Despite being one of the most common and widespread bats in Canada, the little brown bat has declined significantly within the past 10 years. This is due to a fungal disease called white-nose syndrome which likely came from Europe and was first observed in Canada in 2010.

The fungus thrives in wet, cool places such as caves, where the bats hibernate. The disease is caused by a fungus that grows on their nose, wings, and skin during hibernation. It causes bats to frequently wake up during their hibernation, wasting their much-needed energy,  eventually leading to starvation. Survival is low and can wipe out colonies of bats in hibernacula. There has been an observed 94% overall decline in known hibernating bats in Nova Scotia, New Brunswick, Ontario, and Québec.  

Although white-nose syndrome has only been detected in eastern Canada (New Brunswick, Nova Scotia, Prince Edward Island, Ontario, and Québec), the disease is spreading fast since bats travel long distances to roosting areas and swarm in the fall to reproduce. Researchers estimate that the disease will spread the entire range of the little brown bat between 2025 and 2028. 

Researchers expect that the small percentage of bats that can survive the disease will pass their immunity onto the next generation in hopes that the species can avoid extinction. However, since little brown bats only birth 1-2 pups a year, recovery will be very slow.  

Other threats include habitat loss and disturbance of hibernacula, collisions with human structures such as wind turbines, and climate change.  

What’s being done: The little brown bat has been listed federally as endangered under the Species at Risk Act (SARA) under an emergency assessment. Research efforts are being made internationally and within Canada to further understand the disease and to document its spread, as well as determining critical habitat for the species. Scientists are also working to try and develop a cure from the disease. There are a number of education and outreach programs involving the public such as creating bat boxes for habitat and how to monitor populations. In order to save the species from extinction, white-nose syndrome will have to be managed. 


Little Brown Bat