Introducing TRCA’s “Bat Detectives”!

Breaking Ground with Bat Monitoring

NEW: Check Out Our Bat Monitoring Facebook Video!

Detecting where different species of regional bats are found is a new and exciting frontier for Toronto and Region Conservation Authority (TRCA). TRCA has been working hard to expand its knowledge of regional bats over the last three years.

eastern red bat
An eastern red bat. There are eight species of regional bats that call the Greater Toronto Area home, and they deserve our attention year-round so we can better protect them. Four of these eight are Species at Risk in Ontario, which means they are facing local extinction. Learn More.

Bats fly by night, using echolocation to find food and to navigate. By recording their high frequency calls, we can determine which species are using the natural areas on conservation lands for foraging or breeding.

devices used to record echolocation calls
TRCA uses two types of recording devices to record echolocation calls – passive (left) and handheld (right).

TRCA started collecting bat call recordings in 2017 to assist the Toronto Zoo with their Native Bat Conservation Program.

Data recorders were set up on TRCA properties to confirm if bats were present, and the data was sent to the Toronto Zoo for analysis. Toronto Zoo staff visited the areas where calls were detected and set up nets to capture and confirm if Species at Risk were indeed foraging and breeding in those areas.

Check out the video below to learn more.

TRCA learned so much from this partnership that we began monitoring our conservation lands and properties more extensively in 2020 to record bat calls.

We located potential roost buildings on TRCA lands and surveyed those for visual signs utilizing handheld recorders. We also used handheld recorders to capture incidental bat calls while our biologists were out conducting annual breeding frog and bird surveys.

Passive recording devices were installed on trees in ideal foraging areas, such as forest edges near wetlands and ponds. These passive recorders continuously pick up wildlife sounds during the breeding season, between May and August.

MONITORING LOCATIONS 2020

map displaying locations within its jurisdiction where TRCA conducted bat monitoring in 2020In 2020, handheld recorders were used at 11 sites on TRCA properties, while passive recorders were set up at another six sites.

Over the past year, TRCA collected more than 20,000 files of bat call sequences using passive and handheld recorders. We now have the capability to analyze the data in-house using specialized sonic bat analysis software.

sonogram displays call signature of eastern red bat
Each bat species has a different call signature, which we are able to visually identify on a sonogram. This sonogram shows an eastern red bat. The software filters out the bat calls from other wildlife sounds, and then we manually check each call to verify its accuracy.

From the information collected, we are beginning to understand where different species sleep during the day (known as roosting), and where they forage and raise young.

In 2020, we detected five bat species on TRCA lands: the little brown bat, big brown bat, eastern red bat, silver-haired bat, and hoary bat.

We were pleased to confirm the presence of the endangered little brown bat at a number of our conservation areas this year! In previous years, we also recorded eastern small-footed and northern myotis bats.

Infrared footage of bat emerging from building to forage at night. Courtesy of the Toronto Zoo.

Knowing where local bats are living and breeding will help guide management and conservation decisions for protecting and restoring habitat, and ultimately help to protect these species in the Greater Toronto Area.

How Can You Help Bats?

You can join TRCA at a community event to plant trees, build a bat box, or help monitor bats in a local greenspace through our citizen science program.

At home, try installing a bat box if you have room in your yard. Monitor it and share your data! For more information on bat boxes, visit the Toronto Zoo’s Native Bat Conservation Program.


Through scientific data collection, TRCA tells the stories about the changes affecting the natural areas and watercourses within our regions. For more information, please visit our Monitoring webpage, subscribe to our Monitoring Matters e-newsletter, or explore our YouTube playlist.