This summer, we participated in a bat study organized by the Toronto Zoo. Our contribution was installing an acoustic monitor for four nights to record the calls of bats here at the farm. (The two dark smudges in the sky in the photo above are some of the bats that were flying at the start of my bonfire on Friday night.)
We’ve now received a report from the the Native Bat Conservation Program with some of our results.
The monitor recorded a total of 104 “acoustic observations” from five different species.
|Big Brown Bat||73|
|Eastern Red Bat||2|
|Little Brown Myotis||15|
Here’s a little bit more about our bats from the report:
The Big Brown bat is the most commonly observed bat in Southern Ontario. The Hoary bat is Ontario’s largest, weighing as much as three to five toonies (18-39 g).
The Little Brown Myotis was once Canada’s most common bat, but populations have been decimated by white-nose syndrome. This disease affects bat’s hibernation sleep and makes them wake up early. They then can’t find food and starve. The Zoo says, “The impact of the disease has decreased since its discovery, but since bats are slow to reproduce, population levels will not re-establish to pre white-nose syndrome levels in our lifetime.” Isn’t that terrible?
Little Brown Myotis can live up to 40 years and weigh about one to two toonies (4–11 g).
Our report showed that bat activity varied between nights. For example, the two Eastern Red bat calls were recorded on the same night. We don’t know whether the calls were from one bat or two. Each bat species has a unique echolocation call, so the scientists (and their software) can distinguish between species. However, the calls of individuals are difficult to distinguish between one another.
To identify the species, the scientists don’t listen to the recording. Instead they look at the spectogram–the graph produced by the sounds. Here’s what the calls look like for some of the different species.
Bats change the shape of their call based on the type of environment they are in (for example when a bat is flying in an open space, compared to flying in a forest). Their calls also vary whether they’re navigating, feeding or socializing.
We see bats all the time at the farm, so it’s been really special to learn more about them. These results are a sample of the bats here. Some bats are more easily recorded than others. For example, loud, low-frequency bats are easier to detect than quiet, high-frequency bats. Also, the bats had to fly within range of the monitor.
However, the results give us a general idea about the bats here and can help to indicate where we have good habitats. Participating in this study has also helped me to learn more about bats and what I can do to help them.