Working with PhD student Cylita Guy, I examined how bats are coping with city life. Big brown bats are well known for living in attics of homes and businesses. Yet little is know about how they use their surrounding urban landscape. In the summer of 2015, I set out to study the sociality of urban bats in High Park – Toronto’s largest city park (see Bats of High Park). Unfortunately I was only able to locate one colony. However, an interesting trend in the park led to a new line of research…
It turns out High Park is home to an unexpected number of male bats compared to females. Also, females appear to be restricted to a few key spots within the park. We therefore set out to determine why we are seeing these patterns. Perhaps only some areas of the park offer enough food to support females and their young? From June 02 to September 01, Cylita and I (with the help of 3 research assistants and 2 volunteers) spent 6 nights a week catching and radio-tracking bats in the park from dusk til dawn. We also sampled insects to determine what kind of food is available in different parts of the park. With more than 200 bats caught and 20 bats radio-tracked, we have LOTS of data to analyze! This work is currently under review for publication. So stay tuned for more pictures and more information!
It is generally thought that animals using more stable, reliable resources will also live in more stable social groups. It is therefore assumed that bats living in attics have more stable social groups than bats living in trees. Conditions, like temperature, that are important to bat survival are usually more stable in attics compared to trees and bats often return to the same attic every day but those living in trees move to a different tree almost every day or two. But, once bats are in an attic they don’t necessarily hang out with the same individuals in the same spot in the attic every day. And when bats move from tree to tree they don’t stay in the same group every day (a process known as fission-fusion). So, it seems social groups are influenced by more than resources and I predict females are moving around to maintain contact with more “friends”.
Listen to my interview on CBC Radio’s Metro Morning.