People passionate about nature

Canadian Bat Box Project

You can participate in national research to support bat conservation

By: Karen Vanderwolf, PhD student at Trent University

If you have a bat box I want to know about it!

Bats in Canada face multiple threats from habitat loss and disease. All bats in Canada eat only insects, including agricultural and forestry pests. Their voracious appetite for bugs does more than just keep backyard mosquito populations down — bats also help keep crop yield high by scouring farm fields. One study found the global value of bat pest control services is worth US$1 billion for corn crops alone.

As towns and cities expand, the large old trees that bats call home are being cleared, and bats are losing their roosts. Bats need a warm and secure place to roost during the day in the summer. A bat box is a simple and effective way to provide additional roosting habitat for bats, but little is known about bat box use in Canada.

Above: Little brown bats in a bat box in the Maritimes. (Photo by Jordi Segers)

This especially important as three bat species in Canada are listed as endangered: little brown bats, northern long-eared bats, and tricolored bats. Bats now face additional persecution due to worries about COVID-19, but bats in North America do not have the virus that causes COVID-19.

Our research seeks to determine which bat species use bat boxes across Canada, what box designs are preferred by bats, and which temperatures bats prefer for roosting in our northern climate. To accomplish this, we need to know where bat boxes are located in Canada, the physical characteristics of the boxes, and whether or not they are being used by bats!

More information about which box designs bats use in Canada will help bat conservation by providing recommendations for improving bat box design and placement in our northern climate.

How you can help!

We are currently looking for people who have bat boxes installed or are willing to install them for the purposes of the study. Participants will be sent temperature loggers to install in their box and supplies to collect guano (bat poop), as bat species can be identified from guano. We do not provide bat boxes for the study.

If you have a bat box, or plan to install one, and would like to participate in this study, please fill out this online multiple-choice survey with questions about your bat box. Your participation is important even if your box does not have any bats!

This project is in partnership with the Wildlife Conservation Society and the Canadian Wildlife Federation. Read more about the project here.

Which bat species use bat boxes?

Of the 18 bat species that are regularly found in Canada, 13 have been documented using bat boxes, although these data come from studies farther south in the United States. Current recommendations on bat box design are based on research in the United States, especially Texas, and in Europe. Since the box design bats prefer varies by region and species, more information on bat boxes in Canada is urgently needed.

Above: A little brown bat and nursing pup caught by a bat box in New Brunswick July 2019. (Photo by Karen Vanderwolf)

There is very little previous research about which bat species prefer which bat box designs in Canada. Little brown bats are known to use bat boxes throughout Canada, big brown bats use boxes in some parts of Canada, and Yuma bats use boxes in British Columbia.

Why install a bat box?

Installing a bat box gives bats an alternative to roosting in your house, and since all bats in Canada eat only insects, you may even notice a decrease in the insect population around your house! Bats eat a variety of insects, including agricultural and forestry pests. You can watch bats swooping around your backyard at dusk catching insets in midair.

Information and advice on building your own bat box is available here. You can also buy pre-made boxes on amazon or at your local outdoor store. Bigger boxes are generally more successful than smaller boxes. Boxes on buildings are generally more successful than boxes on trees. Installing multiple boxes gives bats more choice as different boxes will have unique microclimates, depending on their design and the amount of sunlight they receive.

Above: Big brown bat (Eptesicus fuscus) in bat box. (Photo by Jordi Segers)

How do I tell if bats are using my box?

You can tell whether your box is being used by bats by searching for guano underneath your box and watching your box at sunset in June to count bats as they emerge for an evening of eating insects. You can watch an example of bats flying out of bat boxes in Prince Edward Island here. You can also shine a light up into the box during the day to see if there are bats inside from May to October in Canada. The boxes will be too cold for bats during the winter.

How do I get bats to use my box?

Not all bat boxes will be occupied in the first year after installation. Occupancy depends on many factors, ranging from the period in which it was installed to the fact that bats are very selective and might need a little time to familiarize themselves with your bat box. There are no lures or attractants, such as guano, that can attract bats to a bat box, although larger bat boxes with multiple chambers more commonly attract bats than smaller boxes.

Bat boxes are most successful when attached to houses or poles as opposed to trees. Trees shade the box and can block access to the box entrance. If bats are not using your box after two years, try moving the bat box to a new location.

Above: This bat box on the side of a house in New Brunswick houses little brown bats and their pups during the summer. (Photo by Karen Vanderwolf)

Like tree hollows, bat boxes need to have temperatures that bats like. Bats like hot temperatures, but even in Canada some bat boxes get too hot during the summer, which can increase bat mortality. Temperatures of over 40˚C in bat boxes is too hot, and temperatures in some bat boxes in Canada have been recorded over 50˚C!

Our research group measures the temperature inside bat boxes using temperature loggers that can take a reading every hour over the whole summer. One way to ensure that bats can choose their preferred roosting temperature is to install multiple bat boxes as they will vary in temperature depending on how much direct sunlight they receive.

About Karen: I started researching bats in 2006 when I did my undergraduate honors thesis on bats with Dr. Brock Fenton at Western University in Ontario. I continued researching bats during my MSc at the University of New Brunswick and then as the 'bat conservation specialist' with the Canadian Wildlife Federation and the New Brunswick Museum. My research has focused on the fungal disease white-nose syndrome, bat ecology, mycology, and cave biology.