NCC works to identify habitat use by little brown and northern myotis
Hoary Bat (Photo by Sarah Ludlow)
The little brown and northern myotis bats are both listed as endangered in Canada. This is largely attributed to devastating population declines in eastern Canada, because of white-nose syndrome. White-nose syndrome is a fungal disease originally from Eurasia. It that infects hibernating bats, causing them to wake up more frequently and burn more of their energy reserves than they can afford. White-nose syndrome has caused a greater than 90 per cent decline in known populations of hibernating myotis bats in Nova Scotia, New Brunswick, Quebec and Ontario.
The fungus is moving west. However, it has not yet been documented in Saskatchewan. There is an urgent need to determine the population status of myotis bats in Saskatchewan, and to determine what habitats they are using for different parts of their life cycle.
The use of buildings by little brown myotis for roosting or hibernation sites has been well documented in other parts of their range. Little is known, though, about the naturally occurring roost and hibernation sites used by this species in the northern boreal part of its range. Similarly, there has been little research to date on northern myotis habitat preferences in western Canada. It is difficult to protect and conserve habitat that is vital for myotis bat survival if we don’t know what habitats these species prefer.
Beginning in 2017, the Nature Conservancy of Canada's Saskatchewan Region has been working on an inventory of the bat species present on our properties, through acoustic surveys. Acoustic surveys involve using an ultra-sonic recording device in areas likely to be used by bats (such as waterbodies and forest trails). Researchers then passively record the echolocation calls of bats as they fly around and forage for insects. Echolocation calls of each species are unique. By reviewing sonograms of the bat calls recorded on each property, we can determine which species are present as well as the levels of activity of each species. To date, we have surveyed eight different properties across the province and documented all eight bat species known to occur in Saskatchewan, including endangered little brown and northern myotis.
In the summer 2018, we initiated a project to identify and characterize habitat use by little brown and northern myotis in the aspen and mixed-wood forests of central Saskatchewan. Both species had been confirmed in the area through acoustic surveys. However, which areas and habitat types they are using and for what purpose (such as day roosting, maternity colony) remains unclear. The project involves capturing bats with mist nets and attaching radio transmitters to the two species. Bats with transmitters are tracked back to their roost sites, which can then be quantified.
Both little brown and northern myotis use tree cavities for roost sites. As a result, the roost trees being used can be compared to other random trees on the landscape to identify characteristics important for selection and use by myotis bats. By understanding what habitat is being used and the extent of that use, we can tailor management in the areas where these species occur to benefit the species and aid in their protection and recovery.
Results from the first season (2018) of the bat-tracking project were mixed. Specifically, we captured zero myotis, five silver-haired and eight hoary bats. Although none of the target species were captured, we learned a lot about the study sites and behaviour of the bat species in the area. As a result, there are multiple adjustments that will be made in the 2019 season that will likely result in increased capture rates of myotis bats. For example, sampling will begin earlier in the season to capture bats before they give birth to their pups, since during this time, the bats are likely to be more active and travelling further to forage.
Our primary goal is to determine habitat usage by endangered myotis bats so that management of the properties where these species occur aligns with conservation efforts that support long-term use of these areas by these species and contributes to the recovery of their populations.
Funding for this project was provided by the Government of Saskatchewan – Fish and Wildlife Development Fund and the Nature Conservancy of Canada.