Summer Roosting and Foraging Habitat of Endangered Little Brown Bats (Myotis lucifugus) in Central Canada

Little brown bats (Myotis lucifugus) are listed as endangered in Canada and by the International Union for the Conservation of Nature (IUCN) due to population declines caused by the fungal disease white-nose syndrome (WNS). Under the Species at Risk Act, conservation efforts must focus on identifying and protecting critical habitats essential for the survival and recovery of listed species. While current efforts for little brown bats emphasize hibernation sites, designating maternity roosts as critical habitats are equally important. Despite some existing data, maternity roosts are not yet designated as critical habitats, but it is crucial as maternity roosts support bats’ recovery from WNS in the spring and successful reproduction and juvenile development in the summer. Understanding both roosting and foraging habitat selection, as well as drivers of foraging behaviour, is important for developing recovery plans, as these habitats are often spatially associated (Balzer et al. 2023). The broad objectives of my thesis are to characterize summer maternity roosts, better quantify roost switching and foraging habitat selection, and better quantify environmental variables that influence bats’ nightly activities. To achieve this, I tagged 30 lactating little brown bats in the summers of 2021 and 2022 (n=15 bats/year) in Ontario, Canada, and tracked them to roosts to identify their roosting habitat selection and quantify roost-switching behaviours. I used data from 2021 (n=15 bats) to understand foraging habitat selection and the influence of factors such as minimum nightly temperatures, maximum wind speed, and air quality on nightly activities and home-range sizes. My Chapter 2 results show that bats predominantly preferred buildings and bat houses over trees, with the largest groups found in buildings, while bats in trees were always solitary. Regardless of roost types, bats preferred structures close to water with southern exposure, possibly to reduce commuting costs to food and drinking areas and to maximize heat gain. These findings should help identify geophysical attributes important for the designation of maternity roosts as critical habitats. Bats in buildings switched roosts significantly less than when they roosted in bat houses or trees, but still switched more than expected, suggesting that management strategies should focus on networks of suitable roosts, rather than individual structures, to meet bats’ roosting requirements. My Chapter 3 results show that bats preferred foraging over wetlands, open water, anthropogenic areas, and forest edges, with bats having larger home-range sizes than observed in comparable studies of this species. Taking advantage of variation in air quality due to wildfire near my study area, I found that bat nightly activities and home-range sizes were significantly affected by air quality, with bats being less active and having smaller home ranges on nights with poor air quality. I found no effect of minimum nightly temperatures or maximum wind speeds on foraging behaviour. These findings underscore the importance of protecting both roosting and foraging habitats to support the recovery of endangered little brown bats.

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