Occurrence of a forest-dwelling bat, northern myotis (Myotis septentrionalis), within Canada’s largest conurbation

Abstract

While some species thrive in urban areas, many are absent from such environments. Those that are successful often have high behavioural flexibility that allows them to exploit new niches in a human-modified landscape. Northern myotis (Myotis septentrionalis) is an endangered bat species rarely identified in urban areas, though it is unclear whether this is due to absence or difficulties in surveying. We investigated the ecology of a population of northern myotis within Canada’s largest conurbation, including reproductive status, roosting preference, and movements. Using capture surveys, we confirmed the presence of reproductive females and healthy juveniles over two seasons. Using radio telemetry and acoustic surveys, we identified a cluster of tree roosts in the centre of the forest, and foraging areas concentrated around waterways within the bounds of the forest. These observations suggest the roosting and movement ecology of this population is similar to that observed for this species in rural environments, despite the urban surroundings. Our results suggest that northern myotis is not a synurbic species but can occur within urbanized environments when suitable habitat is available. We suggest that large forest patches with mature, interior forest cover are likely to be an important resource for northern myotis, and they will be vulnerable to the loss or fragmentation of these features in rapidly urbanizing landscapes. These findings are highly relevant to the ecology and preservation of northern myotis and present a case for greater consideration of this species in urban forests.

Roosting Behavior of Northern Long-Eared Bats (Myotis septentrionalis) in an Urban-Adjacent Forest Fragment

“…In 2021, we tracked two post-lactating bats, one of which we tracked over two separate periods seven days apart. We tracked bats for an average of 5.5 ± 1.2 days (range = 2-7 days) before they dropped their radio transmitters, a time frame consistent with other work on northern long-eared bats [60,65,84]. Bats switched roosts an average of 3.0 ± 1.2 times throughout a tracking period (0.5 ± 0.2 switching events/days tracked).…”

“…We expected roost selection to follow trends identified in previous research, with bats roosting in cavities of live trees within forest fragments [65,67,68]. We also predicted that the main forest patch at Fox Island (approximately 245 ha) would be an important resource, given the results of research conducted in other urbanized areas [65,66]. Regarding torpor use, we expected bats roosting in trees with greater solar exposure to remain normothermic more often [41,69].…”

“…Over the summers of 2020 and 2021, we conducted research with the goal of describing roost selection and torpor use in the remnant population of northern long-eared bats in Fort Wayne, Indiana. We expected roost selection to follow trends identified in previous research, with bats roosting in cavities of live trees within forest fragments [65,67,68]. We also predicted that the main forest patch at Fox Island (approximately 245 ha) would be an important resource, given the results of research conducted in other urbanized areas [65,66].…”

“…Although the exact reasons for such rarity in developed areas are not reported, the depletion of forest and wetland resources in urbanized landscapes [1] and the introduction of anthropogenic stressors such as noise and light pollution [107,108] likely play a role in their exclusion. However, healthy reproductive populations have been reported in heavily forested parks within large cities including Long Island, New York; Washington, D.C; Toronto; Canada [64][65][66]. In these studies, the forest fragments ranged in size from 248-710 ha and contained permanent sources of water, such as rivers and ponds.…”

“…There are also few studies describing habitat use by northern long-eared bats in urban areas, likely because they are uncommon in areas lacking large patches of forest [63,64]. Northern long-eared bats have been reported in a 348 ha forest patch in Toronto, Canada and a 248 ha forest patch in Long Island, New York; however, in both cases their roost selection and foraging activity was limited to forest edges and interiors [65,66].…”