Interspecific competition in bats and diet shifts in response to white‐nose syndrome

Abstract

Since the introduction of white‐nose syndrome (WNS) in North America, numerous species of bat have dwindled in numbers. These declines observed are often species‐specific and thus provides opportunity for a natural experiment to test for shifts in diet through relaxed resource partitioning in bat communities post‐introduction of WNS. Acoustic monitoring at locations in Southern Ontario pre‐ (2009–2011) and post‐WNS (2012–2014) introduction showed an increase in activity of big brown bats (Eptesicus fuscus) corresponding to a decline in the activity of little brown bats (Myotis lucifugus). Next‐generation sequencing of bat stomachs and guano in Southern Ontario before and after WNS allowed for the characterization of diet changes of these species. Post‐WNS, E. fuscus consumed a wider breadth of prey and many of the insect species once consumed by M. lucifugus, including several pest insects. These results suggest that the introduction of WNS has resulted in relaxed interspecific competition within these bat communities in Southern Ontario.

Bats partition activity in space and time in a large, heterogeneous landscape

“…We may have observed niche relaxation associated with a change in the competitive landscape from 2015 to 2016, such as might be caused by the decline of one or more species from an assemblage. For example, there is evidence that the spatiotemporal (Jachowski et al, 2014;Mayberry et al, 2020;Teets, 2018) and dietary (Morningstar et al, 2019) However, the broad observation that bats are expanding their niches through time might be related to other extrinsic factors. For example, because temporal partitioning in predators is inherently tied to the activity patterns of their prey (Kronfeld-Schor & Dayan, 2003;Schoener, 1974), and given the mounting evidence that insects are declining (Wagner, 2020), bats may be expanding their niches through time in response to declines in prey availability.…”

Long‐term changes in occurrence, relative abundance, and reproductive fitness of bat species in relation to arrival of White‐nose Syndrome in West Virginia, USA

“…fuscus showed an increase in diet richness post‐WNS, including an increase in insect species in common with M . lucifugus (from 37 to 58; Morningstar et al., 2019 ). Clare et al.…”

Turning to the dark side: LED light at night alters the activity and species composition of a foraging bat assemblage in the northeastern United States

“…The species has recently been listed as threatened or endangered in several U.S. States, including Connecticut, and at the federal level in Canada in response to the declines caused by WNS. Big brown bat populations initially declined as a result of WNS, but less precipitously than those of the little brown bat and other myotid bats in the northeastern United States (Turner et al., 2011) and now may be increasing possibly as a result of competitive release (Mayberry et al., 2020; Morningstar et al., 2019) and/or greater resistance to infection (Frank et al., 2014). Eastern red bat, silver‐haired bat, and hoary bat are long‐distance migrants that are sympatric with big brown bats and little brown bats in the northeastern United States during the breeding season and then overwinter in the southern United States Their populations have not been impacted by WNS but face threats from wind energy development (Frick et al., 2017).…”