Characterizing Summer Roosts of Little Brown Myotis and Evaluating the Effects of Mountain Pine Beetle Disturbance

Abstract

Mountain pine beetle (MPB, Dendroctonus ponderosae) outbreaks have resulted in large-scale changes in forest structure throughout the western United States. These changes can have large impacts on wildlife, but have not been studied in bats. Given that roosting sites may limit the distribution and abundance of bat populations, we aim to 1) quantify characteristics of roosts in forests during the summer and 2) evaluate how the availability of these characteristics changes with different intensities of MPB disturbance. During the summer of 2017, we mist-netted for bats in forests dominated by lodgepole pine (Pinus contorta) that exhibited varying degrees of tree mortality due to MPB. Three bat species comprised 76% of captures: hoary bat (Lasiurus cinereus, 12%), silver-haired bat (Lasionycteris noctivagans, 29%), and little brown myotis (Myotis lucifugus, 35%).Originally, we intended to tag lactating female little brown myotis to characterize maternity roosts. However, all 42 captures of little brown myotis were male. We attached radiotransmitters to 11 males and located at least 1 roost for 6 individuals (total roosts = 18). All roosts were in rock features, even though lodgepole snags were abundant and in close proximity to roosting sites. These preliminary results suggest that in lodgepole-dominated forests, male little brown myotis choose to roost in rock features over snags, regardless of the severity of MPB disturbance.