Notes on Reproduction, Seasonality, and Roost Sites for Silver-haired Bats (Lasionycteris noctivagans) in Western Nebraska

Silver-haired Bats (Lasionycteris noctivagans) are a migratory species found throughout the United States, southern Canada, and northern Mexico. Throughout their range, Silver-haired Bats roost in various tree species, generally within decaying features like cavities and exfoliated bark. Herein we report on additional reproductive and seasonal data as well as the first data on trees used as roost sites by Silver-haired Bats in Nebraska. We captured individuals along a small tributary of the North Platte River at Ash Hollow State Historical Park, Garden County, Nebraska, and tracked bats to their roosts. At this location, we documented lactation on 17 June 2023 and volant young on 18 July 2024. Our dates of reproductive activity were within the known timing for lactation and volant young reported in Nebraska and Iowa. On 4 May 2024, one Silver-haired Bat was opportunistically observed roosting inside a building, which was the third earliest record for the species in the state. On 28 May 2024, we captured 2 adult males and 4 adult females and tracked 1 male and 2 females in subsequent days to 8 total roosts, all located in Eastern Cottonwood (Populus deltoides) trees. Roosts appeared to be in cavities or exfoliated bark on decaying portions of trees in areas with an open understory below roosts. Roost trees had significantly larger DBHs and heights compared to reference trees, with all other metrics not significantly different. Use of only Eastern Cottonwoods might be related to their overall abundance and large size at the site, and this tree species also commonly cavitates under stressful conditions creating potential roosts. To conserve roosting habitats for Silver-haired Bats in the Great Plains, large, tall Eastern Cottonwoods should be maintained and preserved along riparian corridors, especially in areas where females are known to bear and raise young.