Factors affecting the distribution and roost-site selection of bats on the island of Newfoundland

Abstract

Ecological studies at the periphery of a species' distribution provide an opportunity to explore the limits of population viability under unique conditions. Research regarding specific factors that limit temperate bat distribution is lacking; therefore, the goal of this project was to characterize these factors for resident bats on the island of Newfoundland (NL) by species and sex (four bat groups in total). The first objective was to document the occurrence of little brown (Myotis lucifugus) and northern long-eared (M. septentrionalis) bats throughout NL, and relate their occurrence to stand and landscape factors. All bat groups were patchily distributed. Myotis septentrionalis were present in areas further east and north than previously documented but were not ubiquitous. Factors influencing distributional limits were unique for each bat group, and included number of buildings and forest area in a landscape (for M. septentrionalis females and males, respectively); and number of snags and average tree diameter in a stand (for M. lucifugus females and males, respectively). The second objective was to compare female roost-site selection on NL to that of central areas in their North American distribution. Smaller and shorter softwood trees were common on NL, and frequently used as roosts. The final objective was to characterize roost-site selection of female M. septentrionalis at different reproductive stages (lactation and non-lactation). Sites used during the lactation period were within cavities of large diameter trees that maintained warm, stable microclimates.