Using occupancy estimates to assess habitat use and interspecific interactions of the Indiana bat (Myotis sodalis) and little brown bat (M. Lucifugus) in northeast Missouri

Abstract

The Indiana bat (Myotis sodalis) has been endangered since 1967 and is the focus of a controversial debate among stakeholders on both public and private lands due to a lack due to a lack of understanding the summer habitat needs of the species. In addition, even less is known about interspecific interactions with other bats and if this could be playing a role in the decline of this species. Our objectives were to estimate the probability of site occupancy for the Indiana bat and the little brown bat (M. lucifugus) from which we could model their summer habitat suitability. We then used our occupancy modeling estimates to determine whether the knowledge of the little brown bat's (M. lucifugus) landscape occupancy patterns improved the fit of Indiana bat occupancy models and vice versa. We used an information theoretic approach to examine a priori hypotheses relative to both probability of detection and site occupancy using an objective model selection criterion to rank the candidate models. For the Indiana bat the quantity of bottomland hardwood forest in a 7 km landscape was the single most significant factor in determining Indiana bat occupancy. For the little brown bat, site combined with distance to water and canopy cover created the top model determining little brown bat occupancy. Combined information of both species' occupancy patterns did not improve the probability of either species' occupancy.