Roost tree and habitat characterization of the SouthWestern Myotis (Myotis auriculus) at the northern extremity of its range.

Abstract

Characteristics of potential maternity roosts of the southwestern myotis (Myotis auriculus) at the northern extremity of its range are largely unknown. Maternity roosts are key resources for bat populations. An understanding of roost-site selection is critical for effective bat conservation and management. Over the summers of 2008–2011, we tracked 13 reproductive M. auriculus females to 21 maternity roost sites in pin˜onjuniper– dominated woodlands on Kirtland Air Force Base in Albuquerque, New Mexico. Using point-quarter sampling, we compared the habitat characteristics of roost trees to 100 randomly selected control trees. The best predictors of suitable M. auriculus roost sites were tree diameter and elevation. Roost trees were commonly one-seeded junipers (Juniperus monosperma) with relatively large diameters. Roost stands also contained more ponderosa pines (Pinus ponderosa) and Gambel oak (Quercus gambelii) than expected by chance but less J. monosperma than expected by chance. Roost stands often occurred on flat ground at high elevations and exhibited relatively high solar gain. For effective management of this species, we suggest that habitat supporting large, cavity-containing trees be preserved across the species’ range.