Factors affecting acoustic detection and site occupancy of Indiana bats near a known maternity colony

Abstract

Indiana bats (Myotis sodalis) are capable of exploiting ephemeral resources in structurally complex, interior forests. Consequently, surveying for this species is difficult, and even in areas harboring known populations, documenting presence remains a challenge. We aimed to determine what factors affected probability of detection (p) and site occupancy (Ψ) for Indiana bats when sampling with acoustic bat detectors near an active maternity colony. From May to August 2012 and 2013, we passively sampled 71 random points near Indianapolis, Indiana, with Wildlife Acoustic SM2BAT+ detectors. On average, sampling occurred ∼2.2 km from maternity colony roosts, which contained ≥ 150 bats by mid-July. Habitat and landscape covariates were measured in the field or via ArcGIS. We reduced model covariates with Pearson's correlation and principal component analysis. Indiana bat calls were identified using Bat Call ID software. We used Presence 6.1 software and Akaike's Information Criteria to assess models for detectab...