Manufacturers of acoustic bat detectors use proprietary microphones with different frequency responses, sensitivities, and directionality. Researchers implement various waterproofing strategies to protect microphones from inclement weather. These factors cause different detector models to have unique sampling areas and likely results in dissimilar data recording. We tested whether SM2BAT+ (SM2) and Anabat SD2 (Anabat) bat detectors record dissimilar data when weatherproofed in a manner suitable for long-term passive sampling. We deployed detectors at 71 random points near Indianapolis, Indiana (USA), from May to August, 2012-2013. We used 45° polyvinyl chloride tubes to weatherproof directional Anabat microphones and the stock foam shielding to cover omnidirectional SM2 microphones. Anabat and SM2 microphones were paired at 2-m and 5-m heights. We adjusted file parameters to make Anabat and SM2 data comparable. We identified files to phonic group (low, midrange, and Myotis) using Bat Call ID software. The effects of detector type, phonic group, height, and their interactions on mean files recorded per site were assessed using generalized estimating equations and least-significant-differences pairwise comparisons. Anabats recorded more low and midrange files, but fewer Myotis files per site than did SM2s. When comparing the same model of detectors, deployment height did not affect data acquisition. Weatherproofing may limit the ability of Anabats to record Myotis, but Anabat microphones may have greater detection ranges for low and midrange bats. We demonstrated that the ability to record bat calls in different frequency ranges varies with microphone type and weatherproofing strategy, which implies that best practices for presence-absence surveys may also vary for bats in different phonic groups.
- acoustic monitoring
- Anabat SD2
- generalized estimating equations
- phonic group
- ultrasonic microphone
ASJC Scopus subject areas
- Nature and Landscape Conservation