Abstract
- The primary goal of the study was to collect acoustic information on activity levels of bats during nocturnal hours of spring migration, summer, and fall migration. Specifically, our objectives were to: (1) collect baseline information on levels of bat activity (bat passes/detector -night) for migratory bats (e.g., hoary, big brown, and silver -haired bats); non - migratory species (e.g., Myotis spp.); and species of concern; and (2) examine spatial (height and location) and temporal (within and among nights) variations in bat activity.
- We conducted bat acoustic monitoring for 1,284 potential detector -nights between 3 April 2015 and 2 November 2015 at the proposed Skookumchuck wind energy project, Washington. Each night we conducted bat acoustic monitoring for ~8 –14 h/night (~1h < sunset to ~1h > sunrise).
- We recorded bat activity from Wildlife Acoustics SM2BAT+ detectors positioned at 2 altitudes (~3 m and ~45 m agl) at 2 meteorological towers (Towers 1 and 2) and 2 ground -based stations (~3 m agl) at G1 and G2 for a total of 1,284 potential detector nights (# detectors * # nights) in spring, summer, and fall. We obtained useable data for the majority 97.6% ( n = 1,253) of detector -nights throughout the study.
- Total bat passes from all detectors across the entire study was 5,787.
- Activity (mean passes/detector -night ± SE) for all bats was (6.83 ± 0.82) across the entire study.
- Activity (mean passes/detector -night ± SE) for migratory tree -roosting bats was high (5.75 ± 0.74) across the entire study.
- Activity (mean passes/detector -night ± SE) across all sites appeared higher at 3 m (6.78 ± 0.79) than at 45 m (0.13 ± 0.03).
- Landscape variability (e.g., proximity to roosting or foraging habitat) between stations likely resulted in differences in mean activity (passes/detector-night). The highest activity for All bats was recorded at G2 (17.77 ± 2.57).