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Behavioral patterns of bats at a wind turbine events

Citation

Goldenberg, Shifra; Cryan, Paul; Gorresen, P. Marcos; Fingersh, Lee Jay (2022), Behavioral patterns of bats at a wind turbine events, Dryad, Dataset, https://doi.org/10.5061/dryad.q83bk3jh3

Abstract

Bat fatalities at wind energy facilities in North America are predominantly comprised of migratory, tree-dependent species, but it is unclear why these bats are at higher risk. Factors influencing bat susceptibility to wind turbines might be revealed by temporal patterns in their behaviors around these dynamic landscape structures. In northern temperate zones fatalities occur mostly from July through October, but whether this reflects seasonally variable behaviors, passage of migrants, or some combination of factors remains unknown. In this study, we examined video imagery spanning one year in Colorado to characterize patterns of seasonal and nightly variability in bat behavior at a wind turbine. We detected bats on 177 of 306 nights representing approximately 3,800 hours of video and > 2,000 discrete bat events. We observed bats approaching the turbine throughout the night across all months during which bats were observed. Two distinct seasonal peaks of bat activity occurred in July and September, representing 30% and 42% increases in discrete bat events from the preceding months June and August, respectively. Bats exhibited behaviors around the turbine that increased in both diversity and duration in July and September. The peaks in bat events were reflected in chasing and turbine approach behaviors. Many of the bat events involved multiple approaches to the turbine, including when bats were displaced through the air by moving blades. The seasonal and nightly patterns we observed were consistent with the possibility that wind turbines invoke investigative behaviors in bats in late summer and autumn coincident with migration, and that bats may return and fly close to wind turbines even after experiencing potentially disruptive stimuli like moving blades. Our results point to the need for a deeper understanding of the seasonality, drivers, and characteristics of bat movement across spatial scales.

Usage Notes

det.id

unique identifier of the bat detection

event.id

unique identifier of the bat detection event (detections grouped by maximum of 1-minute interval)

adj.date

adjusted date of detection which is not affected by midnight (retains same date until after noon of following day)

orig.date

original date of detection which is affected by midnight (i.e., changes at 2400 hours)

dt.start

time of detection start (hh:mm:ss)

dt.end

time of detection end (hh:mm:ss)

det.dur

cumulative time of detection (seconds)

frac

time of detection as a fraction of night (scaled as 0 to 1 relative to sunset and sunrise time)

bats.present

total number of bats concurrently visible during the detection duration period

state_1 to state_11

bat activity grouped by outcome (displacement, strike), flight behavior (chase, hovering, non-focal pass), and turbine structural location of close approaches (blade, nacelle, monopole). NA indicates no additional state observed.