Conservation Evidence strives to be as useful to conservationists as possible. Please take our survey to help the team improve our resource.

Providing evidence to improve practice

Individual study: Testing the effectiveness of an experimental bat deterrent at the Maple Ridge Wind farm.

Published source details

Horn J.W., Arnett E.B., Jensen M. & Kunz T.H. (2008) Testing the effectiveness of an experimental bat deterrent at the Maple Ridge Wind farm. Bat Conservation International report.


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Deter bats from turbines using ultrasound Bat Conservation

A paired sites study in 2007 on a wind farm in an agricultural area of New York, USA (Horn et al 2008) found mixed effects on bat activity when an ultrasonic deterrent was used. Significantly fewer bats were observed over 10 consecutive nights at a turbine with an ultrasonic deterrent fitted (average 13 bat passes/night) than at a matched control turbine without a deterrent (average 24 bat passes/night). No significant difference was found in bat activity when this was repeated with a second matched pair (average 10 bat passes/night at both). The deterrent broadcast random pulses of broadband ultrasound from 20–80 kHz, with a range of up to 20 m. For both trials, bat activity was observed simultaneously at treatment and control turbines for 3.6 hours after sunset for 10 consecutive nights in August 2007 using thermal infrared imaging cameras.

(Summarised by Anna Berthinussen)