title: Effects of ambient noise on detectability and localization of avian songs and tones by observers in grasslands.
abstract: Probability of detection and accuracy of distance estimates in aural avian surveys may be affected by the presence of anthropogenic noise, and this may lead to inaccurate evaluations of the effects of noisy infrastructure on wildlife. We used arrays of speakers broadcasting recordings of grassland bird songs and pure tones to assess the probability of detection, and localization accuracy, by observers at sites with and without noisy oil and gas infrastructure in south-central Alberta from 2012 to 2014. Probability of detection varied with species and with speaker distance from transect line, but there were few effects of noisy infrastructure. Accuracy of distance estimates for songs and tones decreased as distance to observer increased, and distance estimation error was higher for tones at sites with infrastructure noise. Our results suggest that quiet to moderately loud anthropogenic noise may not mask detection of bird songs; however, errors in distance estimates during aural surveys may lead to inaccurate estimates of avian densities calculated using distance sampling. We recommend caution when applying distance sampling if most birds are unseen, and where ambient noise varies among treatments.
authors.affiliation: Natural Resources Institute University of Manitoba 70 Dysart Road Winnipeg Manitoba R3T 2M7 Canada.
authors.forename: Nicola
authors.initials: N
authors.lastname: Koper
authors.affiliation: Natural Resources Institute University of Manitoba 70 Dysart Road Winnipeg Manitoba R3T 2M7 Canada; Department of Biological Sciences University of Alberta CW 405 Biological Sciences Building Edmonton Alberta T6G 2E9 Canada.
authors.forename: Lionel
authors.initials: L
authors.lastname: Leston
authors.affiliation: Natural Resources Institute University of Manitoba 70 Dysart Road Winnipeg Manitoba R3T 2M7 Canada; TERA Environmental Consultants 815 8 Ave SW Calgary Alberta T2M 2M8 Canada.
authors.forename: Tyne M
authors.initials: TM
authors.lastname: Baker
authors.affiliation: Natural Resources Institute University of Manitoba 70 Dysart Road Winnipeg Manitoba R3T 2M7 Canada.
authors.forename: Claire
authors.initials: C
authors.lastname: Curry
authors.affiliation: Natural Resources Institute University of Manitoba 70 Dysart Road Winnipeg Manitoba R3T 2M7 Canada.
authors.forename: Patricia
authors.initials: P
authors.lastname: Rosa
keywords: Distance estimation; energy development; grasslands; perceptibility
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