Great Gray Owls hunting voles under snow hover to defeat an acoustic mirage
How do Great Gray Owls (Strix nebulosa) capture voles (Cricetidae) through a layer of snow? As snow is a visual barrier, the owls locate voles by ear alone. To test how snow absorbs and refracts vole sound, we inserted a loudspeaker under the snowpack and analysed sound from the loudspeaker, first b...
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ftcdlib:oai:escholarship.org:ark:/13030/qt8bc6z0ct 2023-11-12T04:26:54+01:00 Great Gray Owls hunting voles under snow hover to defeat an acoustic mirage Clark, Christopher J Duncan, James Dougherty, Robert 20221164 2022-11-30 application/pdf https://escholarship.org/uc/item/8bc6z0ct unknown eScholarship, University of California qt8bc6z0ct https://escholarship.org/uc/item/8bc6z0ct CC-BY Proceedings of the Royal Society B, vol 289, iss 1987 Zoology Biological Sciences Animals Acoustics Arvicolinae Snow Strigiformes Predatory Behavior acoustic camera attenuation playback refraction sensory ecology Agricultural and Veterinary Sciences Medical and Health Sciences Agricultural veterinary and food sciences Environmental sciences article 2022 ftcdlib 2023-10-30T19:04:45Z How do Great Gray Owls (Strix nebulosa) capture voles (Cricetidae) through a layer of snow? As snow is a visual barrier, the owls locate voles by ear alone. To test how snow absorbs and refracts vole sound, we inserted a loudspeaker under the snowpack and analysed sound from the loudspeaker, first buried, then unburied. Snow attenuation coefficients rose with frequency (0.3 dB cm-1 at 500 Hz, 0.6 dB cm-1 at 3 kHz) such that low-frequency sound transmitted best. The Great Gray Owl has the largest facial disc of any owl, suggesting they are adapted to use this low-frequency sound. We used an acoustic camera to spatially localize sound source location, and show that snow also refracts prey sounds (refractive index: 1.16). To an owl not directly above the prey, this refraction creates an 'acoustic mirage': prey acoustic position is offset from its actual location. Their hunting strategy defeats this mirage because they hover directly over prey, which is the listening position with least refraction and least attenuation. Among all birds, the Great Gray Owl has the most extreme wing morphologies associated with quiet flight. These extreme wing traits may function to reduce the sounds of hovering, with implications for bioinspiration. Article in Journal/Newspaper Strix nebulosa University of California: eScholarship |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
unknown |
topic |
Zoology Biological Sciences Animals Acoustics Arvicolinae Snow Strigiformes Predatory Behavior acoustic camera attenuation playback refraction sensory ecology Agricultural and Veterinary Sciences Medical and Health Sciences Agricultural veterinary and food sciences Environmental sciences |
spellingShingle |
Zoology Biological Sciences Animals Acoustics Arvicolinae Snow Strigiformes Predatory Behavior acoustic camera attenuation playback refraction sensory ecology Agricultural and Veterinary Sciences Medical and Health Sciences Agricultural veterinary and food sciences Environmental sciences Clark, Christopher J Duncan, James Dougherty, Robert Great Gray Owls hunting voles under snow hover to defeat an acoustic mirage |
topic_facet |
Zoology Biological Sciences Animals Acoustics Arvicolinae Snow Strigiformes Predatory Behavior acoustic camera attenuation playback refraction sensory ecology Agricultural and Veterinary Sciences Medical and Health Sciences Agricultural veterinary and food sciences Environmental sciences |
description |
How do Great Gray Owls (Strix nebulosa) capture voles (Cricetidae) through a layer of snow? As snow is a visual barrier, the owls locate voles by ear alone. To test how snow absorbs and refracts vole sound, we inserted a loudspeaker under the snowpack and analysed sound from the loudspeaker, first buried, then unburied. Snow attenuation coefficients rose with frequency (0.3 dB cm-1 at 500 Hz, 0.6 dB cm-1 at 3 kHz) such that low-frequency sound transmitted best. The Great Gray Owl has the largest facial disc of any owl, suggesting they are adapted to use this low-frequency sound. We used an acoustic camera to spatially localize sound source location, and show that snow also refracts prey sounds (refractive index: 1.16). To an owl not directly above the prey, this refraction creates an 'acoustic mirage': prey acoustic position is offset from its actual location. Their hunting strategy defeats this mirage because they hover directly over prey, which is the listening position with least refraction and least attenuation. Among all birds, the Great Gray Owl has the most extreme wing morphologies associated with quiet flight. These extreme wing traits may function to reduce the sounds of hovering, with implications for bioinspiration. |
format |
Article in Journal/Newspaper |
author |
Clark, Christopher J Duncan, James Dougherty, Robert |
author_facet |
Clark, Christopher J Duncan, James Dougherty, Robert |
author_sort |
Clark, Christopher J |
title |
Great Gray Owls hunting voles under snow hover to defeat an acoustic mirage |
title_short |
Great Gray Owls hunting voles under snow hover to defeat an acoustic mirage |
title_full |
Great Gray Owls hunting voles under snow hover to defeat an acoustic mirage |
title_fullStr |
Great Gray Owls hunting voles under snow hover to defeat an acoustic mirage |
title_full_unstemmed |
Great Gray Owls hunting voles under snow hover to defeat an acoustic mirage |
title_sort |
great gray owls hunting voles under snow hover to defeat an acoustic mirage |
publisher |
eScholarship, University of California |
publishDate |
2022 |
url |
https://escholarship.org/uc/item/8bc6z0ct |
op_coverage |
20221164 |
genre |
Strix nebulosa |
genre_facet |
Strix nebulosa |
op_source |
Proceedings of the Royal Society B, vol 289, iss 1987 |
op_relation |
qt8bc6z0ct https://escholarship.org/uc/item/8bc6z0ct |
op_rights |
CC-BY |
_version_ |
1782340705954299904 |