Nocturnal and diurnal foraging behaviour of brown bears ( Ursus arctos) on a salmon stream in coastal British Columbia
Brown bears (Ursus arctos) have been reported to be primarily diurnal throughout their range in North America. Recent studies of black bears during salmon migration indicate high levels of nocturnal foraging with high capture efficiencies during darkness. We investigated the extent of nocturnal fora...
Published in: | Canadian Journal of Zoology |
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2002
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Online Access: | http://dx.doi.org/10.1139/z02-123 http://www.nrcresearchpress.com/doi/pdf/10.1139/z02-123 |
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crcansciencepubl:10.1139/z02-123 2024-09-15T18:40:09+00:00 Nocturnal and diurnal foraging behaviour of brown bears ( Ursus arctos) on a salmon stream in coastal British Columbia Klinka, D R Reimchen, T E 2002 http://dx.doi.org/10.1139/z02-123 http://www.nrcresearchpress.com/doi/pdf/10.1139/z02-123 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Zoology volume 80, issue 8, page 1317-1322 ISSN 0008-4301 1480-3283 journal-article 2002 crcansciencepubl https://doi.org/10.1139/z02-123 2024-08-29T04:08:49Z Brown bears (Ursus arctos) have been reported to be primarily diurnal throughout their range in North America. Recent studies of black bears during salmon migration indicate high levels of nocturnal foraging with high capture efficiencies during darkness. We investigated the extent of nocturnal foraging by brown bears during a salmon spawning migration at Knight Inlet in coastal British Columbia, using night-vision goggles. Adult brown bears were observed foraging equally during daylight and darkness, while adult females with cubs, as well as subadults, were most prevalent during daylight and twilight but uncommon during darkness. We observed a marginal trend of increased capture efficiency with reduced light levels (day, 20%; night, 36%) that was probably due to the reduced evasive behaviour of the salmon. Capture rates averaged 3.9 fish/h and differed among photic regimes (daylight, 2.1 fish/h; twilight, 4.3 fish/h; darkness, 8.3 fish/h). These results indicate that brown bears are highly successful during nocturnal foraging and exploit this period during spawning migration to maximize their consumption rates of an ephemeral resource. Article in Journal/Newspaper Ursus arctos Canadian Science Publishing Canadian Journal of Zoology 80 8 1317 1322 |
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Open Polar |
collection |
Canadian Science Publishing |
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crcansciencepubl |
language |
English |
description |
Brown bears (Ursus arctos) have been reported to be primarily diurnal throughout their range in North America. Recent studies of black bears during salmon migration indicate high levels of nocturnal foraging with high capture efficiencies during darkness. We investigated the extent of nocturnal foraging by brown bears during a salmon spawning migration at Knight Inlet in coastal British Columbia, using night-vision goggles. Adult brown bears were observed foraging equally during daylight and darkness, while adult females with cubs, as well as subadults, were most prevalent during daylight and twilight but uncommon during darkness. We observed a marginal trend of increased capture efficiency with reduced light levels (day, 20%; night, 36%) that was probably due to the reduced evasive behaviour of the salmon. Capture rates averaged 3.9 fish/h and differed among photic regimes (daylight, 2.1 fish/h; twilight, 4.3 fish/h; darkness, 8.3 fish/h). These results indicate that brown bears are highly successful during nocturnal foraging and exploit this period during spawning migration to maximize their consumption rates of an ephemeral resource. |
format |
Article in Journal/Newspaper |
author |
Klinka, D R Reimchen, T E |
spellingShingle |
Klinka, D R Reimchen, T E Nocturnal and diurnal foraging behaviour of brown bears ( Ursus arctos) on a salmon stream in coastal British Columbia |
author_facet |
Klinka, D R Reimchen, T E |
author_sort |
Klinka, D R |
title |
Nocturnal and diurnal foraging behaviour of brown bears ( Ursus arctos) on a salmon stream in coastal British Columbia |
title_short |
Nocturnal and diurnal foraging behaviour of brown bears ( Ursus arctos) on a salmon stream in coastal British Columbia |
title_full |
Nocturnal and diurnal foraging behaviour of brown bears ( Ursus arctos) on a salmon stream in coastal British Columbia |
title_fullStr |
Nocturnal and diurnal foraging behaviour of brown bears ( Ursus arctos) on a salmon stream in coastal British Columbia |
title_full_unstemmed |
Nocturnal and diurnal foraging behaviour of brown bears ( Ursus arctos) on a salmon stream in coastal British Columbia |
title_sort |
nocturnal and diurnal foraging behaviour of brown bears ( ursus arctos) on a salmon stream in coastal british columbia |
publisher |
Canadian Science Publishing |
publishDate |
2002 |
url |
http://dx.doi.org/10.1139/z02-123 http://www.nrcresearchpress.com/doi/pdf/10.1139/z02-123 |
genre |
Ursus arctos |
genre_facet |
Ursus arctos |
op_source |
Canadian Journal of Zoology volume 80, issue 8, page 1317-1322 ISSN 0008-4301 1480-3283 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/z02-123 |
container_title |
Canadian Journal of Zoology |
container_volume |
80 |
container_issue |
8 |
container_start_page |
1317 |
op_container_end_page |
1322 |
_version_ |
1810484472442781696 |