Aerial surveys cause large but ephemeral decreases in bear presence at salmon streams in Kodiak, Alaska.
Aerial surveys are often used to monitor wildlife and fish populations, but rarely are the effects on animal behavior documented. For over 30 years, the Kodiak National Wildlife Refuge has conducted low-altitude aerial surveys to assess Kodiak brown bear (Ursus arctos middendorffi) space use and dem...
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ftdoajarticles:oai:doaj.org/article:49c4a8f415d24e5ebda15e1155f709fc 2023-05-15T17:04:37+02:00 Aerial surveys cause large but ephemeral decreases in bear presence at salmon streams in Kodiak, Alaska. William W Deacy William B Leacock Eric J Ward Jonathan B Armstrong 2019-01-01T00:00:00Z https://doi.org/10.1371/journal.pone.0222085 https://doaj.org/article/49c4a8f415d24e5ebda15e1155f709fc EN eng Public Library of Science (PLoS) https://doi.org/10.1371/journal.pone.0222085 https://doaj.org/toc/1932-6203 1932-6203 doi:10.1371/journal.pone.0222085 https://doaj.org/article/49c4a8f415d24e5ebda15e1155f709fc PLoS ONE, Vol 14, Iss 9, p e0222085 (2019) Medicine R Science Q article 2019 ftdoajarticles https://doi.org/10.1371/journal.pone.0222085 2022-12-31T09:07:27Z Aerial surveys are often used to monitor wildlife and fish populations, but rarely are the effects on animal behavior documented. For over 30 years, the Kodiak National Wildlife Refuge has conducted low-altitude aerial surveys to assess Kodiak brown bear (Ursus arctos middendorffi) space use and demographic composition when bears are seasonally congregated near salmon spawning streams in southwestern Kodiak Island, Alaska. Salmon (Oncorhynchus spp.) are an important bear food and salmon runs are brief, so decreases in time spent fishing for salmon may reduce salmon consumption by bears. The goal of this study was to apply different and complementary field methods to evaluate the response of bears to these aerial surveys. Ground-based counts at one stream indicated 62% of bears departed the 200m-wide survey zone in response to aerial surveys, but bear counts returned to pre-survey abundance after only three hours. Although this effect was brief, survey flights occurred during the hours of peak daily bear activity (morning and evening), so the three-hour disruption appeared to result in a 25% decline in cumulative daily detections by 38 time-lapse cameras deployed along 10 salmon streams. Bear responses varied by sex-male bears were much more likely than female bears (with or without cubs) to depart streams and female bears with GPS collars did not move from streams following surveys. Although bears displaced by aerial surveys may consume fewer salmon, the actual effect on their fitness depends on whether they compensate by foraging at other times or by switching to other nutritious resources. Data from complementary sources allows managers to more robustly understand the impacts of surveys and whether their benefits are justified. Similar assessments should be made on alternative techniques such as Unmanned Aerial Vehicles and non-invasive sampling to determine whether they supply equivalent data while limiting bear disturbance. Article in Journal/Newspaper Kodiak Ursus arctos Alaska Directory of Open Access Journals: DOAJ Articles PLOS ONE 14 9 e0222085 |
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Directory of Open Access Journals: DOAJ Articles |
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English |
topic |
Medicine R Science Q |
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Medicine R Science Q William W Deacy William B Leacock Eric J Ward Jonathan B Armstrong Aerial surveys cause large but ephemeral decreases in bear presence at salmon streams in Kodiak, Alaska. |
topic_facet |
Medicine R Science Q |
description |
Aerial surveys are often used to monitor wildlife and fish populations, but rarely are the effects on animal behavior documented. For over 30 years, the Kodiak National Wildlife Refuge has conducted low-altitude aerial surveys to assess Kodiak brown bear (Ursus arctos middendorffi) space use and demographic composition when bears are seasonally congregated near salmon spawning streams in southwestern Kodiak Island, Alaska. Salmon (Oncorhynchus spp.) are an important bear food and salmon runs are brief, so decreases in time spent fishing for salmon may reduce salmon consumption by bears. The goal of this study was to apply different and complementary field methods to evaluate the response of bears to these aerial surveys. Ground-based counts at one stream indicated 62% of bears departed the 200m-wide survey zone in response to aerial surveys, but bear counts returned to pre-survey abundance after only three hours. Although this effect was brief, survey flights occurred during the hours of peak daily bear activity (morning and evening), so the three-hour disruption appeared to result in a 25% decline in cumulative daily detections by 38 time-lapse cameras deployed along 10 salmon streams. Bear responses varied by sex-male bears were much more likely than female bears (with or without cubs) to depart streams and female bears with GPS collars did not move from streams following surveys. Although bears displaced by aerial surveys may consume fewer salmon, the actual effect on their fitness depends on whether they compensate by foraging at other times or by switching to other nutritious resources. Data from complementary sources allows managers to more robustly understand the impacts of surveys and whether their benefits are justified. Similar assessments should be made on alternative techniques such as Unmanned Aerial Vehicles and non-invasive sampling to determine whether they supply equivalent data while limiting bear disturbance. |
format |
Article in Journal/Newspaper |
author |
William W Deacy William B Leacock Eric J Ward Jonathan B Armstrong |
author_facet |
William W Deacy William B Leacock Eric J Ward Jonathan B Armstrong |
author_sort |
William W Deacy |
title |
Aerial surveys cause large but ephemeral decreases in bear presence at salmon streams in Kodiak, Alaska. |
title_short |
Aerial surveys cause large but ephemeral decreases in bear presence at salmon streams in Kodiak, Alaska. |
title_full |
Aerial surveys cause large but ephemeral decreases in bear presence at salmon streams in Kodiak, Alaska. |
title_fullStr |
Aerial surveys cause large but ephemeral decreases in bear presence at salmon streams in Kodiak, Alaska. |
title_full_unstemmed |
Aerial surveys cause large but ephemeral decreases in bear presence at salmon streams in Kodiak, Alaska. |
title_sort |
aerial surveys cause large but ephemeral decreases in bear presence at salmon streams in kodiak, alaska. |
publisher |
Public Library of Science (PLoS) |
publishDate |
2019 |
url |
https://doi.org/10.1371/journal.pone.0222085 https://doaj.org/article/49c4a8f415d24e5ebda15e1155f709fc |
genre |
Kodiak Ursus arctos Alaska |
genre_facet |
Kodiak Ursus arctos Alaska |
op_source |
PLoS ONE, Vol 14, Iss 9, p e0222085 (2019) |
op_relation |
https://doi.org/10.1371/journal.pone.0222085 https://doaj.org/toc/1932-6203 1932-6203 doi:10.1371/journal.pone.0222085 https://doaj.org/article/49c4a8f415d24e5ebda15e1155f709fc |
op_doi |
https://doi.org/10.1371/journal.pone.0222085 |
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PLOS ONE |
container_volume |
14 |
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9 |
container_start_page |
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