Aerial survey estimates of polar bears and their tracks in the Chukchi Sea
Polar bears are of international conservation concern due to climate change but are difficult to study because of low densities and an expansive, circumpolar distribution. In a collaborative U.S.-Russian effort in spring of 2016, we used aerial surveys to detect and estimate the abundance of polar b...
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crplos:10.1371/journal.pone.0251130 2024-05-19T07:38:59+00:00 Aerial survey estimates of polar bears and their tracks in the Chukchi Sea Conn, Paul B. Chernook, Vladimir I. Moreland, Erin E. Trukhanova, Irina S. Regehr, Eric V. Vasiliev, Alexander N. Wilson, Ryan R. Belikov, Stanislav E. Boveng, Peter L. Chiaradia, André National Oceanic and Atmospheric Administration U.S. Fish and Wildlife Service North Pacific Research Board 2021 http://dx.doi.org/10.1371/journal.pone.0251130 https://dx.plos.org/10.1371/journal.pone.0251130 en eng Public Library of Science (PLoS) https://creativecommons.org/publicdomain/zero/1.0/ PLOS ONE volume 16, issue 5, page e0251130 ISSN 1932-6203 journal-article 2021 crplos https://doi.org/10.1371/journal.pone.0251130 2024-05-01T07:02:00Z Polar bears are of international conservation concern due to climate change but are difficult to study because of low densities and an expansive, circumpolar distribution. In a collaborative U.S.-Russian effort in spring of 2016, we used aerial surveys to detect and estimate the abundance of polar bears on sea ice in the Chukchi Sea. Our surveys used a combination of thermal imagery, digital photography, and human observations. Using spatio-temporal statistical models that related bear and track densities to physiographic and biological covariates (e.g., sea ice extent, resource selection functions derived from satellite tags), we predicted abundance and spatial distribution throughout our study area. Estimates of 2016 abundance ( N ^ * ) ranged from 3,435 (95% CI: 2,300-5,131) to 5,444 (95% CI: 3,636-8,152) depending on the proportion of bears assumed to be missed on the transect line during Russian surveys ( g (0)). Our point estimates are larger than, but of similar magnitude to, a recent estimate for the period 2008-2016 ( N ^ * = 2 , 937 95% CI 1,522-5,944) derived from an integrated population model applied to a slightly smaller area. Although a number of factors (e.g., equipment issues, differing platforms, low sample sizes, size of the study area relative to sampling effort) required us to make a number of assumptions to generate estimates, it establishes a useful lower bound for abundance, and suggests high spring polar bear densities on sea ice in Russian waters south of Wrangell Island. With future improvements, we suggest that springtime aerial surveys may represent a plausible avenue for studying abundance and distribution of polar bears and their prey over large, remote areas. Article in Journal/Newspaper Chukchi Chukchi Sea Sea ice Wrangell Island PLOS PLOS ONE 16 5 e0251130 |
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English |
description |
Polar bears are of international conservation concern due to climate change but are difficult to study because of low densities and an expansive, circumpolar distribution. In a collaborative U.S.-Russian effort in spring of 2016, we used aerial surveys to detect and estimate the abundance of polar bears on sea ice in the Chukchi Sea. Our surveys used a combination of thermal imagery, digital photography, and human observations. Using spatio-temporal statistical models that related bear and track densities to physiographic and biological covariates (e.g., sea ice extent, resource selection functions derived from satellite tags), we predicted abundance and spatial distribution throughout our study area. Estimates of 2016 abundance ( N ^ * ) ranged from 3,435 (95% CI: 2,300-5,131) to 5,444 (95% CI: 3,636-8,152) depending on the proportion of bears assumed to be missed on the transect line during Russian surveys ( g (0)). Our point estimates are larger than, but of similar magnitude to, a recent estimate for the period 2008-2016 ( N ^ * = 2 , 937 95% CI 1,522-5,944) derived from an integrated population model applied to a slightly smaller area. Although a number of factors (e.g., equipment issues, differing platforms, low sample sizes, size of the study area relative to sampling effort) required us to make a number of assumptions to generate estimates, it establishes a useful lower bound for abundance, and suggests high spring polar bear densities on sea ice in Russian waters south of Wrangell Island. With future improvements, we suggest that springtime aerial surveys may represent a plausible avenue for studying abundance and distribution of polar bears and their prey over large, remote areas. |
author2 |
Chiaradia, André National Oceanic and Atmospheric Administration U.S. Fish and Wildlife Service North Pacific Research Board |
format |
Article in Journal/Newspaper |
author |
Conn, Paul B. Chernook, Vladimir I. Moreland, Erin E. Trukhanova, Irina S. Regehr, Eric V. Vasiliev, Alexander N. Wilson, Ryan R. Belikov, Stanislav E. Boveng, Peter L. |
spellingShingle |
Conn, Paul B. Chernook, Vladimir I. Moreland, Erin E. Trukhanova, Irina S. Regehr, Eric V. Vasiliev, Alexander N. Wilson, Ryan R. Belikov, Stanislav E. Boveng, Peter L. Aerial survey estimates of polar bears and their tracks in the Chukchi Sea |
author_facet |
Conn, Paul B. Chernook, Vladimir I. Moreland, Erin E. Trukhanova, Irina S. Regehr, Eric V. Vasiliev, Alexander N. Wilson, Ryan R. Belikov, Stanislav E. Boveng, Peter L. |
author_sort |
Conn, Paul B. |
title |
Aerial survey estimates of polar bears and their tracks in the Chukchi Sea |
title_short |
Aerial survey estimates of polar bears and their tracks in the Chukchi Sea |
title_full |
Aerial survey estimates of polar bears and their tracks in the Chukchi Sea |
title_fullStr |
Aerial survey estimates of polar bears and their tracks in the Chukchi Sea |
title_full_unstemmed |
Aerial survey estimates of polar bears and their tracks in the Chukchi Sea |
title_sort |
aerial survey estimates of polar bears and their tracks in the chukchi sea |
publisher |
Public Library of Science (PLoS) |
publishDate |
2021 |
url |
http://dx.doi.org/10.1371/journal.pone.0251130 https://dx.plos.org/10.1371/journal.pone.0251130 |
genre |
Chukchi Chukchi Sea Sea ice Wrangell Island |
genre_facet |
Chukchi Chukchi Sea Sea ice Wrangell Island |
op_source |
PLOS ONE volume 16, issue 5, page e0251130 ISSN 1932-6203 |
op_rights |
https://creativecommons.org/publicdomain/zero/1.0/ |
op_doi |
https://doi.org/10.1371/journal.pone.0251130 |
container_title |
PLOS ONE |
container_volume |
16 |
container_issue |
5 |
container_start_page |
e0251130 |
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1799478483151224832 |