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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...
Autores principales: | , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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Public Library of Science
2021
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8101751/ https://www.ncbi.nlm.nih.gov/pubmed/33956835 http://dx.doi.org/10.1371/journal.pone.0251130 |
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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. |
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. |
collection | PubMed |
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 ([Image: see text] ) 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 ([Image: see text] ; 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. |
format | Online Article Text |
id | pubmed-8101751 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
spelling | pubmed-81017512021-05-17 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. PLoS One Research Article 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 ([Image: see text] ) 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 ([Image: see text] ; 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. Public Library of Science 2021-05-06 /pmc/articles/PMC8101751/ /pubmed/33956835 http://dx.doi.org/10.1371/journal.pone.0251130 Text en https://creativecommons.org/publicdomain/zero/1.0/This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 (https://creativecommons.org/publicdomain/zero/1.0/) public domain dedication. |
spellingShingle | Research Article 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 |
title | 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_short | 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 |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8101751/ https://www.ncbi.nlm.nih.gov/pubmed/33956835 http://dx.doi.org/10.1371/journal.pone.0251130 |
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