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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Autores principales:	Paul B Conn, Vladimir I Chernook, Erin E Moreland, Irina S Trukhanova, Eric V Regehr, Alexander N Vasiliev, Ryan R Wilson, Stanislav E Belikov, Peter L Boveng
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/3b892877181a49f1b746ffbd00c7cd80
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spelling	oai:doaj.org-article:3b892877181a49f1b746ffbd00c7cd802021-11-25T05:54:18ZAerial survey estimates of polar bears and their tracks in the Chukchi Sea.1932-620310.1371/journal.pone.0251130https://doaj.org/article/3b892877181a49f1b746ffbd00c7cd802021-01-01T00:00:00Zhttps://doi.org/10.1371/journal.pone.0251130https://doaj.org/toc/1932-6203Polar 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 ([Formula: 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 ([Formula: 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.Paul B ConnVladimir I ChernookErin E MorelandIrina S TrukhanovaEric V RegehrAlexander N VasilievRyan R WilsonStanislav E BelikovPeter L BovengPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 16, Iss 5, p e0251130 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Paul B Conn Vladimir I Chernook Erin E Moreland Irina S Trukhanova Eric V Regehr Alexander N Vasiliev Ryan R Wilson Stanislav E Belikov Peter L Boveng Aerial survey estimates of polar bears and their tracks in the Chukchi Sea.
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 ([Formula: 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 ([Formula: 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	article
author	Paul B Conn Vladimir I Chernook Erin E Moreland Irina S Trukhanova Eric V Regehr Alexander N Vasiliev Ryan R Wilson Stanislav E Belikov Peter L Boveng
author_facet	Paul B Conn Vladimir I Chernook Erin E Moreland Irina S Trukhanova Eric V Regehr Alexander N Vasiliev Ryan R Wilson Stanislav E Belikov Peter L Boveng
author_sort	Paul B Conn
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	https://doaj.org/article/3b892877181a49f1b746ffbd00c7cd80
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Aerial survey estimates of polar bears and their tracks in the Chukchi Sea.

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