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Estimating abundance of the Southern Hudson Bay polar bear subpopulation using aerial surveys, 2011 and 2012

Wildlife Research Series 2013-01
By: , and 

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Abstract

The Southern Hudson Bay (SH) polar bear subpopulation occurs at the southern extent of the species’ range. Although capture-recapture studies indicate that abundance remained stable between 1986 and 2005, declines in body condition and survival were documented during the period, possibly foreshadowing a future decrease in abundance. To obtain a current estimate of abundance, we conducted a comprehensive line transect aerial survey of SH during 2011–2012. We stratified the study site by anticipated densities and flew coastal contour transects and systematically spaced inland transects in Ontario and on Akimiski Island and large offshore islands in 2011. Data were collected with double observer and distance sampling protocols. We also surveyed small islands in Hudson Bay and James Bay and flew a comprehensive transect along the Québec coastline in 2012. We observed 667 bears in Ontario and on Akimiski Island and nearby islands in 2011, and we sighted 80 bears on offshore islands during 2012. Mark-recapture distance sampling and sightresight models yielded a model-averaged estimate of 868 (SE: 177) for the 2011 study area. Our estimate of abundance for the entire SH subpopulation (951; SE: 177) suggests that abundance has remained unchanged. However, this result should be interpreted cautiously because of the methodological differences between historical studies (physical capture) and this survey. A conservative management approach is warranted given the previous increases in the duration of the ice-free season, which are predicted to continue in the future, and previously documented declines in body condition and vital rates.

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Additional publication details

Publication type Report
Publication Subtype Other Government Series
Title Estimating abundance of the Southern Hudson Bay polar bear subpopulation using aerial surveys, 2011 and 2012
Series title Wildlife Research Series
Series number 2013-01
ISBN 978-1-4606-3321-2
Year Published 2013
Language English
Publisher Ontario Ministry of Natural Resources, Science and Research Branch
Publisher location Peterborough, Ontario, Canada
Contributing office(s) Alaska Science Center Biology MFEB
Description 33 p.
Country Canada
Other Geospatial Hudson Bay
Online Only (Y/N) N
Additional Online Files (Y/N) N