Effects of Earlier Sea Ice Breakup on Survival and Population Size of Polar Bears in Western Hudson Bay
ABSTRACT Some of the most pronounced ecological responses to climatic warming are expected to occur in polar marine regions, where temperature increases have been the greatest and sea ice provides a sensitive mechanism by which climatic conditions affect sympagic (i.e., with ice) species. Population...
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crwiley:10.2193/2006-180 2024-10-13T14:04:05+00:00 Effects of Earlier Sea Ice Breakup on Survival and Population Size of Polar Bears in Western Hudson Bay REGEHR, ERIC V. LUNN, NICHOLAS J. AMSTRUP, STEVEN C. STIRLING, IAN 2007 http://dx.doi.org/10.2193/2006-180 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.2193%2F2006-180 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor The Journal of Wildlife Management volume 71, issue 8, page 2673-2683 ISSN 0022-541X 1937-2817 journal-article 2007 crwiley https://doi.org/10.2193/2006-180 2024-09-17T04:51:51Z ABSTRACT Some of the most pronounced ecological responses to climatic warming are expected to occur in polar marine regions, where temperature increases have been the greatest and sea ice provides a sensitive mechanism by which climatic conditions affect sympagic (i.e., with ice) species. Population‐level effects of climatic change, however, remain difficult to quantify. We used a flexible extension of Cormack‐Jolly‐Seber capture‐recapture models to estimate population size and survival for polar bears ( Ursus maritimus ), one of the most ice‐dependent of Arctic marine mammals. We analyzed data for polar bears captured from 1984 to 2004 along the western coast of Hudson Bay and in the community of Churchill, Manitoba, Canada. The Western Hudson Bay polar bear population declined from 1,194 (95% CI = 1,020‐1,368) in 1987 to 935 (95% CI = 794‐1,076) in 2004. Total apparent survival of prime‐adult polar bears (5–19 yr) was stable for females (0.93; 95% CI = 0.91‐0.94) and males (0.90; 95% CI = 0.88‐0.91). Survival of juvenile, subadult, and senescent‐adult polar bears was correlated with spring sea ice breakup date, which was variable among years and occurred approximately 3 weeks earlier in 2004 than in 1984. We propose that this correlation provides evidence for a causal association between earlier sea ice breakup (due to climatic warming) and decreased polar bear survival. It may also explain why Churchill, like other communities along the western coast of Hudson Bay, has experienced an increase in human‐polar bear interactions in recent years. Earlier sea ice breakup may have resulted in a larger number of nutritionally stressed polar bears, which are encroaching on human habitations in search of supplemental food. Because western Hudson Bay is near the southern limit of the species' range, our findings may foreshadow the demographic responses and management challenges that more northerly polar bear populations will experience if climatic warming in the Arctic continues as projected. Article in Journal/Newspaper Arctic marine mammals Arctic Churchill Hudson Bay Sea ice Ursus maritimus Wiley Online Library Arctic Canada Hudson Hudson Bay Journal of Wildlife Management 71 8 2673 2683 |
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Open Polar |
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Wiley Online Library |
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crwiley |
language |
English |
description |
ABSTRACT Some of the most pronounced ecological responses to climatic warming are expected to occur in polar marine regions, where temperature increases have been the greatest and sea ice provides a sensitive mechanism by which climatic conditions affect sympagic (i.e., with ice) species. Population‐level effects of climatic change, however, remain difficult to quantify. We used a flexible extension of Cormack‐Jolly‐Seber capture‐recapture models to estimate population size and survival for polar bears ( Ursus maritimus ), one of the most ice‐dependent of Arctic marine mammals. We analyzed data for polar bears captured from 1984 to 2004 along the western coast of Hudson Bay and in the community of Churchill, Manitoba, Canada. The Western Hudson Bay polar bear population declined from 1,194 (95% CI = 1,020‐1,368) in 1987 to 935 (95% CI = 794‐1,076) in 2004. Total apparent survival of prime‐adult polar bears (5–19 yr) was stable for females (0.93; 95% CI = 0.91‐0.94) and males (0.90; 95% CI = 0.88‐0.91). Survival of juvenile, subadult, and senescent‐adult polar bears was correlated with spring sea ice breakup date, which was variable among years and occurred approximately 3 weeks earlier in 2004 than in 1984. We propose that this correlation provides evidence for a causal association between earlier sea ice breakup (due to climatic warming) and decreased polar bear survival. It may also explain why Churchill, like other communities along the western coast of Hudson Bay, has experienced an increase in human‐polar bear interactions in recent years. Earlier sea ice breakup may have resulted in a larger number of nutritionally stressed polar bears, which are encroaching on human habitations in search of supplemental food. Because western Hudson Bay is near the southern limit of the species' range, our findings may foreshadow the demographic responses and management challenges that more northerly polar bear populations will experience if climatic warming in the Arctic continues as projected. |
format |
Article in Journal/Newspaper |
author |
REGEHR, ERIC V. LUNN, NICHOLAS J. AMSTRUP, STEVEN C. STIRLING, IAN |
spellingShingle |
REGEHR, ERIC V. LUNN, NICHOLAS J. AMSTRUP, STEVEN C. STIRLING, IAN Effects of Earlier Sea Ice Breakup on Survival and Population Size of Polar Bears in Western Hudson Bay |
author_facet |
REGEHR, ERIC V. LUNN, NICHOLAS J. AMSTRUP, STEVEN C. STIRLING, IAN |
author_sort |
REGEHR, ERIC V. |
title |
Effects of Earlier Sea Ice Breakup on Survival and Population Size of Polar Bears in Western Hudson Bay |
title_short |
Effects of Earlier Sea Ice Breakup on Survival and Population Size of Polar Bears in Western Hudson Bay |
title_full |
Effects of Earlier Sea Ice Breakup on Survival and Population Size of Polar Bears in Western Hudson Bay |
title_fullStr |
Effects of Earlier Sea Ice Breakup on Survival and Population Size of Polar Bears in Western Hudson Bay |
title_full_unstemmed |
Effects of Earlier Sea Ice Breakup on Survival and Population Size of Polar Bears in Western Hudson Bay |
title_sort |
effects of earlier sea ice breakup on survival and population size of polar bears in western hudson bay |
publisher |
Wiley |
publishDate |
2007 |
url |
http://dx.doi.org/10.2193/2006-180 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.2193%2F2006-180 |
geographic |
Arctic Canada Hudson Hudson Bay |
geographic_facet |
Arctic Canada Hudson Hudson Bay |
genre |
Arctic marine mammals Arctic Churchill Hudson Bay Sea ice Ursus maritimus |
genre_facet |
Arctic marine mammals Arctic Churchill Hudson Bay Sea ice Ursus maritimus |
op_source |
The Journal of Wildlife Management volume 71, issue 8, page 2673-2683 ISSN 0022-541X 1937-2817 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.2193/2006-180 |
container_title |
Journal of Wildlife Management |
container_volume |
71 |
container_issue |
8 |
container_start_page |
2673 |
op_container_end_page |
2683 |
_version_ |
1812809243057717248 |