Effects of Earlier Sea Ice Breakup on Survival and Population Size of Polar Bears in Western Hudson Bay

2007 ◽  
Vol 71 (8) ◽  
pp. 2673-2683 ◽  
Author(s):  
ERIC V. REGEHR ◽  
NICHOLAS J. LUNN ◽  
STEVEN C. AMSTRUP ◽  
IAN STIRLING
Keyword(s):  
Sea Ice ◽  
Population Size ◽  
Hudson Bay ◽  
Polar Bears ◽  
Ice Breakup ◽  
Western Hudson Bay

Future sea ice conditions in Western Hudson Bay and consequences for polar bears in the 21st century

2013 ◽  
Vol 19 (9) ◽  
pp. 2675-2687 ◽  
Author(s):  
Laura Castro de la Guardia ◽  
Andrew E. Derocher ◽  
Paul G. Myers ◽  
Arjen D. Terwisscha van Scheltinga ◽  
Nick J. Lunn
Keyword(s):  
Sea Ice ◽  
21St Century ◽  
Hudson Bay ◽  
Polar Bears ◽  
Ice Conditions ◽  
Western Hudson Bay

A Step-Change in the Date of Sea-Ice Breakup in Western Hudson Bay

ARCTIC ◽  
2010 ◽  
Vol 63 (2) ◽  
Author(s):  
Julian B.T. Scott ◽  
Gareth J. Marshall
Keyword(s):  
Sea Ice ◽  
Step Change ◽  
Hudson Bay ◽  
Ice Breakup ◽  
Western Hudson Bay

scholarly journals Trends in body condition in polar bears (Ursus maritimus) from the Southern Hudson Bay subpopulation in relation to changes in sea ice

2016 ◽  
Vol 2 (1) ◽  
pp. 15-32 ◽  
Author(s):  
M.E. Obbard ◽  
M.R.L. Cattet ◽  
E.J. Howe ◽  
K.R. Middel ◽  
E.J. Newton ◽  
...  
Keyword(s):  
Sea Ice ◽  
Body Condition ◽  
Survival Rates ◽  
Ursus Maritimus ◽  
Social Classes ◽  
The Arctic ◽  
Hudson Bay ◽  
Polar Bears ◽  
Western Hudson Bay ◽  
Break Up

Sea ice is declining over much of the Arctic. In Hudson Bay the ice melts completely each summer, and advances in break-up have resulted in longer ice-free seasons. Consequently, earlier break-up is implicated in declines in body condition, survival, and abundance of polar bears (Ursus maritimus Phipps, 1774) in the Western Hudson Bay (WH) subpopulation. We hypothesised that similar patterns would be evident in the neighbouring Southern Hudson Bay (SH) subpopulation. We examined trends 1980–2012 in break-up and freeze-up dates within the entire SH management unit and within smaller coastal break-up and freeze-up zones. We examined trends in body condition for 900 bears captured during 1984–1986, 2000–2005, and 2007–2009 and hypothesised that body condition would be correlated with duration of sea ice. The ice-free season in SH increased by about 30 days from 1980 to 2012. Body condition declined in all age and sex classes, but the decline was less for cubs than for other social classes. If trends towards a longer ice-free season continue in the future, further declines in body condition and survival rates are likely, and ultimately declines in abundance will occur in the SH subpopulation.

scholarly journals The influence of sea ice dynamics on population energetics of Western Hudson Bay polar bears

Authorea ◽  
2020 ◽  
Author(s):  
Amy Johnson ◽  
Jody Reimer ◽  
Nicholas Lunn ◽  
Ian Stirling ◽  
David McGeachy ◽  
...  
Keyword(s):  
Sea Ice ◽  
Hudson Bay ◽  
Polar Bears ◽  
Ice Dynamics ◽  
Sea Ice Dynamics ◽  
Western Hudson Bay ◽  
Population Energetics

Seasonal and annual movement patterns of polar bears on the sea ice of Hudson Bay

2006 ◽  
Vol 84 (9) ◽  
pp. 1281-1294 ◽  
Author(s):  
E.K. Parks ◽  
A.E. Derocher ◽  
N.J. Lunn
Keyword(s):  
Sea Ice ◽  
Polar Bear ◽  
Movement Patterns ◽  
Temporal Changes ◽  
Reproductive Status ◽  
Energy Output ◽  
Hudson Bay ◽  
Polar Bears ◽  
Western Hudson Bay ◽  
Break Up

Polar bears ( Ursus maritimus Phipps, 1774) move thousands of kilometres over sea ice searching for mates and hunting for seals, which are their primary prey. Recently, decreased sea ice extent and earlier ice break-up have been linked to shifts in seal distribution and abundance and to declines in polar bear condition and numbers in the western Hudson Bay polar bear population. We used geographic positioning system and satellite collars deployed between 1991 and 2004 to quantify movement patterns of adult female polar bears on the sea ice of Hudson Bay in relation to reproductive class and temporal variations in sea ice patterns. We tested whether reproductive status and season affected movement and whether temporal changes in movement were correlated with temporal changes in sea ice patterns in Hudson Bay. Movement patterns were not dependent on reproductive status but did change significantly with season. Annual distances moved and areas covered by bears in Hudson Bay have decreased since 1991, which suggests that measured declines in bear condition and numbers are due to reduced prey intake as opposed to increased energy output. These declines in bear movement are correlated with progressively earlier ice break-up in western Hudson Bay.

Distribution of polar bears (Ursus maritimus) during the ice-free period in western Hudson Bay

1990 ◽  
Vol 68 (7) ◽  
pp. 1395-1403 ◽  
Author(s):  
Andrew E. Derocher ◽  
Ian Stirling
Keyword(s):  
Energy Conservation ◽  
Sea Ice ◽  
Ursus Maritimus ◽  
North Coast ◽  
Hudson Bay ◽  
Polar Bears ◽  
Adult Males ◽  
The North ◽  
Western Hudson Bay ◽  
Age And Sex

The distribution and movements of polar bears (Ursus maritimus) during the ice-free period in western Hudson Bay were studied using mark and recapture and radiotelemetry locating of animals of known age and sex collected between 1966 and 1987. Polar bears segregated themselves by age, sex, and reproductive status. Adult males occupied coastal areas. Family groups and pregnant females occupied areas farther inland. Subadult females and males occupied similar habitats which overlapped with those of adult males. Avoidance of conspecifics, energy conservation, philopatry, denning habitat, and habitat selection appeared to influence observed patterns. A southward shift in the population was evident early in the ice-free period and was followed by a return movement northward during October and November. This may be due to ice-formation patterns which permit earlier access to the sea ice along the north coast and hunting habitat to the northeast. All bears moved less than bears on the sea ice, and movements were consistent with a strategy of energy conservation. Most bears appear to have travelled directly from the sea ice to the study area and remained until the sea ice reformed. Little exchange with adjacent populations and a high degree of philopatry were evident for all age and sex groups; this may be a function of the distribution of denning habitat, the winter distribution of sea ice habitat and seals, and the noncompetitive conditions that prevail during the ice-free period which make dispersal of limited benefit.

Heritability of body size in the polar bears of Western Hudson Bay

2018 ◽  
Vol 18 (4) ◽  
pp. 854-866 ◽  
Author(s):  
René M. Malenfant ◽  
Corey S. Davis ◽  
Evan S. Richardson ◽  
Nicholas J. Lunn ◽  
David W. Coltman
Keyword(s):  
Body Size ◽  
Hudson Bay ◽  
Polar Bears ◽  
Western Hudson Bay
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