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

  title={Effects of Earlier Sea Ice Breakup on Survival and Population Size of Polar Bears in Western Hudson Bay},
  author={Eric V. Regehr and Nicholas J. Lunn and Steven C. Amstrup and Ian Stirling},
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 bear population dynamics in the southern Beaufort Sea during a period of sea ice decline.
Investigation of the population dynamics of polar bears in the southern Beaufort Sea from 2001 to 2010 suggests that factors other than sea ice can influence survival, and refined understanding of the ecological mechanisms underlying polar bear population dynamics is necessary.
Demography of an apex predator at the edge of its range: impacts of changing sea ice on polar bears in Hudson Bay.
It is found that survival of female polar bears was related to the annual timing of sea ice break-up and formation, and this support previous evidence for a demographic linkage between sea ice conditions and polar bear population dynamics.
Survival and breeding of polar bears in the southern Beaufort Sea in relation to sea ice.
The effects of sea ice loss on polar bears in the southern Beaufort Sea may apply to polar bear populations in other portions of the polar basin that have similar sea ice dynamics and have experienced similar, or more severe, sea ice declines.
Polar bear population status in the northern Beaufort Sea, Canada, 1971-2006.
The NB polar bear population appears to have been stable or possibly increasing slightly during the period of this study, which suggests that ice conditions have remained suitable and similar for feeding in summer and fall during most years and that the traditional and legal Inuvialuit harvest has not exceeded sustainable levels.
Home range distribution of polar bears in western Hudson Bay
Home range size was predicted by season, ice break-up date, and individual in a multiple regression, though R2 was low, and solitary females had smaller home ranges and were closer to land compared to females with offspring.
Effects of climate warming on polar bears: a review of the evidence.
Evidence that documents how loss of sea ice negatively affects polar bears' long-term survival is summarized, with quantifiable negative effects being documented first in the more southerly subpopulations, such as those in Hudson Bay or the southern Beaufort Sea.
Shifts in female polar bear (Ursus maritimus) habitat use in East Greenland
Results indicate that multi-decadal loss of sea ice has resulted in shifts in polar bear habitat use in EG, and there was a statistically significant and stronger winter preference in the 2000s for adult females to select for higher sea ice concentrations.
Re-assessing abundance of Southern Hudson Bay polar bears by aerial survey: effects of climate change at the southern edge of the range
The Southern Hudson Bay polar bear (Ursus maritimus Phipps, 1774) subpopulation is considered stable, but conflicting evidence lends uncertainty to that designation. Capture–recapture studies
Population ecology of polar bears in Davis Strait, Canada and Greenland
Until recently, the sea ice habitat of polar bears was understood to be variable, but environ- mental variability was considered to be cyclic or random, rather than progressive. Harvested populations
Variation in the response of an Arctic top predator experiencing habitat loss: feeding and reproductive ecology of two polar bear populations
Higher biological productivity and prey availability in the CS relative to the SB, and a shorter recent history of reduced sea ice habitat, may explain the maintenance of condition and recruitment of CS bears.


Possible Effects of Climate Warming on Selected Populations of Polar Bears ( Ursus maritimus ) in the Canadian Arctic
Polar bears depend on sea ice for survival. Climate warming in the Arctic has caused significant declines in total cover and thickness of sea ice in the polar basin and progressively earlier breakup
Long-term Trends in the Population Ecology of Polar Bears in Western Hudson Bay in Relation to Climatic Change
From 1981 through 1998, the condition of adult male and female polar bears has declined significantly in western Hudson Bay, as have natality and the proportion of yearling cubs caught during the
The use of sea ice habitat by female polar bears in the Beaufort Sea
Polar bears (Ursus maritimus) depend on ice-covered seas to satisfy life history requirements. Modern threats to polar bears include oil spills in the marine environment and changes in ice
Polar Bears in a Warming Climate1
It is unlikely that polar bears will survive as a species if the sea ice disappears completely as has been predicted by some, but the effects of climate change are likely to show large geographic, temporal and even individual differences and be highly variable, making it difficult to develop adequate monitoring and research programs.
Polar Bear Distribution and Abundance on the Southwestern Hudson Bay Coast During Open Water Season, in Relation to Population Trends and Annual Ice Patterns
In Hudson Bay, all the ice melts in summer, and the last areas to be ice-free (around mid-to-late July) are usually off the coasts of Manitoba and Ontario. Thus, all polar bears are forced ashore to
Re-estimating the Size of the Polar Bear Population in Western Hudson Bay
A mark-recapture study of polar bears ( Ursus maritimus ) ashore during the ice-free period of Hudson Bay was undertaken in 1994 and 1995 to re-estimate the size of the western Hudson Bay population.
Climate warming is predicted to reduce the extent of ice cover in the Arctic and, within the Hudson Bay region, the annual ice may be significantly decreased or entirely lost in the foreseeable
Distribution and Abundance of Canadian Polar Bear Populations: A Management Perspective
Seasonal fidelity to relatively local areas and natural obstacles to movements allow the range of polar bears ( Ursus maritimus ) in Canada to be divided into 12 relatively distinct populations.
Polar Bears and Seals in the Eastern Beaufort Sea and Amundsen Gulf: A Synthesis of Population Trends and Ecological Relationships over Three Decades
In the eastern Beaufort Sea and Amundsen Gulf, research on polar bear populations and their ecological interrelationships with seals and sea ice conditions began in the fall of 1970. Analysis of
Top Predators in Marine Ecosystems: Spatial and temporal variation in the diets of polar bears across the Canadian Arctic: indicators of changes in prey populations and environment
This work uses quantitative fatty acid signature analysis of polar bear adipose tissue to estimate polar bear diets in the 1980s/90s across three major regions of the Canadian Arctic: Davis Strait, western Hudson Bay and the Beaufort Sea, using a database of the major prey species in each region.