Warmer weather threatens Hudson Bay polar bears

A new study shows disturbing trends along the western Hudson Bay coast.


MONTREAL — Polar bears in the western Hudson Bay area are suffering as a result of warmer climatic conditions.

“Since the early 1980s, there has been a significant decline in the condition of adult polar bears, both female and males,” concludes an article in the Sept. 99 edition of the scientific journal Arctic.

From 1981 to 1998, three researchers with the Canadian Wildlife Service, Ian Stirling, Nicholas Lunn and John Iaco a, followed 41 bears from the Ontario coast up to Chesterfield Inlet and back via radio satellite collars.

They found that earlier ice breakup on the bay meant that bears returned to the land lighter and in worse shape.

Polar bears generally use spring sea ice as a platform from which they hunt baby ringed seals and build up their body fat.

No ice, no spring food

When the ice can no longer support their intensive hunt, the polar bears return to land.

“The earlier the breakup, the poorer the condition of the females,” the study said. There were also fewer cubs and yearlings.

The success of the spring hunt seems to determine the succcess of female polar bears in surviving, reproducing and nursing.

“Factors that influence the distribution and annual duration of sea ice have the potential for profound influence on the population ecology of the polar bear,” says the study.

One factor in this change may be the increased fresh water run-off due to hydroelectric development on the Quebec cost.

Global warming to blame?

Rising spring air temperatures over the past 40 years are also thought to cause ice breakup at progressively earlier dates.

An increase in temperature of only one full degree can result in ice breaking up one week earlier along the western Hudson Bay, and two weeks earlier in eastern Hudson Bay.

The researchers also note that temperatures are expected to rise two to five degrees in this region over the next 55 to 100 years.

Apart from its negative effect on polar bears, this warmer weather may also have an impact on people, by increasings the number of “nuisance” bears in communities.

That’s because when polar bears come off the sea ice underfed, they are more likely to come into communities in search of food.

“For example, in 1995 (when breakup was late) there were 62 calls to the Polar Bear Alert program in Churchill, while in 1996 (when breakup was early) there were 151,” the study says.

The researchers suggest that the same factors that affect polar bears may also have a negative impact on other species such as ringed seals.

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