for National Geographic News
Inuit hunters in the Canadian Arctic have reported more polar bear sightings near their villages in recent years. But a new study says this doesn't mean there are more bears in the regionthere are fewer bears, and they're hungrier.
More sightings means more bears, the reasoning goes, so regional governments have upped their hunting quotas.
In the northern Canadian province of Nunavut (see Nunavut map), wildlife officials upped hunting quotas, increasing the total allowable bear harvest by almost 29 percent 18 months ago.
But the new study suggests that at least two polar bear populations in the Canadian Arctic are in fact shrinking, and three other groups may face similar pressures.
"We have pretty good evidence that the populations are actually being overharvested, and they're both declining," said Canadian Wildlife Service polar bear biologist Ian Stirling, who co-wrote the study.
A more likely explanation for the increased bear sightings, Stirling says, is that Arctic sea ice is breaking up earlier each summer.
"The bears have less time to feed at the best time of year in order to lay on the fat they fast on through the open-water season in the summer and fall," Stirling said.
Because the breakup has arrived progressively earlier in most areas, bears are also spending more time on land instead of on ice, where they hunt. Hungry bears then push into human settlements at the end of their longer summer fasts in search of food.
Stirling and study co-author Claire L. Parkinson, a climatologist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, present their findings in the September issue of the journal Arctic.
In their study the scientists combine long-term polar bear population data with a nearly daily record of Arctic sea ice conditions gathered by two NASA satellites between 1978 and 2004.
The bear populations covered in the study were in Baffin Bay, western Hudson Bay, eastern Hudson Bay, Foxe Basin, and Davis Strait (see Canada map).
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