Global Warming Tied to Arctic Caribou Decline

By Ed Struzik
Canwest News Service

Sunday 11 May 2008

Warm, wet winters and hot, dry summers reduce numbers.

Edmonton - In the summer of 1996, biologist Frank Miller was flying along the coast of Bathurst Island searching for Peary caribou, found only in the High Arctic of Canada, when he spied a dark spot on the sea ice.

Flying in for a look, he could see these animals were not the caribou he was looking for. They were muskoxen. The circle of animals didn't bolt. Miller got the pilot to land a few hundred metres away. Even as he approached on foot, the herd didn't flinch. As he moved closer, it dawned on him - they were all dead. The animals were frozen stiff and leaning against each other like statues.

"It was one of the most strange and gruesome things I'd ever seen as a biologist," the Edmonton researcher recalls.

"They were probably on their last legs and starving when they headed out across the sea ice searching for better food conditions on another island."

In the spring he discovered carcasses of caribou and muskoxen strewn across the tundra. When the die-off ended two years later, almost 98 per cent of the caribou on the Queen Elizabeth Islands three years earlier were gone.

The High Arctic population is in such deep trouble that the Committee on the Status of Endangered Species in Canada has recommended the Peary caribou remain on the endangered list.

Climate change, over-hunting and industrial development are all likely playing a role.

Anne Gunn, a biologist with 30 years' of caribou research behind her, is one of several scientists who have studied how runs of cold, dry winters with less snow tend to favour caribou because there is little to slow them down and sap their energy while they're on the move or being chased by wolves. Less snow also makes it easier for them to dig down to the vegetation they need in order to survive.

Runs of warm, wet winters can be brutal. The snow may be deep during the long migration to the calving grounds and thawing can cause some of it to ice-over. If those winters are followed by hot, dry summers that favour parasites, biting flies and fires that destroy lichen, the results can be catastrophic.

Many of the large mammals of the Arctic, Gunn notes - the wooly mammoth, Yukon horses, Alaskan camels, short-faced bears and American lions - died off during the 8,500 years that the climate began warming after the last great ice age. The animals left are adapting to another period of warming that began 150 years ago when the mini-ice age ended around 1850. That natural warming is now being intensified by the emission of greenhouse gases. "We cannot afford to dither," Gunn says. "Given the rate of changes we are unleashing across the Arctic regions. In addition to the roads, pipelines, mines and other things we have built, or plan to build on caribou habitat, global warming is already threatening the future of these animals."

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