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Size of Western Arctic caribou herd revised downward

March 24th 8:30 pm | Margaret Bauman Print this article   Email this article   Create a Shortlink for this article

A continuing modest decline of Alaska's largest caribou herd is being carefully watched by state wildlife biologists, who see the animals as important not only for hunters, but the environment as a whole.

"It has our attention," said Jim Dau, a biologist at Kotzebue for the Alaska Department of Fish and Game. "We are not ignoring it. This is important not just for subsistence users, but for the whole ecology of the region."

Dau said in an interview today that a couple of detailed health analyses conducted by ADF&G veterinarian Kimberly Beckman in Fairbanks concluded that the Western Arctic caribou herd is among the healthiest of the caribou herds in Alaska. There is no indication that disease is causing the decline, he said.

A recent further analysis of aerial photos of a July 2009 Western Arctic caribou herd census had prompted state biologists to revise the population estimate down to 348,000 caribou in a continued modest decline.

The previous estimate of 401,000 caribou indicated an increase in the herd over the 377,000 animals identified in a 2007 census.

"The herd is still vey large, individual caribou appear to be healthy, the rate of decline is still modest, and harvests are not thought to be affecting its status," Dau said in a statement released a day earlier. "The revised estimate will not result in any immediate changes to management activities or hunting opportunities. The revised total is within a range of acceptable count variation and the herd is still considered stable, though slowly declining."

Biologists intensified monitoring of this herd after the 2007 census suggested the onset of a decline. The revised 2009 count of 348,000 caribou indicates that the Western Arctic herd has declined 4-6 percent annually since its peak of 490,000 caribou in 2003,.

Dau said that after exceeding a population size of 400,000 caribou for over 20 years, a period of slow decline is probably preferable to continued growth and the possibility of an eventual, abrupt decline.

Caribou herds fluctuate naturally due to a variety of factors.

One of those factors, Dau said in an interview, was that in December 2005, there was a mid-winter icing event, with rain on snow . "It created a terrible crust of ice down in the snow," he said. "The food was there, but they couldn't get to it. That spring the ones that didn't die came wobbling out of winter looking terribly thin in the spring of 2006."

That winter alone could have killed 30 percent of the adult cows, he said.

Back in 1970, the Western Arctic herd numbered 242,000 caribou and then declined to 75,000 by 1976. The herd steadily increased until peaking at 490,000 animals around 2003, then fell to 377,000 caribou in 2007, indicating the onset of a decline after more than 25 years of growth.

In years of rising caribou population, the number of predators, including wolves, wolverines, brown bears, eagles and non-subsistence hunters, also increase, Dau said.

State biologists said the accuracy of previous census counts was checked and no errors were detected.

"For now the herd is healthy and the rate of decline is still pretty modest," he said.

 

Margaret Bauman can be reached at mbauman@alaskanewspapers.com, or by phone at 907-348-2438

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