Biologists Will Study Winter Response of Caribou to Alaska Wildfires

Dan Joling / AP / Anchorage Daily News / August 7, 2004

ANCHORAGE - For 10 years, most of the Nelchina caribou herd has wandered north on a winter trip to fatten up on lichens along the Taylor Highway. That could change this year, after the state's second-worst wildfire season.

Lichens on thousands of acres along the highway were turned crispy by summer wildfires. That may be bad for caribou, but it's a splendid opportunity for the scientists who study them.

State biologists this fall plan to fit 40 Nelchina caribou with radio collars to track how they respond to range made unpalatable by wildfire.

"This is a natural process," said Department of Fish and Game biologist Bruce Dale. "They're well adapted to this sort of thing."

The Nelchina herd numbers about 38,000 animals, up from about 30,000 a few years ago. Their summer range is in Unit 13, which starts roughly 100 miles northeast of Anchorage. It's bound by four mountain ranges: the Alaska Range on the north, the Wrangells on the west, the Chugach Mountains in the south and the Talkeetna Mountains to the east.

"It's an area about the size of Indiana," said Department of Fish and Game spokesman Bruce Bartley.

During the last decade, the animals have crossed the Alaska Range and walked north and east of Tok to winter along the Taylor Highway from Tetlin Junction to Mount Fairplay.

"We think primarily because, like caribou are prone to do, they eat themselves out of house and home," Bartley said.

Lichens, small plants composed of a fungus and an algae growing in a symbiotic relationship, are a key winter food for caribou. They paw through snow to find them.

In the late 1990s, a nutrition study indicated caribou would return from the Taylor Highway area in April weighing more than when they left Unit 13 in October. That's the opposite of what's expected of most Alaska land animals in winter

The weight gain was not huge, Bartley said. However, "when you're on winter range, any weight gain is significant."

When caribou stayed in Unit 13 all winter, they lost weight.

Once lichens are gone, it takes 50-60 years for them to regenerate to the point where they are of value to caribou. A nutritional range study completed a year ago showed the Nelchina caribou strongly avoided areas that had been burned in the last 50 years. Instead they chose areas that had burned 75 to 150 years ago.

If they follow that pattern, they will avoid much of the Taylor Highway area this winter.

A series of fires turned black spruce forests carpeted with lichen into black sticks standing on bare black ground, Bartley said. About 842,000 acres were burned, part of 4.5 million acres that burned throughout the state.

Even before this summer's fires, other huge chunks of habitat north of the Alaska Range and south of the Yukon River had burned within the last 50 years.

The effect of widespread fire on caribou populations has long been debated, Bartley said. Most of the scientific literature cites huge fires in the early 1900s as the primary factor in the disappearance of caribou on the Kenai Peninsula. Market hunting to feed hungry gold miners also is believed to have played a major role there.

Dale, who spends much of his time studying Nelchina caribou, said it will be interesting to see how many caribou leave Unit 13, where they go and what they do when they get to burned areas. He has put together a study plan to document the effects. By collaring 40 calves and following them for three years, he can compare feeding activity with the recently completed five-year nutritional study.

Bartley said the caribou could keep moving north to Fortymile country, or east toward Canada. They could walk east and south to the north side of the Wrangell Mountains, or surprise everyone and stay in Unit 13.

"Caribou are good about moving until they find conditions that they get along in," Bartley said. "They're much more mobile than moose."

Moose may be the wildlife winners as the result of fires. The animals browse on willow and other growth that springs up after wildfires.

The Fortymile caribou herd may also prosper because fires farther north burned through its summer range. Unlike lichens, summer forage preferred by caribou flourishes after fire. Caribou graze on forbs, sedges and most anything green that grows around lakes and moist areas, Bartley said.


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