Scientists study voles as part of food chain at Denali National Park

Posted: Thursday, October 26, 2000

FAIRBANKS (AP) -- To understand why scientists are studying voles in Denali National Park and Preserve, all you need do is look at a chart of the park's ecosystem titled, ''Who Eats What?''

The chart features every kind of animal that inhabits the 6 million-acre park 150 miles south of Fairbanks. There are more than 30 of them in all, from grizzly bears to wolves, moose to muskrats, marten to squirrels, ptarmigan to porcupines, grayling to eagles to voles.

The diagram also includes the various plant life in the park, trees, aquatic plants, berries, shrubs, lichen, moss and leaf litter.

The chart is crisscrossed with dozens of arrows showing which animals eat what. There are 10 arrows pointing to the vole, more than any other species on the diagram. Voles may be microtines but they play a big part in the food-chain.

''These are very important components that keep these other guys alive,'' said Susan Bourdreau, long-term ecological monitoring program manager for Denali National Park and Preserve.

Understanding those kinds of relationships, whether between grizzly bears and voles, caribou and lichen or deep snow and Dall sheep, is the first step in maintaining Denali as a pristine environment.

That was the theme behind the Denali National Park and Preserve Long-Term Ecological Monitoring Conference at the Westmark Hotel in Fairbanks on Tuesday.

Scientists and biologists conducting research in the park gathered to discuss findings from their work in an attempt to understand the different relationships that comprise an ecosystem as diverse as Denali's.

''We're just beginning to understand how complex these systems are,'' park Superintendent Stephen Martin said after the first day of the two-day conference.

Denali was one of a handful of parks in the United States selected to serve as a prototype for a long-term ecological monitoring program in 1991. The program is aimed at detecting and documenting resource changes over time in an attempt to help conserve and manage parks.

Denali is the first park in Alaska to initiate a long-term ecological monitoring program. Experts meet every two years to discuss their findings.

''We have a diverse ecosystem and our mission is to keep that intact, but to do that you've got to understand it,'' Boudreau said.

For example, the Denali Caribou Herd has declined from an estimated 25,000 in the early 1940s to under 2,000 today and likely will decline even further as a result of a series of deep-snow years in the early 1990s, which resulted in practically no calf survival.

As a result, the herd is growing old and less productive. Half the herd is older than eight years and 25 percent of the cows are over 11 years, said Dr. Layne Adams with the U.S. Geological Survey Alaska Biological Science Center.

''I think we can expect to see a decline in the population as a whole based on something that happened a decade ago,'' he said. ''That's the kind of information you wouldn't be able to pick up on unless you're able to monitor the herd for 15 years. We'd still be scratching our heads trying to figure it out.''

Wildlife biologist Pat Owen is trying to figure out why almost 75 percent of grizzly bear cubs are killed in their first year. She has tracked grizzly bears on the north side of the Alaska Range since 1991 using radio collars to locate and capture more than 80 bears for study.

''We know we have a real high cub mortality,'' Owen said. ''Now we need to start integrating the bear data we have and the weather data we have to find out why.

''We are sitting on a wealth of data and it's just now that we're going to do something with it,'' she said.

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