Predators and Prey in Denali National Park

I attended another interesting lecture last night. This one was part of the Fireside Chat Series hosted by the Campbell Creek Science Center titled “Predators and Prey in Denali National Park” as presented by Layne Adams, a wildlife biologist with the USGS-Alaska Science Center.

This one was particularly interesting to me since it so closely resembled the work I had done in Mongolia last year, on my Earthwatch expedition to study the Argali (the world’s largest mountain sheep). As I sat in those very uncomfortable chairs for well over an hour and a half, watching the presentation and listening to Layne speak, I got to relive my experiences all over again; only this time, I didn’t go home with a fractured kneecap and a dislocated jaw!

Layne has spent the past 20 some-odd years in the park, studying mainly the caribou/wolf relationship – but also moose, sheep, bear, wolverine, eagle… pretty much every possible connection. He looked at herd/pack size, birthing rates, calf/pup mortality rates, weather conditions, food sources, and competition rates – to name just a few aspects of his research.

Unlike the work we did in Mongolia, where everything had to be done either on foot or on horseback, Layne and his coworkers used helicopters and airplanes to facilitate the gathering of data. They typically would dart the animal from the air, then track it down on foot to attach the radio collar and gather the biological samples and measurements they needed.

They also looked at carcasses found occasionally; gathering data on mortality rates and causes, as well as diet and growth factors.

Weather conditions can be harsh in the Alaskan wilderness. Sometimes they had to work in snowstorms with 12 foot accumulations, as well as summer heat waves and massive mosquito swarms.

The biggest surprise he encountered in his work was the importance of salmon in the dynamics of the predator/prey relationships.

Typically, when you think about a wolf’s diet, you automatically think moose or caribou, not fish. And when you think about the Denali National Park, you just don’t think about salmon at the same time. And yet they are a huge presence.

Salmon follow the Yukon River up from the west, traveling as far as 700 miles to reach several spawning areas throughout the park. Biologists have done a considerable amount of research on the salmon, so they have a pretty good estimate of how many salmon spawn there: of the 4 runs that occur comprised of three different species, they estimate upwards of 260,000 pounds of salmon each year!

Layne did a biomass calculation, and believes that is the equivalent of 750 moose = as you can see, they are indeed an important factor in the park’s food chain.

The presentation ended with Layne stressing the point that predators and prey are both heavily dependant on each other, on the landscape, and on the seasons. Take away or modify just one of those factors, and you change the dynamics in ways that may be detrimental to the ecological balance.