Staff writer
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| Courtesy Photo A caribou bull from the Selkirk herd wanders onto a roadway in British Columbia. The relatively docile animals often wander onto roads to lick salt, imperiling the diminutive population. |
Idaho Fish and Game biologists try to unravel mystery behind shrinking Mountain Caribou population
The biologist looked through the small airplane window, carefully examining the jagged peaks and snow-covered cliffs of the Selkirk Mountains below.
The pilot sitting next to him pointed across the cockpit and out the window. His static voice sounded through the noise-canceling headphones.
"There's tracks down there."
The biologist held his face to the window, studying the track line carved into the snowy ground.
"Could be caribou," he said. "Let's take another pass."
Even from several hundred feet, the animal's tracks were visible in a long, shadowed line -- broken since the last snow fall the day before. It weaved around a rocky ridge and disappeared into a patch of small, shrub-like trees stunted by wind and cold.
The freezing alpine world below is home to the mountain caribou -- the most endangered large mammal alive in North America.
The airplane, contracted by Panhandle National Forest caribou biologist Tim Layser, banked and made a second pass over the tracks. Then another, and another.
"I don't know, it looks like goat to me," Layser said, making a note on his laptop.
The task seems colossal -- spotting through an airplane window tracks made by any of the 46 remaining caribou of the Selkirk herd in an effort to record their movements across their range. The population is so small an avalanche or unwitting truck driver could nearly wipe them out, and the herd ranges across about 2,000 square miles in two countries.
There are few other large mammals adapted to live this high in the Selkirks, but some moose and other animals wander across the mountain tops, making the job of deciphering tracks from hundreds of feet above an extremely difficult one.
According to Layser, no one knows just how many mountain caribou historically lived in the U.S. But researchers know through the 19th century, herds spanned mountain ranges across the northern tier of the United States, as well as much of Canada. In Idaho, caribou lived as far south as the Salmon River.
In 1950 the Selkirk herd numbered an estimated 100 animals. By the 1980s that number had dropped to 25.
Now, only a few herds live north of the Canadian border, and only one south of it in North Idaho and a sliver of Eastern Washington. Rough estimates indicate there are about 1,200 to 1,400 mountain caribou alive on the planet.
"The perception for most people is: there's a lot of them up in Canada, why should we care about these ones?" Layser said. "Understand, these are mountain caribou; they're different."
Mountain caribou are a type of woodland caribou -- a subspecies that includes two other "ecotypes," said Wayne Wakkinen, IDFG biologist. While there are small genetic differences between woodland caribou and the barren ground caribou that cross northern tundras in staggering numbers, there are only behavioral differences between the ecotypes. The primary difference being the mountain caribou's choice of habitat.
During winter months when deer, moose, elk and other herbivores are driven down slope, the caribou follow to lower elevations. But only for a short time. When mountain snows harden, they return to using the firm snow as a platform to reach strands of lichen that drape across high tree branches that were unreachable before.
In that habitat they are removed from competition over food, and they are guarded against predators.
But that survival strategy has its drawbacks, Wakkinen said.
"Their whole evolutionary behavior has been to live where nothing bothers them, that's why they're up on the top of a mountain," he said. "They're actually pretty docile. If they see people they're not just going to fade into the trees and get away from you. It's actually one of their downfalls."
Wakkinen said declines in Caribou populations likely resulted from destruction of old growth forest through logging, development and wildfire.
WIth habitat changes, as well as an increase in sport hunting through the 19th century, came the restructuring of a variety of species in the Selkirks. Whitetail deer populations grew more numerous, driving up mountain lion populations -- caribou's primary predator.
Game managers say because virtually no data were recorded, the events that led to the caribou's collapse are not fully understood.
"I'm not sure anybody knows the whole answer," Wakkinen said.
More than 20 years ago a series of transplanting efforts were undertaken by IDFG and the Washington Department of Fish and Wildlife. Over the course of 11 years, ending in 1998, more than 100 caribou were taken from herds in British Columbia and released with radio collars in the 950,000-acre recovery area.
During a 2008 census, only about five of the original radio collared caribou were located. The rest have "either died, or the batteries are dead," Wakkinen said.
Wakkinen, who unlike Layser uses radio telemetry rather than binoculars to track caribou, said there has been a small but noticeable increase in the population over the past five years. It has risen an average of two to four each year from about 33 in 2003.
"It's a slow increase, and a total population of 46 is tenuous regardless, but at least we're going in the right direction," Wakkinen said. "It's actually somewhat encouraging."
The transplanted population has also received some protection from the courts.
In 2007, a Federal Court issued a ruling that banned snowmobiling within portions of the recovery area. The ruling resulted from concerns that motorized vehicles cutting through caribou habitat were putting added strain on the herds. Recreationalists still ride through closed areas, however.
The Idaho Panhandle National Forest reported it cited three snowmobilers by April in 2008 for riding in restricted areas where three caribou had been seen a month earlier. The violation is punishable by a $5,000 fine, six months in jail or both; however, each rider was given a $125 fine.
Wakkinen said the few members of the Selkirk herd make a population so small that, in the long run, it would not be able to support itself. But animals sometimes move across corridors that link their ranges, occasionally contributing new members, and rescuing the herd from local extinction.
Wakkinen said if resource management decisions continue to be made with caribou in mind, the Selkirk population could grow to around 100. But, because that entails growing more of the caribou's lichen-sustaining old growth forest, any benefits may take as long as 50 years to document.
Although the small population has little affect on the regional ecosystem, Wakkinen said he thinks it is important to work to boost their numbers.
"I think it certainly is an ethical decision," he said. "Those animals existed here before we came, so maybe we can make some management accommodations and keep them on the landscape."
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