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Experiment under way to help Yukons Chisana caribou herd

Posted: Friday, April 18, 2003

WHITEHORSE, Yukon (AP) The very existence of the Chisana woodland caribou herd may depend on the success of a unique experiment under way in southwest Yukon to save more newborn calves, says territorial caribou biologist Rick Farnell.

Farnell and a team of 12 others captured 20 pregnant cows from the herd in late March. They placed them in a 25-acre enclosure to protect the calves from predation after they're born late next month.

It's expected the cows and calves will be released from the compound in late June, once the calves are well past the first 10 days after birth. That's a period Farnell describes as the most bountiful for wolves and bears preying on the infant caribou. After 10 days, the calves really do have their legs, and are quite capable of avoiding predators, Farnell said in a news briefing Monday afternoon.

He expects with close to a month in the compound, on a diet of commercial reindeer feed mixed with natural lichens collected by local elementary students last fall, the calves and cows will leave the compound in good shape.

The hope is that by protecting the calves from predation, calf survival will increase dramatically, resulting in the program being expanded three-fold over the next three years.

We are afraid there could be a massive die-off of this population,'' Farnell said. They could functionally (disappear) within a few years if something is not done.''

The Chisana herd ranges in the Yukon's Klutan Plateau during the winter months and in Alaska's Wrangell-St. Elias National Park and Preserve in the summer. It's the region's only woodland caribou herd.

Numbering approximately 1,800 in the late 1980s, the herd, like all caribou populations, was hit hard by the inclement winters and summer droughts of the early 1990s. But while other populations rebounded, the Chisana continued a decline to an estimated 300 animals today.

Also of concern is the high number of older caribou and the low number of young, Farnell says. The calf survival rate is 6 percent, while the rule-of-thumb among wildlife managers is a calf survival rate of at least 25 to 30 percent to ensure a stable or growing population.

These guys have been at 6 percent for 14 years, without a break,'' Farnell said.

The goal of the captive rearing experiment the first of its kind is not to return the size to 1,800, but to return a stable mix of young and old caribou to the herd.

Otherwise, we are fairly certain the herd will extirpate,'' he says. If we can maintain 300 for now with a balance in age and sex composition, I think that herd will be viable and able to increase.''

The problem of the shrinking Chisana population was first brought to the attention of wildlife managers by big game outfitter Dave Dickson. He implemented his own hunting ban on the Chisana caribou in the early 1990s. Dickson's voluntary ban was followed in 1994 with a hunting closure implemented by the Yukon government and an emergency ban imposed by the state of Alaska.

Today, the herd is designated special protected wildlife, which affords the Chisana caribou the highest order of protection under territorial legislation. Farnell says wildlife officials on both sides of the border began discussing recovery options in earnest last spring, and finalized plans in December.

A Wrangell-St. Elias National Park policy prohibiting any human interference with natural wildlife populations except endangered species says that whatever is to be done has to be done while the caribou were on the Yukon side of the border, Farnell said. He says a predator control program like a wolf kill was ruled out because of the controversial nature of sacrificing one wildlife population to benefit the other.

Similarly, it was felt that starting a captive breeding program by capturing cows and bulls and relocating them for an extended period of time to a game farm would leave the caribou less sensitive to the realities of life in the wild upon their eventual release.

To prepare for a recovery effort this spring, elementary students in the Yukon were recruited by Department of Environment staff last October to collect lichen to ensure there was a natural food source included in the diet of the captured caribou. It's important, says Farnell, that the caribou have a natural lichen source, so as not to disrupt their digestive system.

The 25-acre compound is enclosed with a dark but transparent geocloth used in highway construction, suspended on cables. Wildlife staff will be erecting an electric fence around the perimeter to guard against any intrusion by predators. However, Farnell points out that two wolves who visited the compound the other day were deflected'' by the geocloth curtain.

The 20 cows were captured over a three-day period by the team of 13 people using net-guns, three helicopters and a spotter plane. The animals were blindfolded and tied in deer bags before they were placed in the helicopter for transport. A blood test was taken from each cow, an ultrasound was performed and each was fitted with a radio collar.

Troughs with a mixture of the lichen and commercial reindeer food have been placed around the compound.

The success of the captive rearing program will be measured this fall, when the recovery team conducts an aerial survey of the 20 collared cows to see how many are still with calves. Farnell says he'd like to see at least 50-percent survival.

If the program is seen as a success, Alaska has already committed $200,000 to continuing the work next year, he said.

Devi Sharp, head of natural and cultural resources at Wrangell-St. Elias, said the park has worked with the territory for years to monitor the caribou herd, helping provide money for flights and radio collars.

It is an important resource for us,'' she said.



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