WHITEHORSE, Yukon An effort to bulk up numbers in the Chisana caribou herd is paying off for the second consecutive year, Canadian biologists said.
Surveys by Alaska wildlife officials involved with the international effort indicate 22 of the 29 calves born in captivity are still alive, said biologist Rick Farnell.
In the project's 2003 inaugural year, and again this year, statistics show calves born captive in a makeshift wilderness pen have a much greater chance of survival than calves born in the wild, Farnell said.
Of 28 calves born to radio-collared cows, eight were still alive following the dangerous 10-day post-calving period when young calves are easy prey for bears and wolves. Through the summer, another six of the wild-born calves were lost to nature.
Farnell said it's generally believed a survival rate of 26 calves per 100 cows is required to stabilize a herd. Any higher, and the herd is likely growing, but any lower and it's likely declining, he said.
The transboundary Chisana herd spends its winters in the Yukon and summers in Alaska.
In the late 1980s and early 1990, when warning bells started going off about the state of the herd, calf survival was as low as six calves for every 100 cows.
''We are really quite pleased to see all the energy and effort put into the project with such results being really, really positive,'' Farnell said.
In a Yukon-based proposal, wildlife officials on both sides of the border decided to try an experiment where the cows were captured by netguns from helicopters. They were flown to a wilderness pen, then released if they weren't pregnant.
The pregnant cows were kept inside the pen built on their natural range until at least a week after the last calf was born. This year, calving went from mid-May to early June.
The rationale behind the program is to keep the calves out of harm's way for 10 or so days after calving, when predation is heaviest on newborns still developing their strength and the ability to escape.
Farnell said members of the project team from both sides of the border will meet in Alaska Nov. 9 to discuss upcoming plans for a third capture next spring. There is talk among those involved of increasing the number of cows captured to at least 40, and quite possibly more.
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