Thursday, April 27, 2006

Wolf packs boom after sterility experiment fails

A plan to reduce the carnivore's population by birth control has backfired

Larry Pynn - Vancouver Sun

It was a strange experiment from the start: Biologists netting wolves from helicopters in an area of B.C. known as the Serengeti of the North, immobilizing them with tranquillizer darts, whisking them away to a laboratory where a veterinarian would perform sterilization surgery, then returning them to the wild as though nothing had happened.

The simple theory: If you reduce the ability of wolf packs to breed, you end up with fewer wolves and more ungulates such as moose, mountain sheep, and caribou -- the sort of big-game animals that two-legged predators also like to kill.

Midway through the five-year experiment, the B.C. Environment Ministry is finding that when you mess with nature, the outcome is rarely that simple. Documents obtained by The Vancouver Sun through freedom of information legislation show that that the wolves being studied have actually increased in number and perhaps increased their level of predation on ungulates as well.

"This is a learning process, part of the research," Andy Ackerman, regional manager with the environment ministry, said Tuesday in an interview from Fort St. John. "You do expect behaviour change. When you make changes within their social structure, their normal behaviour, you're going to see changes happening."

The setting is the Muskwa-Kechika management area, a vast roadless wilderness area encompassing 6.4 million hectares that has the continent's largest and most diverse game population. Declines in certain ungulate populations, however, served as impetus for the sterilization experiment, the sort of kinder-gentler program that, presumably, would not generate the sort of negative publicity associated with a direct wolf-kill program. Since the study started in 2003, ministry officials have sterilized 26 wolves in two packs at a cost of up to $2,500 per wolf. All wolves within Gemini pack were sterilized, whereas only some members of Birches pack were sterilized.

That's where it gets interesting. The ministry documents show that one wolf left Gemini pack and two other adults joined, "resulting in a 15-per-cent increase in size. In contrast, some members of the Birches pack were sterilized but the pack produced pups."

Typically, only the alpha male and alpha female breed in a wolf pack, raising the question whether biologists in fact sterilized the dominant pair in the Birches pack or whether other members of the pack figured that if the dominant wolves were not going to raise pups, they might as well give it a try. Regardless, the Birches pack wound up splitting twice, into three packs, and increasing its size by 25 per cent.

"Again, that is something we didn't predict," Ackerman said. "These are things we're learning."

The documents also note that depriving a wolf pack of pups may alter its foraging behaviour. Pups require the pack to stay closer to the den in summer and feed more heavily on beaver. Without pups, the wolves are free to roam more widely and perhaps take even more ungulates than if humans had not intervened.

"That's one of the side-effects of not having kids," Ackerman quipped. "They have less to support, they are more mobile."

Despite the setbacks, Ackerman remains philosophical, saying that the whole purpose of research is to see what happens. "The idea is to find what works and what doesn't work, and whether it's a feasible way of doing business in that part of the world. This is a very wild population."

Monitoring will continue for another two years before any decision is made on the effectiveness of the sterilization program.

The documents report that sterilization in arctic and subarctic regions has proven to be "reasonably straightforward," however in forested northern B.C. "it is much more difficult to use this technique." The forests have made it almost impossible to spot wolves from the air. Biologists are relying largely on tracks and radio collars to monitor behaviour although even that is proving difficult, because the wolves that left for other packs are not radio-collared.

The documents include a letter from Environment Minister Barry Penner saying "the research project has been very successful."

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