The first evidence of wolves preying on bison was confirmed earlier this winter.

Big game biologist Tom Jung of the Department of Environment said Tuesday conservation officers on patrol in the area at the north end of Aishihik Lake recorded two separate incidents of wolves killing bison last December.

One kill site was located along the river linking the Aishihik and Stevens lakes. The other was about 25 kilometres south of the northern tip of Aishihik Lake.

Jung said the two sites are close enough to each other that it may have been the same wolves, but there's really no way of knowing.

One of the bison was an adult cow and the other an orphaned calf whose mother had been shot by hunters, Jung explained.

He said it's encouraging to finally have confirmed evidence of wolf predation on the bison which were first transplanted here in the mid-1980s to assist with the threatened status of the animals internationally.

Efforts to manage the increasing population have so far relied on the annual hunt, now in its 10th year, though the success rate has been dropping over the years as the bison become more and more wary of human presence and snowmachines.

This winter's annual hunt, for instance, ended Monday with a total reported harvest of 50 bulls and 30 cows, including 13 animals shot last fall under a special hunting window created to deal with a group of bulls crowding the Alaska Highway. Hunters have 10 days to report their kill.

A low snow year, coupled with the cold snap in February, are believed to have hampered this year's success rate.

Jung pointed out, however, that with the longer days and warmer weather recently, there's been more opportunity. He expects the department will receive more reports of confirmed harvests in the next few days.

This winter's harvest target was about 100 animals. The harvest level was set by the bison technical team prior to last July, when a census of the herd indicated the population was about 1,109, but could be as high as 1,300 or as low as 970.

Wildlife officials have identified 500 bison as the ideal population to minimize the impact on habitat and the natural moose and caribou populations.

Jung said predation is not likely to be a factor in limiting the population anytime soon, but it's a start.

"What you see is when wolves learn how to prey on something, they use that knowledge," Jung said.

"Once they learn how to hunt something, they will do it again, and maybe with increasing frequency."

Jung pointed out that when bison were first introduced, wildlife officials anticipated it would take about 20 years before wolves would catch on, based on what they saw with the introduction of bison to the Wood Buffalo National Park.

Today, there are packs of wolves in the park that straddle the Alberta-N.W.T border which depend almost exclusively on bison for food, Jung pointed out.

And in Yellowstone National Park in the lower 48 states, both wolves and grizzly bears prey on the large animals.

It's fact in Yellowstone that a grizzly will take on and kill an adult bison, as formidable as that task may seem, he said.

Jung agreed the law of probability suggests the two confirmed wolf-kills this winter are not the only wolf predation that's occurred.

But with the amount of monitoring wildlife staff are doing in the area, both in the air and on the ground, together with the number of hunters out there, it's not likely too much evidence of predation is going unnoticed, he said.

Jung said it could be another story with predation by grizzly bears if indeed they've started to hunt bison.

Grizzly bears prey heavily upon moose calves in the spring.

If they've started to prey upon bison and bison calves, there is less chance of coming across evidence because there is less monitoring and a lot fewer people in the field at the time of year, Jung said.

The harvest level for next winter's hunt will be set by the technical team later this spring.

Meanwhile, Premier and Environment Minister Dennis Fentie confirmed this morning he has accepted recommendations from the Yukon Fish and Wildlife Management Board to increase harvest opportunties for bison.

Changes to the Wildlife Act include giving the Environment minister a much greater hand through an adaptive bison management plan that would allow the minister, for instance, to change season dates or permit numbers without going through exhaustive steps.

Fentie also accepted the recommendation to remove the restriction limiting bison hunters to applying for a permit only once every five years. Hunters will now be able to apply for a permit every year.

The rationale provided to the wildlife board by Envirnoment staff and the Alsek Renewable Resource Council suggested that removing the one-in-five rule would hike the number of seasoned veteran hunters in the field, and ultimately increase the harvest.