by Margaret Evans
Researchers have found that killing a wolf can significantly increase the potential for more livestock losses
LINDELL BEACH, B.C. — The potential for more livestock losses increases significantly when a wolf is killed, two U.S. researchers argue in a recent report.
The same may hold true when a cull targets wolves to protect endangered wildlife, wildlife biologist Rob Wielgus and data analyst Kaylie Peebles of Washington State University wrote in the journal PLOS ONE.
The British Columbia government announced plans this winter to cull wolves in two regions of the province to save endangered mountain caribou.
Officials in the South Peace region are targeting four of the region’s seven herds (Quintette, Moberly, Scott, and Kennedy-Siding) where populations are declining and where at least 37 percent of adult mortalities have been attributed to wolf predation. The planned shoot is to kill 120 to 160 wolves so that the population of all seven herds can increase to 1,200 animals over two decades.
In the South Selkirk region, the caribou population is critically endangered, declining from 46 in 2009 to 27 in 2012 and 18 as of March 2014. Evidence has pointed to wolves being a leading cause of death.
The small trans-boundary herd ranges between British Columbia, Washington and Idaho, and government agencies have radio-collared six animals to track movements and identify mortality incidents.
The plan in the South Selkirk is to remove 24 wolves.
The success of the cull depends on the strategy.
Wielgus said the loss of an alpha wolf can disrupt the social cohesion of the pack. That’s because their social structure is such that only the alpha male and female breed. Subordinates assist in the raising of those pups.
While an intact breeding pair will keep young offspring from mating, a profound disruption to the pack through the loss of an alpha wolf can set sexually mature wolves free to breed.
That social change will lead to more breeding pairs, which must find food for their pups. As opportunistic predators, wolves will capitalize on wild game or livestock.
The study, which was the largest of its kind, analyzed 25 years of lethal control data from U.S. Fish and Wildlife Services reports in Montana, Wyoming and Idaho.
The researchers found that the odds of predations the following year are four percent for sheep and five to six percent for cattle if one wolf is killed. Livestock losses double if 20 wolves are killed.
The same scenario holds true for predation on livestock by cougars.
Another study by Wielgus and Washington State University colleagues published in PLOS ONE last year found that younger, less disciplined big cats will prey on more livestock, especially if their mothers had taught them to select for livestock prey.
Wolf populations are healthy in B.C.: 8,500 animals and growing.
While the mountain caribou range in the South Peace region is southwest of the closest ranching community, many ranchers in the province have had to deal with wolf predation losses.
“The ministry of forests, lands, and natural resource operations undertook a very comprehensive study of the grey wolf and came up with a draft management plan,” said Mike McConnell, rancher and director with the B.C. South Peace River Stockmen’s Association.
“We have producers in the Chilcotin who are unable to use their crown range because their predation losses are so high. We have a number of people now in the north Okanagan whose cows are not used to dealing with wolves at all (because wolves have moved back into the area after being gone for 50 years). A number of producers there aren’t using their crown range because predation losses are high.”
The province’s grey wolf management plan, which was released in April 2014, summarized a variety of management approaches, noting that direct removal of individuals or packs can have a moderate effect overall but a fragmented pack will ultimately result in more packs and predation.
McConnell said calves are worth around $1,800 and asked: “How many is it reasonable to expect a rancher to lose before something is done about predators?”
Direct losses by wolf predation are only part of the problem.
“There are cows that will be maimed,” said McConnell.
“There’s harassment that can lead to lighter calf weights. Cows can get scattered, sending them to areas where there are no bulls, therefore no breeding. They may be moved from one grazing area to another, which can result in one area being overgrazed while another is under-utilized.”
Wolves aren’t the only threat to endangered mountain caribou herds. Habitat disruption from gas exploration, seismic lines, roads, leases, pipelines and recreational activities also cause problems.
As well, climate change may disrupt habitat in the future with shifts in seasonal temperatures, precipitation, snow pack, wildfires and outbreaks of insects and diseases.
The wolf cull targets are specific to the South Peace and South Selkirk regions, and there is no plan for a general aerial wolf cull.
McConnell said ranchers do what is practical to protect and watch their herds, but it’s not always easy.
“We have labourer issues,” he said.
“It’s hard to pay rates. Certainly people do ride and check on cows, but the thing is that you don’t see these wolves. They are secretive and they are successful. You might hear them howling. That’s not an issue. It’s the actual action of harassment that causes problems.”