Where wolves prey on elk mostly dependent on landscape

Wednesday, 26 September 2007

In 1995, 14 wolves from an area west of Edmonton were introduced to Yellowstone National Park as part of a long-term study done by U of A biological sciences professor Mark Boyce. The experiment sought to find out what effects re-introducing wolves Yellowstone would have; twelve years after this reintroduction, Boyce has found that while wolf and elk populations overlap in certain areas, it’s terrain features, and not location, that determine where wolves hunt their prey.

According to Boyce, the study found that wolves focus on “riparian areas”—that is, areas situated on or near the banks of a river—while “the elk would much rather be up in an … upland area where they can see a long ways so they can see the wolves coming.”
However, it seems territorially influenced hunting patterns are not unique to wolves.

“There has been some work showing similar kinds of [patterns] for lions in east Africa,” Boyce said. “Likewise in Yellowstone, there are places where the wolves do really well at killing prey.

“There are certain types of landscapes and certain types of habitats that just make it much easier for predators to kill prey.”

According to Boyce, wolves employ co-operative hunting techniques, and the animals are generally quite efficient predators. However, he added that in Yellowstone, only about 20 per cent of the animals that wolves pursue are killed.

Many of the animals hunted by wolves, such as elk and moose, have proven either to be capable of outrunning their group hunts or of fending them off. Boyce, however, doesn’t believe this is a significant factor for the wolves.

“The main thing limiting wolves at the moment is not prey, but other wolves,” he said, adding that they’re currently more likely to suffer from pack squabbles over food or territory than they are from any limitations on their food source.

The effects wolves are having on the elk populations in Yellowstone are also affecting other forms of life. As the elk population is reduced, the plants that elk have been eating to near extinction are given a chance to recover. As the plants regrow, other animals reliant on them for food or shelter are able once again to survive.

As the distribution of wolves changes throughout the park, so too do the distributions of biodiversity, which rely on trees that have been having trouble growing in the park because the elk are now flourishing.

According to Boyce, as a result of the increased vegetation, “there is going to be potential for habitat for beavers, and songbirds and a spectrum of animals.

“You have a whole spectrum of animals that can come in because of the wolves ultimately. They are shaping the community structure and composition.”

Because of the success of the reintroduction efforts, Boyce has reviewed a delisting proposal for the US government that would take wolves off of the endangered species list; he’s also recommended that the management of wolves be returned to state agencies in those states containing wolf populations. In the future, this may allow for there to be a hunting season on wolves, though it’s not yet clear what the decisions will be.

“The States can make those kinds of decisions now, as soon as [wolves are] delisted.”

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