Experts Warn Of ‘Intrapack Aggression’ Territorial Disputes May Arise After Wolves’ Release From Pens

With eight wolves safely released into pens in Yellowstone National Park, biologists warn that the animals still could turn on each other in territorial disputes.

The wolves, brought from Canada last week, will spend the next six to eight weeks in their pens getting acclimated to the park. Biologists hope they will stay once released from the pen, restoring the wolf to Yellowstone for the first time in decades.

But they warn that the wolves - social yet territorial animals - still have a mind of their own.

The animals could attack, even kill, one another in what experts call “intrapack aggression” as they work out a new pack hierarchy. Or the groups of wolves could split up once the pens are opened, forming new packs or striking out on their own.

“We can’t be sure how they will behave,” said Mike Phillips, the Yellowstone National Park biologist handling the wolves that arrived in the park last week. “We’ve never done this before, so we just have to be flexible and see how it works.”

When last checked on Friday, all of the animals - six in one pen and two in another - seemed relatively chummy. The animals had been feasting on deer and elk carcasses left for them.

The wolves were left alone over the weekend.

“The wolves are relaxing,” said Yellowstone wildlife veterinarian Mark Johnson. “They deserve to be let alone after all we’ve put them through over the last few days.”

A federal wolf reintroduction plan calls for 15 wolves from Canada to be released each into Yellowstone and central Idaho during each of the next three to five years. The plan predicts that wolves, now an endangered species in the West, will rebuild their populations by 2002.

Ideally, another batch of wolves to round out Yellowstone’s initial eight should arrive within another week, said Wayne Brewster, assistant director of the national park’s resource division.

As of the weekend, capture teams in Canada had six animals in holding pens.

Johnson, the Yellowstone veterinarian who examined wolves as they were captured in Canada, said even if wolves placed together in pens are related, infighting is still possible.

“There can still be, and will likely be, aggression within the group during confinement,” he said.