Wolf-Watchers Hope For Den-Digging Signs Biologists Say Behavior Would Indicate One Is Pregnant

Federal biologists have taken on the air of prospective grandparents in their surveillance of the wolves that were released in Yellowstone National Park.

Their fondest hope now is that one of the females is pregnant.

They watch intently for any sign that any of the three packs is digging and hovering around a den.

One pack has spent six days along a stretch of the Lamar River in the park’s northeast corner, but Yellowstone biologist Mike Phillips said that’s too soon to draw any conclusions.

“Their movements have been very restricted, not unlike what we would expect to see around a den,” Phillips said. Still, he said, “six days in the life of a wolf is not a long period of time.”

The three packs formed from 14 transplanted Canadian wolves that were released last month under a federal wolf recovery plan. They had been held in pens in the Lamar Valley about nine weeks to condition them to the park.

The other two packs have continued prowling, and one group of five wolves, which had been penned along Soda Butte Creek, was outside the park near Cooke City on Friday.

Friday’s tracking flight, the first since Tuesday because of weather, did not spot the third pack.

While the wolves seem to have been exploring throughout the Lamar Valley, Phillips said he would expect during the next two to four weeks to see signs they are beginning to set up territories.

Prey is so abundant in Yellowstone, Phillips said, that park wolves need not go far to find food, so they may stake territories much smaller than wolves would elsewhere.

“Within a few weeks, they’re going to be developing patterns,” he said. “I have no doubt they’ll figure things out.”

It’s about time that packs with a pregnant female begin seeking out a den.

Wolves in each of the three park pens exhibited breeding behavior, but biologists do not know whether they actually conceived because of the stress of their capture in Canada and trip to Yellowstone.

Typically, wolves mate around mid-February and pups appear about mid-April. Packs usually dig dens about a week ahead of time.