Since their visit to Yellowstone National Park's headquarters this winter and spring, wolves in the Canyon pack have been "model citizens," said Doug Smith, the park's wolf biologist.

The pack of three males and one female caused quite a stir with their trek from Canyon, 32 miles away by car, to the residential confines of Mammoth, Wyo. They were visible next to the road and even killed a cow elk near the park's grade school.

To move the human-habituated wolves away from the small community, Smith shot at them with rubber bullets and cracker shells when they ventured too close. The park even roped off a portion of the hillside just outside Mammoth this spring to keep curious tourists away when the pack's lone female denned to give birth to pups.

It was believed the pack picked the small area between other packs because of the abundance of elk. Once the elk dispersed in spring, the pack moved, too, traveling back to the Hayden Valley near the Grand Canyon of the Yellowstone in the park's interior.

One report had the pack moving a pup as far as Obsidian Cliff, between Hayden and Mammoth, this spring. But the average litter size in Yellowstone is five to six pups, making wolf researchers wonder whether the other pups died.

Since their adverse conditioning, the wolves have kept a low profile in the Hayden Valley.

"They haven't been on the road once this summer," Smith said. "I think wolves are teachable. The hazing we've done seems to be working."

At the end of 2008, Yellowstone was home to 124 wolves in 12 packs. This spring, those packs have produced 43 pups.

Last year, only eight pups survived in Yellowstone's Northern Range. Blood tests of some of the survivors captured this winter confirmed the presence of distemper, which may have been the cause of the die-off. The hardest-hit pack was probably the Leopold, which had four litters, all of which died.

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