"All of a sudden I heard a whimper, kind of a squeal, and there they were," " said U.S. Fish and Wildlife biologist Joe Fontaine, who stumbled across the litter May 3.
Fontaine was tracking signals from the adult wolf's radio collar, looking for signs of a den.
Although the black female ran off as Fontaine approached, her seven or eight pups - blind, deaf and about the size of a human fist - wriggled in a depression underneath a spruce tree. After counting the litter, Fontaine left the animals alone.
No more than a week old, the pups were born into the Rose Creek wolf pack about the same time their father was killed illegally, authorities suspect. Only his radio collar has been found.
The U.S. Fish and Wildlife Service and nonprofit Defenders of Wildlife have offered rewards totaling $6,000 for information leading to a conviction.
The parents were roaming east of Yellowstone, perhaps on a den-seeking expedition, when the male vanished near Red Lodge. Biologists guess the female, while waiting for her missing mate, had no time to prepare an underground den before giving birth.
It was the first sure sign of reproduction among wolves shipped from Canada to Yellowstone under a federal plan to repopulate America's first national park with its leading predator. Biologists had not counted on any pups this year and were elated that one of the three park wolf packs had launched a family so soon.
"It's a great, promising sign that the process has worked so far," " said Yellowstone Park biologist Mike Phillips.
The find was not without its drawbacks.
Wildlife managers feared for the pups, born some 40 miles from Yellowstone Park, without a father, on private land and near the homes of Red Lodge, population 2,000.
Since the female wolf has no pack to bring her food while she nurses, biologists will fill in by hauling meat to her. They must also try to earn the support of local residents. Landowners have been cooperative so far.
"It would be nicer if it were in the park, but this is reproduction and that's part of what we're trying to do," " Fontaine said.
The reporter works in Cody, Wyoming.