Group dynamics also change significantly, sometimes in mercurial ways, when membership shifts or a pack loses individuals. “Personalities matter,” Dr. Smith said, noting that science doesn’t have a good way to assess the effect. “It’s really hard.”
Then there is the role of the wise wolf to consider. During pack warfare, a deciding factor can be the presence of an elder, a single wolf older than five, that is even more important than the number of wolves, researchers found.
“It was a surprise,” said Kira Cassidy, a Park Service biologist and an author of the study. “I attribute it to the fact that older wolves will only engage their neighbors if they feel they are likely to win.”
Research here also leads Dr. Smith to believe that wolf packs are matrilineal. Males come and go, he said, but “Gramma, Mom and the daughter are the ones that stick around” and carry on the pack through generations.
There is some evidence that the increase in hunting could alter this research. When the alpha female in the Lamar Canyon pack left Yellowstone in 2012 and was shot, the pack split into two and the alpha male left because the new alpha female was his daughter. (Wolves avoid inbreeding.)
Of course, the life of a wolf is a high-risk occupation and natural deaths occur all the time, especially when a pack tries to kill animals with hooves and horns 20 times their size. In early April, an alpha female with “a belly full of pups” was killed either by an elk or a bison, Dr. Smith said. Because only the alpha female in a group reproduces, “that means the pack won’t have pups this year,” he said.
Outside the park, ranchers have been vocal in their support of expanding hunting, citing real threats to their livestock.
Jon Robinett of Dubois, Wyo., says he has lost hundreds of cattle, several horses and six dogs to wolves over the last 20 years. While there are 50 wolves in his part of the Dunoir Valley, allowing hunters to take out five won’t accomplish much, he said.
“Killing is what wolves do,” he said, adding that even with reduced numbers, “they aren’t going to quit their home range.” The state compensates him for lost cattle, he said, “but it doesn’t make you whole.”
Some biologists say there are legitimate reasons to allow hunting, perhaps most important to placate residents. “A little blood satisfies a lot of anger,” said Ed Bangs, a retired Fish and Wildlife biologist who led the effort to restore wolves to the northern Rockies.
“The wolf most likely to get harvested by a hunter is one that is in open areas with road access,” the interface between ranches and wild land, Dr. Bangs said. “So hunters are removing the animals with the highest probability of getting in trouble with livestock.”
Dr. Smith says the wolf personality is not the only wild card in the Yellowstone frame — humans figure in as well.
Last year, the famed white wolf left the park and went into Montana for a few days. Dr. Smith said a hunter who hates wolves sought the 11-year-old female out as a prize trophy. But the animal returned to safety in the park.
Just last month, the wolf was found with severe injuries and was euthanized. Law enforcement is investigating her death. She was almost twice as old as most wolves here, but will be missed. “She was the most coveted wolf to see,” Dr. Smith said.