Yellowstone wolf population drops

Predator-prey numbers stabilizing, official says
2009-12-16T21:40:00Z Yellowstone wolf population dropsBRETT FRENCH Of The Gazette Staff The Billings Gazette
December 16, 2009 9:40 pm  • 

For the first time, Yellowstone National Park’s wolf population has declined two years in a row and the decrease was not associated with disease.

“To be honest, I think it will go down more in the future,” said Doug Smith, Yellowstone’s wolf biologist.

As the park nears its 15th year of the wolf reintroduction program, the park’s northern range is starting to see a stabilization of prey vs. predator numbers, Smith said. Weak, old and young elk — the wolves’ main food source — are less abundant.

“I think the wolves are coming into equilibrium with the elk,” Smith said.

He estimated the northern range’s elk herd at about 10,000.

“The key part of this story is there are still plenty of elk, there just aren’t many weak ones,” he said. “Fifteen years of culling by wolves, cougars and bears, there’s not a lot of weak elk left.”

Smith said he has seen a number of battles this fall where bull elk have successfully fended off attacking wolves.

“That suggests that on average, these elk are healthier,” he said. “What’s left is a pretty strong, healthy population of elk.”

Canine distemper outbreaks in 2008, 2005 and 1999 were blamed for wolf population declines. Last year saw only 29 percent of the park’s pups survive, one of the worst rates on record, from an outbreak of distemper. But this year, the causes of wolf mortality were lower-than-average pup survival, a documented case of starvation by a lone adult wolf, wolves killing other wolves and Montana’s first wolf hunting season.

Smith won’t compile his annual wolf report until after the end of the year, but preliminary numbers show that 44 pups were born but only 25 survived, nine of those on the northern range. The popular Druid pack, often visible in the Lamar Valley, lost all eight of its pups. In the past, Smith said, pup survival in Yellowstone has been about 70 to 80 percent, or 40 to 50 pups.

The most dramatic drop in wolf survival continues to be in the park’s northern range.

Last year, 56 wolves inhabited the park’s northern portion; there are 46 this year. And last year’s number was down from the 94 wolves counted in 2007. In comparison, the park’s interior packs are more stable. Last year there were 68 wolves in the interior; this year there are 57. In 2007, interior wolves numbered 77.

“In the long term we could have about 100 wolves in the park,” Smith said.

Although there are fewer wolves, pack numbers have remained stable: 13 last year and 14 this year. That means fewer wolves per pack.

“We used to have numerous packs over 10,” Smith said. “The biggest now on the northern range is nine.”

That compares with a high of 37 wolves in the Druid pack in 2001.

In the park’s interior, two packs have more than 10 wolves.

In 1995, 14 wolves from Alberta were transplanted into the nation’s first national park. In 1996, another 17 wolves from British Columbia were transplanted. After building fairly steadily, the population peaked in 2003.

This year, Montana and Idaho held their first wolf hunting seasons since wolves were reintroduced. A pack that roamed north of Yellowstone’s boundary into the Absaroka-Beartooth Wilderness — the Cottonwood pack — saw four members killed by Montana hunters. The pack’s other six members, which included two pups, have not been sighted since the hunt, so Yellowstone’s wolf count and pup survival could be even lower than preliminary reports show.

Whether Montana and Idaho will have wolf hunting seasons next year is up in the air. A lawsuit filed by environmental groups arguing that wolf recovery is not complete is before U.S. District Judge Donald Molloy. His ruling is expected early next year.

Contact Brett French at french@billingsgazette.com or at 657-1387.

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