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Distemper, an often fatal disease common in carnivores, had a devastating effect on Yellowstone National Park wolves last year, especially northern packs. But the disease may have run its course, a Yellowstone official said. Across the park, the population has declined 27 percent, from 171 wolves in 2007 to 124 in 2008.
Wolf numbers dropped by 40 percent in the northern range, the most concentrated wolf community, from 94 wolves in 2007 to 56 wolves in 2008, said Yellowstone Wolf Project Leader Doug Smith.
Distemper is more likely to spread in denser populations such as the northern range, Smith said.
In the interior, the decline was 11 percent — from 77 in 2007 to 68 in 2008, Smith said.
Puppies are the most susceptible to the viral disease, which affects respiratory, gastrointestinal and central nervous systems. But adults can contract the disease too, through secretions, especially saliva.
Distemper was here long before wolves arrived in Yellowstone in 1995, and the disease is spread by all predators, Smith said. Other carnivores can spread the disease from chewing on the same carcass.
Eight puppies were born in the northern range and 14 in the interior last year, Smith said.
Inoculating for distemper requires three injections. That would be expensive, and catching all the wolves in the park likely would not be possible, he said.
The good news is the 2008 distemper outbreak probably is over, he said.
Smith said he believes the population can recover. Distemper clobbered park wolves In 1999 and 2005 as well.
“Both times, they bounced back,” he said.
Mange also killed two or three wolves in 2008. Currently, 20 wolves are suffering from mange across the park, Smith said.
“It’s the worst year yet for mange,” Smith said, adding he hopes it does not increase this year.
Mange is a parasitic infection of the skin. It can weaken the animal, making it susceptible to infections and other problems that can lead to death, a Yellowstone news release said.
The number of breeding pairs dropped from 10 to six in 2008. That’s the lowest since 2000, the news release said.
Distemper and mange aren’t the only slayers.
Wolves often kill each other competing for food or territory, and population density could contribute to an increase in wolf-on-wolf mortality, the release said.
A mountain lion will kill a wolf occasionally, but the only unequivocal wolf predators are humans, Smith said.
Wildlife biologists say the Yellowstone wolf population has recovered, and wolf numbers can be expected to fluctuate like other wildlife species, according to the release.
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