Wildlife officials at the Yellowstone National Park have expressed concerns that the deaths of the majority of gray wolf pups born at the natural preserve might be due to a dog disease. Only about 22 wolf pups survived out of the 69 that were born in the park in 2005, said Doug Smith, who heads the Yellowstone Park's wolf project. “It's cause for concern, a great deal of concern,” he said.
The deaths are suspected to be due to the parvovirus, which leads to severe diarrhea and dehydration in the infected animal. While an adult might be able to tide this over, a pup is more vulnerable and can succumb to the disease. Dogs are usually protected from the disease by way of vaccinations.
Smith said that plans are in the offing to draw blood samples from some of the pups in the park and test them for the parvovirus. “All the symptoms are consistent with a parvovirus outbreak,” Smith said.
However, even a positive diagnosis is made, it might not be possible to vaccinate all the wolves, he added. “It requires two vaccinations to build up an immunity, and we'd have to catch every wolf. Both those things are impractical,” Smith said, expressing hopes that the animals would develop immunity to the virus.
Mark Atkinson, wildlife veterinarian for Montana Fish, Wildlife and Parks, said that parvovirus uses the fecal route to spread and is very hardy, surviving for several months in the absence of a host. “It's quite hearty in the environment,” he said. He cited the results of a clinical study that had resulted in one-third of the wolves exposed to the virus showing the symptoms of illness and 10 per cent of those succumbing to it.
The results of exposure to the disease in the wild, however, are not clear. “With any disease in wildlife, there are so many factors, getting a good handle on it can be difficult,” Atkinson said.
Basing her decision den-site monitoring, Carolyn Sim, chief of the state's wolf program, said she also believed that parvovirus was responsible for the high mortality rate of the pups. Blood samples to detect the virus would be drawn not only from wolves that are alive but also from those who have been dead for less than a day, she added.
Last year's figures of the pups survival are a record low in the 11 years history of the wolf's reintroduction to the park. In the Yellowstone Park's northern region, as many as 41 pups out of the 49 born succumbed to disease last spring. The Leopold pack, which has been the most dominant one for the last few years, showed only two surviving pups from the 19 born. The Slough Creek pack also saw similar results, with 12 out of 15 pups dying. “That's just catastrophic mortality,” Smith said.
According to Terry Kreeger, of the Wyoming Game and Fish Department, the number of wolves in the park has fallen to 118 from 171 last year. “A lot of people thought wolves are going to keep going up in Yellowstone, and they're not,” he said.
The last time a major drop was seen in the population of the animals in the park was in 1998-99. At that time too, parvovirus was suspected to be the culprit. But the situation was better than this time. The pup survival rate now is now 15 per cent, down from the 1998-99 rate of 40 per cent. “Wolf populations can generally take a 30 per cent mortality rate and stay stable. If this is one year, there's nothing to worry about. If it comes to successive years, we could have a problem,” Smith concluded.
