July 15, 2008

Ferrets Face Plague

By Michelle Dynes

By Michelle Dynes

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CHEYENNE - Plague is threatening black-footed ferrets in South Dakota and putting local biologists on alert for signs of the disease in Wyoming.

About 10,000 acres of prairie dog colonies have been infected in South Dakota's Conata Basin, tainting the endangered ferrets' favorite meal, said Martin Grenier, non-game mammal biologist for the Wyoming Game and Fish Department.

It's still too early to calculate the impacts to South Dakota's ferret population, but Wyoming's experts are monitoring local prairie dog and ferret populations for a similar outbreak.

A large portion of the black-footed ferrets in the Shirley Basin area were wiped out by plague in the 1990s. But until recently, there was no evidence of plague in South Dakota. He said he does not know whether climate change pushed the disease into unexpected territories or whether biologists were even looking for an unusual epidemic. The bacterial disease is transmitted by fleas and infected rodents. And while the risk of transmission to humans is low, it isn't uncommon to diagnosis a few housecats with plague.

"It's in Wyoming right now," Grenier said. "But there are not large die-offs of prairie dogs or ferrets."

Plague hit the prairie dog populations in the Thunder Basin National Grassland in 2002, and regular declines were reported through the fall of 2007. A multi-year event, as well as a disease that spreads over great distances, indicates a more serious form of the plague.

Grenier said experts are dusting prairie dog burrows and vaccinating ferrets against plague in South Dakota. But neither of these options is viable for Wyoming. Dusting for fleas is a labor- intensive process, and the Shirley Basin area is too large for a similar project.

"You are talking about dusting tens of thousands of acres," he added. "We don't have the manpower for that."

It's also expensive, costing hundreds of thousands of dollars that the agency does not have. Vaccinating the animals is another costly and time-consuming alternative. But it's possible to learn from South Dakota's experts as they continue to fight the plague, Grenier said.

Travis Livieri, a biologist with Prairie Wildlife Research, said the Conata Basin is a more accessible habitat for mitigation efforts. Flea dusting and vaccines are a more practical approach for South Dakota than for Wyoming or Colorado.

He added that the Wyoming Game and Fish Department has done a good job of ensuring that there is a large enough population of prairie dogs to withstand colony die-offs.

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