More than 100 black-footed ferrets have died in recent months, victims of a disease we don't hear much about anymore — plague.

The long-endangered species nearly went extinct in the 1970s, but the last population of just 18 animals formed the core of a breeding program that has increased the number of ferrets to between 1,000 and 1,300, depending on which source you read.

The species is uniquely adapted to live in conjunction with the black-tailed prairie dog, which forms the basis of the ferret's diet. The ferrets also live in underground prairie-dog dens, where they spend up to 90 percent of their time.

Unfortunately, black-tailed prairie dogs carry fleas, which transmit sylvatic plague (similar to bubonic plague) to the black-footed ferrets. And as wildlife biologist Travis Livieri told the New York Times, "They are exquisitely sensitive to the plague. They don't just get sick, they die. No ifs, ands or buts."

Livieri, the U.S. Fish and Wildlife Service, and other volunteers are trying to inoculate the remaining 200 ferrets (not an easy process) at Conata Basin colony in South Dakota, as well as kill off the fleas with insecticide.

Meanwhile, the ferrets also face another threat: the potential loss of their main source of life, the black-tailed prairie dog. Reviled as a pest, the prairie dog is itself a threatened species, although it lacks any official status as such to offer it protection. Decisions on whether to poison the prairie dogs or protect them are both pending.

Yes, it's another battle of ranchers vs. conservationists. We'll see which side wins out.

This article originally appeared in "Plenty" in July 2008.


Copyright Environ Press 2008

Plague strikes down black-footed ferrets
U.S fish and Wildlife Service and other volunteers are trying to inoculate ferrets in South Dakota.