Rescued Ferrets in Trouble Again
Wednesday, October 10th, 2007Disease that’s afflicting their only prey, the prairie dog, is slowing their rebound in wild.
WALL, S.D. — Black-footed ferrets — weasels with a burglar’s mask that were brought back after reaching the brink of extinction — are facing a new challenge from the spread of plague in prairie dogs, their only prey.
The disease has slowed the growth of the wild population, which is constantly replenished by the introduction of captive-bred ferrets. And plague is approaching a colony of prairie dogs that supports half the wild ferret population. Wildlife biologists are waiting to see if the disease will reach the Conata Basin here, a treeless moonscape next to Badlands National Park with the largest population of the highly endangered black-footed ferrets anywhere in the country.
“If we lose Conata, oh boy, the program is in trouble,” said Michael Lockhart, coordinator of the black-footed ferret recovery program for the federal Fish and Wildlife Service. There are about 850 of the ferrets in the United States: about 350 in a breeding center at Fort Collins, Colo., and the rest at 10 sites in the West and one in Mexico. About 250 of the wild ferrets live in the Conata Basin.
The plague bacteria, Yersinia pestis, is the one that caused the Black Death in Europe. A few cases of plague occur in humans in the United States each year, according to the Centers for Disease Control and Prevention, but the disease can be treated with antibiotics.
It takes a huge toll among prairie dogs, however. Little is known about the spread of plague, except that fleas spread it from rodent to rodent, but researchers suspect outbreaks may depend on climate.
In 2005, one of the warmest years on record in South Dakota, plague wiped out hundreds, perhaps thousands, of acres of black-tailed prairie dogs 38 miles south of here on the Pine Ridge Indian Reservation.
It is likely that if plague shows up it will be this spring, though no one really knows.
“It might be OK or it might be a salvage operation, it’s hard to say,” said Pete Gober, with the Fish and Wildlife Service.
Biologists have begun weekly patrols for dead prairie dogs. If signs of plague appear, they may begin quickly removing or vaccinating ferrets. But prairie dogs cannot be vaccinated, so even if ferrets survived the plague they would most likely lose their only prey and starve.
A ferret eats about 140 prairie dogs each year, and black-footed ferrets, the only ferrets native to North America, live in prairie dog towns, in the midst of their food supply. Prairie dogs are despised by many ranchers and farmers because they eat grass and often live near cattle herds, so a ruthless private and federal campaign wiped out 99 percent of them by 1960. By the late 1970s, the black-footed ferret, deprived of its prey, was thought to be extinct.
Then in 1981 a dog on a ranch near Meeteetse, Wyo., brought home a ferret it had killed. John and Lucille Hogg, the ranchers, took it to a taxidermist, who recognized it and called federal officials. Eighteen ferrets were found living on the ranch, the last of their kind. In a delicate operation, all were trapped and moved to a captive breeding center in Sybille, Wyo. The 18 soon became about 300.
In 1991, 48 ferrets, the first crop of the breeding program, were released in the Shirley Basin in southeastern Wyoming.
SOURCE: New York Times
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