Liberty Belle
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Endangered, Rescued, Now in Trouble Again
By JIM ROBBINS
April 18, 2006
WALL, S.D. — Black-footed ferrets, the weasel with the burglar's mask that was brought back to life 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 now 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 now about 850 of the ferrets in the United States, about 350 in a captive breeding center at Fort Collins, Colo., and the rest at 10 sites around the West and one site in Mexico. About 250 of the wild ferrets live in the Conata Basin.
The plague bacteria, Yersinia pestis, is the same one that caused the Black Death in Europe. It came to the West Coast of the United States from China around 1900, and slowly spread in rodents and other animals to the Rocky Mountain West. Black-footed ferrets are extremely sensitive to plague.
"It took 50 years to get to the South Dakota line," said Dean E. Biggins, a research biologist with the United States Geological Survey who has studied the effects of plague on ferrets and prairie dogs. "Then it stopped and didn't go further until last year when it went into the Black Hills."
A few cases of plague occur in humans each year in the United States, 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 be climate dependent.
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, where there are no ferrets.
Last fall officials dusted 300,000 prairie dog burrows in the Conata with insecticide to kill fleas. This year a coyote shot on the edge of the Conata was tested and shown to have been exposed to plague.
It is likely that if plague shows up it will be this spring, though no one really knows what to expect. "It might be O.K. or it might be a salvage operation, it's hard to say," said Pete Gober, with the Fish and Wildlife Service. "Plague is like fire: sometimes it smolders, sometimes it sweeps right through." And it may not show up at all.
Biologists have begun weekly patrols to watch for dead prairie dogs. If signs of plague appear they may begin hastily removing or vaccinating ferrets. Ferrets, but not prairie dogs, can be vaccinated, so even if ferrets survived the plague they would most likely lose their only prey and starve.
The black-footed ferret, the only ferret native to North America, was part of the Great Plains ecosystem that spread from Canada to Mexico, an expanse that was perforated with sprawling prairie dog towns. Because of predators, prairie dogs are vigilant and need clipped grasslands to feel secure, so they stayed near grazing buffalo herds. Ferrets, in turn, lived in the prairie dog towns, right in the midst of their food supply.
One ferret eats about 140 prairie dogs each year. The prairie dogs are despised by many ranchers and farmers because they eat grass and often live near cattle herds, which substitute for buffalo. A ruthless private and federal campaign wiped out 99 percent of them by 1960. By the late 1970's, the black-footed ferret, deprived of its only prey, was thought to be extinct.
Then in 1981 a dog named Shep 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. "We were nervous about whether we'd save them or drive them to extinction," said Dr. Biggins, who was part of the team.
The 18 soon became about 300. The program might not have been a success if not for a male ferret biologists named Scarface, which turned out to be an extremely robust breeder, fathering most of the first litters.
In 1991, 48 ferrets, the first crop of the breeding program, were released in the Shirley Basin in southeastern Wyoming.
There are now 11 separate populations of black-footed ferrets, with the largest in Conata, Colo. Only one, at the Fort Belknap Indian Reservation in Montana, has been wiped out. Others have been hit hard, though. In Colorado, more than 200 ferrets have been reintroduced, but the population is down to 5 to 10 because of plague.
While the population of 850 ferrets is the highest since the program began, the scientists running it say that without plague there would be a lot more in the wild. And numbers do not tell the whole tale, because ferrets depend on one food source, the one that may suffer more devastation.
Ferrets, which are nocturnal and secretive, are hard to count, and numbers are always an approximation. With spotlights at night, researchers search for an emerald green eye shine, the ferret's hallmark.
Ferrets dwell in the prairie dog burrows, and kill and devour the prairie dogs underground at night. Ferrets typically strike sleeping prairie dogs, Mr. Lockhart said. "When the prairie dog wakes up and turns around they grab them by the throat."
Reintroduction sites are limited to places where there is vast acreage of prairie dogs, which are rare, even in the sprawling open spaces of the American West. It takes about 670 prairie dogs a year to sustain one average ferret family, which is a mother, half a father and 3.3 kits.
Scientists hope the insecticide will work. Dr. Biggins said he had seen an outbreak of plague hit a line of dusted test burrows and stop cold. Budget cutbacks, however, have been severe and money is not available for more dusting. A salvage operation, if it takes place, has to happen as soon as prairie dogs start dying. Once large numbers of prairie dogs start dying, it is likely too late.
Plague is not the only threat to the highly endangered ferrets, which are not protected as fully endangered, but designated an experimental population, which exempts them from stringent protections and makes their presence more palatable to some. But it comes at a cost. In Colorado and Utah, the Bureau of Land Management plans to lease oil and gas on land where tiny, precarious populations of black-footed ferrets live.
Last year the Forest Service poisoned prairie dogs on 5,000 acres of federal land in the Conata Basin, despite concern for the ferret, after a rancher complained.
While many Westerners consider prairie dogs pests, and locals often shoot them for sport, biologists and environmentalists see them as a linchpin of a healthy native American prairie that was all but destroyed by settlers.
"Ferrets are the charismatic representative of a healthy prairie ecosystem," said Travis Livieri, director of Prairie Wildlife Research, a nonprofit research organization based here.
"If we can restore ferrets to the prairies of the U.S.," Mr. Livieri said, "that means prairie dog numbers are healthy, which mean ferruginous hawks, swift foxes and burrowing owls."
http://www.nytimes.com/2006/04/18/science/18ferr.html?_r=1&hp&ex=1145332800&en=d3e0432f1b4bba27&ei=5094&partner=homepage&oref=slogin
By JIM ROBBINS
April 18, 2006
WALL, S.D. — Black-footed ferrets, the weasel with the burglar's mask that was brought back to life 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 now 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 now about 850 of the ferrets in the United States, about 350 in a captive breeding center at Fort Collins, Colo., and the rest at 10 sites around the West and one site in Mexico. About 250 of the wild ferrets live in the Conata Basin.
The plague bacteria, Yersinia pestis, is the same one that caused the Black Death in Europe. It came to the West Coast of the United States from China around 1900, and slowly spread in rodents and other animals to the Rocky Mountain West. Black-footed ferrets are extremely sensitive to plague.
"It took 50 years to get to the South Dakota line," said Dean E. Biggins, a research biologist with the United States Geological Survey who has studied the effects of plague on ferrets and prairie dogs. "Then it stopped and didn't go further until last year when it went into the Black Hills."
A few cases of plague occur in humans each year in the United States, 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 be climate dependent.
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, where there are no ferrets.
Last fall officials dusted 300,000 prairie dog burrows in the Conata with insecticide to kill fleas. This year a coyote shot on the edge of the Conata was tested and shown to have been exposed to plague.
It is likely that if plague shows up it will be this spring, though no one really knows what to expect. "It might be O.K. or it might be a salvage operation, it's hard to say," said Pete Gober, with the Fish and Wildlife Service. "Plague is like fire: sometimes it smolders, sometimes it sweeps right through." And it may not show up at all.
Biologists have begun weekly patrols to watch for dead prairie dogs. If signs of plague appear they may begin hastily removing or vaccinating ferrets. Ferrets, but not prairie dogs, can be vaccinated, so even if ferrets survived the plague they would most likely lose their only prey and starve.
The black-footed ferret, the only ferret native to North America, was part of the Great Plains ecosystem that spread from Canada to Mexico, an expanse that was perforated with sprawling prairie dog towns. Because of predators, prairie dogs are vigilant and need clipped grasslands to feel secure, so they stayed near grazing buffalo herds. Ferrets, in turn, lived in the prairie dog towns, right in the midst of their food supply.
One ferret eats about 140 prairie dogs each year. The prairie dogs are despised by many ranchers and farmers because they eat grass and often live near cattle herds, which substitute for buffalo. A ruthless private and federal campaign wiped out 99 percent of them by 1960. By the late 1970's, the black-footed ferret, deprived of its only prey, was thought to be extinct.
Then in 1981 a dog named Shep 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. "We were nervous about whether we'd save them or drive them to extinction," said Dr. Biggins, who was part of the team.
The 18 soon became about 300. The program might not have been a success if not for a male ferret biologists named Scarface, which turned out to be an extremely robust breeder, fathering most of the first litters.
In 1991, 48 ferrets, the first crop of the breeding program, were released in the Shirley Basin in southeastern Wyoming.
There are now 11 separate populations of black-footed ferrets, with the largest in Conata, Colo. Only one, at the Fort Belknap Indian Reservation in Montana, has been wiped out. Others have been hit hard, though. In Colorado, more than 200 ferrets have been reintroduced, but the population is down to 5 to 10 because of plague.
While the population of 850 ferrets is the highest since the program began, the scientists running it say that without plague there would be a lot more in the wild. And numbers do not tell the whole tale, because ferrets depend on one food source, the one that may suffer more devastation.
Ferrets, which are nocturnal and secretive, are hard to count, and numbers are always an approximation. With spotlights at night, researchers search for an emerald green eye shine, the ferret's hallmark.
Ferrets dwell in the prairie dog burrows, and kill and devour the prairie dogs underground at night. Ferrets typically strike sleeping prairie dogs, Mr. Lockhart said. "When the prairie dog wakes up and turns around they grab them by the throat."
Reintroduction sites are limited to places where there is vast acreage of prairie dogs, which are rare, even in the sprawling open spaces of the American West. It takes about 670 prairie dogs a year to sustain one average ferret family, which is a mother, half a father and 3.3 kits.
Scientists hope the insecticide will work. Dr. Biggins said he had seen an outbreak of plague hit a line of dusted test burrows and stop cold. Budget cutbacks, however, have been severe and money is not available for more dusting. A salvage operation, if it takes place, has to happen as soon as prairie dogs start dying. Once large numbers of prairie dogs start dying, it is likely too late.
Plague is not the only threat to the highly endangered ferrets, which are not protected as fully endangered, but designated an experimental population, which exempts them from stringent protections and makes their presence more palatable to some. But it comes at a cost. In Colorado and Utah, the Bureau of Land Management plans to lease oil and gas on land where tiny, precarious populations of black-footed ferrets live.
Last year the Forest Service poisoned prairie dogs on 5,000 acres of federal land in the Conata Basin, despite concern for the ferret, after a rancher complained.
While many Westerners consider prairie dogs pests, and locals often shoot them for sport, biologists and environmentalists see them as a linchpin of a healthy native American prairie that was all but destroyed by settlers.
"Ferrets are the charismatic representative of a healthy prairie ecosystem," said Travis Livieri, director of Prairie Wildlife Research, a nonprofit research organization based here.
"If we can restore ferrets to the prairies of the U.S.," Mr. Livieri said, "that means prairie dog numbers are healthy, which mean ferruginous hawks, swift foxes and burrowing owls."
http://www.nytimes.com/2006/04/18/science/18ferr.html?_r=1&hp&ex=1145332800&en=d3e0432f1b4bba27&ei=5094&partner=homepage&oref=slogin
