A plague is decimating prairie dog towns and imperiling the black-footed ferret, one of the most endangered mammals in North America.
Sylvatic plague is a bacterial disease that is transmitted by wild rodents via their fleas and can afflict numerous species of animals. Black-footed ferrets, which are the only ferret species native to the Americas, are vulnerable because their diet consists primarily of prairie dogs.
A new oral vaccine, currently being field tested in 29 locations throughout the western United States, including three sites in South Dakota, could provide a more effective, less expensive way to protect prairie dogs.
“Right now, we have two tools in our toolbox to combat sylvatic plague,” said Travis Livieri, executive director of Prairie Wildlife Research, a non-profit with extensive experience in black-footed ferret recovery. “We dust prairie dog burrows with an insecticide to kill the fleas, and we give black-footed ferrets a shot to vaccinate them. Both are effective, but we have to do it every year, and it’s costly.”
“An oral vaccine can be delivered much more efficiently to large numbers of animals, because we are putting it in bait that we can broadcast widely from planes, trucks or other vehicles,” said wildlife biologist Tonie Rocke of the U.S. Geological Survey National Wildlife Health Center, which is testing the vaccine.
Testing the New Vaccine in South Dakota
Randy Griebel, a wildlife biologist with the U.S. Forest Service, is leading testing of the oral vaccine near Wall, South Dakota, in the Buffalo Gap National Grasslands. The site is located near Badlands National Park and Conata Basin, where The Nature Conservancy is working with landowners and other partners to protect grassland habitat.
“We’re in the first year of a three-year study,” said Griebel. “We put out the vaccine-laden bait, which tastes like peanut butter, and then we capture the prairie dogs; take blood, hair and whisker samples; comb them for fleas and tag them before releasing them back to their burrows.“
According to Rocke, a biomarker was added to the bait that marks the hair, so she and others at the National Wildlife Health Center can look at the hair under a microscope to determine which prairie dogs have ingested the bait.
“A year from now, we’ll come back and capture the prairie dogs again to see if the ones that consumed the vaccine-laden bait have higher survival rates than the others,” Griebel added.
The bait will be distributed and prairie dog survival will be monitored for three years to determine if the vaccine is effective at protecting prairie dogs from plague.The National Wildlife Health Center, which developed the oral vaccine with scientists at the University of Wisconsin-Madison, is overseeing this same type of research in prairie dog colonies in Arizona, Colorado, Montana, Utah, Texas, Wyoming and two other locations in western South Dakota.
Protecting Black-footed Ferrets at Conata Basin
The Nature Conservancy is protecting grasslands that provide cattle and bison grazing as well as habitat for prairie dogs and black-footed ferrets in several western states and Mexico, so we are watching the research on the oral vaccine closely.
Conata Basin in South Dakota, where we have been conserving grassland habitat for more than a decade, is home to one of the largest existing populations of black-footed ferrets. Prairie dogs are the ferret’s primary food source, so protecting them from plague is vital.
Hated by some, adored by others, the black-tailed prairie dog is not only food for black-footed ferrets, but for a whole host of other wildlife that live in grasslands, including ferruginous hawks, eagles and swift foxes. Their extensive network of tunnels provides homes to burrowing owls, prairie rattlesnakes and other species.
The Nature Conservancy began building relationships with private ranchers and public agencies in Conata Basin area in 2002. Since then, we have purchased more than 6,000 acres in the basin and protected another 25,000 acres of federal grazing allotments as part of those acquisitions.
We have focused on places where we can help ranchers, the National Park Service and the U.S. Forest Service consolidate large expanses of grassland for either grazing or prairie dogs and ferrets, while minimizing conflict between prairie dogs and ranchers, who see them as competition for livestock forage.
“Through their digging and other actions, prairie dogs create diversity in the grassland landscape, which benefits many other species of grassland plants and animals we are working to protect,” said Bob Paulson, who directs the Conservancy’s Western South Dakota Program.
While it won’t end sylvatic plague entirely, the new oral vaccine could make it a lot easier to protect wildlife in America’s western grasslands.
View a slideshow of engaging images by photographer Michael Forsberg to see the prairie dog research happening at Buffalo Gap National Grasslands in South Dakota.