Imperiled prairie dogs find hope in vaccine fighting flea-borne disease
June 24, 2014
Colorado Parks and Wildlife biologists have been working to protect the Gunnison's prairie dog from a plague that has long threatened the species, and their efforts during the last four years have proven successful.
"Overall the population is down historically," said Joe Lewandowski, spokesman for the Colorado Parks and Wildlife southwest region. "This is a very important project for Colorado Parks and Wildlife mainly because these species are what is known as a keystone species."
The ecosystems where prairie dogs live are dependent on the animals. Their burrowing freshens the soil, adds organic matter and increases water penetration, and the holes they dig create habitats and expose food sources for other creatures.
Prairie dogs support different species, he said, like burrowing owls, badgers, eagles and other predator birds.
"They get a bad rap," he said, and people often see them as pests because they burrow and eat lots of grass. "A lot of private landowners don't like them on their land, which is understandable."
Colorado is home to three species of prairie dogs. Summit County residents might see the occasional Gunnison's prairie dog, the species that resides more in the southwest part of the state.
The others two species are the white-tailed prairie dog, mainly in northwestern Colorado, and the black-tailed prairie dog, in areas along the Front Range and eastern plains.
The Gunnison's prairie dog populations are threatened by a plague caused by a non-native bacteria carried by fleas.
The bacteria that causes plague was brought to North America around 1900 and found in Colorado around 1940. Because prairie dogs did not evolve with the bacteria, they carry little immunity to fight off the disease.
The plague is not easily contracted by pets, but it can affect other wildlife species. Prairie dogs are more susceptible to the disease because they are highly social.
"A whole bunch of them live in close quarters," Lewandowski said. "When one of them gets sick, it spreads through the colony."
The plague can wipe out whole colonies, which can range in size from 20 to 200 or more, in days.
To combat the disease, agency biologists have been dusting prairie dog burrows with an insecticide powder that kills fleas. Researchers are also testing oral vaccine baits.
"We're not attempting to upset nature's balance with these treatments. We are working to restore balance in the environment and reduce the risk of major plague outbreaks in prairie dog colonies," said Dan Tripp, a wildlife disease researcher with Colorado Parks and Wildlife, in a press release. "We lose a lot of resilience in the environment when we lose prairie dogs."
In 2010, biologists started dusting some burrows in the Gunnison Basin with the insecticide. The experiment worked.
In some cases, nearby colonies that weren't dusted were devastated by plague while colonies that were dusted remain healthy. Biologists also say they're seeing more prairie dogs in more areas in the basin this year compared to five years ago.
However, the insecticide must be applied to each burrow of a colony annually to be effective. That means thousands of burrows and an expensive, labor-intensive treatment.
A promising new treatment is the oral sylvatic plague vaccine.
Developed by the U.S. Geological Survey's National Wildlife Health Center, the vaccine works well in the laboratory and is given inside a cubed bait flavored with peanut butter.
The baits also contain a red dye that sticks to the animals' coats and helps researchers track the prairie dogs that eat the bait.
This is the second year the vaccine has been tested in the field in Colorado.
In the Gunnison area, four prairie dog colonies are being used for vaccine testing. Two colonies are receiving the vaccine bait, and two are receiving no treatment. In Teller County the test is being conducted with two colonies.
"So far we're encouraged by the results, and we are optimistic that the vaccine will be effective in limiting future plague outbreaks," Tripp said. "We won't be able to prevent plague in every colony. But this work will help to stabilize the overall population at its current distribution and benefit this important species."
The vaccine is also being tested in Arizona, Montana, South Dakota, Texas, Utah and Wyoming. The experiment will continue for another two years and is a collaborative effort among more than 30 federal, state and tribal agencies and nongovernmental organizations.
In Colorado, the vaccine research in Gunnison's prairie dogs is occurring on public land including state wildlife areas, Bureau of Land Management and National Park Service property.
Contrary to public perception, prairie dogs don't reproduce prolifically. Females have one litter of three to five pups each year, and about 50 percent of young survive to adulthood.
Colonies generally do not spread rapidly over wide areas, and few connections between colonies exist across a landscape. Once a colony is wiped out, it may have little chance of being re-colonized.
The conservation work is aimed at preserving the ecological niche of prairie dogs and preventing a listing of the Gunnison's prairie dog under the federal Endangered Species Act. Last October, officials decided not to list the prairie dog, which would have led to land-use restrictions.
J Wenum, area wildlife manager in Gunnison, explained that when landscapes are restored to a more natural condition, the landscape can support more uses.
"If you have healthy, functioning landscapes you don't have to be focused on limiting uses," Wenum said. "A healthy landscape will accommodate agriculture, recreation and wildlife."
For more information about prairie dogs and other wildlife species, visit cpw.state.co.us.