The white-tailed prairie dog won't be listed as a threatened or an endangered species partly due to extensive survey work by biologists from Colorado Parks and Wildlife and other state wildlife agencies where the species exists.
Petitions to list the white-tailed prairie dog on the federal endangered species list were filed with the U.S. Fish and Wildlife Service (USFWS) starting in 2002. The USFWS did not have enough information to make a listing determination, so the wildlife agencies in Colorado, Utah and Wyoming -- the states with the most extensive habitat for this species -- conducted wide-ranging surveys that showed white-tailed prairie dogs still occupy areas throughout their known historic range.
"Petitions for listing species are often based on incomplete information," said David Klute, species conservation unit supervisor for Colorado Parks and Wildlife. "On issues like this we rely on our scientists and proven scientific methods to determine the reality on the ground. It's always good news when we help to keep species from a federal listing."
The USFWS announced Dec. 5 that the species was not warranted for listing.
The white-tailed prairie dog is one of three species of prairie dogs in Colorado. The white-tailed variety occupies areas in western Colorado primarily below 6,000 feet from Ridgway to the Grand Valley to northwest Colorado and North Park. The Gunnison's prairie dog is found in the Gunnison area, the San Luis Valley and other areas in southern Colorado; and the black-tailed prairie dog occupies areas along the Front Range and eastern plains. All prairie dogs burrow underground which also helps to provide habitat for a variety of other species, including burrowing owls, badgers, small mammals and hawks. On ranches on the eastern plains, colonies of the black-tailed prairie dog are playing a critical role in the reintroduction of the endangered black-footed ferret.
Large tracts of public lands managed primarily by the Bureau of Land Management (BLM) are critical for the white-tailed prairie dog species and those species associated with it, explained Amy Seglund, a CPW species conservation coordinator in Montrose who helped to design and conduct the surveys. To determine the health of the population of white-tailed prairie dogs, scientists used a study technique called an "occupancy survey." Basically, it works like this: Scientists first model areas of known and suitable habitat where the species is expected to live. Then, they overlay a grid of plots measuring 500 x 500 meters and randomly select plots to sample over an extended time frame to look for trends in changes in distribution of the animals. Field crews visit randomly selected plots from the ground and also view them from airplanes to see if animals are living on the plots.
In Colorado, crews have visited the same 317 plots in 2004, 2008, 2011, and 2016 and found that though prairie dog occupancy fluctuated, overall the number of occupied plots across the range has not changed enough to warrant concern, Seglund said. Most of the changes have been influenced by known plague outbreaks that have caused populations to decline, and by several wet seasons that have caused populations to increase. Similar results were found in Utah. Wyoming conducted its first occupancy surveys in 2016. The next surveys in Colorado and range-wide will be conducted in 2022.
The primary limiting factor for all prairie dog species is plague, a deadly non-native disease that can wipe out huge prairie dog colonies in a matter of days. The disease is transmitted by fleas. Fortunately, Seglund explained, populations of white-tailed prairie dogs are wide-spread so the species, so far, has been able to weather plague infestations.
"Plague is the big issue. We've seen ups and downs in our surveys but prairie dogs are resilient. Humans have tried to eradicate the species through extensive poisoning campaigns and now this non-native disease has impacted populations range-wide. Though it appears the white-tailed prairie dog is not a species that's going extinct, we need to continue to monitor it and manage populations not only to benefit this species but also all of the other species associated with it," Seglund said.
Brian Holmes, a CPW conservation biologist in Meeker, explained that the largest stronghold for the white-tailed prairie dog species in Colorado is in Moffat and Rio Blanco counties where they occupy vast areas of BLM managed public lands. CPW biologists, in cooperation with the BLM and Dinosaur National Monument, are developing management plans that could help the long-term survival of the species. Plans could include habitat improvement projects and deploying a vaccine bait to help protect animals on an annual basis from contracting plague.
The USFWS announced its decision in a news release. It said: "After a thorough review of the best-available scientific and commercial information, the U.S. Fish and Wildlife Service announced that the white-tailed prairie dog is not currently in danger of extinction and is not likely to become in danger of extinction within the foreseeable future. Consequently, the service has released a 12-month finding stating that the species is not warranted for listing under the Endangered Species Act at this time."
Prairie dogs breed once a year and can produce litters from 4-8 young. They usually go into hibernation in early autumn when their food sources dry up. They emerge again at the first sign of warm weather, usually in March.