Arizona agencies reintroduce prairie dogs
By Ryan Olinger
The smell of freshly mowed grass floats across the rolling golden prairie at Las Cienegas National Conservation Area. Tucson’s highest peak, Mount Wrightson, stands 20 miles toward the Southwest as the hawk flies. Keith Arnold, a wildlife conservation student at the University of Arizona, shoves a black-tailed prairie dog into an artificial burrow dug nearly 8 feet into the clay soil.
On a Saturday in mid-October under clear skies, the Arizona Game and Fish Department continued their reintroduction efforts for the species. Being one of the largest and most social ground squirrels, black-tailed prairie dogs let their presence be known with loud squeaks when handled, displaying their chisel-like teeth.
Reintroductions like this have been going on for nearly three years now. The first batches of prairie dogs came from a once augmented wild population in New Mexico. However, the newest additions of 60 prairie dogs to Las Cienegas are special in that they come from a self-sustaining wild colony in northern Mexico.
Purchased from a private rancher, the immigrating prairie dogs will bring greater genetic diversity to the current population, explained Robert Fink, an AZGFD regional wildlife program manager. After pausing on the phone during a Border Patrol check station just outside of Cienegas, Fink said, “It is quite important genetically because we did certainly have potential for a major genetic bottleneck.”
Because of a lack of genetic diversity, the reintroduced colony had the possibility for facing a bottleneck that could have decreased the prarie dog's ability to fight off disease and potentially limit the dispersal of useful traits.
This most recent reintroduction doubled the Cienegas populationa great feat- but a relatively microscopic addition compared to historical populations.
In the late 1800s, the U.S. black-tailed prairie dog colonies stretched across 699 million acres, according to the well-known naturalist C.H. Merriam, who had done extensive research throughout the Southwest. Merriam also noted colonies were often 20 to 30 miles wide.
Today, they are believed to cover only “one to two million acres” which is less than 1 percent of its historical range, according to the U.S. Fish and Wildlife Service.
How did they decline to a miniscule remnant? The same way other species with abundant populations fell within one or two generations around the turn of the 19th Century – by the hands of humans. For example, bison herds that would shake the ground during migrations dropped to 1,091 individuals in 1889 from an estimated 25 million strong, according to the American Bison Society.
Passenger pigeons, which numbered in the billions, also became extinct by the 1920s, due to the open markets allowing people to sell as many as they could kill.
Black-tailed prairie dog numbers were decimated by federally backed poisonings, which started in 1915 and ended in the 1960s.
Why were they being poisoned?
Ranchers and landowners formed a strong opinion in the early 1900s that prairie dogs competed with cattle for food. This opinion still lingers in some ranching communities today. Also, many felt livestock that wandered through the prairie dog colonies were falling into burrows and breaking limbs. Others even feared obtaining the plague, which prairie dogs can carry in the form of fleas.
Organizations that administered the poisonings included various state game and fish departments, U.S. Fish and Wildlife Service, the U.S. Department of Agriculture, and the federal Bureau of Land Management, according to a publication by Valerie Barko of the Oklahoma Cooperative Fish and Wildlife Research Unit. Those same agencies that led the poisonings are now in charge of the reintroduction programs.
Why the recent change of heart? As Fink put it, “We are trying to undo some of the mistakes of the past.”
Research is indicating prairie dogs are a keystone species in grasslands. A 1996 Environmental Management article by Mary Power and colleagues calls a keystone species “one whose overall impact on a community is large, as well as disproportionately large relative to its abundance.”
“They provide a service that no other species can provide,” said Sarah Hale, a University of Arizona graduate student whose thesis research is on black-tailed prairie dogs. These services include increasing plant species richness and making the soil more nutrient rich by consistent turnover in burrow creation and maintenance, Hale said.
Another trait of prairie dogs is to consume pods of mesquite, which are now becoming a somewhat invasive species throughout Southwestern grasslands. Their burrows also provide shelter for a variety of species, Hale said, supporting this by adding, “There are now two burrowing owls living in the colony.”
Another value of prairie dogs is they provide food to a large variety of predators, from coyotes to hawks.
Despite the services prairie dogs provide, not everyone supports the plan to continue the reintroductions of black-tailed prairie dogs.
“Unless we need it for the greater benefit of mankind, then why are we wasting money?” asked Patrick Bray, executive vice president of the Arizona Cattlemen’s Association.
Landowners in South Dakota, where black-tailed prairie dogs are self-sustainable, might agree with him. Forty landowners there took a lawsuit all the way to the state Supreme Court to argue for regulatory control by the state on colonies encroaching private land. Wild colonies are so successful in Badlands National Park that prairie dogs are extending outside of their borders. After a seven-year court battle, a ruling allowed private landowners to hunt prairie dogs on their personal property, but not on public lands.
This case is a hopeful warning to the Arizona reintroduction program, in that the South Dakota initial release only contained 74 prairie dogs at one site. While they might hope for such a big, expanding colony like the one in South Dakota, that might bring its own problems.
With the new introduction of genetic variation, a continuing safe cattle/prairie dog association, and an open-ended offer for as many black-tailed prairie dogs as the state can afford, the population is heading towards self-sustainability. The ultimate goal of Arizona Game and Fish Department to cover some 7,200 acres with black-tailed prairie dog colonies, Fink said, in a chuckling tone, “is a long, long, ways to go.”
Some people fight in court to once again rid them from the land while others attempt to increase their populations. Meanwhile, the black-tailed prairie dogs are just trying to survive.
At the Cienegas colony, a red-tailed hawk soars over, and a dozen or so foraging prairie dogs stop to sound an alarm. Balanced on their back legs, looking toward the sky, they signaled one another with high-pitched squeaks regarding the danger above. The prairie dogs seem unaware of the real danger that their ancestors and they themselves have faced by the other animal that determines virtually every other species’ ultimate fate – humans.
Ryan Olinger is a wildlife enthusiast and conservation management undergraduate from the University of Arizona. He wonders how a generation can decimate populations of prairie dogs and another can work to save them.