One hundred twenty-three black-tailed prairie dogs (Cynomys ludovicianus) were trapped and evaluated during the 2021 Arizona Game and Fish Department’s (AZGF) Fall Prairie Dog Census which took place Sept. 17, 18, and 19 at four locations in the Sonoita area.
This annual event helps monitor the re-introduction of the species into its historic natural habitat. Black-tailed prairie dogs were once widely distributed over western North America. However, at the beginning of the 20th century, they were seen as pests, and control programs were put into action. Over the last century, their distribution within their range has dwindled to 2% of what it had been. By 1960, the species was extirpated in Arizona.
Later research found that the black-tailed prairie dog was a keystone species in grassland environments. It provided a unique, significant service, disproportionate to its numbers that no other species could fill in the absence of the prairie dogs. It was found that many different species relied on prairie dogs. According to AZGF, “Many species utilize prairie dog burrows such as burrowing owls, black-footed ferrets, swift foxes and rattlesnakes. Prairie dogs are a common prey for raptors, coyotes, and badgers, and they are the primary diet for black-footed ferrets. When prairie dogs are removed from the landscape, many of these animals decline as well.”
Research also established that there were at least five major benefits to prairie dogs’ presence. They provided nutrient rich soil which produced rich vegetation for grazers. Their excavated burrows provided dwellings for other animals, such as burrowing owls. Prairie dogs served as a food source for many carnivores and predatory birds. The maintenance of their colonies prevented woody encroachment, adding to biodiversity, and created natural fire breaks.
Reintroduction efforts were instituted in 2008 on the Las Cienegas National Conservation Area (Las Cienegas). A reintroduction site in Road Canyon was chosen based on factors such as historic locations, grass cover, forb cover, bare ground, lack of visual obstruction, shrub density, tree density, gravel, sand, silt/clay, grass species richness, and distance from private property. Invasive mesquite trees were removed, the grass was mowed, and 25 artificial burrows were installed to give the new arrivals a head start. In October of that year, 74 prairie dogs were trapped at the Ladder Ranch in New Mexico and released at the reintroduction site. “Since then, additional translocations in 2009 and 2010 have occurred to create two additional black-tailed prairie dog colonies at Las Cienegas,” according to AZGF. Additionally, in 2017, a colony was established on Pima County land at Sands Ranch. The local prairie dog population is now estimated conservatively to be between 200 – 250 animals.
Annual censuses allow researchers to monitor black-tailed prairie dog populations. Humane wire cage traps are set. Once the animal is inside the closed trap, AZGF personnel and volunteers move the trap to a processing location slightly away from the colony. There the animal is weighed, key measurements taken (i.e. body length, tail length, ear size, hind foot length), and gender and age class are established. Individuals are scanned to see if they have a microchip from a previous census. Those without one are given a microchip. Individuals are marked with a black dye on the rump so that researchers have a visual indicator of which prairie dogs have already been assessed. The animal is quickly returned to the same burrow location from which it came.
AZGF biologists analyze the data collected at the trapping. This year’s trend showed that productivity was low due to last year’s dryness and this year’s low rainfall in winter and spring. However, some pups did survive. The forecast for this coming year is that current colony residents will go into the winter well fed, leading to a larger crop of pups in the spring.
Volunteers interested in helping AZGF conduct the Fall 2022 census are welcome to participate. Check for details at https://volunteer.azgfd.gov. People from around the state traveled to the Las Cienegas to be a part of the activities this past Sept. Volunteers aid in nearly every aspect of the census and walk away with a new insight on the prairie dog program.