When plague struck black-tailed prairie dogs in the Thunder Basin National Grassland in Wyoming in 2017, a huge die-off followed. It spelled disaster for the burrowing rodents. But for researchers, it provided an opportunity for a “natural experiment” in the consequences of a single species’ collapse.
Researchers looked at data on prairie dog distributions before and after the plague, along with surveys of the area’s vegetation and its animals — including carnivores such as badgers, foxes and coyotes; deer and elk; and 80 species of birds.
Before the plague, prairie dogs stretched over 10,000 hectares (about 39 square miles) in the grassland. Afterward, they could be found only in an area of less than 50 hectares.
Substantial declines in prairie dog predators in the area followed, the researchers write. Badgers declined to “near-zero” levels, and the numbers of hawks, foxes and bobcats dwindled.
Another factor combined with the prairie dog deaths to change the region’s wildlife. In 2018, abnormally high precipitation dumped 13.3 inches of rain on the area between May and July, up from just 5.4 inches the year before.
The prairie dog population would usually feed on the abundant grass that followed. But without the prairie dogs, the grass grew unchecked. As a result, the numbers of mountain plover, a bird that thrives in short vegetation, dropped to near zero. Other species such as burrowing owls and horned larks dropped, too. In their place came songbirds that prefer tall grasses. One such species, the lark bunting, increased more than threefold.
Prairie dogs play a “critical role” for vegetation and wildlife within their habitats, the researchers conclude, and plague creates a “major conservation challenge” that can affect a variety of species.
More research is needed to help better predict these cycles, they write. Given the likelihood of future animal diseases and climate extremes, they say, collaboration between researchers, landowners and others is needed to help protect other animals from similar cascades after one species’ decline.