Sometimes, it’s the small things that make the biggest difference. Consider viruses. Or electrons. Or prairie dogs.
That last one might seem like a bit of a stretch, but bear with me. A few weeks ago I wrote about the transformative power of Yellowstone’s bison herd. Their revival has led to a cascade of effects across the landscape. Grasses are more nutritious. Microbes are more active creating nitrogen that then helps fuel plant growth.
Well, move over bison. Make way for the lowly prairie dog.
Just a few weeks after the bison paper appeared in Science, scientists working northeast of Yellowstone revealed in the journal Ecology that these small, burrow-dwelling rodents, though more than 600 times smaller, outweigh bison when it comes to their effect on prairie vegetation.
“While the presence of some smaller herbivores such as prairie dogs and grasshoppers may not be as obvious, the impact they have on grassland ecology is considerable,” said Julie Rebh, who conducted much of the research in 2022 as an intern at the Smithsonian’s National Zoo and Conservation Biology Institute.
Rebh’s tried to gauge the effects of herbivores of wildly varying size on the health of grasslands, a critical type of ecosystem that’s under siege around the world by wildfires, invasive species, loss of native species and urban and agricultural development. She set out to compare how northern Montana grasslands responded depending on whether they were being grazed by (in ascending size) grasshoppers, prairie dogs, cows, bison, or some combination.
The experiment used land owned by the state and federal governments and the conservation group American Prairie. Rebh selected 15 different sites to track. Some were grazed just by cattle. Others by bison. Some bison areas also hosted prairie dog “towns” as their colonies are known. Some of those towns were also home to a lot of grasshoppers, while others had none, thanks to insecticides meant to control fleas that can spread prairie dog-borne plague. Other study plots were not grazed by any of these mammals.
When the scientists examined plant tissue and soil collected at each of the sites, a clear pattern emerged. Grasses in places with prairie dogs had higher levels of the nutrients nitrogen, potassium and magnesium. The soil there also had more nitrogen and carbon. Bison and cattle each showed a smaller effect, though there was a correlation with higher levels of phosphorous and magnesium compared to ungrazed prairie.
The prairie dog’s outsized effect could come because of their eating and pooping habits, the scientists surmised. Smaller herbivores tend to dine on higher-quality vegetation, and their feces have been found to have higher concentrations of nutrients like nitrogen.
Rebh’s work also showed an interesting twist on the prairie dog effect. It was strongest in places where there were also grasshoppers. It’s not clear why. Perhaps the presence of grasshoppers made for higher quality vegetation in some way, the authors wondered.
The findings aren’t just a curious footnote. With prairie dog populations at 1% of historic levels, it also suggests that recovering these little animals might be an important part of successful prairie restoration.
Charismatic megafauna like bison are bound to hog the headlines. But give the little guys their due.
Rebh, et. al. “Herbivore effects on plant quality and quantity in a shortgrass prairie.” Ecology. Sept. 10, 2025.
