The coyote effect

The coyote population at Fermilab has recently plateaued after a steady 15-year increase. Photo: Marty Murphy, AD

In the 1990s, Fermilab Lead Groundskeeper Jim Kalina would often get called upon to remove a raccoon that had taken up residence above the ceiling of a laboratory building.

“I would have to crawl around in the buildings, up in the attics, trying to get the raccoons out,” he said. “But now with the coyotes, we rarely have that problem.”

The coyote population at Fermilab has steadily increased since 1998, Kalina said, though it has plateaued of late, since predator populations tend to limit themselves. Since the ’90s, there’s also been a correlated drop at the lab in populations of foxes, opossums, raccoons and squirrels. Even the geese population has shrunk, though their smarter nesting habits—laying eggs near places that humans frequent and away from places coyotes can get to—keep them highly visible.

Whether the uptick in coyote numbers is good or bad news for the ecology of Fermilab’s 6,800 acres of prairie depends on the view you take.

“We have to remember the complexity of the whole thing, the ecosystem,” said scientist Peter Kasper, AD, who monitors the bird population at the laboratory. “One small change can have domino effects all over the place, in all sorts of surprising ways.”

For Fermilab’s Roads and Grounds crew, the coyotes have been a positive influence. Far fewer woodchucks, for example, are around to chew on the bison pasture fence posts or to burrow through the berms that shield the accelerator tunnels.

“I used to be a hunter,” Kalina said. “I hated foxes and coyotes going after game. But I learned that they’re an essential part of the ecosystem.”

At the same time, with the decline of rodents and other prey in the cold seasons, predatory birds that used to winter at Fermilab, such as the short-eared owl and rough-legged hawk, are an increasingly rare sight as well.

“Coyotes come in and can change the balance,” Kasper said. “Bird populations today are not the same as what they were before.”

Since Roads and Grounds began keeping electronic records of wildlife incidents, the rodent population is at a low, which means that, for now, it’s unlikely that the established coyote population will allow additional coyotes on site.

“Coyotes don’t kill other coyotes, they just let others know they don’t belong there,” Kalina said, noting that roughly 30 pairs of coyotes currently inhabit the lab grounds.

So where were the coyotes 20 years ago, when nary a one was to be seen at the lab? A hard-hitting sarcoptic mange epidemic in the northern Illinois region routed them, said Fermilab Ecologist Rod Walton.

Who can predict what the lab’s ecosystem will be like 20 years from now?



The decline of the rough-legged hawk population at the lab is likely due to the reduction in prey populations. Photo: Dave Spleha