How Coyotes Are Helping Other Species
February 12, 2016
It wasn't too long ago that Steve Colvin could count on a bountiful fox harvest on his central Virginia trap line. A typical season would produce a "couple hundred" cherry-pelted foxes. Now, however, the fifth-generation trapper might catch 50.
"As soon as coyotes started showing up, our fox numbers started going down," says Colvin, president of the Virginia Trappers Association and a full-time nuisance animal trapper.
He caught the first known coyote in his home county in 2001 and he is on track to catch close to a hundred throughout his trapping territory during the 2014 season. Colvin still catches red foxes, but nowhere near the number he used to, and those he does catch are different creatures.
"Many of the nuisance calls I go on in cities like Charlottesville and Richmond are for red foxes. That was rare five or ten years ago, but it's very common now. People have them living under their houses or outbuildings or I find them right next to roads," he says.
It's a trend that is taking place throughout historic red fox range, including North and South Dakota, where red foxes were once abundant and coyotes were virtually non-existent. Coyote numbers were kept low throughout much of the 20th century thanks largely to government-sanctioned poisoning, aerial gunning and hunting from snowmobiles.
"Up until about 20 years ago, there were a lot more people out riding around the countryside with a rifle in their truck, as well. Any time they saw a coyote, they shot it. That's just what people did back then," says retired US Geological Survey research biologist Alan Sargeant. "As the rural population declined and poison and aerial hunting were banned, we just aren't killing coyotes in the numbers we used to. Their numbers went up and fox numbers went down."
Coyotes do kill foxes on occasion. Research on the impact of coyotes on swift foxes in Colorado found that coyotes are the primary source of mortality among the smaller canids. Colvin recalls finding dead adult red foxes as well as dead fox pups near dens that had been dug up. He suspects coyotes were the culprits. Sargeant says while coyotes will kill foxes, the smaller predator mostly avoids the larger one just as freshmen tend to avoid the senior football players in the high school hallway. In fact, he recalls seeing foxes walking near coyotes without any fear on numerous occasions.
Mostly, though, they seem to have no interest in sharing the landscape with coyotes, so foxes in parts of the Dakotas now live where coyotes normally won't go — near human development. It's a phenomenon known as human shielding, says Oregon State University wildlife professor Dr. William Ripple.
Coyotes are undergoing the same behavior in the Greater Yellowstone Ecosystem, thanks to the addition of wolves to the landscape. However, instead of burrowing under barns and homes, they are learning exactly how much distance they need to keep between themselves and wolves and people in order to survive.
"It's pretty common to see them right next to roads inside Yellowstone Park because wolves won't normally get close to roads. The coyotes know they are safe," says Ripple.
Coyote populations fell by as much as 50 percent after the introduction of wolves into the national park, according to one study. However, the study's co-author, Michigan Tech professor Dr. Rolf Peterson, isn't sure what percentage of that decline can be attributed directly to wolf-related mortality.
"Wolves certainly kill coyotes, but we don't know how often that is. I suspect that in most cases, the coyotes simply leave and find a sort of safe area where there are no wolves," he says. "I talk to trappers in Michigan who say coyotes vanish from an area as soon as wolves show up. They aren't finding coyote carcasses. They just aren't finding any coyote sign at all."
Wolves, however, don't seem bothered by the presence of foxes, notes Ripple. As such, the reintroduction of wolves into the Yellowstone region seems to have benefited red foxes. That's because wolves are generally unable to catch foxes, while coyotes, which are more agile than wolves, can catch a fox.
"There's no question wolves kill foxes, but all the fox kills I've found have been on frozen lakes. Wolves can outrun a fox on open ground, but they probably have a much more difficult time catching them in trees because foxes are just more agile," says Peterson. "Wolves will kill anything they perceive as competition as long as it does not cost them anything. When they kill a fox or coyote, they usually just continue on their way. They don't eat it."
Eaten or not, a dead coyote is nothing but a good coyote in the mind of many hunters. The impact of coyotes on whitetails in the southeastern United States is well-documented: The predators are taking a heavy toll on fawns. As a result, deer numbers have slipped in some regions.
Despite that, competition among predators may actually benefit some game species. Research conducted in North and South Dakota found that duck nest success was considerably higher in areas with higher coyote populations. Sargeant says that's a direct result of the coyote-fox population dynamic.
"Coyotes rarely eat duck eggs or nesting hens, but foxes are a major factor in nest predation, so more coyotes equal more ducks," he says.
The same dynamic may be occurring throughout the southeast. The theory is that coyotes are killing or displacing ground-nesting bird predators such as raccoons, possums and armadillos and benefiting quail and turkeys in return. However, Dr. Theron Terhune, game bird program director at Florida's Tall Timbers Research Station, says it's unlikely the growth in coyote numbers in the southeast is having much impact.
"We know it's very rare for coyotes to depredate the eggs of ground-nesting birds, but they don't do a near good enough job controlling major nest predators, either. Small mammals produce so many offspring, coyotes just can't keep up to have any significant impact on their numbers," he says.
They can have a major impact on foxes, though. Just ask Steve Colvin or anyone else that runs a trap line where red foxes used to be abundant.