Compared with the ancestral coyotes from the plains, the northeastern coyote–wolf hybrids have larger skulls, with more substantial anchoring points for their jaw muscles. Thanks in part to those changes, these beefy coyotes can take down larger prey; they even killed a 19-year-old female hiker in Nova Scotia in 2009. The northeastern coyotes have expanded their range five times faster than coyote populations in the southeastern United States, the members of which encountered no wolves as they journeyed east.
New to the city
Coyotes have even moved into Washington DC, appearing in Rock Creek Park in 2004, just a few miles from the White House. Christine Bozarth, a conservation geneticist at the Smithsonian Institution in Washington, has tracked their arrival and has shown that some of them are descended from the larger northeastern strain and carry wolf DNA. Bozarth says the coyotes are there to stay. “They can adapt to any urban landscape; they'll raise their pups in drainage ditches and old pipes,” she says. She hopes that the coyotes will help to control the deer, whose numbers are booming. But Kays says that coyotes have not made a significant dent in the northeast's deer population. “Coyotes fill part of the empty niche, but they don't completely replace wolves,” he says.
Oddly enough, it is the smaller coyotes in the southeastern United States that seem to be having a real impact on deer. About the same size as western coyotes, the southeastern ones have begun to exploit a niche left empty by the red wolves (Canis lupus rufus) that once roamed the southeast and specialized in hunting the region's deer, which are smaller than those in the northeast.
John Kilgo, a wildlife biologist with the US Forest Service in New Ellenton, South Carolina, and his colleagues found in a 2010 study that South Carolina's deer population started to decline when coyotes arrived in the late 1980s. More recently, he and his colleagues have studied deaths among fawns, using forensic techniques right out of a murder investigation. They analyzed bite wounds on the carcasses and sequenced DNA in saliva left on the wounds. They also searched for scat and tracks left by the killers and noted how they had stashed uneaten remains. More than one-third of the fawn deaths were clearly caused by coyotes, and circumstantial evidence suggests that the true number might be closer to 80%. “Coyotes are acting as top predators on deer, and controlling their numbers,” says Kilgo.
At first, many researchers had a hard time accepting that conclusion because they thought that coyotes were too small to affect deer populations, Kilgo says. He hopes to study how the newly arrived coyotes will affect other members of the southeastern ecosystem, including wild turkeys and predators such as raccoons, foxes and opossums.
There is no danger that the southeastern coyotes will drive the abundant deer in that region to extinction. But at the northern extreme of their range, coyotes are threatening a highly endangered band of woodland caribou (Rangifer tarandus caribou) in the mature forests of Quebec's Gaspésie National Park. Logging and other changes there had taken a toll on the caribou even before coyotes arrived in the region in 1973 and settled into newly cleared parts of the forest. But then coyotes started hunting caribou calves and the population dropped even further.
A 2010 study found that coyotes accounted for 60% of the predation on these caribou, which now number only 140. Dominic Boisjoly, a wildlife biologist with Quebec's Ministry of Sustainable Development, Environment and Parks in Quebec City, says that the best way to protect the caribou would be to cease clear-cutting of the forest, thereby denying the predators a home.
Coyotes have been taking advantage of the changes wrought by humans for many thousands of years, according to a study of coyote fossils published this year. Evolutionary biologist Julie Meachen at the National Evolutionary Synthesis Center in Durham, North Carolina, and Joshua Samuels at the John Day Fossil Beds National Monument in Kimberly, Oregon, made that discovery by measuring the size of coyote fossils dating back over the past 25,000 years. During the last ice age, coyotes were significantly larger than most of their modern counterparts and resembled the biggest of the present-day coyote–wolf hybrids in the northeast. They probably scavenged meat from kills made by dire wolves and saber-toothed cats, and preyed on the young of the large herbivores, such as giant ground sloths, wild camels and horses, that thronged North America at that time.