By Sharon Levy of Nature magazine
Near the dawn of time, the story goes, Coyote saved the creatures of Earth. According to the mythology of Idaho's Nez Perce people, the monster Kamiah had stalked into the region and was gobbling up the animals one by one. The crafty Coyote evaded Kamiah but didn't want to lose his friends, so he let himself be swallowed. From inside the beast, Coyote severed Kamiah's heart and freed his fellow animals. Then he chopped up Kamiah and threw the pieces to the winds, where they gave birth to the peoples of the planet.
European colonists took a very different view of the coyote (Canis latrans) and other predators native to North America. The settlers hunted wolves to extinction across most of the southerly 48 states. They devastated cougar and bobcat populations and attacked coyotes. But unlike the other predators, coyotes have thrived in the past 150 years. Once restricted to the western plains, they now occupy most of the continent and have invaded farms and cities, where they have expanded their diet to include squirrels, household pets and discarded fast food.
Researchers have long known the coyote as a master of adaptation, but studies over the past few years are now revealing how these unimposing relatives of wolves and dogs have managed to succeed where many other creatures have suffered. Coyotes have flourished in part by exploiting the changes that people have made to the environment, and their opportunism goes back thousands of years. In the past two centuries, coyotes have taken over part of the wolf's former ecological niche by preying on deer and even on an endangered group of caribou. Genetic studies reveal that the coyotes of northeastern America — which are bigger than their cousins elsewhere — carry wolf genes that their ancestors picked up through interbreeding. This lupine inheritance has given northeastern coyotes the ability to bring down adult deer — a feat seldom attempted by the smaller coyotes of the west.
The lessons learned from coyotes can help researchers to understand how other mid-sized predators respond when larger carnivores are wiped out. In sub-Saharan Africa, for example, intense hunting of lions and leopards has led to a population explosion of olive baboons, which are now preying on smaller primates and antelope, causing a steep decline in their numbers.
Yet even among such opportunists, coyotes stand out as the champions of change. “We need to stop looking at these animals as static entities,” says mammalogist Roland Kays of the North Carolina Museum of Natural Sciences in Raleigh. “They're evolving”.
At a fast rate, too. Two centuries ago, coyotes led a very different life, hunting rabbits, mice and insects in the grasslands of the Great Plains. Weighing only 10 to 12 kilograms on average, they could not compete in the forests with the much larger grey wolves (Canis lupus), which are quick to dispatch coyotes that try to scavenge their kills.
The big break for coyotes came when settlers pushed west, wiping out the resident wolves. Coyotes could thrive because they breed more quickly than wolves and have a more varied diet. Since then, their menu has grown and so has their range; they have invaded all the mainland United States (with the exception of northern Alaska) and Mexico, as well as large parts of southern Canada.
The animals that arrived in the northeastern United States and Canada in the 1940s and 50s were significantly larger on average than those on the Great Plains, sometimes topping 16 kilograms. Kays and his colleagues studied the rapid changes in coyote physique by analyzing mitochondrial DNA and skull measurements of more than 100 individuals collected in New York state and throughout New England. They found that these northeastern coyotes carried genes from Great Lakes wolves, showing that the two species had interbred as the coyotes passed through that region. “Coyotes mated with wolves in the 1800s, when wolf populations were at low density because of human persecution,” says Kays. In those circumstances, wolves had a hard time finding wolf mates, so they settled for coyotes.