When carnivores clash: what happens when hunter becomes hunted? - includes related article on saving wolves

National Wildlife, June-July, 1998 by Gary Turbak

Nine wolves rushed to encircle a male grizzly on a Yellowstone hillside, and a clash of wild titans appeared inevitable. That day in 1996, Steven French believed he was about to witness the first documented battle between grizzlies and wolves since the canids were released in the park in 1995. But no attack ever came. "I realized these animals were playing, not getting ready to fight," says French, a researcher with the Yellowstone Grizzly Foundation. The animals romped downhill together and eventually arrived at a rotting elk car- cass. A brief discussion of ownership ended with the 350-pound grizzly chasing off all nine wolves, proving that when predators meet, almost anything can happen.

At first glance, predation seems an easy way to make a living. Hungry? Simply catch something to eat. Tired? Sleep where you will. Armed with talons, claws, fangs and beaks, predators sit safely atop the food chain--right? Not neces- sarily, because often another carnivore stands ready to compete for that tasty piece of meat. Competition may determine when predators hunt, what they kill, how often they eat, where they live and whether their young survive. "Being a predator can actually be a hard way to make a living," says Marsha Sovada, a biologist with the Northern Prairie Wildlife Research Center in Jamestown, North Dakota.

Shy and often nocturnal, predators can be difficult to study, but biologists are gradually unlocking the secrets of how these creatures interact in the wild. Rivalry between species can instantly turn a hunter into the hunted, a predator into prey. Just when these rivalries start to make sense, however, up pops a grizzly that yields to a coyote, or two could-be enemies that become teammates.

One weighty predator drama is currently being staged in Yellowstone, where gray wolves were reintroduced after an absence of about 70 years. Almost immediately, the immigrants began battling coyotes, the park's previous reign- ing canine. The wolves attempted to dig coyote pups from dens, appropriated coyote ranges and attacked adults. Wolves have thus far eliminated about half the coyotes from places where the two species overlap in the park's northern range, according to Bob Crabtree, a wildlife ecologist and director of Yellow- stone Ecosystem Studies, a research group. "Wolves are now the top dog," says Doug Smith, Yellowstone's chief wolf recovery biologist. "And they're swagger- ing through [the park] putting the fear of God in these coyotes."

In addition to their orchestrated return to Yellowstone, wolves also have recently recolonized Glacier National Park and other parts of northwestern Montana. Combined, these immigrations have suddenly put North America's three premier predators (wolves, grizzlies and cougars) in the same habitat for the first time in decades in the 48 states. "Having these three together again creates an extremely valuable natural laboratory," says Howard Quigley, presi- dent of the Hornocker Wildlife Institute (HWI) in Moscow, Idaho. "It's a microcosm of the way things used to be over much of the United States and a great opportunity for predator study."

Because cougars are smaller than grizzlies (160 pounds versus 250 to 800 pounds) and do not travel in packs like wolves, they rank lowest in the tri- umvirate--although one-on-one a cougar would be a formidable opponent for any wolf. "The wolves and cougars behave just like cats and dogs," says Quigley. "The wolves follow cougars around, steal their food and even kill some of the cats. The competition is tremendous." In 1994, HWI researchers in Glacier watched electronically as a young, radio-collared cougar set out to find a home range of its own. A few days later, they found the cat's torn and fed-upon body--obviously the work of a wolf pack.

Though grizzlies likely kill few cougars, they may see the cats as a feline gravy train. Between 1990 and 1995, wildlife biologist Kerry Murphy and other HWI researchers monitored 113 cougar kills (mostly deer and elk) in Glacier and Yellowstone and discovered that bears (grizzlies and blacks) were claiming a significant share of the spoils. Bruins visited about one of every four cougar kills, robbing the feline owner of as much as 26 percent of its food requirement, sometimes for several days running. "It appears," says Murphy, "that competition for kills creates significant gains for bears and sig- nificant losses for cougars."

Wolves and grizzlies have a more complex relationship. With rare exceptions, a lone wolf is no match for a grizzly, but there is strength in numbers and deaths have occurred on both sides. "The relationship seems to be a toss-up," says Toni Ruth, wildlife biologist with the HWI. "Grizzlies sometimes chase wolves off kills, and sometimes wolves do the chasing."

In Yellowstone, French tells of watching two yearling grizzlies and three yearling wolves romp and chase together in what apparently was pure play--while the respective parents looked on. The adult wolves then departed with one offspring in tow, but for two days, the remaining pair of young wolves traveled and hunted with the bears. At mealtime, they ate last, but the grizzlies showed them no real animosity.