National Geographic : 2010 Mar
• species downstream through the dry months. Ponds and marshes that form behind the dams create habitat for moose, muskrat, mink, waterfowl, wading birds, and an array of other wildlife. After wolves moved in, cougars that had begun hunting the valleys retreated to the steep, rocky terrain they normally inhabit. e big canines killed nearly half the coyote population. They may have rebounded a bit, but the coyotes now live in groups with shrunk territories or as vagabond " oaters." With less competition from elk for grasses, bison may be doing better than ever. From a single new predatory force on the land- scape, a rebalancing e ect ripples all the way to microbes in the soil. Biologists de ne the series of top-down changes as a trophic cascade. In a nod to the behavioral factors at play, others speak of the "ecology of fear." is a five-foot-two-inch, hundred-pound answer to the question of how dangerous wolves are to people. Over the past four years she has studied wolves, elk, and aspen in Glacier Park, o en on its west side among two large wolf packs, one with 20-plus mem- bers. ey sometimes watch as she and an assis- tant measure habitat features. en the wolves pull out her marker stakes. During a blinding snowstorm, they silently took down an elk a stone's throw from Eisenberg. Our a ernoon survey leads to a trampled- down rendezvous site. The Dutch pack has dragged in ceramic shards, cans, pots, pieces of iron tools from abandoned homesteads in the park. Canine junk collectors. Who knew? But what Eisenberg wants to show me is an aspen stand. Its upper tier consists of towering trees that arose between 1840 and the 1920s, before wolves were eliminated. The bottom row, 15 feet high, is of saplings that shot up a er wolves returned. ere are no aspens in between. None got past the elk's mouths. By contrast with Yellowstone, elk numbers haven't changed much here. As far as Eisenberg can tell, the recent aspen growth is almost all due to wolf-inspired changes in elk behavior. e wolves' diet here is mostly white-tailed deer. Northwestern Montana has at least twice as many cougars as wolves and twice as many grizzly bears. Together they kill more adult deer and fawns than wolves do. Coyotes and black bears take a share as well. On top of that, the area has had two tough winters in a row. Deer totals dropped even where few predators prowl. Yet overall deer numbers remain within the historical average. For that matter, both elk and deer are doing well across the West. As game manager Jim Williams puts it, "With wolves back in the picture along with cougars and bears, we'll have places where elk and deer may never be as abundant again as people remem- ber, and we'll have other places where they'll do ne. ere are bigger drivers than wolves in these systems." Studies have shown that winter weather and the quality of wintering habitat are really what control deer and elk populations over time. at and human hunting. Craig Jourdonnais is the state game depart- ment's wildlife biologist for Montana's Bitterroot Valley, near the Idaho border. Until recently, he says, most gripes about wildlife concerned elk raiding haystacks and deer damaging crops and gardens and being a danger on highways. "Now we have 10 to 12 wolf packs for a mini- mum of 45 to 60 wolves. We also have 14,000 hunters coming through the Bitterroot check station in a given year." e main complaints he hears these days are about wolves overrun- ning the place and wiping out elk and deer. "I've been on the job 30 years, and I've never worked with any critter that raised so much emotion." Somehow, Jourdonnais is supposed to make a (Continued from page 43) Large mammals are learning and changing their behavior all the time: deer, elk, bears, wolves, and yes, humans too.