Not just a predator
Wolves bring a suprising ecological recovery to Yellowstone
LAMAR VALLEY, YELLOWSTONE NATIONAL PARK -- It's a morning of freezing rain in the valley and a pack of wolves is roaming around Black Tail Creek. A few pups gnaw on an old elk carcass while some adults scout the nearby valleys for prey. Not far away, a few elk have sensed the impending danger and are dashing about. To the tourists in the park, the prospect of a wolf attacking an elk is riveting. To the biologists staring into their binoculars, the real action is taking place in Black Tail Creek itself.
There, a cluster of willow plants is flourishing along the creek bed -- a small but crucial sign that wolves are boosting biological diversity and restoring balance to America's oldest national park.
According to numerous biologists and wolf-watchers, the willows have grown because the elk, worried about staying too long in open streambeds, no longer gorge on the nutritious plants. Since the reintroduction of wolves in 1995, the elk have been increasingly itinerant and drawn up out of the wetlands to high rocky areas where they eat more grass. As hunters, soldiers, and elk all know, streambeds and valleys are dangerous. Attackers can scout from up high and pounce.
This is just one of the biologically salutary effects that wolves may have brought to the park, restoring a centuries-old balance that was upset when humans exterminated Yellowstone's wolves in 1926. Though no peer-reviewed proof exists of their impact on the willows, wolves may well be demonstrating their role as a "keystone species," an animal whose presence in the area increases diversity and overall ecological health -- even as they spend much of their time lunging at other animals' throats.
"Wolves are to Yellowstone what water is to the everglades," said Doug Smith, the National Park Service's director of the Wolf Restoration Project.
Willows help the park's northern Lamar Valley, which was beggared of the plant before the wolves returned, in several ways. For one, they provide a decent nesting and migratory stopover site for many birds. According to Roger Pasquier, an ornithologist with Environmental Defense, several bird species that nest in the park could particularly benefit, including the yellow warbler, warbling vireo, and the tellingly named willow flycatcher.
Perhaps more important, beavers thrive on willows and those waddling creatures have recently returned to the Lamar Valley after a long absence.
Wolves do eat beavers, but the beavers seem to be quite willing to exchange a small chance at ending up in a wolf's belly for a good chance at their own tasty willow lunches. There are now four beaver colonies in and around the valley. There were none before wolves returned. One colony even lives right near a wolf den.
Almost wherever they exist, beavers create biological diversity when they build pools of slow-moving water around their dams. These pools create habitat for otters, muskrats, insects, moose, and many bird species.
Wolves also appear to be helping other larger species. Rick McIntyre, another wolf biologist in the park who has tracked the animals by radio nearly every day for more than three years, notes that many scavenging species, such as ravens, magpies, and even grizzly bears, eat the leftovers from wolf kills. A pack of wolves generally eats only about half of each of its kills, leaving plenty for other species to dine on.
A number of scientists caution that much is still unknown. "You can expect changes as a result of wolves being [introduced] in an ecosystem," said David Mech, a biologist with the US Geological Survey who has done wolf research in Yellowstone. "But I have been cautioning people not to jump to conclusions. It's early." Mech adds that wolves could also bring about potential unhelpful biological change, for example through the cascading effects of the reduction in the coyote population.
Smith acknowledges the large uncertainty over future effects and concedes that there isn't absolute scientific certainty either that the willows have regrown or that the wolves deserve credit. But, he said, "when I walk over to Black Tail Creek, I see willows that are over my head. Five years ago, they were barely at dirt level." Smith also has studied aspen trees, another key species for many animals that appears to be doing slightly better than before wolves were reintroduced.
When it comes to aspen and willows, changes in elk behavior seem to have much more effect than changes in the elk population. The National Park Service has tried several times to help plant species by killing elk, with little impact. In the mid-1960s, the Park Service tried killing elk hoping that would restore aspen growth. But it "didn't have any effect on the aspen," according to John Good, a now-retired Park Service employee who participated in the elk hunts.
Instead of simply killing them, the wolves -- who hunt year-round and at night -- keep the elk on their hooves all the time. According to Carl Swoboda, director of Safari Yellowstone, "The elk used to be relaxed. They'd go up to everyone and shake their hands and say `welcome to Yellowstone.' They even said that to the first wolves."
In 1995 and 1996, wolves from Canada were brought to Yellowstone and to central Idaho. Similar efforts by activist groups to restore wolves to the Adirondacks and northern Maine have not gone far. Currently, about 250 wolves live in Yellowstone and the surrounding area, a number unlikely to increase since wolves tend to kill each other off at higher population densities.
Local ranchers have long opposed wolf reintroduction, fearing livestock predation. Wolves, however, have killed far fewer livestock than even the biologists predicted, and coyotes killed 28 times more sheep and lambs in 2002 than wolves did, according to the Montana Agricultural Statistics Service.
Proponents of restoration noted the potential biological benefits, increased tourism, and a sense that there is something special about restoring a dangerous mammal that roamed across the continent before humans killed most of them off.
"It's almost like we are making up for what we did to them," said Tony Martinez, a visitor to the park who drove from Colorado to scout the wolves. "Sometimes just thinking about them back here brings me to tears."
© Copyright 2003 Globe Newspaper Company.