Predator control: two words to raise the hair on the back of the neck of many a good environmentalist. The gruesome images spring readily to mind, of paws chewed off in leghold traps, aerial gunning, cyanide capsules, Compound 1080, baby critters gassed in their dens.
Traditionally, predators have been killed by government agencies for the sake of livestock or game — that is, for private human advantage. Lately, however, it’s getting more complicated. Some blue-chip wildlife biologists are controlling predators for the sake of rescuing endangered or declining species. Sound risky? It is — and controversial, too.
An excellent place to look at some of this controversy is the vast sagebrush steppe of southern Idaho. What boring country it seems, mile after dull gray mile of boring — the kind of place you want a good, long book on tape, as you blast through it at 80 mph on your way to the wildflowers, skiing, elk, forests and/or bears of the mountains. An occasional jackrabbit dead by the roadside, an occasional far cloud of pronghorns. Scraggy cattle crowding a stock tank. The sagebrush steppes feel eternal, unalterable, lifeless, the empty place between everything else.
We all know better, though it may sometimes be hard for the heart to feel it. We know that these places between give life to the high country. They are winter range, migration corridors, spring growth when the mountains are still under snow, fall grass when summer’s meadows are gnawed bare. The sagebrush steppes and the dry grasslands among them are a world of their own, splendidly rich, vulnerable, much abused — and neglected by many of us mountain-loving passers-through.
There is great debate on the sagebrush steppe over one humble, round-bellied denizen: the sage grouse. The species has been gradually declining for a hundred years, and it is now in real trouble (HCN, 2/4/02: Last dance for the sage grouse?). In an effort to save the sage grouse, in 2001, the Idaho Department of Fish and Game, in conjunction with the U.S. Department of Agriculture’s Wildlife Services agency, proposed to kill a wide range of predators — from ravens to badgers — that make meals out of the birds and their eggs and chicks.
The plan met a fusillade of protest, and it was quickly, though temporarily, enjoined in federal court. When it resurfaced in 2002, a coalition of conservation groups — Defenders of Wildlife, the Committee for Idaho’s High Desert, the Idaho Conservation League and the Western Watersheds Project — filed suit against the plan, describing it as a "poorly thought-out and totally unjustified killing of thousands of animals across a huge swath of southern Idaho." They said Wildlife Services, which was formerly known as Animal Damage Control and has increasingly found itself in the harsh glare of public scrutiny, had just found a new rationale for its inveterate war on predators.
The story of the fight in Idaho shows that predator control, railed against for decades by wildlife advocates, is very much alive throughout the West. It raises a wide range of fascinating questions about how humans ought and ought not to intervene in human-altered ecosystems. And it poses philosophical and ecological dilemmas that we in the West are going to be wrestling with for the rest of our lives.
AN AMBITIOUS EXPERIMENT
Alma Winward puts the quandary plainly. "In a healthy sagebrush ecosystem, predators aren’t a problem for sage grouse," says the retired regional ecologist for the U.S. Forest Service. "They evolved with predators, after all." The rub lies in Winward’s term "healthy sagebrush ecosystem." We’ve been stamping out natural small fires in sagebrush country for as long as a century, leading to dense canopies that shade out understory growth. At the same time, catastrophic large fires, fueled by the invasion of non-native cheatgrass, wipe out sage landscapes by the dozens of square miles — reducing and fragmenting sage grouse habitat (HCN, 5/22/00: Save our sagebrush).
In addition, overgrazing thins out both brush and grasses — making grouse easier to spot for coyotes, foxes, badgers, hawks, owls and eagles. Nest raiders like ravens and magpies also find easier pickings.
Other human-caused changes have also increased predation on sage grouse, at least indirectly. Farming, says University of Idaho biologist Kerry Reese, seems to be associated with a tremendous increase in red foxes. The extirpation of the wolf probably brought about a big increase in the numbers of coyotes and other medium-sized carnivores, all of which prey on sage grouse (as wolves virtually never do).
Which predators do how much of the damage, nobody knows. "There’s no single predator that specializes in sage grouse," says Reese. "So there’s no use in targeting a single predator."
Thus, the wide-ranging Idaho plan, which had its genesis in a smaller experiment. "Idaho Fish and Game came to us, saying sage grouse were in trouble in the Curlew Valley area," says Mark Collinge, state director for Wildlife Services. The agencies decided to test predator control. They set out 50 artificial sage grouse nests in two similar areas there, baited with chicken eggs, and within a week, predators had destroyed about 60 percent of the nests. Then came a month’s worth of predator control in one of the two areas.
"In the untreated area, 98 percent of the nests were destroyed," says Collinge, "but in the treated area, only 28 percent were destroyed."
The state then proposed a much more ambitious plan. First, the agencies would select five to seven areas of sage grouse habitat, each between 75 and 100 miles square. Then, in three or four of those areas, between February and June — when sage grouse chicks are especially vulnerable — government agents would trap, poison and shoot the whole range of sage grouse predators, with the exception of raptors, which are protected by law. "Bobcats would not be specifically targeted, but ... would be considered target animals and would be killed," according to Wildlife Services’ environmental assessment. Coyote pups, fox kits, and other young, left orphaned in their dens, would be humanely dispatched — when they could be found.
The intention of the plan was not to wipe out predators, according to the environmental assessment, "but rather to temporarily reduce their numbers to a point where they would be unlikely to have a detrimental impact on sage grouse nesting success and chick survival."
In the two or three other areas, no predators would be killed. On both the "treated" sites and the nontreated, the sage grouse chicks would be equipped with tiny transmitters so that biologists could monitor their fate. This would be repeated for two or three successive years, and then there would be a rest period of a year or two, during which predator populations might be expected to recover in the treated areas. Finally, Wildlife Services would kill predators in the untreated areas, while the original treatment sites became the new controls.
A CASCADE OF CONSEQUENCES
Questions about the proposal abound. Do we have any idea what the indirect effects of our interventions are? If we did reduce the whole suite of predators, what would be the effects on all the prey animals that aren’t sage grouse? What would be the effects on populations of nontargeted predators? And what would the effects of those effects be?
We know that when we intervene on a big scale, changes cascade vertically through every level of an ecosystem, and horizontally across immense stretches of time. Understanding those changes in terms of traceable cause and effect, however, is almost unfathomably complex.
Consider the story of the bighorns of the Great Basin of Wyoming, Utah and Nevada. A hundred years ago, much of the Great Basin was grassland, poor habitat for mule deer. Pronghorn antelope and bighorn sheep were both present, but they made inadequate prey for mountain lions — the former too fast, the latter too few — so there were no mountain lions there. Then came cattle, domestic sheep and fire suppression, which together, over time, turned the grasslands into shrublands — good habitat for mule deer, of which there was then an influx. The deer were followed by mountain lions, which are now snacking on the now-isolated bighorns, whose populations in turn have declined, sometimes sharply.
Consider also the return of the wolf to Yellowstone, which began in 1995 (HCN, 2/6/95: The wolves are back, big time) — and which may have surprising relevance to sage grouse. The still-unfolding ramifications of that species’ restoration beautifully illustrate an ecological principle critical to our worry about sage grouse and other declining species — especially if we’re thinking about large-scale predator control: the trophic cascade.
A trophic level (from the Greek trophikos, from trophe , nourishment) can be thought of as a group of organisms that feed in more or less the same way. Generally, trophic levels are divided into four groups. The lowest level is made up of the worms, bacteria, and other little creepy-crawlies that turn dead things into soil — in short, decomposers. The next level up is the primary producers — aka, plants. The third trophic level is occupied by the herbivores that eat the plants, and the fourth by the carnivores that eat the herbivores. Some of the most dramatic trophic cascades happen when you intervene at the carnivore level — and the consequences shimmer like waves through the other trophic levels.
Here’s how the phenomenon seems to be working in Yellowstone’s famous Northern Range. By the mid-1990s, beavers had disappeared from the whole stream system in the Lamar Valley and the upper tributaries of the Yellowstone River. The hypothesis was that the very large population of elk tended to clip off every little willow or aspen sprout that dared to show its head. Aspen groves entirely lacked trees of any age other than newborn and ancient. The cottonwood bottoms were the same: geriatric communities. Willows, once the ubiquitous soft outline of every stream in northern Yellowstone, were down to knobbly stumps, no sooner sprouted than pruned (HCN, 9/15/97: Is nature running too wild in Yellowstone?). Aspen, cottonwood and willow are the sine qua non food and building material of the beaver. Lose them, lose the beaver. Lose also songbird nesting habitat, perches for raptors, streambank stabilization, coarse woody debris from which holding pools and spawning gravels form for cutthroat trout, and a few hundred other nice things.
Enter the wolf. The most noticeable immediate effect was havoc in the coyote population. Wolves really have no use for coyotes whatever. They killed every adult coyote they could catch, they dug infant pups out of their dens. In due course, there will be effects on all the many creatures that coyotes prey on — and on those creatures’ food plants, hence on habitat structure, and so on and on.
The ecologically most powerful effect of the wolf’s return, however, was on its primary prey, elk. "We haven’t seen a significant reduction in elk numbers yet," says Doug Smith, the wolf project leader for Yellowstone National Park, "but elk distribution has changed." The casual streamside stroller, dipping her head for an occasional nip of willow sprout, has been replaced by the shadowy skulker hanging uneasily back in the forest edge, ears and nose twitching for sound or scent of wolf.
As a result, says Smith, "we’re seeing aspen and willow returning to the riparian zones." Meanwhile, in the headwaters of Slough Creek on the adjacent Gallatin National Forest, reintroduced beavers are spreading down into the returning aspen, willows and cottonwood of the Northern Range as fast as they can munch.
Raptors, nesting songbirds, trout, and trout fishermen will all benefit from the regrowth of riparian woodland, and all sorts of scavengers are already dining on the wolf packs’ slovenly leavings — coyotes (very cautiously), foxes, ravens, grizzly bears.
What will be the next effects? Predictive ecology is a notoriously uncertain art, but Doug Smith believes that the trophic cascade begun by the return of the wolf to Yellowstone "is going to take decades to unfold, and to understand it all, we’re going to have to do really comprehensive and long-term research."
THE IMPORTANCE OF BIG MEAT-EATERS
The wolf’s return is particularly dramatic, because the wolf is what ecologists have come to call a "keystone species." Keystone species are capable of causing changes out of proportion to their abundance, and far beyond their immediate realm. The metaphor derives from the central stone at the top of a classical arch — lose that one, and your arch falls to pieces. Yank out a keystone species, and chaos ensues. Put one back in place before everything has fallen apart, and you may have saved an ecosystem from ruin.
Witness the story unfolding in Grand Teton National Park. Ecologist Joel Berger of the Wildlife Conservation Society studied moose in Grand Teton, a place where, for about 75 years, moose had been untroubled by wolves, grizzly bears or human hunters. He compared that habitat with one that was basically the same but had been hunted by humans, on the Bridger-Teton National Forest.
The moose population was five times more dense in the national park study area, and, says Berger, "Those moose had really hammered the riparian vegetation." As a result, songbird species diversity had been drastically reduced. Two bird species present in the national forest were gone altogether from the supposedly protected national park area.
Now, the Yellowstone wolf population is moving in nicely, and the grizzly population is growing as well. "In Alaska and the Yukon," says Berger, "the carnivore communities are intact, and grizzlies and wolves kill about 90 percent of the juvenile moose every year. So as grizzlies and wolves return to Grand Teton, we might predict a decrease in the moose population. And if so, then we can expect improvement in the riparian vegetation, and that’s going to mean more food, cover and nesting sites for songbirds."
Again, it was the loss of keystone species — the wolf and the grizzly — that put moose country in Grand Teton out of whack, and it is the return of those keystone species that is setting it straight again.
PREDATOR CONTROL — AN INDISPENSABLE TOOL?
In the absence of the wolf keystone, then, mightn’t Idaho’s sage grouse country now be unnaturally overloaded with coyotes and other medium-sized predators — making Wildlife Services’ idea at least partly right? After all, as Aldo Leopold wrote, "To keep every cog and wheel is the first precaution of intelligent tinkering." And that means using every tool in the box — including one that doesn’t sit well with some conservationists: predator control. More and more biologists trying to save species are finding it useful.
Non-native lake trout were discovered in Yellowstone Lake in 1994, and they have proved to be voracious predators on the native Yellowstone cutthroat trout. In one of the most ambitious, and costly, predator control programs ever undertaken, the National Park Service has gill-netted some 56,000 lake trout so far, at a cost of nearly $1.5 million. "In 1995," says John Varley, director of the Yellowstone Center for Resources, "the ratio of lake trout to cuts was one-to-one. We’ve now got it to one lake trout for every 280 cutthroat."
The Turner Endangered Species Fund is conducting conservation experiments on a number of Ted Turner’s vast land holdings, under the leadership of Mike Phillips, formerly chief biologist of the Yellowstone wolf reintroduction. At the Bad River Ranch in South Dakota and on the nearby Fort Pierre National Grassland, the Turner group plans to reintroduce the rare swift fox — and, says Phillips, "We’ve got to knock the hell out of the coyotes at the beginning. It won’t last long. Killing coyotes is like pouring water into a bucket with a hole in it."
On the Armendaris Ranch in the Fra Cristobal Mountains of New Mexico, the Turner biologists are working to restore desert bighorn sheep — and have been able to increase the population only after killing a number of mountain lions.
Mike Lockhart, the leader of the black-footed ferret recovery effort for the U.S. Fish and Wildlife Service, says that at the reintroduction site at Badlands National Park in South Dakota in 1994, some of the local great horned owls started in on the newly released ferrets. The poor captive-raised ferrets had no clue — they’d never seen an owl, or any other predator — and the owls kept coming back for more. "We popped a few owls," says Lockhart, "and the problem was over."
Another ace ferret killer is the coyote. At some sites, wildlife managers have experimented with killing all the coyotes in the area just before the ferrets are released to the wild. "They’re just vulnerable for the first few days," says Lockhart. "New coyotes come in pretty quickly, but by then the ferrets are okay."
Predator control can serve a surgical role on a small scale, but, adds Lockhart, it doesn’t override the long-term solution that reintroducing keystone species would provide: "My idea of a great ferret recovery area," he says, "would be one with a lot of wolves."
In wolf country, coyotes are usually confined largely to the buffer zones between wolf packs, areas typically about four miles wide. In other words, there used to be a lot fewer coyotes. Before we wiped out the wolf and turned America into a great civilization, coyotes didn’t even exist east of the Great Plains. Now they’re nabbing cats off the porch in the suburbs of Atlanta. One poor lost soul turned up in New York City’s Central Park.
Studies by Wildlife Services — the agency that carries out most coyote control, to the tune of about $10 million per year — show that you can kill up to about 70 percent of a coyote population, year after year, without ultimately reducing it. When you kill a whole bunch of coyotes, there’s more food available for those remaining alive — which translates to bigger litters and higher pup survival. Also, as Mike Phillips notes, other coyotes will quickly recolonize any habitat you’ve rendered vacant.
Wildlife Services has a stack of studies showing magnificent successes — "benefit-to-cost ratios from 3:1 to 27:1 for agriculture and 2:1 to 22:1 for wildlife protection." Their opponents can show you the opposite. For example, in one federal program in Idaho, according to Defenders of Wildlife, the costs were "$167 per coyote killed, $368 per extra deer produced, and $1,262 per huntable buck deer produced."
COULD WOLVES DO THE JOB?
What might happen to sage grouse predators if wolves returned to southern Idaho? Certainly coyotes would be fewer. Wolves are already moving into the sagebrush steppe, as colonizers move out from the now-established wolf populations of Yellowstone and central Idaho (HCN, 2/26/01: Return of the natives). Of all the different kinds of tinkering we subject our ecosystems to, perhaps the safest — in a sense, the most conservative — is the restoration of keystone species. It’s conservative because it allows an ecosystem to re-assemble itself along natural patterns. "In the long run," says conservation biologist Michael Soulé, "without restoration of top predators, we’ll never be able to protect most biodiversity."
Yet we can’t seem to rethink our strategy. When something’s out of whack in an ecosystem, our response is nearly always the same: Let’s get in there and kill something — or, as in the Idaho sage grouse plan, a whole bunch of things.
It may be true that reducing predation in certain parts of the sagebrush steppe would benefit sage grouse recovery. But shouldn’t we first try some habitat improvement? Mightn’t we monitor sage grouse and predator populations where wolves are beginning to colonize southeastern Idaho and (soon) northern Utah? The sage grouse certainly evolved with predation over thousands of years, but the mix of predators is quite different today, and some sage grouse habitat may be irreparably damaged. Can we somehow compensate for those changes?
If we do, in the end, decide to do some predator control, shouldn’t we first know precisely which predators to target, and precisely where? And shouldn’t we consider the secondary and tertiary effects, and at least try to project the possible changes down through the food chain? Why do we seem to be incapable of the three-bumper shot that an intentional trophic cascade would have to be? Or should we in fact wait until we’re capable of seventeen-bumper shots?
"The older I get," says wildlife biologist John Weaver of the Wildlife Conservation Society, "the more skeptical I become of large-scale interventions, because we truly know so little about ecosystems — usually not enough even to ask the right questions."
In the U.S. district court for Idaho in March, a judge apparently concurred with this assessment. Proponents and critics of the Idaho plan had made their cases over the previous few months. The crux of the legal debate boiled down to this: Wildlife Services had concluded that, under the terms of the National Environmental Policy Act, its plan would have "no significant impact" — and hence was not a big-enough deal to require a full environmental impact statement, with extensive public participation and substantive environmental analysis.
The plaintiffs argued that it was a very big deal indeed. "Killing 75 percent of all the predators on 1,300 square miles?" said lead attorney Todd Tucci of Advocates for the West, an environmental law firm based in Boise, Idaho. "That’s huge. Of course, they should have done an EIS." To make matters worse, he said, the agency had never examined the specific sites where the experiment would be carried out — sites that would include wilderness study areas, areas of critical environmental concern, and crucial habitat for a number of species.
Some of the critics’ strongest testimony came from Ted Chu, a former regional wildlife manager for Idaho Fish and Game, who has studied sage grouse extensively. "During my 30 years of employment with the Idaho Department of Fish and Game, I was periodically directed to invent projects for Wildlife Services (then called Animal Damage Control)," he said. "This proposal is top-down driven, and is not supported by the professional biologist staff of the Idaho Department of Fish and Game, except as under duress."
Chu wound up with a wallop: "Even if Wildlife Services is correct in their contention that predators are depressing sage grouse populations, in spite of overwhelming evidence to the contrary, their unblemished record of futility in attempting to control predator populations would indicate this proposal too is a waste of time and money."
Finally, on March 4, Judge B. Lynn Winmill released a summary judgment. He stated that not only did Wildlife Services fail to study the specific areas where it intended to kill predators, but it based its entire plan on the concept of "floating" study sites, meaning that the sites could be changed as the experiment proceeded. The plan assumed that after predators were shot and poisoned out of the study areas, they would be repopulated by predators in the surrounding steppe, yet "(Wildlife Services) never studied adjacent areas." In the end, the judge concluded that Wildlife Services had acted arbitrarily in issuing the finding of "no significant impact." In short, the agency had violated the National Environmental Policy Act. The predator control plan was dead — for now.
"Our view," said Rodger Schlickeisen, president of Defenders of Wildlife, "is that while Wildlife Services claimed that the purpose of this was to protect the grouse, the truth of the matter was it was an attempt to broaden the scope of their traditional predator control program. We saw it as very ill-conceived, and we’re very grateful that it was defeated." That battle may be over, and it may not. The agencies can appeal, or try a modified plan.
Regardless, the practical question raised in the Idaho sage grouse case is a broad one: Can we entrust the recovery of declining wildlife species and damaged ecosystems to agencies that have consistently failed to consider the large-scale and long-term implications of their interventions? The issue is not whether predator control is some sort of evil, heedless slaughter. We know that it can be useful; even, perhaps, in a few cases, indispensable. We’re learning that tinkering can be intelligent. We can learn from trophic cascades. We can learn from keystone species.
The ultimate question raised in Idaho is one of human nature, and a very old one at that: Can we ever learn to think beyond the nearest horizon?
Thomas McNamee writes from San Francisco. He is the author of The Grizzly Bear, Nature First: Keeping Our Wild Places and Wild Creatures Wild and The Return of the Wolf to Yellowstone.