Predator Control is a Risky Road
Posted March 6, 2012
A grizzly bear and a gray wolf in Yellowstone National Park.
A recent article in High Country News extols the virtues of controlling predators (e.g., wolves and bears) to boost ungulate populations (e.g., moose and caribou) in Alaska. It is an interesting article, and the author was thoughtful in her analysis of the issue.
But there was nary a mention of the ecological benefits that come with having top predators on the landscape, and thus I write to tell the infamous “rest of the story.”
Just a few dozen miles south of where I’m writing is Yellowstone National Park, where one of the greatest examples of the importance of top predators – the reintroduction of gray wolves – continues to unfold.
By the 1930s, wolves had been eradicated from the West. They were then reintroduced into Yellowstone and central Idaho in 1995 and 1996. In the decades between their eradication and reintroduction, Yellowstone changed.
Coyote numbers skyrocketed, and then pronghorn antelope numbers dropped. Elk numbers soared (and elk behavior changed), and then streamside trees and bushes became less common. Without streamside vegetation, beaver numbers dropped, songbird numbers dropped, and less shade was provided along streams for coldwater fish species such as Yellowstone cutthroat trout.
Without wolves performing their role on the landscape, things began to fall out of whack.
And, then, following the reintroduction of wolves in 1995-96, Yellowstone again began to change. Coyote numbers decreased, and pronghorn numbers increased. The elk population dropped to healthier numbers, and elk again began behaving like wild elk. Streamside trees and bushes sprouted, beavers returned, songbird numbers increased, and all sorts of species (from grizzly bears to eagles) started scavenging on wolf-killed carcasses.
The return of wolves to Yellowstone is a powerful story about nature’s need for apex predators on the landscape – and a striking cautionary tale about what can happen when we remove them.
And the story is not limited to wolves and Yellowstone. As we continue to kill off apex predators (e.g., sharks), more and more research shows that the loss of such predators greatly affects the ecosystems where those carnivores once lived.
Wolves and bears, just like elk and deer, need to be managed (and the above article discusses reducing predator numbers, not eradicating them), but the larger point is that we need to appreciate the ecological importance of top predators, and our management practices should ensure that the populations of such predators are sufficient enough that they are able to meaningfully play their role on the landscape over the long term.
But while the science is abundantly clear that top predators are important for healthy functioning ecosystems, the social values involved are murkier. While some want to see large carnivores and healthy intact ecosystems, others would prefer inflated game populations. For me, as a hunter and angler, I’ll cast my vote for the former – for wildness – as there are enough neutered landscapes out there that I don’t want to see the Northern Rockies added to that list. But those are my values, and while I hope others will agree that robust populations of wolves and grizzlies belong in the Northern Rockies, I understand that others may – and, of course, have every right to – feel differently.
Like I said, it’s murky, and these questions are more sociopolitical-based than they are science-based, and they will continue to play out for years to come in Alaska, the Northern Rockies, and other places.
But as we grapple with these big questions, there is no more cogent voice to influence our thinking than that of the great hunter-angler-conservationist Aldo Leopold, who wrote the following many decades ago:
In those days we had never heard of passing up a chance to kill a wolf. In a second we were pumping lead into the pack, but with more excitement than accuracy: how to aim a steep downhill shot is always confusing. When our rifles were empty, the old wolf was down, and a pup was dragging a leg into impassable slide-rocks.
We reached the old wolf in time to watch a fierce green fire dying in her eyes. I realized then, and have known ever since, that there was something new to me in those eyes - something known only to her and to the mountain. I was young then, and full of trigger-itch; I thought that because fewer wolves meant more deer, that no wolves would mean hunters' paradise. But after seeing the green fire die, I sensed that neither the wolf nor the mountain agreed with such a view.
Since then I have lived to see state after state extirpate its wolves. I have watched the face of many a newly wolfless mountain, and seen the south-facing slopes wrinkle with a maze of new deer trails. I have seen every edible bush and seedling browsed, first to anaemic desuetude, and then to death. I have seen every edible tree defoliated to the height of a saddlehorn. Such a mountain looks as if someone had given God a new pruning shears, and forbidden Him all other exercise. In the end the starved bones of the hoped-for deer herd, dead of its own too-much, bleach with the bones of the dead sage, or molder under the high-lined junipers.
I now suspect that just as a deer herd lives in mortal fear of its wolves, so does a mountain live in mortal fear of its deer. And perhaps with better cause, for while a buck pulled down by wolves can be replaced in two or three years, a range pulled down by too many deer may fail of replacement in as many decades.
So also with cows. The cowman who cleans his range of wolves does not realize that he is taking over the wolf's job of trimming the herd to fit the range. He has not learned to think like a mountain. Hence we have dustbowls, and rivers washing the future into the sea.
We all strive for safety, prosperity, comfort, long life, and dullness. The deer strives with his supple legs, the cowman with trap and poison, the statesman with pen, the most of us with machines, votes, and dollars, but it all comes to the same thing: peace in our time. A measure of success in this is all well enough, and perhaps is a requisite to objective thinking, but too much safety seems to yield only danger in the long run. Perhaps this is behind Thoreau's dictum: In wildness is the salvation of the world. Perhaps this is the hidden meaning in the howl of the wolf, long known among mountains, but seldom perceived among men.
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