People have been suppressing predators since our terrified ancestors first banded together around campfires. Oddly, though, we only began to notice the catastrophic aftereffects in the 1960s. That’s when biologists first demonstrated that taking out a top predator has a knock-on effect for almost every plant and animal below it on the trophic ladder, or food web.
It’s called a “trophic cascade,” and when settlers eradicated wolves from the Lower 48, they set off a cascade on “a continental scale,” according to a new study published in the Journal of Animal Ecology. Where the wolf’s howl once could be heard from the Arctic to the Gulf of Mexico and from Cape Cod to the Olympic Peninsula, the night went silent. And coyotes, once confined to the Great Plains, were suddenly free to increase their populations almost astronomically, extending their range from coast to coast and north into Alaska.
Wolves out, coyotes in. Almost a wash, right?
On the contrary, coyotes are “mesopredators,” meaning midsize, and they favor smaller prey than do wolves. So the proliferation of coyotes caused a
The story of how wolves transformed the Yellowstone National Park landscape, beginning in the 1990s, has become a favorite lesson about the natural world. A video recounting (above) has gone viral lately, with British writer George Monbiot re-telling the story in his best breathy David Attenborough.
I don’t like the NYT headline “Is the Wolf A Real American Hero?” which seems to fault the wolf for our myth making. But otherwise, this op-ed is a good reminder that nature is almost always more complex than the stories we tell about it :
FOR a field biologist stuck in the city, the wildlife dioramas at the American Museum of Natural History are among New York’s best offerings. One recent Saturday, I paused by the display for elk, an animal I study. Like all the dioramas, this one is a great tribute. I have observed elk behavior until my face froze and stared at the data results until my eyes stung, but this scene brought back to me the graceful beauty of a tawny elk cow, grazing the autumn grasses.
As I lingered, I noticed a mother reading an interpretive panel to her daughter. It recounted how the reintroduction of wolves in the mid-1990s returned the Yellowstone ecosystem to health by limiting the grazing of elk, which are sometimes known as “wapiti” by Native Americans. “With wolves hunting and scaring wapiti from aspen groves, trees were able to grow tall enough to escape wapiti damage. And tree seedlings actually had a chance.” The songbirds came back, and so did the beavers. “Got it?” the mother asked. The enchanted little girl nodded, and they wandered on.
This story — that wolves fixed a broken Yellowstone by killing and frightening elk — is one of ecology’s most famous. It’s the classic example of what’s called a “trophic cascade,” and has appeared in textbooks, on National Geographic centerfolds and in this newspaper. Americans may know this story better than any other from ecology, and its grip on our imagination is one of the field’s proudest contributions to wildlife conservation. But there is a problem with the story: It’s not true.
We now know that elk are tougher, and Yellowstone more complex, than we gave them credit for. By retelling the same old story about Yellowstone wolves, we Read the rest of this entry »
Right about now, the grizzlies of Yellowstone National Park are starting to think about hibernation. This week or next, as food becomes scarce, they’ll head up into the mountains and hunker down in dens under rocks and trees. They’ll cut their metabolic rate in half, drop their heart rate down to about 18 beats a minute, and take a breath only once every 45 seconds. And they’ll stay like that until springtime.
Many of the park’s bears will be getting by for the winter largely on the energy built up from gorging on moths. That’s right: The largest and most ferocious predator in North America eats fluttery little army cutworm moths (Euxoa auxiliaris).
A grizzly researcher first discovered this strange behavior in 1952. But nobody paid much attention until the mid-1980s, when a radio-collared grizzly bear wandered up to the steep rocky slopes, and researchers started to wonder just what it was doing there.
A couple of amateur naturalists were at the time spending half of every year in the field watching grizzly bears, and they did the first real study of moth-eating behavior. I met Steve and Marilyn French back then and spent some time wandering with them in grizzly habitat, as they studied how grizzlies adapted to every possible food source in their environment, including the moths.
Those kinds of details mattered then because grizzlies had been listed as a threatened species. The U.S. Fish and Wildlife Service delisted them in 2007, under pressure from politicians in Wyoming. But a federal judge reinstated protection two years later, and grizzly diet was a critical factor. He noted that the bears depended on nuts from whitebark pine trees, a species that had sharply declined because of tree-killing beetles. Environmental groups are now suing to block the continued FWS effort to delist the species, which could happen as soon as next year. Fewer than 1,000 individual grizzlies survive in the lower 48 states, down from 50,000 in the 19th century.
This commentary aired yesterday as part of the NPR Marketplace series “What’s The Fix?” As soon as I heard it, I thought, “Oh, my god, I said ‘fawns’ when I should have said ‘calves.’ Feed me to a grizzly bear!” But I really like that idea that CEOs at companies taking a federal bailout should do their job for $1 a year. If we are all going to have to learn to sacrifice, I can hardly think of anyone I’d rather sacrifice first have as our heroic leaders.
I spend a lot of time with animals, so I look to the natural world for ways to fix the financial panic. Let’s take a herd of elk at Yellowstone National Park, for example. They really know what it means to have a bear threaten their security. So when they’re out grazing, somebody’s always popping his head up and keeping an eye out. It’s an early warning system. When all the elk start to turn and stare in the same direction, it generally means there’s a grizzly bear out there. Smart animals sidle off in the opposite direction.
What’s that got to do with the stock market? We were all staring at the bear for more than a year as the credit crisis unfolded. But let’s say you ignored the warning signals and missed the chance for a graceful exit.
A couple of lessons from the natural world can still help. First, when a herd panics, animals just get trampled and become food for the bear. We need to calm down and look out for each other. And we need real leaders to help. In the wild, strong animals sometimes walk straight toward the bear, as if to say, “I see you and you don’t scare me.” At Yellowstone, I’ve also seen mother elk band together and run interference to protect fawns from a charging bear. That’s kind of what Warren Buffett’s been up to lately. But now we need other big-money types to get into the market with everything they’ve got and show some nerve defending the system that made them rich. It’s a chance for the golden parachute gang to redeem themselves. If you’re a CEO taking federal bailout money, do your job for a dollar a year and be an American hero.
I saw forest fire ravage Yellowstone in 1988. It looked like the end of the world then, too. But when I went back a few years later, the blackened areas were flourishing with new growth. The same thing happens when financial markets go up in flames. Buck up your courage, buy some stock, and the grass can be green again for us, too.