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.
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