Yellowstone Wolves

Print More

(Host) Commentator Ruth Page has an example of why many people believe that re-introduction of wolves into their historic habitats in this country may help entire ecosystems recover their lost diversity.

(Page) Recently I arranged a class of second-graders in a big circle and gave each a card to hold: wolf, elk, willow tree, beaver, red fox, coyote, trout and others. Each represented one bit of historically normal Yellowstone Park wildlife. Most had to crouch down, because the thing they represented had become so scarce in the park until recently. Elk, though, stood tall. We were having a lesson in ecology, and each child held a piece of a long string that criss-crossed from one piece of the circle to another, to show that all were connected. It looked like a huge game of cat’s cradle.

From 1920, when Yellowstone’s wolves were all killed or chased away, until 1995, when re-introduction began, the park’s normal mix of plants and animals thinned out badly. Elk that had historically been controlled by wolves took over. By 1995, 10,000 elk burgeoned to 20,000. Old, tall willow and aspen trees survived, but younger ones were devastated by the legions of elk.

That left nothing for the beavers to eat; and THAT meant no deep beaver-pools, therefore fewer succulent plants that helped nourish grizzlies. Trout disappeared from warming waters that had formerly been kept cool and shady by growing willows. Stream-banks eroded as tree-roots failed, their silt sullying the water. Without competition, coyotes flourished in size and numbers.

Wolves were brought in, a few at a time, until now there are 16 packs with about 10 wolves in each. Each pack kills an average of one elk a day. They never “clean” their kills completely, so bears, cougars, magpies, golden eagles, and ravens feast on every kill. The largest number of ravens on a wolf kill ever recorded, one hundred and thirty-five, happened in Yellowstone.

Bringing in wolves appears to be returning the ecosystem to what it had been before 1920. The variety of life in the ecosystem is enormous. Coyote prey such as rodents, including mice and voles, is more abundant for red foxes and raptor birds, another sign the former wealth of life is returning.

The children saw how that could happen; those who had been diminished by the elks’ voracity started out kneeling or sitting; after the boy representing the wolf stood up to represent their increase, so did all the plants and animals whose return wolves assisted. The elk had to kneel, as did the coyote, but the willow-aspen group of trees stood tall.

Is there 100 percent proof that the wolf did all this alone? No, because ecosystems are densely complex; but much appears to have been driven by Yellowstone’s wolves, the Park’s natural top predator, and so far they have greatly enriched the park.

This is Ruth Page, offering an example of how removal of a single piece of an ecosystem can affect the whole.

Comments are closed.