A young forest service employee named Aldo Leopold, charged with killing wolves in New Mexico in the early 1900's started to notice that as the wolves died off, the deer population boomed and ate all the plants to nothing. In his groundbreaking work, "Thinking Like a Mountain", Leopold put forth an idea 50 years ahead of his time: predators control ecosystems.
Since the reintroduction of wolves to Yellowstone National Park in 1995, we have learned much about the effect large carnivores have on an ecosystem. In the past it was thought that an ecosystem was built from the bottom up... with plant life as the basis from which everything grew. Once healthy plants were established, insects, small rodents, birds, larger herbivores and finally the top predators fell into a balance with each other. Almost all conservation and reintroduction efforts were based on this idea. In a damaged area, biologists would first try to rebuild the plant life before doing anything else. However, some ecosystems could not be fixed before reintroducing an endangered top-level animal. In Yellowstone National Park, the US Fish and Wildlife Service was required by the Endangered Species Act to reintroduce wolves before balancing the plant base and herbivore populations.
Since the reintroduction of wolves to Yellowstone National Park in 1995, we have learned much about the effect large carnivores have on an ecosystem. In the past it was thought that an ecosystem was built from the bottom up... with plant life as the basis from which everything grew. Once healthy plants were established, insects, small rodents, birds, larger herbivores and finally the top predators fell into a balance with each other. Almost all conservation and reintroduction efforts were based on this idea. In a damaged area, biologists would first try to rebuild the plant life before doing anything else. However, some ecosystems could not be fixed before reintroducing an endangered top-level animal. In Yellowstone National Park, the US Fish and Wildlife Service was required by the Endangered Species Act to reintroduce wolves before balancing the plant base and herbivore populations.
In the years since the wolf reintroduction, Yellowstone has become a premiere scientific laboratory for wilderness observation and ecosystem recovery. Scientists have come from around the world to watch the effect wild wolves have on the park. They have discovered that an ecological effect called the “trophic cascade” has taken over Yellowstone, with the wolves initiating a more natural ecosystem balance than has been seen in over 65 years:
