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Bits & Pieces: From Sustainable Man: “How Wolves Changed an Entire Ecosystem”

Ann Welch
Ann Welch

From Sustainable Man, which is a conversational blog exploring, discussing, and brainstorming sustainability topics, came a beautiful video explaining “How Wolves Changed an Entire Ecosystem”. Friends in Adel shared this video with me, and I am so glad they did because the video explains so clearly how wolves initiated great changes in the ecology of Yellowstone National Park. As the video states, “when wolves were reintroduced to Yellowstore National Park after being absent nearly 70 years, something astounding happened. That something astounding is called trophic cascade, an ecological phenomenon that starts at the top of a food chain and falls to the bottom of it. A classic example of trophic cascade occurred when wolves were reintroduced to Yellowstone in 1995. Over populations of deer had caused overgrazing of grasses in the park, and when the wolves started killing some of the deer the vegetation started to recover. Wolves also preyed upon coyotes, which caused rodent populations to increase, which in turn brought birds of prey such as hawks and eagles to feed upon the increasing rodent populations. Bears also preyed upon deer young which added to the decreasing deer population brought about by wolves. The bears were able to feed on berries reaching maturing by reduced grazing by deer.

In addition to changing wildlife populations in the park, wolves influenced river systems because increased vegetation served to hold soil better along river banks, thus decreasing erosion. More pools in rivers created habitats for beavers, fish, and otters. Although the wolves were small in number they transformed the physical geography of Yellowstone. This video is only 4+ minutes long and is a great depiction of the effects of wolves on their environment. Go to “Sustainable Man” and you should be able to find it and view it. The video is a very clear representation of how the natural elements of our world are interlinked and dependent upon each other.