Anyone questioning the value that wolves have, or why they should be protected, should watch the Sustainable Man production “How Wolves Change Rivers.”

On the National Geographic website, Paul Steyn describes the theme of this video as “one of the most important conservation concepts to come out of natural science in the last half century. The thing about this case study is that the same can be applied to apex predators around the world: lions in Africa, tigers in Asia. Sharks, bears, and wild dogs are all species sitting at the top of their respective food chains …”

Far fetched as the title sounds, this was the trophic cascade that the reintroduction of wolves brought to Yellowstone Park in 1995.

“Now we all know that wolves kill various species of animals,” narrator  George Monbiot explains, “but perhaps we’re slightly less aware that they give life to many others.”

During their 70 year absence from Yellowstone, there had been little check on the deer population. This resulted in overgrazing, and the eradication of much vegetation. After the wolves where reintroduced, the deer started avoiding the areas where they could most easily be trapped. As a result, the valleys and gorges were able to recuperate. Forests of aspen, willow and cottonwood grew up. This is turn, attracted birds. Beavers moved in, to eat the trees, and in the process started an entirely different ecologic chain of events.

The film follows numerous creatures whose lives were improved as a result of the wolves return.

It takes its name from the fact that as the trees were allowed to replenish, they anchored river banks so they collapsed less often and there was less erosion. This led to less meandering and the formation of deep pools. The introduction of wolves actually did change the rivers.

or watch at http://sustainableman.org/how-wolves-change-rivers/

(Image above taken from the video “How Wolves Change Rivers”)