Environment

George Monbiot – How Wolves Change Rivers

George Monbiot

George Monbiot, the esteemed writer and environmentalist narrates a fascinating video on how wolves can have a direct effect on their environment.

In the 1920s, wolves had vanished from Yellowstone. Due to a mixture of factors (hunting being the predominant one), the animals had been driven from lands which they once frequented in droves.

Throughout the next 50-70 years, there were occasional sightings, but these were attributed to transient individuals or, at the very most, small packs.

It was only in the mid-nineties that a monitored and planned reintroduction programme was implemented. This saw the grey wolf return to both Lamar Valley of Yellowstone National Park and Idaho.

Since then, naturalists and scientists have noticed some pretty remarkable occurrences.

Not only has the biodiversity of the area changed, but damage caused by elk began to subside:

The wolves’ predation on the elk population, until then unchallenged, produced a significant increase of new-growth in various plants. Aspen and willow trees, previously grazed by the elks more or less at will, got suddenly a chance to grow. With the presence of the wolves, the elks stopped venturing into deeper and for them dangerous thickets where they could easily be surprised. They began to avoid areas of low visibility, which would increase the chances of wolf attacks.

The elks began avoiding open regions such as valley bottoms, open meadows and gorges, where they would be at a disadvantage in case of an attack from a wolf pack. William J. Ripple and Robert L. Bestcha dubbed this process top-down control. In ecology, top-down control denotes that top predators regulate the lower sections of the trophic pyramid. In other words: a top predator controls the structure or population dynamics of a particular ecosystem.

With new vegetation growing and expanding came subtle changes in the waterways running through the park. That had an impact on other species as well. Various bird species came back to Yellowstone with the increased number of trees. The beaver, previously extinct in the region, returned to the park. Their dams across the rivers attracted otters, muskrats, and reptiles.

Probably due to the wolves keeping the coyote populations at bay, the red fox got suddenly a chance to survive because the number of rabbits and mice grew considerably. The raven, always the wolf follower, came back to the park as well, now able to feed on the leftovers of the wolves.

The wolves changed the rivers, in as much as they readdressed the lost balance within the region, one we had created when we exterminated them. With a better balance between predator and prey, top meat eaters and top grazers, came the possibility for other species to thrive. With the increased vegetation growth, erosion decreased and the river banks stabilized.” – (Sc.)

In this subsequent talk, George Monbiot further examines the role of wolves within our ecosystem, as well as the importance of ‘rewilding’ the world.

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