How the wolves saved Yellowstone National Park

It all began in 1995 when Yellowstone Park workers released 31 grey wolves into the wild over the year, and did not interfere with their lives at all. Although they expected certain changes, they certainly did not expect the cascade of environmental change it will cause. To this day, ecologists are astonished by the continuing wave of direct and indirect consequences of this step throughout the ecosystem.

Thanks to this one-time human intervention, the ecosystem of the park became more complex and unusually prosperous. The presence of wolves caused an ever-evolving cascade effect between animals and plants, like when you throw a pebble from a rocky slope that causes an avalanche on its way down.

The wolf population stabilized at about one hundred individuals. This resulted in a reduction in the reindeer population, which previously had no natural predator in the park. New carnivore and herbivore species also appeared. Even the dominant herbivore species in the area changed - the mentioned reindeer was replaced by the bison, and even the grizzly bear population began to prosper. On the other hand, moose withdrew from the area. The return of the beaver was also a welcome change (only one colony lived here before the wolves were released).

All these changes in animal life have had a beneficial effect on local vegetation, which had suffered until then. This was because since the 1930s, when wolves were eradicated here, there was an overpopulation of elk and reindeer that did not migrate much in the winter. This had a negative effect on young willows, awn and cotton, which had unfortunate consequences for the beavers, who needed willows to survive the winter.

With the return of the beavers, the cascade effect of changes continued. They began to build new dams and ponds, which have an impact on current hydrology. They can even offset seasonal differences and provide cold, shaded water for fish, while the overgrown heath on the shore gives shelter to songbirds.