( mals that contribute to diversity of li...)Proposal would allow wild animals to roam North America

mals that contribute to diversity of life and which the rewilding researchers would like to reintroduce -- play a disproportionate role in an ecosystem. Extinction of a keystone species can lead to homogenous landscapes with less biodiversity and different species proliferating and dominating the ecosystem.

For example, when humans almost wiped out wolves and grizzly bears in the United States, the species dynamics shifted. The loss of wolves and grizzlies allowed elk populations to soar. Elk, in turn, ate willows, a favorite food of beavers. As a result, along winter elk ranges in Colorado, beaver populations have declined by 80 to 90 percent. With fewer beavers to create dams that raise water tables, fewer wetlands developed to support willows. Today, there are 60 percent fewer willows in parts of Colorado where beavers have declined.

Similarly, after major predators became extinct in Montana and Wyoming, the number of moose, which eat willows, increased in the Yellowstone National Park area. The loss of willows has negatively impacted the numbers of nesting migrant songbirds.

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Source:Cornell University News Service


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