Cheetahs could roam parts of North America?

Source: Wild animals could again roam parts of North America | Science Blog.

If Cornell University researchers and their colleagues have their way, cheetahs, lions, elephants, camels and other large wild animals may soon roam parts of North America.

…ecologists and conservationists have authored a paper, published in the latest issue of Nature (Vol. 436, No. 7053), advocating the establishment of vast ecological history parks with large mammals, mostly from Africa, that are close relatives or counterparts to extinct Pleistocene-period animals that once roamed the Great Plains.

The plan, which is called Pleistocene rewilding and is intended to be a proactive approach to conservation, would help revitalize ecosystems that have been compromised by the extinction of many of the continent’s large mammals, many of them predators. It would also offer ecotourism and land-management jobs to help the struggling economies in rural areas of the Great Plains and Southwest.

…large tracts of private land are probably the most promising places to start, with each step carefully guided by the fossil record and the involvement of experts and research.

Evidence shows that animals near the top of the food chain play important roles in structuring ecological systems and maintaining biodiversity, according to the paper. These keystone species — animals 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.