by Whit Gibbons

March 19, 2006

Mammoths and mastodons. Giant ground sloths and Pleistocene giant beavers. Saber-toothed tigers and America grasslands cheetahs. All are extinct. Seeing reconstructions of such creatures and their habitats recently in the Smithsonian Natural History Museum in Washington, D.C., and the State Museum in Columbia, S.C., made me muse. What would it have been like to live when such magnificent megafauna roamed the landscape? Would the thrill and excitement of experiencing them in the wild have outweighed concerns for personal safety? We could find out.

Related to the well-documented disappearance of most of America’s megafauna, a commentary titled “Re-wilding North America” in the scientific journal Nature introduced me to a new word and a controversial concept. Josh Donlan and Harry Greene of Cornell University with several colleagues have proposed a rewilding effort that would bring free-ranging lions, elephants, and camels to the southwestern United States. The verb “rewild,” which is not yet in the dictionary, means to replenish a region with present-day extant species that are closely related to wild species that formerly inhabited the area but became extinct. The proposal to rewild North America brings to light an intriguing conservation approach.

The rewilding plan advocates establishing populations of large wild animals, mostly African and Asian mammals, in western North America as a conservation strategy to restore extinct species by replacing them with closely related modern species. The extinct forms disappeared approximately 11,000 to 13,000 years ago near the end of the Pleistocene geologic epoch. “Pleistocene rewilding” would be accomplished through careful manipulation and management of the ecosystems into which the species are introduced. The authors hope to shift the conservation biology mindset from one of constantly dealing with extinction to one of “actively restoring natural processes.” They propose a positive, proactive approach rather than simply reacting to the downward spiral of species declines and extinctions.

The authors justify the rewilding proposal on the basis of four observations that are difficult to dispute. First, no pristine environments remain because of the world’s most destructive invasive species, humans. Second, environmentalists are too often viewed as doomsday prophets rather than environmental saviors, especially when they emphasize the reality of the previous sentence. The authors seek to remedy this widely held attitude. Third, some areas, notably the Great Plains, with declining human populations may serve as a region for innovative conservation approaches. Finally, humans are ethically responsible and should attempt to rectify human-caused declines and extinctions of large vertebrates.

The rewilding plan has several phases. The least controversial to most people is the proposed translocation of Bolson tortoises, one of the few extant species under consideration in the rewilding effort. The desert-dwelling tortoises, which can weigh more than a hundred pounds, once ranged into the U.S. Southwest but are now restricted to a small region in Mexico. One proposal is to move tortoises to Texas and New Mexico, thereby reintroducing them to where they once lived.

Included among mammals to be introduced to the Southwest are Przewalski’s horses, a rare species native to Mongolia. The intent is to replace the ecovoid left by the extinction of North American horses. Conservationists who consider free-ranging mustangs and donkeys to be destructive invasive species will probably have issues with this part of the plan. But the most exciting phase is to introduce free-roaming African cheetahs, Asian and African elephants, and African lions. The first stage will be to work with animals that are already in captivity on private lands in the Southwest.

The article addresses obvious concerns that might be voiced including introduction of alien diseases, unanticipated interactions with native animals and plants, and negative contacts with people. Imagine the story behind the first road-killed elephant, or the poodle that tries to outrun a cheetah. But the article also makes the indisputable point that most humans are intrigued by large animals, and later phases of the plan would include the development of “ecological history parks” in the Great Plains, as well as a positive step toward preventing extinction of critically endangered African and Asian species. A move to rewild America will have its supporters and detractors. Some will think it captivating and doable; others will think it a wild idea too reminiscent of Jurassic Park.

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