'Rewilding' North America would bring back lions, elephants, camels and more
By Scott LaFee
UNION-TRIBUNE STAFF WRITER
August 30, 2007
Thousands of years ago, North America was a place where the buffalo roamed and the deer and the antelope prayed – prayed because the continent was also home to many large predators, including cheetahs quite capable of chasing down a pronghorn antelope, the world's second fastest land animal.
Pleistocene rewilding calls for reintroducing large mammals once indigenous to North America. Because the original species are extinct, closely related surrogates would be used, such as the African cheetah and lion and the modern camel.
Now, of course, the cheetahs are gone, pushed to extinction by over-hunting and cataclysmic environmental changes spawned at least in part by human settlement some 10,000 years ago.
Gone, too, are almost all of the other large animals – megafauna – that once dwelled here: wild horses and asses, several kinds of mammoth, lions, camels and giant tortoises among them.
To be sure, the pronghorn (Antilocapra americana) remain, but they exist in much reduced numbers and seem almost an anachronism: animals out of time and place. They are over-built, having evolved the ability to outrun a predator that no longer exists. While that may be good news for the surviving antelopes, their world is, in fact, much poorer for it.
And so is ours, say some scientists.
“These big animals – the cheetahs, wolves and lions – were not just pretty ornaments of nature, characters for children's stories,” said Don Waller, a professor of botany and environmental studies at the University of Wisconsin-Madison. “The more we learn, the more we discover about the crucial roles top predators played – and play.”
Indeed, whole ecosystems depend upon them, said Michael Soulé, professor emeritus in environmental studies at UC Santa Cruz and a renowned conservation biologist. “When keystone predators are removed, ecosystems implode.”
But if modern North America is just a pale and shrunken imitation of itself, Waller, Soulé and others say it doesn't have to remain that way.
“The history of conservation is full of gloom and doom, of extinctions and lost habitat,” said Waller. “Instead of endless games of retreat and losing battles, we need a more positive vision. We need to say, 'Hey, we can put things back together again.' ”
That vision is called rewilding.
No fantasy
“There are two kinds of rewilding,” said Soulé, who once taught at UCSD. “Ordinary rewilding means bringing back native species that were recently extirpated or removed – ungulates like elk or predators like wolves and coyotes. We've already had some success doing this.”
Asian elephants are more closely related to North American mammoths than they are to African elephants. They also fill the same environmental niche: maintaining the health of grasslands and inhibiting the spread of woodlands.
Roughly 1,100 grizzly bears remain in the continental United States, less than 2 percent of their historical population. The last grizzly in California was killed in 1922. Efforts to reintroduce the bear to its original habitat are hotly contested.
Przewalski's horse, the world's last true wild horse, once was on the verge of extinction (just 31 were left in 1945). Small populations now exist in Mongolia, Ukraine, the United Kingdom and the United States.
More dramatic is Pleistocene rewilding, a term that refers to a period roughly 1.8 million years to 11,000 years ago. It was during the Pleistocene epoch that North America boasted more large animal species than any other continent on Earth, including Africa.
With careful planning and hard work, say conservation scientists, North America could regain that status: Elephants might graze upon the Great Plains, stalked again by lions. Camels might wander parts of the American Southwest. And cheetahs might once again chase after pronghorn antelope.
At first glance, such notions seem fantastical. “When it was first proposed 10 or 15 years ago,” said Soulé, “people called Pleistocene rewilding wacko. Some still do.”
But Soulé and others say that as the idea has settled and been debated, it has grown in acceptance. And they insist it makes a kind of compelling, urgent sense. In papers published in Nature, American Naturalist, Scientific American and elsewhere, advocates have argued that rewilding may indeed be bold action, but it's fully justified on ecological, evolutionary, economic, aesthetic and ethical grounds.
“All the evidence points to the strong role that humans played in the extinctions of some 40 species of large mammal toward the end of the Pleistocene,” said Dave Maehr, a professor of conservation biology at the University of Kentucky and a science fellow for The Rewilding Institute, an advocacy think tank based in New Mexico. (Waller and Soulé are also fellows.)
“Now, in the Holocene, local and global extinctions continue,” Maehr added. “These have clearly been caused by people. Responsible scientists and citizens should accept the responsibility of maintaining and restoring biodiversity for two reasons: The critical importance that biodiversity plays in allowing human life, and the intrinsic value of nature and all of its components.”
Josh Donlan, a biologist at Cornell University who has written extensively about rewilding, said restoring large animals to the North American landscape is imperative. Many large species in Africa and elsewhere are in decline. Some will not survive the century. Rewilding parts of North America may provide a last haven.
“Our vision might strike some as playing God,” Donlan said, then dismissed the contention. “Earth is nowhere pristine. Human technology, economics, politics and presence pervade every ecosystem. Why not make those influences work to the good?”
Plus, rewilding is eminently doable, he asserted.
There is ample space, Donlan argued, most notably in sprawling private ranches and preserves where the first projects would likely be based. In fact, he said more than 77,000 large exotic mammals (most of them ungulates, but also cheetahs, camels and kangaroos) already live inside fenced private ranches in Texas alone.
More particularly, Donlan and other rewilding advocates emphasize they are not trying to re-create a lost world. Most of the big animals that lived during the Pleistocene are extinct. But the African cheetah (Acinonyx jubatus) is a close relative of the long-gone American cheetah. The African lion (Panthera leo) is actually a more modest version of the American lion (Panthera leo atrox), which once ranged throughout much of North and South America.
Extant African and Asian elephants are reasonable surrogates for vanished mammoth species, Donlan said. They fill the same basic environmental niches as their woolly forebears did. So, too, do wild equines like Przewalski's horse (Equus caballus przewalski) and the Bactrian camel (Camelus bactrianus), which now teeters on the verge of extinction in China's Gobi desert.
Past is prologue
To promote their idea, rewilding proponents point to current projects that have had encouraging results. At a private ranch in New Mexico, for example, the 110-pound Bolson tortoise has been reintroduced. The tortoise once ranged widely throughout parts of the American Southwest and northern Mexico, but it is critically endangered.
“Restoring North America's largest surviving temperate terrestrial reptile to its prehistoric range could bring ecological, evolutionary, economic and cultural benefits, with no apparent costs,” said Donlan.
More controversial has been the reintroduction of wolves into Wyoming's Yellowstone National Park.
The last wild wolf there was shot and killed in 1926. In the mid-1990s, scientists launched a much-debated experiment: Introducing into the park 15 gray wolves imported from Canada.
The wolves have thrived. The current population is estimated to be almost 300. Ecologically, the park appears to be doing better, too. The wolves have reduced the once-burgeoning elk population, their kills providing leftover meals for bears, eagles and ravens.
The thinning of elk herds has also reduced grazing pressure upon indigenous plants. Aspen forests, which had shown no sign of significant growth for decades, have begun to regenerate. Riverine plants are growing taller and more abundantly, providing better food and habitat for birds, beavers and other species.
“Yellowstone today is a lot more like it once was,” said Waller.
To be sure, reintroducing wolves seems a lot less dramatic than, say, repopulating parts of Kansas with pachyderms. But Harry Greene, a professor of ecology and evolutionary biology at Cornell University, said the process of rewilding would be slow and incremental, starting with small-scale, rigidly controlled studies that would lead to larger, more ambitious projects only if the results supported and merited the next step.
“We wouldn't just dump a bunch of elephants south of Wichita,” he said.
The reasons are obvious. Although African cheetahs, elephants and other large mammals have all been studied for decades, plenty of unknowns remain: Will these animals acclimate to a new (if similar) environment? Can the North American landscape sustain them? How will native species respond? How will humans? What about disease transmission? What about consequences unexpected and unintended?
These are legitimate questions and concerns, concedes Soulé. “They are the kinds of things people say when other people want to try something new. Cautious people have a point. A lot of environmental mistakes have been made in the past. People have introduced plants and insects as new crops or biological controls, only to have them become destructive pests or scourges.
“But serious rewilding would proceed extremely carefully. It would begin with ungulates, not predators. Animals would be quarantined. They would live inside large, fenced areas. If any got out, they would be easy to find. It's hard to miss an elephant. It's not like having billions of insects flying around.”
Some mainstream conservation groups, however, have balked at the idea of rewilding, suggesting it is inherently unrealistic and problematic. (The Yellowstone wolf project continues to face opposition from local ranchers worried about their cattle.) These groups also express concern that rewilding efforts might divert public support from current conservation efforts in Africa, Asia and elsewhere.
Soulé gives these concerns no credence. Indeed, he said, conservation programs in Africa are an established success, the primary and perhaps only reason big animals like lions and elephants survive.
“Tourism and sport hunting have kept them alive. These animals really only exist nowadays in national parks.”
When South Africa's Kruger National Park was created in 1903, it contained just nine lions, eight buffalo, a few cheetahs and no elephants – the survivors of decades of over-hunting.
Today, Kruger is a famous haven of biological diversity, containing 2,300 lions, 28,000 buffalo, 250 cheetahs and 7,300 elephants. More than 700,000 ecotourists visit annually, bring in tens of millions of dollars in revenue.
Rewilding proponents believe something similar can happen here – maybe even to a greater degree. An estimated 1.5 million people visit San Diego's Wild Animal Park each year, Donlan noted. Why wouldn't they also want to visit places where they might see entire herds of elephants essentially roaming free?
The persistent reluctance to embrace rewilding, said Greene at Cornell, may reflect modern humanity's distance from and fear of nature, particularly the kind that's red in tooth and claw. The image of an African lion crouched in a former cornfield is, frankly, scary.
“Why is (rewilding) the Bolson tortoise OK, but the lion is not? My experience is that although folks jump to discussions of disease, habitat, costs, etc., for the lion, the tortoise forces them to acknowledge that the real problem is our fear of being eaten.
“Fair enough, but unless we find ways to live with dangerous animals, there won't be any anywhere one day.”
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