The answer, says our scientist, raises a philosophical question: Is reintroducing species to their former habitats the right thing to do, or a case of mankind playing God?
Either way, he says, in the end there's a very practical reason for not reintroducing species.
Find out what it is in this month's "Ask the Conservationist." And when you're done reading, send us your questions on any conservation subject for one of the Conservancy's 720 staff scientists. (Note: We regret that we can only answer one or two questions each month and that we cannot answer the others offline.)
Bill Cody of Camillus, NY, writes:
"Why hasn't the conservation community embraced the idea of returning wildlife that became extinct in the rather recent pre-Columbian era back to the lands they roamed for millions of years? It would probably save some endangered species from disappearing in the wild completely."
Some conservationists in fact have suggested introducing or re-introducing a variety of large animals ("megafauna") to places where similar large animals lived before humans ever came to North America some 13-18,000 years ago.
The suggestion was first published by Josh Donlan and colleagues in a 2005 issue of Nature magazine. Many have debated the idea since then, making hypothetical points pro and con.
On the one hand, some people feel that it's just the right thing to do since those early humans are suspected of wiping out most of the megafauna in the first place. But others say the approach is too much like toying with a miniature train set landscape.
Many species introduced into new habitats, for any number of reasons, have caused huge biodiversity disasters. For example, the cane toad, which has toxic skin and no predators, was introduced into Australia and is now eating its way through most of the native Australian amphibians, causing the largest modern-day extinction of amphibians in the world.
Similarly, introducing the mongoose into Caribbean islands such as Hispaniola to control snakes resulted in the mongoose wiping out many of the islands' native birds. There are hundreds of cases like these.
But beyond the hypothetical and philosophical back and forth, conservationists who actually get land preserved and save species from the brink of extinction are, out of sheer necessity, hard core realists. While there is no lack of "big ideas" in conservation today, we focus on the ones that are most likely to succeed and return a solid known benefit.
Populating the Americas or Europe with wild elephants, wildebeests, cheetahs, and lions would take a level of effort that would dwarf John Hammond's grandest "Jurassic Park" fantasy. In the meantime, we have to ask ourselves, what other critically important conservation priorities would we not do instead? Which of today's habitats would we be willing to give up on?
About the Conservationist
Michael Jennings is a senior terrestrial scientist at The Nature Conservancy's Center for Global Trends.