Tiny deer and rising sea levels: how climate change tests the Endangered Species Act

Some people keep dogs in their backyard. In Florida Keys, some residents have deer the size of golden retrievers living in their yards. As sea levels rise and saltwater encroaches on the islands, the habitat of these deer, whose population already numbers no more than 1,000 individuals, is shrinking.

Chris Berg, program manager for The Nature Conservancy in South Florida, says that over the past decades, sea-level changes have caused the pine rocklands in the Keys, the primary habitat of the Key deer, to retreat by hundreds of meters.

This reduction raises serious ethical and logistical questions for federal wildlife managers tasked with preserving endangered species like the Key deer.

"If you move Key deer to the mainland, they'll mate with regular deer, and then it's just a matter of generations before you don't have Key deer anymore," Berg says. "If you put Key deer in a bunch of zoos, like they did with pandas and, what do you call it, endangered species, you can do that and keep them going. But at what cost and for what purpose? Is it really the future of the species, the subspecies?"

Nikki Colangelo, a biologist with the U.S. Fish and Wildlife Service, says saving a species takes time, money, public support, and state cooperation.

"The options range from throwing in the towel and letting the species go extinct to doing absolutely everything you can, and that includes putting animals in zoos or collecting plants and putting them in botanical gardens," Colangelo says. "And I mean, I don't want to see any species go extinct under my watch. I don't think anybody does. But where is society on this?"

Climate change poses a threat to thousands of species, especially those like the Key deer, which exist only in one place.

Some scientists predict that as society pays more attention to the impact of climate change on people, animals like deer will become an afterthought.

"You're not going to be worrying about deer when you're going to be worrying about people. That's my concern," says Nova Silvy, a now-retired biologist who spent much of his career studying Key deer at Texas A&M University.