Tiny Deer and Rising Sea Levels: How Far Should People Go to Save an Endangered Species?

Millennia ago, when much of North America was covered in ice, a distant relative of the white-tailed deer grazed down a limestone ridge to the southeastern edge of the continental United States. The ridge turned into a series of diminishing islands—or keys—off the coast of South Florida. The deer, trapped and isolated from their mainland counterparts, also diminished in size.

Today, the key deer—or toy deer, as it's sometimes called due to its dog-sized stature—is the smallest deer species in North America. It is genetically unique and ridiculously cute. It's the embodiment of Bambi.

It's also, perhaps, doomed.

Toy Deer Photo: Ryan Kellman/NPR

Rising sea levels have created the Key deer. The rapidly rising sea level, a symptom of anthropogenic climate change, poses a challenge to its continued existence and raises complex questions for those attempting to save more than 1,300 other threatened species.

"How do we save a species like the Key deer that's endangered when we know that despite anything we do, in the future, we're going to lose its habitat?" asked Nikki Colangelo, the South Florida regional manager for endangered species at the U.S. Fish and Wildlife Service.

The Key deer was one of the first species protected by the Endangered Species Act. Like 99% of other species protected under the Endangered Species Act, the Key deer avoided extinction thanks to the U.S. Fish and Wildlife Service. However, now, rapid sea-level rise, a symptom of anthropogenic climate change, challenges its continued existence. Ryan Kellman / NPR The Endangered Species Act, celebrating its 50th year this year, tasks wildlife managers like Colangelo with stopping extinction, protecting threatened species, and restoring them to a point where they no longer need federal protection.

"Saving life on Earth," said Martha Williams, director of the U.S. Fish and Wildlife Service. "That's what we do."

But in the era of rapid climate change, where entire ecosystems are disrupted due to high temperatures, forest fires, hurricanes, and drought, what does "saving" a species even mean? What matters?

Left: Key deer illuminated by car headlights on Big Pine Key. Right: Twilight descends on a slice of island on the horizon. Over the past century, the global sea level has risen 6-8 inches. In South Florida, authorities are preparing for another 17-inch increase by 2040. Ryan Kellman / NPR "The Endangered Species Act is being stress-tested by climate change and sea-level rise, in particular, in these low-lying island ecosystems," said Chris Bergh, the director of field programs for The Nature Conservancy in Florida.

Ninety percent of Florida Keys' land is at or below 5 feet above sea level. The islands are home to 31 plants and animals protected by federal law and around 80,000 people.

Bergh, a native and resident of Key West who has spent most of his life trying to protect endangered island species, has watched the habitat shrink. He noted that pines, as well as plants and animals dependent on freshwater, have moved "up and inland." However, the "sobering" forecasts of sea-level rise (expected water levels in feet) are causing an almost existential crisis.