A tiny deer and rising seas: How far should people go to save an endangered species?

Millenia ago, when much of North America was covered in ice, a distant relative of a white-tailed deer grazed its way down a limestone ridge to the southeast edge of the continental U.S. Over time, as the ice melted and seas rose, the limestone ridge was reduced to a series of shrinking islands — or keys — off the South Florida coast. The deer, trapped and isolated from its mainland relatives, shrank too.

Today, the Key deer — or toy deer, as it's sometimes called because of its dog-size stature — is the smallest deer species in North America. It is genetically unique and ridiculously cute. It is Bambi, incarnate.

It is also, possibly, doomed.

Rising seas created the Key deer. Rapidly rising seas, a symptom of human-caused climate change, are challenging its continued existence and raising tough questions for the people trying to keep the nation's more than 1,300 other threatened and endangered species alive.

How do we save an endangered animal like the Key deer when "we know, no matter what, we're going to lose its habitat in the future?" asked Nikki Colangelo, endangered species manager for the U.S. Fish and Wildlife