Fifteen years ago, the future looked bleak for the Antiguan racer (Alsophis antiguae), the world's rarest snake. In 1995 just 50 of the creatures survived on the isolated 8.4-hectare Great Bird Island off of Antigua in the Caribbean. Introduced mongooses had wiped out the species on Antigua itself; invasive rats almost did the same trick on Great Bird.

Black rats came to the Caribbean on ships. Plantation owners released the mongooses in the 1890s to kill snakes in their fields.

But today there is good news. Six conservation groups teamed up to boost the population of the Antiguan racer, and now the snake's population has grown 10-fold to 500 individuals. Its habitat, meanwhile, has expanded to other islands and a total of 63 hectares.

Achieving this required efforts on multiple fronts: The snakes required a captive-breeding program as well as another program to reintroduce them into new habitats. Locals had to be convinced not to fear and kill the harmless snakes. Most of all, conservation groups needed to rid the island of the invasive black rats, a feat they accomplished not just on Great Bird Island but 11 other offshore islands.

"Many people have contributed over the years, but special credit must go to the local volunteers" who monitor the snakes and help keep the islands rat free, Fauna & Flora International (FFI) senior conservation biologist Jenny Daltry said in a prepared statement. "This success is a testament to their dedication."

Almost all of the racers in the wild are implanted with microchips to help monitor their health.

Removing the rats has done more than help the Antiguan racer—it has also benefited Great Bird Island's other wildlife. According to FFI, which founded the Antiguan Racer Conservation Project, the number of birds on the island has increased more than 500 percent, sea turtle and lizard populations are on the rise, and even plant species have recovered.

The Antiguan racer isn't out of the woods yet. They are still severely inbred, making them prone to infection, and conservationists need to keep circulating the snakes among their population groups to help expand their genetic diversity. Meanwhile, Great Bird Island, like many of the racers' new habitats, is just a tiny cay—a sandy island on the surface ofcoral reefs, which could disappear if global sea levels rise. But for now, at least, this is a rare case of an endangered species that has a chance at survival, thanks to the efforts of the people determined to save it.

Photo courtesy of Fauna & Flora International