The Guam rail was extinct in the wild for nearly 40 years. Now it’s back.

CNN  — 

Almost four decades after completely disappearing from the wild, a bird that had survived only in captivity now roams freely on two tropical islands.

The Guam rail’s native home is a remote, 212-square-mile island in the Pacific Ocean, half way between Australia and Japan.

Known locally as the ko’ko’, the rail, which had been classified as “extinct in the wild,” was promoted to “critically endangered” by the International Union for the Conservation of Nature’s (IUCN) 2019 red list of threatened species. Only one bird – the California condor – has previously taken that crucial step back from the brink.

What happened to the Guam rail?

During World War II, the island of Guam was occupied by the Japanese military. Soon after the island was liberated by US forces in 1944, brown tree snakes appeared – it is thought they hitched a ride there as stowaways on an American cargo ship.

For the predatory snakes, which grow up to eight feet in length, Guam was a food-filled paradise. As they feasted on the island’s defenseless native animals, their population exploded, reaching peak density of 20 plus snakes per acre of jungle.

The voracious serpents wiped 10 out of 12 native forest birds off the island.