Birds
Guam Rail
Hypotaenidia owstoni · also called ko'ko'
Wiped out across its entire native island by an invasive snake, a Guam rail exists today only because a handful of individuals were rescued into captivity just in time, a flightless bird known locally as the ko’ko’ now slowly returning to predator-managed forests.
Overview
The Guam rail, Hypotaenidia owstoni, is a flightless forest bird native to Guam, declared extinct in the wild in the 1980s after invasive brown tree snakes devastated the island’s native bird population. Its recovery through sustained captive breeding, reintroduction to snake-free and predator-controlled sites, and continued local recognition as the ko’ko’ make it one of conservation’s most remarkable comeback stories among flightless island birds.
Back from extinction in the wild
Few birds have returned from as close to the edge as the Guam rail, whose entire modern population traces back to a small group of survivors rescued into captivity before brown tree snakes could finish what they had started across the island.
Status
Critically Endangered, though showing a rare increasing trend thanks to sustained captive breeding and reintroduction to predator-managed sites.
Guam Rail: common questions
Did the Guam rail actually go extinct?
This species was declared extinct in the wild in the 1980s after invasive brown tree snakes devastated the native bird population of Guam, and it survived only because a small number of individuals had already been brought into captivity for breeding.
How was the Guam rail saved?
This species was saved through sustained captive breeding followed by reintroduction to areas managed to exclude brown tree snakes, including nearby predator-controlled sites and snake-free islands, one of conservation's most determined recovery efforts.
Why is the Guam rail called the ko'ko'?
This species is known locally as the ko'ko', a name that echoes the sound of one of its distinctive calls, a term still widely used by residents of Guam.
Can the Guam rail fly?
No, this species is flightless and was historically one of the most abundant native birds across the island of Guam before the brown tree snake invasion nearly wiped it out entirely.