The Ko'ko or Guam rail, is the Territorial Bird of Guam.  The Guam rail is mostly dark brown with white stripes on the bottom of its stomach.  This flightless bird is endemic to Guam, meaning it occurs naturally here and nowhere else in the world.  Thousands of years ago when the bird first came to Guam it was able to fly, but because it had no natural predators on Guam it slowly lost the ability to fly.  When the brown tree snake found its way to Guam the Guam rail was easy pray for the snake since it was flightless and the birds always built their nests on the ground.  The Koko bird is an endangered species of birds because of the destruction the brown tree snake have caused to the bird population on Guam.

Guam's territorial bird, the Koko or Guam rail.