[citation needed] The Guam flycatcher was a small bird measuring 5 inches (13 cm) long with different coloration for the males and females.

It had a wide bill with long "whiskers" which helped it locate its food.

[citation needed] The bird was secretive and occurred mainly in limestone and ravine forests.

Although common on Guam as recently as the early 1970s, the flycatcher's population went into a rapid decline due to predation by the brown tree snake, Boiga irregularis, which was accidentally introduced to the island in the 1940s.

[5] Given the small size of the island, the complete absence of recent sightings, and the universal presence of the brown tree snake in the bird's former habitat, the Guam flycatcher is considered extinct.