Smithsonian National Zoological Park l Friends of the National Zoo



Guam Rail

Guam rails (Rallus owstoni) are a small flightless bird that lived only on the island of Guam in the Mariana Archipelago in the Pacific. They are omnivorous, eating leaves, seeds, fruits, small lizards, bird eggs, small mammals, and carrion.

Introduction of Predator

The introduction of brown tree snakes (Boiga irregularis) in the 1950s almost spelled doom for the rails. Snakes feeding on the rails' young and eggs caused the Guam rail population to crash to only 21 birds by 1985. Other birds on Guam have been similarly affected by the brown tree snake. Guam Micronesian Kingfisher

Captive Breeding Program

Scientists from the National Zoo rushed to Guam to rescue the last individuals of this species and start a captive breeding program. The captive population slowly grew until enough animals were available to start a reintroduction program.


With the brown tree snake still on the island of Guam, conservation biologists looked elsewhere for a safe haven. They found one on the island of Rota about 31 miles away in the Northern Mariana islands. Reintroduction of a few individuals started in 1989 and by 1999 267 birds were released. The reintroduction has been difficult, but during the summer of 1999 at least three pairs of reintroduced rails produced five nests with eggs and hatchlings.

Reintroductions have also since taken place on the island of Guam itself. Although the brown snake still poses a threat to the species, in 1997 a large 60-acre area has been fenced off and after many weeks of trapping and re-trapping, snakes were removed from the area. In November of 1998 16 rails were released and produced 46 by 1999.