Species Fact Profile: Guam Rail (Gallirallus owstoni)

Guam Rail

Gallirallus owstoni (Walter Rothschild, 1895)

Range: Previously Guam, now Rota (Reintroduced)
Habitat: Secondary Growth, Mixed Forest
Diet: Gastropods, Lizards, Insects, Seeds, Palm Leaves
Social Grouping: Territorial Pairs
Lifespan: 10 Years (Captivity)
Reproduction: Breed year-round, lay 2-4 eggs in a shallow nest of leaves and grasses on the ground; both parents share incubation and chick-rearing duties; chicks leave the nest within 24 hours of hatching and are independent at one month.  Sexual maturity is reached at 4-6 months.
Conservation Status: IUCN Extinct in the Wild

• Body length 28 centimeters, weight 170-300 grams
• Brown back, head (with a white stripe above the eye), and neck with a gray underside, striped with brown on the lower breast and abdomen.  
• Males and females look alike, but males are slightly larger
• Flightless (though it can flutter up to 3 meters) ground-dweller, they have well-developed leg muscles and are quick runners; they can also swim and even dive underwater
• The rail was driven almost to extinction by the brown tree snake's introduction to Guam, with the population in the low double digits by 1980.  It was last seen in the wild in 1987
• In the mid-1980s, 21 birds were captured to form a captive breeding population in Guam and the continental United States.  Reintroductions in snake-free zones are occurring
• The species is called the ko'ko in native languages