The Guam Rail (Gallirallus owstoni) is a flightless bird, endemic only to the United States territory of Guam. In the Chamoru language, used on Guam, it is known as Ko'ko'. Before 1960 it was common, though it has a secretive lifestyle living in scrubby secondary growth or mixed forest. The Guam Rail disappeared from southern Guam in the early 1970’s and was extirpated from the entire island by 1987 due to the accidental late-1940’s introduction of the brown tree snake Boiga irregularis. Department of Agriculture biologist Bob Beck found that Guam rails breed well in captivity and established a breeding program which keeps birds at the Division of Aquatic and Wildlife Resources on Guam and at 15 mainland U.S. zoos. Captive grown rails were reintroduced to Guam in 1998 with no long-term success, and subsequently introduced to the snake-free island of Rota (Northern Mariana Islands), where two small breeding populations were able to persist despite hunting pressure from feral cats. In 2011 birds were also introduced to the island of Cocos, where they appear to be breeding.
The Guam rail is a medium-sized rail about 28 cm (11 in) in total length. The body is elongated and laterally compressed, particularly in the neck and breast regions, allowing the birds to move rapidly through dense vegetation. Males are slightly larger than females but have similar appearance with brown head and back, a dark breast barred with white, grey eye stripe and dark brown legs and beak. Gallirallus owstoni are generalists; they eat slugs, snails, lizards, insects, carrion and plant matter such as seeds, leaves, flowers and grasses. They nest year-round on the ground, with a usual clutch size of 3-4 eggs. They are territorial, usually silent but will give a loud whistle or series of whistles in response to the call of another bird or a disturbance. (BirdLife International 2012; Fritts and Leasman-Tanner 2001; Wikipedia 2013)
BirdLife International, 2012. Gallirallus owstoni. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.1.
. Downloaded on 13 November 2013.
- Fritts, T.H., and D. Leasman-Tanner, 2001. The Brown Treesnake on Guam: How the arrival of one invasive species damaged the ecology, commerce, electrical systems, and human health on Guam: A comprehensive information source. Available Online: http://www.fort.usgs.gov/resources/education/bts/bts_home.asp
- Wikipedia, the Free Encyclopedia, 27 October 2013. Guam Rail. Retrieved November 13 2013 from http://en.wikipedia.org/w/index.php?title=Guam_Rail&oldid=579023388.
Western Pacific Ocean_U.S.A. (Guam)
- Clements, J. F., T. S. Schulenberg, M. J. Iliff, B.L. Sullivan, C. L. Wood, and D. Roberson. 2012. The eBird/Clements checklist of birds of the world: Version 6.7. Downloaded from http://www.birds.cornell.edu/clementschecklist/downloadable-clements-checklist
Habitat and Ecology
Molecular Biology and Genetics
Statistics of barcoding coverage: Gallirallus owstoni
Public Records: 0
Specimens with Barcodes: 4
Species With Barcodes: 1
Date Listed: 04/11/1984
Lead Region: Pacific Region (Region 1)
Where Listed: except Rota
Status: Experimental Population, Non-Essential
Date Listed: 10/30/1989
Lead Region: Pacific Region (Region 1)
Where Listed: Rota
Population location: Entire, except Rota
Listing status: E
Population location: Rota
Listing status: EXPN
For most current information and documents related to the conservation status and management of Gallirallus owstoni, see its USFWS Species Profile
IUCN Red List Assessment
Red List Category
Red List Criteria
- 2008Extinct in the Wild
- 2004Extinct in the Wild
- 2000Extinct in the Wild
- 1996Extinct in the Wild
- 1994Extinct in the Wild
Captive breeding started in 1984. Since 1987, efforts have been under way to establish a self-sustaining, experimental population on the nearby snake-free island of Rota2. In 1999, birds bred there for the first time1; birds have since been released at four sites and success has been mixed10. In late 1998, some captive-reared birds were released in northern Guam, into a small area (24 ha) protected from snakes by a barrier and trapping, and though these birds were breeding1, this population is now extinct10. Conservation Actions Proposed
Continue the captive-breeding programme. Control B. irregularis in additional areas on Guam so that more introductions can take place1. Continue to manage the released populations on Rota to maximise the retention of the species's genetic diversity1. Implement stringent measures to prevent the spread of B. irregularis from Guam to Rota. Before considering another reintroduction to Guam, control feral cats.