Guamralle
| Guamralle | ||||||||||||
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Guamralle ( Gallirallus owstoni ) |
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| Scientific name | ||||||||||||
| Gallirallus owstoni | ||||||||||||
| ( Rothschild , 1895) |
The guamralle ( Gallirallus owstoni ) is a railing bird that can fly a maximum of 1 to 2 meters. 6 7
Appearance
Adults weigh around 200 g. The back, neck, trunk, tail, legs and beak are dark brown. There is a pattern of black and white feathers on the wing, lower part of the chest, belly and under the tail. There are gray spots on the neck, upper chest, and above the eyes. As with other rails, the body is elongated and compressed at the sides so that the animals can move quickly through dense vegetation. Young animals have black downy plumage for the first three weeks. They reach their full weight at eight weeks and can live to be over 11 years old. 6 7
Way of life
The Guamrale is endemic to Guam and was originally found in most of the island's habitats, such as forest, savannah , bushland, secondary grassland , fern thickets, agricultural areas. She mainly hangs out in places where there are both bushes and grass. They are rarely seen in forests or in wetlands. 6 8
The guamralle prefers to eat animal rather than vegetable food. These include snails, carrion, geckos, insects. The introduced African agate snail ( Achatina fulica ) forms an important part of the diet. On plants they eat seeds, palm fronds but also various types of vegetables and fruit. 6th
It usually picks up its food from the ground, especially snails. It also catches low-flying insects, especially butterflies, with its beak from the air. By stretching, they can reach forage that is 40 cm or more above the ground. Pieces of snail shells and shards of coral are picked up to aid digestion. 6 8
Reproduction
Captive animals first hatched at five months of age. They breed throughout the year, especially often during the rainy seasons in July and November. It is believed that they breed several times a year, how often is unknown. 6 8
In a nest with a diameter of 13 cm that is built by both parents, the female lays 3–4 eggs of 3 × 4 cm in size. As with many animals on islands that used to be predator-free, the clutch is smaller than the clutch of their mainland relatives. Both parents incubate alternately for about 20 days. The chicks do not hatch at the same time. A parent animal eats the eggshells. 6th
The 1–4, but on average 2 young animals flee the nest and leave the nest with their parents within 24 hours. Chicks are sometimes made aware of the food by their parents and then pick it up on their own, but sometimes they are also fed with caught flying insects. 6th
Threat status
The railing used to be widespread in Guam and was hunted by the island's residents. In 1960 the trade in young birds and eggs and the hunting of the birds were prohibited. 1964–1976 limited hunting was allowed. It died out on the southern part of the island in the early 1970s, but there is no evidence that hunting, which was already forbidden at the time, could be responsible. In 1981 only about 2300 birds were found in the north of the island. In 1983 there were only two small, disjointed populations left. The cause of the extinction were introduced carnivores, especially the brown night tree snake ( Boiga irregularis ) and car accidents. 4 5 7
Ralle has been bred very successfully in captivity since 1984 and since 1995 more than 100 of them have been released. After the successes were small at first, the night tree snakes were killed by traps and kept away from the birds' habitat. Breeding successes have been reported since then. 1 2 3 4 5 7
In addition, attempts have been made since 1987 to settle the Ralle on the nearby island of Rota. In 1999 the first successful broods were reported there. 8th
swell
- Delany, S. and S. Scott. 2002. Waterbird Population Estimates? Third edition. Wetlands International Global Series No. 12, Wageningen, The Netherlands. Pp: 115
- Taylor, Barry. 1998. Guam Rail. In Rails: A guide to the Rails, Crakes, Gallinules and Coots of the World. Yale University Press. Pp: 258259.
- Fritts, TH, 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. (World Wide Web page). Available: http://www.fort.usgs.gov/resources/education/bts/bts_home.asp (Dec. 1, 2005)
- Julie A. Savidge: Extinction of an Island Forest Avifauna by an Introduced Snake. Ecology, vol. 68, no. 3 (Jun., 1987), pp. 660-668. doi : 10.2307 / 1938471
- Thomas H. Fritts, Gordon H. Rodda: The Role of Introduced Species in the Degradation of Island Ecosystems: A Case History of Guam. Annual Review of Ecology and Systematics, Vol. 29, 1998 (1998), pp. 113-140
- J. Mark Jenkins: Natural History of the Guam Rail. The Condor, Vol. 81, No. 4 (Nov. 1979), pp. 404-408. doi : 10.2307 / 1366967
- Robert E. Beck, Jr. and Julie A. Savidge: NATIVE FOREST BIRDS OF GUAM AND ROTA OF THE COMMONWEALTH OF THE NORTHER1 ~ MARIANA ISLANDS RECOVERY PLAN. Division of Aquatic and Wildlife Resources Department of Agriculture Government of Guam Agana, Guam
- Hypotaenidia owstoni in the endangered Red List species the IUCN 2011. Posted by: BirdLife International, 2010. Accessed November 13, 2011th
Web links
- Videos, photos and sound recordings of Gallirallus owstoni in the Internet Bird Collection