Laysan rail
| Laysan rail | ||||||||||
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Laysan rail ( Porzana palmeri ) with young |
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| Porzana palmeri | ||||||||||
| ( Frohawk , 1892) |
The Laysan rail ( Porzana palmeri ) is an extinct flightless bird from the island of Laysan , which belongs to the group of the Northwestern Hawaiian Islands .
Appearance and build
The flightless rail was 15 cm long and had very small rounded wings. While airworthy railing birds usually have eleven hand wings , the Laysan railing ( Porzana palmeri ) only had eight. The eighth was about as long as the first.
Way of life
The Laysan rail mainly ate insects and bird eggs, as well as carrion, more rarely green plants and seeds. The insects often caught them with their beak out of the air.
They were very lively and often jumped on the table to look for pieces of meat. But they never came out of holes that were 1.50 m deep. The rail was extremely curious and tame. She had no serious natural enemies on the island. Palmer wrote at the time that he caught them by spreading his net on the ground, with the result that the birds came immediately and looked to see what it was. It sounds even stranger to our ears that a rail was returning to its nest while a photographer 60 cm away adjusted his apparatus to take a picture of the nest. The photographer took the rail from the nest, but it returned to the nest almost immediately twice.
Reproduction
The nest of the Laysan rall was built under thick tufts of grass. It was a flat bowl, but the rail made sure that the nest was well hidden under tufts of grass or in the bushes and, if necessary, built a better camouflage for its nest itself. She also made sure that the access to the nest was not straight, obviously to protect herself from nest robbers. The eggs were 3.1 × 2.1 cm in size and were incubated from May to June. While mainland rail species often lay six to ten eggs, the Laysan rail clutch consisted of only three eggs on average.
The black, yellow-billed cubs hatched in June. They quickly learned to take care of themselves and could run as fast as their parents in five days. In the Midway population, the chicks hatched in March, so the whole development there should have happened three months earlier.
die out
The rail was first observed by the Moller crew who visited the island in 1828. They were quite common on Laysan in 1891, they had a population of about 2,000 and some Rothschilds were caught. The species was named in 1892.
Originally the Laysan Canal was restricted to the approximately 5 km² large island of Laysan. At the beginning of the 20th century it was successfully settled on the Midway Islands .
The rail on Laysan survived for the next 30 years, although guano was mined for 15 years during this time . Then, however, when the workers released rabbits, most of the island's vegetation was eaten and destroyed. This led partly due to lack of food, partly due to insufficient cover from birds of prey, to the disappearance of three terrestrial bird species: the Laysan breed of the South Sea warbler ( also called Laysan warbler ) ( Acrocephalus familiaris familiaris ), the Laysan apapane ( Himatione sanguinea freethi (fraithii) ) and the Laysan rail. In 1923 most of the rabbits were exterminated, the rest died out of natural causes.
Resettlement, which was attempted with birds from the Midway Islands in the same year, did not succeed. Then the Rallen died out through rats and the destruction of the bushes on the Midway Islands.
origin
The closest relative of the rail is the pygmy moorhen ( Porzana pusilla ).
The laysan rail was likely to become a flightless bird in less than 125,000 years.
swell
- ^ A b c d Walter Rothschild: The Avifauna of Laysan and the neighboring islands with a complete history to date of the birds of the Hawaiian possession. London: RH Porter, 1893-1900.
- ↑ a b c d e f g h i j Paul H. Baldwin: The Life History of the Laysan Rail. The Condor, Vol. 49, No. 1 (Jan. - Feb., 1947), pp. 14-21 doi : 10.2307 / 1364423
- ^ Waldron DeWitt Miller : Further Notes on Ptilosis. Bulletin American Museum of Natural History 306 (Vol. L 1924) (PDF; 2.9 MB)
- ^ J. Mark Jenkins: Natural History of the Guam Rail. The Condor, Vol. 81, No. 4 (Nov. 1979), pp. 404-408. doi : 10.2307 / 1366967
- ↑ Beth Slikas, Storrs L Olson, Robert C Fleischer: (2002) Rapid, independent evolution of flightlessness in four species of Pacific Island rails (Rallidae): an analysis based on mitochondrial sequence data. Journal of Avian Biology 33 (1), 5-14. doi : 10.1034 / j.1600-048X.2002.330103.x
- ↑ Brian K. McNab: Minimizing energy expenditure Facilitates vertebrate persistence on oceanic islands. Ecology Letters, (2002) 5: 693-704
Web links
Entry of the Laysan Rail in the IUCN Red List of Threatened Species (Engl.)