Gray-footed booby
| Gray-footed booby | ||||||||
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Young gray-footed booby ( Papasula abbotti ) |
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| Systematics | ||||||||
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| Scientific name of the genus | ||||||||
| Papasula | ||||||||
| Olson & Warheit , 1988 | ||||||||
| Scientific name of the species | ||||||||
| Papasula abbotti | ||||||||
| ( Ridgway , 1893) |
The gray-footed booby ( Papasula abbotti ), also known as Abbott's booby , is a rare sea bird in the booby family . Its only breeding area is Christmas Island , a 135 square kilometer island in the Indian Ocean. Gray-footed boobies can be found in a region around this island all year round.
description
The gray-footed booby reaches a body length of 79 centimeters and weighs an average of 1,460 grams. He is black and white in his general appearance. The eyes are black. The beak is light gray in males, pink in females and has a black tip. The head, neck, and most of the underside are white in color. The black upper wings are spotted white on the ceiling.
Gray-footed boobies have a very steady flight beat of about three beats per second, in between they always insert longer flight phases. Like other boobies, he is also a shock diver.
Way of life
The gray-footed booby breeds in the tropical rainforest of Christmas Island on high plateaus and on western slopes. It depends on nothing hindering its direct approach to its breeding trees. There are no north-facing slopes because these are particularly exposed to gusts of wind during the monsoon season. Its preferred breeding trees protrude above the tops of other trees. He often uses trees of the genus Planchonella , Syzygium , Celtis and Tristiropsis .
The reproductive biology of the gray-footed booby has not yet been very well researched because the nests are difficult to access. Egg-laying falls between April and October, with a peak in June and July. The clutch consists of only one egg. The young birds grow up very slowly and are dependent on the parent birds for food until they are around 230 days old. Couples that successfully raise young birds therefore usually only breed once every two years. Overall, it is assumed that a couple needs 9.5 years to raise at least two young birds. The low reproductive rate is due to the fact that every fourth nestling dies in the first four weeks because they either starve to death or are beaten by the banded goshawk ( Accipiter fasciatus ). In addition, many fledglings die of starvation, and birds that have not yet fled are injured when they land in the treetops. They also fall victim to strong storms.
Danger
The IUCN classifies the Abbott's Booby as endangered ( endangered one). When the gray-footed booby was discovered in 1892 by the American ornithologist William Louis Abbott on the island of Assomption in the western Indian Ocean , it had a wider range than it is today. On Assomption it died out due to deforestation and guano mining in the 1920s or 1930s. Bone finds on Rodrigues and the Marshall Islands indicate that it was common on these islands in earlier centuries. The name of the extinct subspecies from the Marshall Islands - Papasula abbotti costelloi - was given in 1988 by David William Steadman, Susan Schubel and Dominique Pahlavan. In allusion to the comedian Lou Costello , the epithet costelloi was added as a play on words.
From 1965 to 1987, the main threat was guano mining on Christmas Island . Its breeding trees were cleared and the deposits left bare spots in many places. In 1988 a cyclone destroyed a third of the breeding population. From the 1990s onwards, the introduced yellow spider ant , which killed a large part of the young birds, posed a further threat .
After a protracted containment of the ants plague, conservationists succeeded in increasing the population from 1900 pairs in 1992 to 3000 pairs in 2002.
Individual evidence
- ↑ Higgins, p. 792
- ^ Higgins, p. 791
- ^ Higgins, p. 791
- ^ Higgins, p. 795
- ^ Higgins, p. 795
- ^ Higgins, p. 795
- ↑ BirdLife International: Species Factsheet - Papasula abbotti , accessed May 3, 2011
- ^ Steadman, David William (2006): Extinction and Biogeography of Tropical Pacific Birds. University of Chicago Press. ISBN 0-226-77142-3
literature
- Diamond, AW; Schreiber, RL (1987): Save the world of birds , Ravensburger Verlag
- PJ Higgins (Ed.): Handbook of Australian, New Zealand & Antarctic Birds , Volume 1, Ratites to Ducks, Oxford University Press, Oxford 1990, ISBN 0195530683 .
Web links
- Papasula abbotti inthe IUCN Red List of Threatened Species 2018.1. Listed by: BirdLife International, 2016. Retrieved July 7, 2018.
- Abbott's Booby on Assumption (English PDF; 3.42 MB)