Thick-billed petrel
| Thick-billed whale bird | ||||||||||
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| Systematics | ||||||||||
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| Scientific name | ||||||||||
| Pachyptila crassirostris | ||||||||||
| ( Mathews , 1912) |
The thick-billed petrel ( Pachyptila crassirostris ) is a species from the petrel family. It is a rather small member of this family that can only be observed in the region of the southern oceans. There are two subspecies.
The IUCN classifies the thick-billed petrel as 
(= least concern - not endangered), because the range of this species is very large and the population numbers seem to be stable. The worldwide population is estimated at 150,000 to 300,000 sexually mature individuals.
Appearance
The thick-billed petrel reaches a body length of 24 to 28 centimeters. The wing length is between 15.6 and 19 centimeters and the wingspan is 60 centimeters. Thick-billed petrels weigh between 102 and 185 grams. Males tend to be slightly larger than the females.
Compared to other representatives of the whale bird genus , the thick-billed petrel has relatively pale plumage. the top of the body is a pale blue-gray. As with all other whale birds, a conspicuous, black and gray "M" runs over the wings. The thick-billed petrel also has a very broad black tail band. A dark gray eye streak runs through the pale gray face. Due to this dark coloring, the facial drawing is less noticeable than is the case with other whale birds. The underside of the body is white with pale brown sides of the chest. Fledglings do not differ in their plumage from the adult birds.
There is a possibility of confusion with the other species from the genus of whale birds. The resemblance to the fairy petrel is particularly pronounced .
Distribution area
The thick-billed petrel breed in the Snare Islands , Heard , Auckland Islands , the Bounty Islands, and the Chatham Islands . The exact limits of the distribution area outside of the breeding season are unknown, but the thick-billed petrel seems to be mostly in the latitudes of its breeding islands. However, it has also been observed off the southeast coast of Australia and off the coast of South Africa.
Way of life
The thick-billed petrel mainly eats small crustaceans and stays near the coast while foraging. It can usually be seen in schools both at sea and on land. They are monogamous birds with a longstanding pair bond.
The thick-billed petrel breeds in crevices, in caves, in hollows in scree slopes and under boulders. The actual nesting trough is lined with feathers and other materials. The thick-billed petrels usually breed in dense colonies that are often close to colonies of albatross. The clutch consists of a single egg. This is white-skinned. The laying time falls in October and November. On the Bounty Islands, the chicks usually hatch from mid to late December. So far, no studies have been carried out on the age at which the young birds fledge. Only one clutch is raised per year and both parent birds are involved in the brood and care of the young bird.
Internal system
There are two subspecies:
- The nominate form Pachytila crassirostris crassirostris breeds on the Chatham Islands, the Snares Islands and the Bounty Islands.
- The subspecies Pachytila crassirostris eatoni breeds on Heard and the Auckland Islands. The subspecies is slightly smaller than the nominate form and has a slightly narrower beak.
A third subspecies Pachytila crassirostris pyramidalis is occasionally mentioned in the literature, but is generally not recognized.
supporting documents
literature
- Hadoram Shirihai: A Complete Guide to Antarctic Wildlife - The Birds and Marine Mammals of the Antarctic Continent and Southern Ocean , Alula Press, Degerby 2002, ISBN 951-98947-0-5
Single receipts
- ↑ BirdLife factsheet on the thick-billed petrel , accessed December 13, 2010
- ↑ Shirihai, p. 180
- ↑ Shirihai, p. 180
- ^ Shirihai, p. 181
Web link
- Pachyptila crassirostris in the Red List of Threatened Species of the IUCN 2013.1. Listed by: BirdLife International, 2012. Retrieved November 7, 2013.