Blue petrel
| Blue petrel | ||||||||||
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Blue petrel ( Halobaena caerulea ) |
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| Scientific name | ||||||||||
| Halobaena caerulea | ||||||||||
| ( Gmelin , 1789) |
The blue petrel ( Halobaena caerulea ) is a monotypic bird art from the family of the Petrels (Procellariidae). It is a very small petrel that is very similar to the whale birds . The main distinguishing feature is the dark head cap, which is not found in whale birds.
The IUCN classifies the blue petrel as harmless ( least concern ), since the range of this species is very large and the population numbers seem to be stable. The world population is estimated at three million sexually mature individuals.
Appearance
The blue petrel reaches a body length of 26 to 32 centimeters. The wing length is 19.8 to 23.3 centimeters and the wingspan is 62 to 71 centimeters. The weight of blue petrels varies between 152 and 251 grams. Males tend to be slightly larger and heavier than females.
The top and tail are blue-gray, the crown, neck and shoulder feathers are darker in color. Similar to the whale birds, a dark "M" runs over the wings. The front of the head is predominantly white with some dark speckles. The underside of the body is predominantly white. The feet are blue and webbed flesh-colored. Fledglings have a plumage similar to that of adult birds.
voice
The blue petrel is mostly silent on the high seas. In the breeding colonies, however, the adult birds can mainly be heard during the night. They utter calls that are reminiscent of the utterances of pigeons. Onomatopoeia, they are described as kuk-kuk-kuk coo-coo . There are geographical differences in the calls of the males. This has not yet been observed in females.
Distribution area
The blue petrel is found in the Antarctic waters. It is only very rarely found north of 40 ° S. It breeds on the Prince Edward Islands , the Crozet Islands , the Kerguelen and Macquarie as well as in the south of Chile. Outside of the breeding season, it is observed as far as the coasts of South Australia, New Zealand, southern South America and South Africa. However, most of the population stays in the breeding islands region all year round.
Way of life
The blue petrel eats crustaceans, fish, cephalopods and occasionally insects. While foraging it is often associated with whale birds and occasionally it also follows ships. It is sociable all year round and breeds in colonies.
Bluebirds breed in self-dug earthen burrows between 15 and 37 centimeters long. These are usually dug between tufts of grass on gently sloping slopes facing the sea. On the Kerguelen there seems to be competition for nesting sites with Belcher petrels . The actual nesting trough is occasionally covered with leaves and small branches.
The breeding season falls from September to February. Egg-laying usually occurs in October. The clutch consists of a single, white-shelled egg. The breeding season is 45 to 49 days. The young birds fledge after 43 to 60 days. Both parent birds are equally involved in the breeding and rearing of the young bird.
Like many other seabirds breeding in earthworks , the blue petrel suffers from the introduction of mammals to its breeding islands. Rats have helped reduce the number of breeding birds on Macquarie Island significantly. On Possession Island the breeding colonies have died out due to the introduced rats. Feral domestic cats also affect breeding populations in the Kerguelen and Prince Edward Islands.
Research history
The French doctor and naturalist Prosper Garnot reported in 1822 that he had seen a blue petrel in the Falkland Islands. However, there is no evidence that this species has ever bred in the Falkland Islands . There were comparable reports from later years, although as early as the 1950s ornithologists point out that this species certainly did not breed in the Falkland Islands. The birds observed are almost always Belcher petrels from the whale species , which are very similar to the blue petrel.
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
- Robin and Anne Woods: Atlas of Breeding Birds of the Falkland Islands , Anthony Nelson, Shorpshire 1997, ISBN 0904614-60-3
Web links
- Halobaena caerulea in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed on December 18 of 2008.
- Videos, photos and sound recordings of Halobaena caerulea in the Internet Bird Collection