Bitterns
| Bitterns | ||||||||||
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| Systematics | ||||||||||
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| Scientific name | ||||||||||
| Botaurus | ||||||||||
| Stephens , 1819 |
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The bitterns ( Botaurus ) are a genus of the herons . They occur in four types almost worldwide.
features
All four species are compact in shape with a short, thick neck and short legs and a relatively short, strong green-yellow to brownish beak . The plumage is finely striped black, yellow-brown and white. Chin and throat are noticeably lighter than the rest of the plumage in all species. The breast shows brownish longitudinal stripes in all species. The legs are olive green to brownish. The irises are yellowish. In terms of plumage, bitterns do not show any conspicuous sexual dimorphism. However, the females are often drawn a little less contrast than the males. There is a noticeable sexual dimorphism , however, at least in the bittern and the Australian bittern, as the males are considerably larger and heavier than the females. In the Eurasian bittern, females weigh between 817 and 1,150 grams, the males between 966 and 1940 grams.
The appearance and behavior of all bittern species is inconspicuous. For this reason, many details of their breeding biology and their food spectrum have not yet been conclusively investigated. They are well camouflaged in the reeds and reeds with their heavily piebald plumage in warm brown tones. The plumage of all kinds imitates a pattern of light and shadow that dissolves the contours of the bird. This form of camouflage is known as somatolysis . If they are disturbed, they adopt a characteristic posture in which the beak is pointed straight up. At least for the bittern, it has been proven that it sways in the wind with the surrounding reeds. Their longitudinal stripes then act like individual stalks.
Distribution area, population and habitat
The range of the bittern are North and South America, Eurasia, Africa as well as Australia and New Zealand. There are two species in North America, as the range of the South American bittern extends from southern Mexico to northern Argentina. The distribution area of the bittern, which also occurs in Central Europe, extends from Great Britain to Japan. A subspecies breeds in the Natal and Transval provinces of South Africa. The Australian bittern occurs in the extreme southwest and southeast of Australia, Tasmania and New Zealand. It is the rarest species in the genus; their population is estimated at fewer than 2,500 birds and the IUCN lists them as endangered .
Bittern populations are declining worldwide. They are dependent on large belts of reeds that are lost when draining or converting wetlands into agricultural land. The bittern species, which are not threatened, are also not common anywhere in their range.
Way of life
Bitterns eat fish, frogs, amphibians and reptiles, small mammals, birds and insects. They usually look for their food at dusk in the cover of the dense reed belt and are able to climb very skillfully through the reeds. They move very slowly when foraging for food. It is characteristic of their mode of locomotion that they draw their feet very close to the body as they progress slowly.
species
The following species belong to the bittern genus:
- South American bittern , Botaurus pinnatus
- North American bittern , Botaurus lentiginosus
- Bittern , Botaurus stellaris
- Australian bittern , Botaurus poiciloptilus
supporting documents
Single receipts
- ↑ Kushlan et al., P. 296
- ↑ Christopher McGowan: The Raptor and the Lamb - Predators and Prey in the Living World. Penguin Books, London 1998, pp. 100, 101, ISBN 0-14-027264-X
- ↑ BirdLife Factsheet on the Australian Bittern , accessed September 13, 2009
literature
- James A. Kushlan & James A. Hancock: Herons. Oxford University Press, 2005, ISBN 0198549814 .
