Red-footed Atlas widow
| Red-footed Atlas widow | ||||||||||||
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Red-footed Atlas widow, male in breeding dress |
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| Scientific name | ||||||||||||
| Vidua chalybeata | ||||||||||||
| ( Statius Müller , 1776) |
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The red-footed atlas widow ( Vidua chalybeata ) is a bird from the family of widow birds native to sub-Saharan Africa . Several subspecies occur within the large distribution area. Like all widow birds, the red-footed atlas widow is an obligatory brood parasite that has its young birds raised by the Senegalese amaranth as the only host bird species.
The species is occasionally kept as an ornamental bird in Europe.
description
Red-footed atlas widows reach a height of 11 to 12 centimeters. The male has a black to black-brown plumage in its splendid plumage, which, depending on the distribution area and subspecies, shines iridescent green-blue to black-violet. The plumage of red-footed atlas widows, whose distribution area is in western Equatorial Africa, has a green-blue sheen. The color of the beak and legs also varies with the area of distribution. In West Africa the beak is horn-colored and the legs orange. In southeast Africa, the beak is pinkish yellow, the feet and legs are red.
Unlike many widow birds, the male of the red-footed atlas widow has no elongated control feathers, but the tail is the same in both sexes with 3.6 to 4.2 centimeters. The weight of both sexes is between 11.1 and 15.1 grams.
When resting, the male resembles the female. Its color is reminiscent of a sparrow: it has a light brown upper body. The underside is whitish and turns brown on the chest and flanks. The coloring of the beak and feet corresponds to that of the males in the respective distribution area.
The male's calls include wehet-wheet.wheeto calls and harsh, clattering calls, but he also mimics the calls of the Senegalamarant , his host bird.
distribution and habitat
The distribution area of the red-footed Atlas widow extends from Senegal to Ethiopia and in a southerly direction to South Africa.
The habitat of the red-footed atlas widow are dry savannah and bush landscapes. He avoids deserts, wet forest areas and dense forests. It is also a cultural follower that can be observed in agricultural areas as well as in the outskirts of cities and villages.
Way of life
Their food is grass and millet seeds.
The red-footed atlas widow is a breeding parasite exclusively or almost exclusively of the Senegalamarant , which belongs to the finch family . The adult Senegal amaranth weighs around 8.3 grams, the red-footed atlas widow has an average of 13.2 grams, almost 60 percent more body mass. There are a few observations that also suggest parasitization of the little lobster.
Breeding season and eggs
The eggs of the red-footed atlas widow are pure white and are among the smallest of the widow birds. They correspond in color and shape to that of the Senegalamarant, but the eggs are around 50 percent heavier than those of the host bird. The breeding period is largely synchronized with the host bird and varies according to the distribution area. In South Africa, the breeding season of both species falls in the months of November to April with a peak in January and February. A female of the red-footed atlas widow can lay up to 26 eggs within such a breeding period of several months. During this breeding period, a single female goes through laying cycles of 10 days in which she lays an average of up to 3 eggs. The laying interval between the individual eggs is at least one day.
Red-footed atlas widows minimize the risk of losing an egg through predation by laying an average of three eggs per laying cycle in nests of different Senegalese amaranth pairs, if possible.
Correlation between red-footed atlas widow and Senegalese amaranth
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Senegalese marants show little defensive behavior against the brood parasitic behavior of the red-footed Atlas widow. The red-footed atlas widow even lays eggs while one of the Senegalese's two parent birds is sitting on the eggs. The red-footed atlas widow even regularly lays the egg on the back of the host bird. Unlike many other brood parasitic bird species, the red-footed Alta widow does not remove an egg from the host bird's clutch. Johngard points out, however, that the eggs for the red-footed atlas widow are not visible when they are laying their eggs, since a parent bird of the Senegalese amaranth sits firmly on the nest from the first egg onwards. It happens again and again that several females of the red-footed atlas widow lay eggs in a specific nest. Up to six red-footed atlas widow eggs have been found in a single nest of Senegalese marants. However, more than four eggs from red-footed atlas widows are the exception.
There are many indications that the Senegalese amaranth does not suffer any reproductive disadvantages due to the parasitism of the red-footed atlas widow. One study showed that the nests of non-parasitized Senegalese marants contain an average of 3.5 eggs. In parasitized nests, on the other hand, there are only slightly fewer Senegalamarant eggs: on average, the parasitized Neuer had 3.4 Senegalamarant eggs and 2.2 eggs from the red-footed atlas widow. In a study published in 1973, MY Morel came to the conclusion that the higher number of eggs in the nest represented a " super stimulus " for the host bird parents, since parasitized nests are on average less abandoned by the host birds than non-parasitized ones. With parasitized nests, nest abandonment occurs in only 45.7 percent of cases. In the case of non-parasitized nests, brood is broken off in 56.3 percent. The fact that on average only 2.1 nestlings of the host bird fledge in a parasitized nest, while there are 2.8 nestlings in a non-parasitized nest, is compensated for by this lower degree of nest losses. The breeding success measured in terms of fledgling species-specific young per egg laid is the same for the Senegalese amaranth. This also explains why there is no evolutionary pressure for the Senegalese amaranth to develop defense mechanisms against the brood parasitic behavior of the red-footed atlas widow.
Breeding success of the red-footed Atlas widow
MY Morel was also able to prove in their study that from 100 eggs laid by the red-footed atlas widow 17 to 20 fledgling young birds emerge. The rule here is that the chance of a newly hatched red-footed Atlas widow nestling of surviving until they fled, the higher the fewer other nestlings of the same species are in the nest. On average, 1.3 nestlings of the red-footed atlas widow fledge in addition to 2.1 nestlings of the host bird.
literature
- Horst Bielfeld : Knowing and caring for 300 ornamental birds. Ulmer Verlag, Stuttgart 2009, ISBN 978-3-8001-5737-2 .
- Paul A. Johnsgard: The Avian Brood Parasites - Deception at the Nest . Oxford University Press, Oxford 1997, ISBN 0-19-511042-0 .
- MY Morel: Contribution á l'etude dynamique de la population de Lagonosticta senegala L. (estrildides) à Richard-Toll (Senegal). Interrelations avec le parasite Hypochera chalybeata (Müller) (viduines). Mem. Mus. Nat. d'Hist. Nat., Ser. A (Zool.) 78: 1-156, 1973.
Web links
- Vidua chalybeata onthe IUCN 2013 Red List of Threatened Species . Listed by: BirdLife International, 2012. Retrieved February 6, 2014.
- Voice of the Red-footed Atlas Widow on Xeno-Canto
Single receipts
- ↑ a b c Johnsgard: The Avian Brood Parasites . P. 285.
- ^ A b Johnsgard: The Avian Brood Parasites . P. 286.
- ^ Voice of the Red-Footed Atlas Widow on Xeno-Canto , accessed on September 8, 2016.
- ↑ a b c d e Johnsgard: The Avian Brood Parasites . P. 288.
- ↑ a b c d Johnsgard: The Avian Brood Parasites . P. 289.
- ↑ Johnsgard: The Avian Brood Parasites . P. 291.
- ^ Morel: Contribution á l'etude dynamique de la population de Lagonosticta senegala L. (estrildides) à Richard-Toll (Senegal).
- ^ A b Johnsgard: The Avian Brood Parasites . P. 290.