Widow birds

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Widow birds
Dominican widow (Vidua macroura)

Dominican widow ( Vidua macroura )

Systematics
Subclass : New-jawed birds (Neognathae)
Order : Passerines (Passeriformes)
Subordination : Songbirds (passeri)
without rank: Passerida
Superfamily : Passeroidea
Family : Widow birds
Scientific name
Viduidae
Cabanis , 1847
Pointed tail widow of paradise
A male cuckoo finch . Cuckoo finches differ in their appearance from those of other species in this family

The widow birds (Viduidae) are a family from the order of the passerine birds (Passeriformes). It is a breeding parasite with a conspicuous sexual dimorphism ; in most species the males develop very long tail feathers during the reproductive period. The plain dress, on the other hand, is inconspicuous. The tail has a total of 12 feathers, of which the two inner pairs are moulted by the males twice a year. The other control springs are only moulted once a year. Widow birds are found exclusively in sub-Saharan Africa.

Deviating from this, the males of the cuckoo widow ( Anomalospiza imberbis ) have bright yellow plumage, while the females are brownish. Cuckoo finches inhabit open grasslands and they parasitize several species of the stalk warbler .

Widow birds as breeding parasites of the finches

All widow bird species are breeding parasites, whereby only species of the finch are used as breeding hosts . Most of the widow species have specialized in one species of finch; Only in a few species are two or three very closely related finch species used by widow birds as breeding hosts. The tendency of some African finch finches to build so-called cock nests is seen as a possible defense strategy of these species in order to prevent brood parasitism.

The adaptation between the host birds and the widow birds goes very far. The eggs of the widow birds of the genus Vidua resemble those of the fine finches; they are just a little bigger. NB Davies points out, however, that both the Vidua species and the parasitized host birds lay white eggs. He interprets this as an indication that both have a close history of development. The females of the Vidua usually only lay one egg in the nest of their host bird and do not remove any of the eggs from the clutch. In contrast to the cuckoo , a hatching widow bird does not remove the eggs and young birds of its host family, but grows up together with the step-siblings. The young birds of the widow birds have the same throat markings, papillae or beak edge bulges as the young splendid finches. Also in their plumage, with their begging movements and sounds, they resemble the young birds of the breeding hosts. In adult male widows you can tell from the song which finch was raised. Only the Dominican widow , who uses the wave and gray reeds as breeding birds, and the gloss widow , who has their young raised by elves and fairies , have their own singing that does not resemble that of the host family.

There is evidence for individual species of fine finch that parasitization by a widow bird need not be accompanied by a reproductive disadvantage. This applies at least to the red-footed atlas widow and the Senegalese amaranth , which it only parasitizes . 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 level 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.

In the cuckoo finch, the only member of the genus Anomalospiza , the eggs are pale bluish with red spots. According to NB Davies, this is the result of an adjustment trend. Deposition by the cuckoo finch is also usually associated with the disappearance of an egg from the host bird's clutch. However, this has never been directly observed. The nestlings of the cuckoo finches also differ significantly from that of their host bird and there is no mimicry of the throat markings. Nestlings of the cuckoo finch do not throw eggs or nestlings out of the nest, as a newly hatched cuckoo does, for example. However, the nestling of the cuckoo finch is more assertive when begging for food, and a nestling of the host bird usually does not grow in a parasitized nest.

Genera and species

supporting documents

literature

  • NB Davies: Cuckoos, Cowbirds and Other Cheats . T & AD Poyser, London 2000, ISBN 0-85661-135-2 .
  • C. Hilary Fry and Stuart Keith (Eds.): The Birds of Africa. Volume VII. Christopher Helm, London 2004, ISBN 0-7136-6531-9 .
  • 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

Commons : Viduidae  - Collection of images, videos and audio files

Single receipts

  1. ↑ Fry et al., P. 419
  2. ↑ Jürgen Nicolai (ed.), Joachim Steinbacher (ed.), Renate van den Elzen, Gerhard Hofmann, Claudia Mettke-Hofmann: Prachtfinken - Afrika , series Handbuch der Vogelpflege, Eugen Ulmer Verlag, Stuttgart 2007, ISBN 978-3-8001 -4964-3 , p. 258
  3. ↑ Davies: Cuckoos, Cowbirds and Other Cheats . P. 22
  4. ^ Morel: Contribution á l'etude dynamique de la population de Lagonosticta senegala L. (estrildides) à Richard-Toll (Senegal).
  5. ↑ Johnsgard: The Avian Brood Parasites . P. 290.
  6. ↑ a b Davies: Cuckoos, Cowbirds and Other Cheats. P. 23.