| Bay-winged Cowbird (Agelaioides badius)
(aka Baywing, Molothrus badius)
Brazilian name: asa-de-telha |
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Brazil There are two main areas where the Bay-winged Cowbird is found: firstly, from Bolivia, through Paraguay, south Brazil and Uruguay to central Argentina and, secondly, in north east Brazil. There are further isolated small areas in São Paulo state and in central Chile. |
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The taxonomy of this species appears a bit confused mainly because it seems to be only distantly related to true cowbirds and it behaves a lot more like the Chopi Blackbird Gnorimposar chopi. Unlike other cowbirds it is not a brood parasite and, in fact, the Bay-winged Cowbird itself is a victim of brood parasitism by other cowbirds mainly the Screaming Cowbird Molothrus rufoaxillaris. While the Bay-winged Cowbird breeds normally and sometimes builds its own nest, it often uses old nests of other species such as the Rufous-fronted Thornbird Phacellodomus rufifrons. This "nest parasitism" has been interpreted as a primitive stage of parasitism. |
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These and other differences are supported by molecular variation compared to other cowbirds which has led Jaramillo & Burke to suggest that the English name for this species be changed to Baywing and that the generic name be changed from Molothrus to Agelaioides. |
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They further suggest that the subspecies found in the north east of Brazil, M. b. fringillarius shown in the first photo (taken at Mocambinho in Minas Gerais) may best be considered as a different species, the "Pale Baywing". This is on the basis of the much paler colouration, the much buffier tone of the underparts and the more extensive as well as more contrasting black mask. Compare with the other photos all of the nominate sub-species. Vocalisations are also different between these subspecies as you can hear on xeno-canto. |
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In October 2007, the American Ornithologists' Union have still to recognise this split while the Comitê Brasileiro de Registros Ornitológicos - CBRO, have recognised it. The Bay-winged Cowbird is normally found in dry, scrubby open woodland such as the caatinga of north east Brazil. They are often seen in small flocks. There are illustrations in Ridgely & Tudor, Volume 1, Plate 22; and Jaramillo & Burke, Plate 37. |
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