Costs of brood parasitism and the lack of defenses on the yellow-winged blackbird - Shiny cowbird system

The shiny cowbird (Molothrus bonariensis) is a generalist brood parasite that lays either white-immaculate or spotted egg morphs in eastern Argentina and Uruguay. Some hosts accept both morphs, others accept spotted eggs and reject the white morph, but no host has been found to accept white eggs and...

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Detalles Bibliográficos
Autores principales:	Massoni, Viviana, Reboreda, Juan Carlos
Publicado:	1998
Materias:	Agelaius thilius Brood parasitism Molothrus bonariensis Shiny cowbirds Yellow-winged blackbirds brood parasitism egg polymorphism host-parasite relationship reproductive success
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03405443_v42_n4_p273_Massoni http://hdl.handle.net/20.500.12110/paper_03405443_v42_n4_p273_Massoni
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_03405443_v42_n4_p273_Massoni
record_format	dspace
spelling	paper:paper_03405443_v42_n4_p273_Massoni2023-06-08T15:33:59Z Costs of brood parasitism and the lack of defenses on the yellow-winged blackbird - Shiny cowbird system Massoni, Viviana Reboreda, Juan Carlos Agelaius thilius Brood parasitism Molothrus bonariensis Shiny cowbirds Yellow-winged blackbirds brood parasitism egg polymorphism host-parasite relationship reproductive success Agelaius thilius Agelaius thilius Molothrus bonariensis Molothrus bonariensis The shiny cowbird (Molothrus bonariensis) is a generalist brood parasite that lays either white-immaculate or spotted egg morphs in eastern Argentina and Uruguay. Some hosts accept both morphs, others accept spotted eggs and reject the white morph, but no host has been found to accept white eggs and reject spotted ones. It has been suggested that the yellow-winged blackbird (Agelaius thilius) may be that type of host. The finding of a white acceptor-spotted rejector species would help to explain the occurrence and maintenance of the parasite egg polymorphism. We studied the incidence of shiny cowbird parasitism on this host, its costs for their reproductive success and the presence of antiparasitic defenses in the yellow-winged blackbird - shiny cowbird system. The parasite affected the reproductive success of the host in two ways. Cowbirds punctured host eggs causing a reduction in clutch size, and yellow-winged blackbirds deserted their nests whenever they suffered high egg loss. In addition, parasitized nests suffered higher predation during the nestling stage, but not during egg stages, indicating that the difference found was related to the presence of the cowbird chick, and not to higher exposure of parasitized nests to both parasites and predators. Despite the costs imposed by the parasite, yellow-winged blackbirds have not evolved antiparasitic defenses. This host did not reject any egg morph of the shiny cowbird nor desert parasitized nests unless it had suffered high egg loss. Current explanations for the host lack of defenses, the 'time lag' and the 'equilibrium' hypothesis, are discussed. Fil:Massoni, V. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Reboreda, J.C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 1998 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03405443_v42_n4_p273_Massoni http://hdl.handle.net/20.500.12110/paper_03405443_v42_n4_p273_Massoni
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Agelaius thilius Brood parasitism Molothrus bonariensis Shiny cowbirds Yellow-winged blackbirds brood parasitism egg polymorphism host-parasite relationship reproductive success Agelaius thilius Agelaius thilius Molothrus bonariensis Molothrus bonariensis
spellingShingle	Agelaius thilius Brood parasitism Molothrus bonariensis Shiny cowbirds Yellow-winged blackbirds brood parasitism egg polymorphism host-parasite relationship reproductive success Agelaius thilius Agelaius thilius Molothrus bonariensis Molothrus bonariensis Massoni, Viviana Reboreda, Juan Carlos Costs of brood parasitism and the lack of defenses on the yellow-winged blackbird - Shiny cowbird system
topic_facet	Agelaius thilius Brood parasitism Molothrus bonariensis Shiny cowbirds Yellow-winged blackbirds brood parasitism egg polymorphism host-parasite relationship reproductive success Agelaius thilius Agelaius thilius Molothrus bonariensis Molothrus bonariensis
description	The shiny cowbird (Molothrus bonariensis) is a generalist brood parasite that lays either white-immaculate or spotted egg morphs in eastern Argentina and Uruguay. Some hosts accept both morphs, others accept spotted eggs and reject the white morph, but no host has been found to accept white eggs and reject spotted ones. It has been suggested that the yellow-winged blackbird (Agelaius thilius) may be that type of host. The finding of a white acceptor-spotted rejector species would help to explain the occurrence and maintenance of the parasite egg polymorphism. We studied the incidence of shiny cowbird parasitism on this host, its costs for their reproductive success and the presence of antiparasitic defenses in the yellow-winged blackbird - shiny cowbird system. The parasite affected the reproductive success of the host in two ways. Cowbirds punctured host eggs causing a reduction in clutch size, and yellow-winged blackbirds deserted their nests whenever they suffered high egg loss. In addition, parasitized nests suffered higher predation during the nestling stage, but not during egg stages, indicating that the difference found was related to the presence of the cowbird chick, and not to higher exposure of parasitized nests to both parasites and predators. Despite the costs imposed by the parasite, yellow-winged blackbirds have not evolved antiparasitic defenses. This host did not reject any egg morph of the shiny cowbird nor desert parasitized nests unless it had suffered high egg loss. Current explanations for the host lack of defenses, the 'time lag' and the 'equilibrium' hypothesis, are discussed.
author	Massoni, Viviana Reboreda, Juan Carlos
author_facet	Massoni, Viviana Reboreda, Juan Carlos
author_sort	Massoni, Viviana
title	Costs of brood parasitism and the lack of defenses on the yellow-winged blackbird - Shiny cowbird system
title_short	Costs of brood parasitism and the lack of defenses on the yellow-winged blackbird - Shiny cowbird system
title_full	Costs of brood parasitism and the lack of defenses on the yellow-winged blackbird - Shiny cowbird system
title_fullStr	Costs of brood parasitism and the lack of defenses on the yellow-winged blackbird - Shiny cowbird system
title_full_unstemmed	Costs of brood parasitism and the lack of defenses on the yellow-winged blackbird - Shiny cowbird system
title_sort	costs of brood parasitism and the lack of defenses on the yellow-winged blackbird - shiny cowbird system
publishDate	1998
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03405443_v42_n4_p273_Massoni http://hdl.handle.net/20.500.12110/paper_03405443_v42_n4_p273_Massoni
work_keys_str_mv	AT massoniviviana costsofbroodparasitismandthelackofdefensesontheyellowwingedblackbirdshinycowbirdsystem AT reboredajuancarlos costsofbroodparasitismandthelackofdefensesontheyellowwingedblackbirdshinycowbirdsystem
_version_	1768542552719360000

Costs of brood parasitism and the lack of defenses on the yellow-winged blackbird - Shiny cowbird system

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