La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Contrasting breeding strategies of two sympatric orioles: first documentation of double brooding by Orchard Orioles
Auteurs :	Spring Ligi, Auteur ; Kevin Omland, Auteur
Type de document :	Article
Dans :	Journal of Field Ornithology (78(3) SEP 2007)
Article en page(s) :	298-302
Langues:	Anglais
Résumé :	Although many studies have revealed intraspecific variation in the number of broods raised per breeding season, less is known about the causes of variation between species. We monitored the breeding behavior of congeners traditionally thought to raise one brood per breeding season, Orchard Orioles (Icterus spurius) and Baltimore Orioles (I. galbula). Both species have similar habitat and nesting requirements. We captured and banded orioles at three study sites in Maryland in 2004 and 2005. No pairs of Baltimore Orioles (N = 26) were double brooded, whereas 8 of 24 pairs (33%) of Orchard Orioles had a second brood and 7 of 16 pairs (44%) of Orchard Orioles that successfully raised a first brood also successfully raised a second brood during the same breeding season. Our findings provide the first documentation of double brooding by Orchard Orioles. The timing of molt and the amount of time and energy devoted to postfledgling parental care may contribute to this difference between species in terms of the number of broods per breeding season.

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