SIMILAR PARENTAL PROVISIONING PATTERNS IN A MONOGAMOUS AND A POLYGYNOUS HOUSE WREN POPULATION

LLAMBÍAS, PAULO E.; LABARBERA, KATIE; ASTIÉ, ANDREA ALEJANDRA

THE CONDOR

COOPER ORNITHOLOGICAL SOC

Año: 2012 p. 629 - 638

0010-5422

In the House Wren (Troglodytes aedon), polygyny is characterized by males’ partial desertion, malesproviding little or no help in feeding the nestlings of one of their mates. We evaluated whether contributions to feedingnestlings and patterns of provisioning by partially deserted females can explain geographic variation in the species’ rateof polygyny. From 2003 to 2007, we studied two populations differing in polygyny rate (U.S., 40%; Argentina, 2%).We induced polygyny in the monogamous population by removing males from their territories before the onset of egglaying. We predicted that if patterns of parental care are related to variation in the social mating system, monogamousmales should contribute more in the monogamous population than in the polygynous population, in the monogamouspopulation partially deserted females should not compensate for the lack of help by feeding at rates higher than do aidedfemales, and partial desertion should be more costly in the monogamous population. Monogamous males of the twopopulations did not differ significantly in their contribution to provisioning. Females’ pattern of provisioning was alsosimilar; partially deserted females fed nestlings at a rate higher than did aided females but did not fully compensate forthe lack of help. Furthermore, the cost of male desertion seems greater in the polygynous population, as the breedingand fledging success of poorly aided females were lower. We suggest that the male’s contributions to parental care andthe patterns of unaided females’ feeding cannot explain the geographic variation in the House Wren’s mating systems.