Similar parental provisioning patterns in a monogamous and a polygynous House Wren population

PAULO E LLAMBIAS; KATIE LABARBERA; ANDREA A. ASTIE

THE CONDOR

COOPER ORNITHOLOGICAL SOC

Año: 2012 vol. 114 p. 629 - 638

0010-5422

Polygyny in House Wrens (Troglodytes aedon) is characterized by male partialdesertion, with males providing little or no help in feeding the nestlings of one of theirmates. We evaluated whether contributions to feeding nestlings and provisioning patternsof partially deserted females can explain geographic variation in polygyny rate within thespecies distribution. During 2003-2007, we studied two House Wren populations thatdiffer in polygyny rate (U.S., 40% vs. Argentina, 2%). We induced polygyny in themonogamous 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 socialmating system, 1) monogamous males should contribute more in the monogamouspopulation than in the polygynous population, 2) partially deserted females in themonogamous population should not compensate for the lack of help by feeding at higherrates than aided females, and 3) partial desertion should be more costly in the monogamouspopulation. Monogamous males in the monogamous and polygynous populations did notsignificantly differ in their provisioning contribution. Female provisioning also showedsimilar patterns in both populations; partially deserted females fed nestlings at higher ratesthan aided females but did not fully compensate for the lack of help. Furthermore, the costof male desertion seems to be greater in the polygynous population as poorly-aidedfemales had lower breeding and fledgling success. We suggest that male parental carecontributions and feeding patterns of unaided females cannot explain the geographicvariation in House Wren mating systems.