Effects of nestboxes on the breeding biology of Southern House Wrens Troglodytes aedon bonariae in the Southern Temperate Zone

PAULO E. LLAMBIAS; GUSTAVO J. FERNANDEZ

IBIS

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Hertfordshire; Año: 2009 vol. 151 p. 113 - 121

0019-1019

Nestboxes are known to increase clutch size, enhance breeding success and affect the socialmating system of several cavity nesters. Although in recent years various cavity nesters havebeen studied in nestboxes in South America, the effects of boxes on the biology of the studyspecies are unknown. We evaluated the effects of nestboxes on the breeding biology andsocial mating system of Southern House Wrens Troglodytes aedon bonariae by comparing birds breeding in nestboxes and tree cavities in two cattle ranches in Buenos Aires Province,Argentina. Southern House Wrens nesting in boxes had higher breeding success but, contraryto studies on the temperate zone, we did not find differences in clutch size betweenWrens breeding in nestboxes and tree cavities. The main causes of nest failure in tree cavitieswere nest predation and flooding of the cavity (70 and 23% of the failures, respectively)while in nestboxes predation and desertion were the most important causes of failure (38and 34% of the failures, respectively). The social mating system of Southern House Wrensis monogamy with biparental care, and neither was affected by the boxes. Males did notattract secondary females to additional nestboxes; however, nestboxes are safer breedingsites than tree cavities, and females seemed to prefer males with nestboxes on their territory.These results suggest that nest quality alone might be not enough for secondary females toaccept polygyny.