Factors affecting the probability of double brooding by Southern House Wrens

CARRO, M. E.; MERMOZ, M. E:; FERNÁNDEZ G. J.

JOURNAL OF FIELD ORNITHOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2014

0273-8570

Seasonal fecundity of birds is influenced by clutch sizes and the number of successful breedingattempts during a breeding season. As such, understanding the factors that determine the decision to initiatemultiple broods within a season and the consequences of this reproductive tactic is important. We examined thefrequency of double brooding by Southern House Wrens (Troglodytes aedon musculus) in eastern Argentina. Weanalyzed inter- and intraseasonal variation in double brooding and evaluated the effect of weather conditions andlaying date on the frequency and occurrence of this behavior. Finally, we assessed the effect of double broodingon the seasonal and lifetime productivity of female Southern House Wrens. During our 8-year study, we foundthat 43% (range = 17?83% each year) of breeding pairs attempted a second brood after successfully raising afirst brood. The probability of females having a second brood was affected by the laying date of the first nestingattempt, but was independent of the number of young fledged. About 65% of females that started laying eggs beforethe first quarter of each breeding season produced a second brood, and this percentage decreased to 40% afterthis period. In addition, variation in double-brooding frequency among years was related to weather conditions,with the proportion of pairs double brooding increasing with increased precipitation early in the breeding season.More precipitation likely contributed to an increase in insect abundance. Although double brooding increased theseasonal and lifetime productivity of female Southern House Wrens, additional study of the survival and fate offledglings from first and second broods is needed to assess the importance of multi-brooding in the reproductivesuccess of these wrens.