Latitudinal differences in life-history traits and parental care in northern and southern temperate zone House Wrens

PAULO E LLAMBIAS; MARIANA E. CARRO; GUSTAVO J. FERNANDEZ

JOURNAL FUR ORNITHOLOGIE

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2015 p. 933 - 942

0021-8375

South temperate songbirds differ from north temperate species in life-history traits, having greater adult survival, smaller clutch size, longer developmental periods and extended parental care. Due to its broad distribution, the House Wren, Troglodytes aedon, is an excellent model to evaluate selective pressures that may influence the maintenance of present clutch size. Here we report data on life-history traits and parental care of socially monogamous House Wrens from a north temperate and a south temperate population. Southern House Wrens exhibited smaller clutch sizes and longer developmental periods than Northern House Wrens; however we did not find significant differences in adult survival probability between populations, contrary to a critical prediction of the cost of reproduction hypothesis. Our data did not support the hypothesis that smaller clutches are the consequence of greater food limitation in the south; southern wrens have greater adult body mass but smaller territories, southern nestlings reached a greater proportion of adult body mass 6-7 days before fledgling and provisioning rates to the nest per nestling were greater in the south. We did not find support for the hypothesis that reduced clutch size is a consequence of limited parental activity at the nest as southern wrens did not reduce parental care during the incubation and nestling stage. Our data better supports the offspring quality hypothesis; southern wrens invest more per nestling than northern wrens as provisioning rates per nestling were significantly higher and developmental periods longer in the south. Published results from Tropical House Wrens suggest that neither food limitation nor nest predation can explain reduced clutches in Central America. We suggest that south temperate and tropical wrens may differ in parental investment strategies as tropical wrens seem to invest even less per nestling than north temperate wrens.