Time of breeding and female condition affect chick-growth in the Chilean Swallow (Tachycineta meyeni)

LILJESTHRÖM, M; ADRIAN CARLOS MIGUEL SCHIAVINI; REBOREDA, J.C.

EMU

CSIRO PUBLISHING

Lugar: Collingwood; Año: 2012 vol. 112 p. 157 - 161

0158-4197

We analysed growth of nestling Chilean Swallows (Tachycineta meyeni) over four consecutive breedingseasons and determined the factors that explain variation in growth rate, asymptotic body mass and length of the nestlingperiod. As the breeding season advanced nestlings grew more slowly and attained lower asymptotic mass, but the length ofthe nestling period and nestling survival did not show any seasonal trend. Asymptotic body mass of nestlings increased withfemale body condition, which was negatively correlated with time of breeding, suggesting that a seasonal decline inasymptotic body mass could be the result of changes in environmental conditions or lower quality of females breeding later inthe season. There was no relationship between average minimum ambient temperature and either growth rate or asymptoticmass during the nestlings first 10 days. However, short periods of poor weather and snowfall had a significant effect onnestling survival. Growth rate (0.43) was lower than that of other Tachycineta species nesting at similar latitudes in thenorthern hemisphere but similar to those of subtropical species of the genus, suggesting that the factors that have influencedthe evolution of this life-history trait differ between Chilean Swallows and other species of Tachycineta.