Seasonal changes in cell-mediated immunocompetence and mass gain in nestling barn swallows: a parasite-mediated effect?
Article first published online: 16 APR 2003
Volume 90, Issue 2, pages 327–332, August 2000
How to Cite
Merino, S., Møller, A. P. and De Lope, F. (2000), Seasonal changes in cell-mediated immunocompetence and mass gain in nestling barn swallows: a parasite-mediated effect?. Oikos, 90: 327–332. doi: 10.1034/j.1600-0706.2000.900213.x
- Issue published online: 16 APR 2003
- Article first published online: 16 APR 2003
- Accepted 14 February 2000
- Cited By
Reproduction in seasonal environments is usually timed so peak demand for food by offspring coincides with peak availability. Hence, late breeders will encounter a scarcity of food. Since parasite populations grow during the reproductive season of their hosts, late reproducing animals will also face an increasing challenge by parasites. We hypothesised that seasonal decrease in food availability and seasonal increase in parasite abundance will cause a trade-off between growth and immune function. This prediction was tested in nestling barn swallows ( Hirundo rustica) from first and second broods. Nestlings from second broods mounted stronger T cell mediated immune responses to a challenge with a novel antigen, but had lower rates of mass gain, than nestlings from first broods, consistent with the prediction. Broods in which at least one nestling died had lower levels of T cell mediated immune response, but not lower rates of mass gain, than broods without mortality, suggesting that brood reduction is mediated through an inability of offspring to defend themselves against parasites rather than an inability to grow. Possible mechanisms include scarcity of specific nutrients needed for immune responses, and/or parasites being concentrated on a single or few nestlings.