Suchergebnisse

8 pages, 3 figures, 1 table ; Offspring of long-lived species should face costs of parental trade-offs that vary with overall energetic demands encountered by parents during breeding. If sex differences exist in how parents make the trade-off, sex-specific differences may exist in the contribution of each parent to those costs. Adaptations of offspring facing such costs are not well understood, but the hormone corticosterone probably plays a role. We manipulated breeding effort in Cory's shearwaters (Calonectris diomedea) to increase costs to offspring and used an integrated measure of corticosterone from chick feathers to investigate how experimental variation in parental investment influences offspring physiology. Average foraging trip duration and foraging efficiency (FE) of breeding pairs were not related to chick corticosterone, but sex biases in FE were. Adult male investment was more strongly related to chick corticosterone than was female investment. Importantly, we show for the first time suppression of adrenocortical activity in nestling Procellariiform seabirds, and explain how our results indicate an adaptive mechanism invoked by chicks facing increased costs of parental trade-offs ; Funding for this work was provided by the Natural Sciences and Engineering Research Council of Canada and the Stuart and Mary Houston Professorship in Ornithology (to G.R.B.), and projects REN2002-01 164 and BOS2000-0569-CO2-01 from the Spanish Government. G.D.F. was supported by a University of Saskatchewan Dean's Scholarship, a Ruby Larson Scholarship, a Malcolm A. Ramsay Memorial Award, and the Nature Saskatchewan Graduate Student Grant ; Peer reviewed