Pre- and post-hatching effects on nestling growth and brood reduction

Abstract

Developmental trajectories are considered plastic phenotypic traits that allow animals to adjust their growth in response to environmental conditions. Plasticity in growth trajectories is likely mediated by parental effects occurring before and after offspring birth, but its relative contribution has rarely been explored in the wild. By swapping first, intermediate, and last hatched nestlings between nests of the European hoopoe ( Upupa epops ), a species with pronounced hatching asynchrony, we experimentally broke the natural association between laying and hatching order to explore their effects on nestling growth and survival. First-hatched nestlings grew faster and experienced the lowest probability of death and cannibalism regardless of their rank hierarchy in their nest of origin. Growth rate of intermediate nestlings was lower than that of first and last nestlings, but deficiencies were compensated for afterwards, and they showed an intermediate probability of death and cannibalism. Finally, most of the last-hatched nestlings showed deficient growth during the nestling period, and the highest probability of death and cannibalism. The hatching position of experimental nestlings in their nest of origin had little effect on their growth patterns in the nest of rearing, and did not affect their probability of death. These results suggest that post-hatching effects are responsible for nestling probability of death and cannibalism, while pre-hatching effects associated with egg-laying order may be partially responsible for the particularities of growth patterns among nestlings of different hatching order. We discuss the importance of these results under the hypothesis that animals should adjust pre- and post-hatching investment according to the fitness value of their offspring.

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