DYNAMIC STATE-VARIABLE MODELS FOR PARENTAL CARE .1. A SUBMODEL FOR THE GROWTH OF THE CHICKS OF PASSERINE BIRDS

As part of a larger modeling effort to understand the evolution of par ental care in birds, we develop a model to predict the masses of devel oping passerine chicks based on assumptions about the amount of food f ed to the chicks and published estimates of their metabolic costs, eff iciencies and requirements as functions of chick mass and/or age. The model predicts sigmoid trajectories similar to those observed in natur e. The model fails to predict post-peak declines in mass in some speci es, and we suggest that one reason for this failure is that the model does not account for parent-offspring conflict over food deliveries la te in the chick's development.