A dynamic model of food allocation to starling (Sturnus vulgaris) nestlings

We present a dynamic model of food allocation to starling nestlings. Based on the premise that current reproductive activities may have detrimental effects on future breeding episodes, the model is elaborated around the concept of a state variable. In this implementation, the state variable represents body mass. A number of activities can be followed during the breeding season, and we measured the value of these actions in terms of the contribution of the action to the fitness of the animal at the end of the nestling period. Using the final states reached by parents and young, we determined fitness by summing current breeding production and future reproductive potential. We used backward induction to find for each combination of states and nestling age the behavioral options that maximize fitness. Subsequently, forward simulations were used to find average trajectories across time of the following variables: parental and offspring states, foraging time, and allocation of energy. We also investigated the effects of brood size and harvest. Physiological parameters, necessary to translate foraging decisions into body mass changes, are taken from studies on starlings (Sturnus vulgaris). The results appear to closely fit available evidence for this species. The discussion relates basic findings of the model to previous results of static and deterministic approaches. Limits to the usefulness of the model are discussed. [Behav Ecol 1991; 2: 21-37]