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 mayhave detrimental effects on future breeding episodes, the modelis elaborated around the concept of a state variable. In thisimplementation, the state variable represents body mass. A numberof activities can be followed during the breeding season, andwe measured the value of these actions in terms of the contributionof the action to the fitness of the animal at the end of thenestling period. Using the final states reached by parents andyoung, we determined fitness by summing current breeding productionand future reproductive potential. We used backward inductionto find for each combination of states and nestling age thebehavioral options that maximize fitness. Subsequently, forwardsimulations were used to find average trajectories across timeof the following variables: parental and offspring states, foragingtime, and allocation of energy. We also investigated the effectsof brood size and harvest. Physiological parameters, necessaryto translate foraging decisions into body mass changes, aretaken from studies on starlings (Sturnus vulgaris). The resultsappear to closely fit available evidence for this species. Thediscussion relates basic findings of the model to previous resultsof static and deterministic approaches. Limits to the usefulnessof the model are discussed. [Behav Ecol 1991; 2: 21-37]