The optimal diet model is dependent on:
The optimal diet model depends centrally on prey energy yield and handling time because their ratio, E/h, ranks prey profitability. Handling includes capture, subdual, ingestion, and processing after encounter. High-energy prey with short handling are ranked above low-yield or difficult prey. Search time then determines diet breadth: when top-ranked prey are encountered frequently, rejecting poorer items is worthwhile; when they become scarce, the forager may include lower-ranked prey to avoid long unproductive searches. Thus, prey abundance matters indirectly through encounter rate, but handling time and energy gain establish the ranking identified here. Competition and genetic variation can influence foraging evolution, yet they are not the immediate variables in the classic decision rule. Real predators may optimize protein, micronutrients, safety, or reproductive success rather than gross energy, and capture probability can be folded into expected gain. The model remains useful because it derives testable acceptance thresholds from the trade-off between rewards and time costs rather than assuming that predators eat every prey they encounter.
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 14