The Optimal Diet Model Explained

According to the optimal diet model (a core component of optimal foraging theory), a predator should always prefer the most profitable prey (A) when it is sufficiently abundant and easy to find. The profitability of a prey item is determined by the energy it provides divided by the handling time (E/h). However, search time—the average time it takes to encounter each prey type—also plays a critical role.

• When high-value prey (A) is abundant and easy to find: The predator should specialize and ignore low-value prey (B).

• When high-value prey (A) is rare or takes too long to find: The predator increases its overall energy intake by including low-value prey (B) in its diet, rather than waiting too long for the preferred prey.

This means that the predator’s diet is flexible and will shift based on the availability and encounter rate of each prey type.

What Happens When A Takes Too Long to Find?

If the search time for high-value prey (A) becomes too long, the optimal strategy is not to specialize exclusively on B, nor to ignore B entirely. Instead, the predator should eat both A and B, whichever is encountered, to maximize its energy intake per unit time.

Why Not the Other Options?

• Option 1: Switching to eating only B is not optimal unless A is virtually absent; including both A and B is generally more efficient.

• Option 3: Feeding only on B regardless of search time ignores the higher profitability of A.

• Option 4: Never feeding on B is suboptimal when A is rare and search times are long.

Conclusion

According to optimal foraging theory, if it takes too long to search for high-value prey A, predators may eat both A and B, whichever is encountered. This strategy maximizes energy intake and aligns with observed foraging behaviors in nature.

Correct answer: (2) If it takes too long to search for A, predators may eat both A and B, whichever is encountered.