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#prey profitability

3 public questions tagged with this topic.

Predator Prey Model

In optimal foraging theory, the most profitable prey is one with:

Prey profitability in optimal diet theory is commonly measured as energy gained per unit handling time, E/h. Handling includes pursuing, subduing, processing, and consuming an item after it is encountered. A prey type with high energetic content and short handling time therefore yields a high return rate and should rank above prey with less energy or longer handling. Search time affects whether a predator should broaden its diet, but it is not included in the basic ranking of prey types because the decision to attack is made after encounter. When highly profitable prey become rare and search time rises, accepting lower-ranked prey can increase the predator’s long-term average intake. Thus, optimal does not mean choosing only the largest prey; capture risk, digestion, nutrients, toxins, and predation danger may also matter in real animals. The high-energy, low-handling combination best expresses the model’s core currency. Its prediction is conditional on natural selection favoring behavior that approximately maximizes net energy gain over foraging time.

Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 14

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PREDATOR

What reduces profitability of a prey item?

Prey profitability is commonly measured as energetic value E divided by handling time h. A long handling interval lowers E/h because the predator spends more time capturing, subduing, opening, or consuming the same energy package. High energy raises profitability, while rapid capture tends to shorten handling and increase it. Search time affects the habitat-wide rate of intake and whether lower-ranked prey should be accepted, but it is not part of the basic post-encounter profitability ratio. Natural defenses such as shells, spines, toxins requiring careful processing, or difficult body size can therefore make prey less profitable even when their tissues contain substantial energy. The distinction is biologically useful because ecological labels summarize mechanisms that generate testable predictions. Evaluating costs, benefits, timing, and the identities of interacting organisms prevents confusion between terms that may look similar in a short description. Mechanistic reasoning is essential here: classifications should follow measurable consequences for survival, reproduction, resource acquisition, or detection. Context can modify interaction strength, but it does not erase the defining contrast among the alternatives presented.

Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 10

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PREDATOR

In OFT, if prey2 is more abundant but less profitable, predator should:

A lower-ranked prey should not be accepted merely because it is abundant. In the classic optimal diet model, acceptance depends on whether its energy per handling time exceeds the average return expected from rejecting it and searching for more profitable prey. If prey 1 remains sufficiently available, consuming prey 2 would occupy handling time that could be spent obtaining a better item, so prey 2 is rejected. The density of prey 2 itself has little effect on this encounter decision because the choice is made after prey 2 has already been found. However, the statement is conditional: if preferred prey become scarce enough, the optimal diet broadens and the less profitable prey can be included. This interpretation follows ecological definitions based on effects on fitness, energy flow, behavior, and population performance. It also shows why superficially similar alternatives can represent different mechanisms once the direction of benefit, harm, or resource transfer is considered.

Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 10

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