Summary
Predicts animals select prey and patches that give the greatest net energy return.
In depth
Marginal value theorem predicts when to leave a patch: when the rate of gain falls to the average for the habitat. Predictions test well in birds and insects, though animals also consider predation risk and nutrient balance.
The theory predicts that diet breadth expands when preferred prey is scarce and contracts when it is abundant. The currency is usually net energy per unit time, though predators sometimes maximise other nutrients.
Remember: optimality models are tools to generate testable predictions, not claims that animals calculate.
Optimal foraging theory uses economic models to predict feeding choices that maximise net energy intake per unit time. The prey model says a predator should include a lower-value item in its diet only when higher-ranked prey are too scarce to make ignoring it worthwhile.
The marginal value theorem predicts that animals should leave a food patch when the intake rate falls to the average for the whole habitat, including travel time. Tests with great tits, crabs and bees broadly support the predictions, although constraints like predator risk and nutrient needs can change them.
Example: shore crabs choose mussels of intermediate size that give the best energy return per handling time.
Remember: models are tools, not claims that animals calculate.
Frequently asked questions
What is Optimal Foraging Theory?
Predicts animals select prey and patches that give the greatest net energy return.
Which area of biology covers Optimal Foraging Theory, and how advanced is it?
Optimal Foraging Theory is one of the 53 topics in Animal Behaviour. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Foraging Behaviour, Territoriality, Migration Behaviour.
Can you give an example of Optimal Foraging Theory?
Bumblebees leave flowers when nectar returns decline.
What should I learn before Optimal Foraging Theory?
Work through the Beginner topics in Animal Behaviour first, such as Animal Behaviour, Innate Behaviour, Learned Behaviour, then return to Optimal Foraging Theory. Intermediate topics assume the Beginner vocabulary.
What topics are related to Optimal Foraging Theory?
The closest topics to Optimal Foraging Theory are Foraging Behaviour, Territoriality, Migration Behaviour, Communication. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Optimal Foraging Theory?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Optimal Foraging Theory. To practise the whole of Animal Behaviour, use the Animal Behaviour quiz.
How is Optimal Foraging Theory different from Foraging Behaviour?
Optimal Foraging Theory: Predicts animals select prey and patches that give the greatest net energy return. Foraging Behaviour: Animals choose food in ways that maximise energy gained for time and effort spent. Read both side by side and note what each one explains.
How should I study Optimal Foraging Theory step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Foraging Behaviour and explain the difference aloud. Finally, take the Animal Behaviour quiz and come back to this page for any question you miss.