--- title: "Optimal Foraging and the Currency of a Behavioural Decision" description: "Foraging decisions can be modelled as maximising energy gained per unit of time, once handling time and travel time are counted. Predictions from that currency can be tested, and where they fail the f" canonical: https://lightmysky.com/learn/science/optimal-foraging-and-the-currency-of-a-behavioural-decision-mt_9iNYB7d1Rh source: https://lightmysky.com/learn/science/optimal-foraging-and-the-currency-of-a-behavioural-decision-mt_9iNYB7d1Rh.md retrieved: 2026-09-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Optimal Foraging and the Currency of a Behavioural Decision Foraging decisions can be modelled as maximising energy gained per unit of time, once handling time and travel time are counted. Predictions from that currency can be tested, and where they fail the failure usually names a cost the model left out. Subject: Science · Area: Ecology & Conservation · Ages 20 to 21 Page: https://lightmysky.com/learn/science/optimal-foraging-and-the-currency-of-a-behavioural-decision-mt_9iNYB7d1Rh ## Ready when they can - Predicts which prey types should be taken from their energy values and handling times. - Explains what a patch-leaving rule follows from when returns decline with time in the patch. - Names one cost, such as predation risk, that changes the prediction when included. ## Lesson: Eating smart against the clock Foraging is a race between energy earned and time spent. Every food choice costs travel time plus handling time and pays back energy. The winning currency is energy gained per unit of time, not the biggest bite. A rich item that takes forever to open can lose to quick small prey. **Example.** Compare two prey in energy per minute. A big prey gives 20 units of energy for 10 minutes of handling, which is 2 per minute. A small prey gives 12 units for 3 minutes, which is 4 per minute. The smart forager takes the small prey and ignores the rich one, because the rate is what matters. Patches follow the same time logic with a leaving rule. Quit a patch when its current return drops to the average rate of the whole habitat, travel included. Where the habitat average is high, a patch falls below it sooner, so stays run short in rich habitats and long in poor ones. A distant rich patch earns its trip only if the surplus beats the travel bill. **Tip.** When real animals ignore your prediction, look for the hidden tax you left out. Predation risk tops the list: the richest patch is worthless if feeding there gets you eaten. Add one named cost at a time, such as competition or missed matings, until the failures stop. **Recap.** Foragers maximize energy per unit of time, leave patches at the habitat average, and trade food for safety when risk enters. ## Practice 8 questions on this page, each with its working shown. ## Needs first - [Ecosystem Energy Budgets: GPP, NPP and Transfer Efficiency](https://lightmysky.com/learn/science/ecosystem-energy-budgets-gpp-npp-and-transfer-efficiency-mt_D81CKcOdBI) ## Opens up - [Sexual Selection, Mate Choice and Parental Investment](https://lightmysky.com/learn/science/sexual-selection-mate-choice-and-parental-investment-mt_6oTPGFw_p5)