Marginal Value Theorem
A mathematical model predicting when a forager should leave a depleting resource patch. The optimal strategy is to leave when the current patch's returns drop to the average rate for the habitat.
Biological Context
As foragers exploit a patch, returns diminish (fewer berries left, prey become wary). The theorem shows that staying too long wastes time that could be spent on fresh patches, but leaving too early wastes the remaining value. The optimal departure time depends on travel costs between patches.
Business Application
The marginal value theorem applies to resource allocation: when should you stop investing in a depleting opportunity? Leave when marginal returns drop to your average opportunity cost—not when the current opportunity is exhausted, and not before it's fully exploited.