When we watch animals in the wild, most often we see them foraging for food. The foraging behaviour of animals has been a focus of behavioural studies for many decades.

Natural selection shapes this behaviour so as to maximize net energy gain as a function of time. Corvous caurinus, a species of crow, forages mostly on the bivalves found in the inter-tidal zones. After searching and locating the prey, the crow picks up the bivalve.

To break open the bivalve, it flies to a certain height and then drops the bivalve on a rock. Profitability of a prey is the most significant consideration in any such behaviour and is explained as the net energy gained per unit of prey handling time.