Foraging: a fundamental activity for all life

Foraging by animals is such an important and fundamental aspect of animal behaviour, that we need to understand it as well as possible, which means we need to be successful in our attempts to explain and predict observed foraging behaviour. The best way to achieve such success is to invoke evolutionary theory with animals hypothesised to forage in ways that maximise their biological fitness.

This evolutionary approach leads to Optimal Foraging Theory (OFT), which includes Classic OFT, if individual animals do not respond directly to the foraging behaviour of others, and the more-general Foraging Game Theory, if such responses do occur. In either case, the basic hypothesis is that animals in a population will adopt a foraging strategy such that no individual can achieve higher biological fitness by deviating from the rest of the population. If individuals do not respond to the foraging behaviour of others, this hypothesis is equivalent to classic maximisation of some currency that acts as proxy for biological fitness. If such responses do occur, then individuals are collectively involved in foraging ‘games’ that are expected to be at equilibrium.

The foraging process involves different stages (e.g., pre- and post-ingestion) and a number of types of decision (e.g., patch choice, diet choice, patch exploitation, movements, group membership, producer vs scrounger, foraging mode), leading to studies that focus on such different foraging stages and decisions. Studies of foraging behaviour have consequently focused on one or other of these stages and decisions.

OFT has grown and developed enormously during its 50-year history, through expansion, extension, application and inspiration, with observations generally supporting expectations, to the point where it is now a ‘strong theory’ of behaviour and ecology. Understanding foraging behaviour remains an area of much interest and research, as befits its fundamentally important role in all of life.

The articles in the section on Foraging in this Encyclopedia illustrate these general aspects of foraging in that they rely on evolutionary theory to understand observed foraging behaviour, embrace OFT in particular, describe how OFT has grown and developed, and indicate current research interest. They also focus on the foraging stages and decisions outlined above