Table 1.

Some examples of individual and social foraging models with key references.

Model type	Model	Principal effect	Key papers
Individual	Prey choice	Prey items are evaluated in terms of their calories and their individual handling costs such that individual outcomes will enable a rank ordering of available prey items. This preference structure is dependent upon the encounter rate with more profitable items.	(Davies, Krebs, & West, 2011)
Individual	Patch	The marginal value theorem states that an animal should leave a depleting patch, incurring travel costs to move to another patch, only when the rate of return in the first patch falls below the mean rate of return of all background patches.	(Charnov, 1976a; Nonacs, 2001)
Individual	Diet choice – generalism versus specialism	Search time (relative abundance) of high value prey items can be offset by more readily available lower value items, such that an animal will either eat both low and high value items when encountered, or only high value items when they drop below a search time threshold.	(Charnov, 1976b; Krebs, Erichsen, Webber, & Charnov, 1977)
Social	Producer-scrounger	A certain proportion of a population will actively find (produce) food, whilst the remainder of the population will instead scrounge food from those producers. Effectively producers have to share a proportion of their yield with scroungers. Scrounging can amount to following producers and harvesting a portion of the found food before the producer can, or to consuming by-catch (e.g. the fragments beneath a bird feeder caused by the production activity of a bird above), through to direct theft of food items once extracted. Scroungers can do well with relatively few producers in the population, but when producers increase scroungers are often beaten to resource.	(Barnard & Sibly, 1981; Hamilton, 2002)