Dominance and social foraging: a laboratory study

Analysis of an asymmetric two-player game, in which a dominant forager and a subordinate individual each choose between two patches of food, suggested conditions that might induce solitary or social foraging. To investigate the game's predictive value, pairs of juncos, Junco hyemalis, were exposed to particular combinations of food density and dispersion in an aviary. Estimated feeding rates were taken as payoffs in the patch-use game. Solutions to the game indicated reasonable interpretations of (1) the transition rates between the various states of the system, (2) the amounts of time spent feeding socially and as solitaries, (3) the transition probabilities estimated from the observed sequence of states, and (4) the number of occurrences of each state. Subordinate birds terminated bouts of social foraging significantly more often than dominant birds, but subordinates did so at a slower rate when the game suggested stability for social foraging. Dominat birds followed subordinates and initiated significantly more than half of the bouts of social foraging. In general, the statistical pattern in the sequence of states did not change with variation in the density or degree of clumping of the food, but the amount of time spent feeding in the social states did depend on food availability and feeding rates.