Patch choice and meal size of foraging rats as a function of the profitability of food

Abstract Rats lived in a laboratory environment that simulated foraging costs with bar-pressing requirements. The rats encountered sequential opportunities to eat meals in two food patches that differed in the size and/or price of food pellets. The rats accepted more opportunities and ate larger meals in the patch offering the more-profitable food, whether the larger or the lower-priced pellets. Despite widely varying patterns of intake between the patches, total daily intake was constant across most conditions. The extent to which the less-profitable food was included in the diet was a function of the size of the profitability difference. Profitability at each patch was calculated both as g earned per bar press and as g earned per min during meals. These two measures were correlated, but relative g/min was a better predictor of the relative feeding patterns. The results were not in accord with a simple, effort-minimization model of optimal foraging, although they were compatible with the notion that the cost of suboptimal behaviour will influence its occurrence.