Foraging for covered and uncovered food on a radial maze

Rats were trained to forage for food on a four-arm radial maze. Each arm of the maze was defined as a patch and contained four feeding stations. Each patch contained a total of 20 45-mg food pellets, with the first feeding station in each patch baited with 1 pellet and the remaining stations baited with 1, 5, or 13 pellets. In Experiment 1, one group of rats was tested with feeders open and food readily accessible, and another group was tested with metal covers on the feeders, which necessitated extra time to gain access to food. With open feeders, the rats visited each feeder in a patch in the order in which they encountered the feeders, from the center of the maze to the end of the arm. The rats in the group with the covered feeders often visited the feeders containing 5 or 13 pellets first and the feeders containing 1 pellet last. In Experiment 2, it was found that the rats switched readily between these two foraging strategies when tested with covered and open feeders on alternate sessions. The extra time and effort required to uncover food appeared to produce selective foraging in rats.