Abstract In two experiments with five pigeons behaviour patterns that developed in association with periodic, response-independent presentations of food and water were studied. In experiment 1, the pigeons were deprived primarily of food or of water and given presentations of the appropriate reinforcer on a response-independent, fixed-time 15-s schedule. In experiment 2, the birds were deprived of both food and water and studied in a procedure where on a fixed-time 15-s schedule, concurrent access to food and water was provided at opposite ends of a long response chamber. As Staddon & Simmelhag (1971) reported, periodic response-independent reinforcement produced two dominant patterns of behaviour for each subject: interim responses that occurred early in the interreinforcement interval, and terminal responses that occurred later in the interval. Food presentations produced interim and terminal responses that differed among birds but were highly consistent for each individual bird. Water presentations produced a more limited range of interim and terminal behaviour patterns that were observed in most subjects. The terminal behaviour indicates that response topographies depend on the nature of the forthcoming reinforcer whereas the interim behaviour suggests differences in how pigeons react to the unavailability of food and water.