Rufous hummingbirds' (Selasphorus rufus) memory for flowers: Patterns or actual spatial locations?

Two field experiments were performed to examine the use of absolute and relative spatial cues by foraging rufous hummingbirds (Selasphorus rufus). Presented with 5 flowers arranged in a cross, birds learned that only the center flower was rewarded. When the array was shifted, birds returned to the relative center of the array when flowers were closely spaced but to the absolute location of the reward when spacing was greater than 40 cm. In Experiment 2, a 16-flower array was used, spaced either at 10 or 80 cm. Flowers were either visually identical or different, and 8 were rewarded with sucrose. Birds learned the rewarded locations more quickly when flowers were visually different. When the arrays of flowers were moved, performance was independent of flower visual patterns. At 10-cm spacing, birds tended to use relative location to recall rewarded flowers but used absolute location at 80-cm spacing.