Memory for location and visual cues in white-eared hummingbirds Hylocharis leucotis

In nature hummingbirds face floral resources whose availability, quality and quantity can vary spatially and tempo- rally. Thus, they must constantly make foraging decisions about which patches, plants and flowers to visit, partly as a function of the nectar reward. The uncertainty of these decisions would possibly be reduced if an individual could remember locations or use visual cues to avoid revisiting recently depleted flowers. In the present study, we carried out field experiments with white-eared hummingbirds Hylocharis leucotis, to evaluate their use of locations or visual cues when foraging on natural flowers Penstemon roseus. We evaluated the use of spatial memory by observing birds while they were foraging between two plants and within a sin- gle plant. Our results showed that hummingbirds prefer to use location when foraging in two plants, but they also use visual cues to efficiently locate unvisited rewarded flowers when they feed on a single plant. However, in absence of visual cues, in both ex- periments birds mainly used the location of previously visited flowers to make subsequent visits. Our data suggest that humming- birds are capable of learning and employing this flexibility depending on the faced environmental conditions and the information acquired in previous visits (Current Zoology 57 (4): 468-476, 2011).