Migratory Status Shapes Exploratory Behavior but Not Learning Performance in Hummingbird Color Discrimination

Behavioral flexibility allows animals to adjust their behavior in response to environmental changes. Hummingbirds, with their tetrachromatic color vision and enlarged hippocampal formation, represent an excellent model for studying cognitive flexibility in color discrimination. We evaluated three components of behavioral flexibility (exploration, exploitation, and inhibition) in two sympatric hummingbird species, the resident White-eared Hummingbird (Basilinna leucotis) and the migratory Broad-tailed Hummingbird (Selasphorus platycercus), using a reversal learning task with artificial flowers of different colors for evaluating exploration, exploitation, and inhibition simultaneously. Birds were trained to associate nectar rewards with either spectrally similar (red-yellow) or dissimilar (red-violet) color pairs. Our results revealed interspecific differences in exploration behavior depending on the rewarding color during training, while both species showed similar exploitation and inhibition capacities. The migratory S. platycercus showed stronger neophobia toward non-red flowers compared to the resident B. leucotis. Both species quickly learned the color-rewarding association when red was rewarding but required more visits when non-red colors were rewarding. These findings suggest that while both species can flexibly adjust their foraging behavior, differences in their ecology and migratory behavior may influence their initial responses to novel color cues.