FLEXIBILITY OF FORAGING BEHAVIOR IN HUMMINGBIRDS: THE ROLE OF ENERGY CONSTRAINTS AND COGNITIVE ABILITIES

We assessed how individual foraging preferences and cognitive performance affect foraging bout interval and the flexibility of foraging behavior in the nectarivorous Green-backed Firecrown (Sephanoides sephaniodes). Our field experiment evaluated the ability of these hummingbirds to recall nectar-renewal rates in two groups of artificial flowers with the same nectar concentration in the absence of visual cues. In a second experiment, we assessed their ability to remember differences in nectar quality combined with different nectar-renewal intervals, given artificial flowers with identical visual cues. Our results indicate that Green-backed Firecrowns adjusted their foraging intervals according to nectar-renewal rates and, furthermore, that birds were able to recall nectar concentration as well as nectar-renewal rate. Individual differences in memory performance resulted in differences in energy intake. These results strongly suggest that individual preferences and individual cognitive performance could play a central role in energy intake and, therefore, in the probability of survival. Received 30 September 2009, accepted 27 October 2010.