Comparison of Flower Feeding Behavior of Two Neotropical Hummingbird Species

Abstract

Hummingbirds, which are largely nectarivorous, often compete for food sources with other pollinators, leading to the establishment of different foraging strategies and social dominance hierarchies. I studied hummingbird feeding behavior at Camaquiri Conservation Initiative in the Caribbean lowlands of Costa Rica. The most abundant hummingbirds at this site were Blue-chested and Rufous-tailed hummingbirds; all data I collected were from these two species. Both species frequent porterweed bushes but have different feeding strategies—territoriality and traplining, respectively. Hummingbirds made 1,300 stops at a flower or cluster of flowers, for which I recorded 1) the duration of the stop and 2) the flower position on the plant (upper half or lower half). Feeding time varied by species: on average, Rufous-tailed Hummingbirds fed at a flower cluster for 18.6% longer than Blue-chested Hummingbirds. Both species of hummingbirds preferred feeding at higher flowers, and flower height did not affect feeding time for Rufous-tailed Hummingbirds, although Blue-chested Hummingbirds displayed longer feeding times at the less-visited lower flowers. These results suggest that Rufous-tailed individuals exhibit social dominance as the larger and more territorial species. Such dominance relationships may influence outcomes of interspecific competition, place species into unique ecological niches, and have broader implications for species diversity and structure in ecological communities.