By specializing on specific resources, species evolve advantageous morphologies to increase the efficiency of nutrient acquisition. However, many specialists face variation in resource availability and composition. Whether specialists respond to these changes depends on the composition of the resource pulses, the cost of foraging on poorly matched resources, and the strength of interspecific competition. We studied hummingbird bill and plant corolla matching during seasonal variation in flower availability in a montane cloud forest from Northwest Ecuador. Combining time-lapse cameras, computer vision tools, and image analysis, we greatly increased interaction sampling in time and space. Using a hierarchical Bayesian model, we accounted for the detectability and spatial overlap of hummingbird-plant interactions.
We found that despite seasonal pulses of flowers with short-corollas, hummingbirds consistently foraged on well-matched flowers, leading to low niche overlap among species. This behavior suggests that the costs of searching for rare and more specialized resources are lower than the benefit of switching to super-abundant resources. Our results highlight the trade-off between foraging efficiency and interspecific competition, and underline the importance of niche partitioning in maintaining tropical diversity.