Abstract
Niche partitioning of pollinators promotes the maintenance of high plant diversity in tropical environments. The role of animal pollinators in this partitioning has been evaluated predominantly at individual and species levels. However, pollinators can carry pollen on different parts of their bodies, potentially resulting in an increase in plant niche partitioning. Nonetheless, studies of pollen loads on different body parts of pollinators and how those patterns influence in plant niche partitioning remain scarce. Here, we 1) measure pollinator niche partitioning of plants considering hummingbird body parts, and 2) explore the contribution of hummingbird traits to niche partitioning of plants. We used mist nets to capture hummingbirds in the southern Andes of Ecuador, and took pollen samples from their bill, base of the bill, forehead, throat and chest-belly using fuchsin-gel. We evaluated plant niche partitioning at the species level based on all pollen found on a given species and at the body-part level by considering pollen loads on different hummingbird body parts, using the specialization metric (d') and beta diversity analysis. Niche partitioning of plants was higher when the different body parts of hummingbirds were considered than specialization at the species level. The contribution to plant niche partitioning by hummingbird species was positively related to tarsus length, potentially because this trait is associated to hummingbird perching behavior and longer contact times with flowers. In sum, we show that plants increase niche partitioning as a result of pollen deposition on different body-parts, which may help explain coexistence in species-rich systems where many plant species co-flower and share pollinators.