A non-hermit hummingbird as main pollinator for ornithophilous plants in two isolated forest fragments of the Cerrados

Hummingbirds are the most common group of vertebrate pollinators in the Neotropics, associated with pollination of ornithophilous flowers. The group can be divided into hermits and non-hermits, in which hermits are often regarded as the most specialized group closely associated with more specialized ornithophilous plants. In this study, we investigated the association of ornithophilous flowers and hummingbirds in two small fragments of forest surrounded by an urban matrix. We characterized the species composition, abundance and phenology of the hummingbirds and ornithophilous plants and related pollinator abundance to floral resource availability. Our results were compared to published data from other forest areas from the Cerrado. In our study areas, the diversity of ornithophilous plants and hummingbirds was similar to what has been reported for forest fragments in the Cerrado. Nevertheless, we found Thalurania furcata, a non-hermit, acting as the most frequent hummingbird pollinator in contrast to more preserved areas in which a hermit, Phaethornis pretrei, is commonly found as the main pollinator for ornithophilous plants. The nectar energy availability at the plant population level was the only factor associated with hummingbird visitation rates, suggesting that a higher availability of nectar resources in the fragments attracts greater abundance of birds. The unusual setting of having a non-hermit species as the main hummingbird pollinator in forest areas suggests that habitat fragmentation can favor more generalist hummingbird species, and this potentially has consequence for the pollination of associated plants.