Floral phenology of an Andean bellflower and pollination by buff-tailed sicklebill hummingbird.

The Andean bellflowers comprise an explosive radiation correlated with shifts to specialized pollination. One diverse clade has evolved with extremely curved floral tubes and is predicted to be pollinated exclusively by one of two parapatric species of sicklebill hummingbirds (). In this study, we focused on the floral biology of , a bellflower thought to be specialized for pollination by , in a montane cloud forest site in southeastern Peru. Using camera traps and a pollination exclusion experiment, we documented . as the sole pollinator of . . Visitation by . was necessary for fruit development. Flowering rates were unequivocally linear and conformed to the "steady-state" phenological type. Over the course of >1800 h of monitoring, we recorded 12 . visits totaling 42 s, indicating traplining behavior. As predicted by its curved flowers, . is exclusively pollinated by buff-tailed sicklebill within our study area. We present evidence for the congruence of phenology and visitation as a driver of specialization in this highly diverse clade of Andean bellflowers.