Floral phenology of an Andean bellflower and pollination by Buff-tailed Sicklebill

<b>Abstract</b><br/><p class="MsoNormal"><span lang="EN-US">The Andean bellflowers comprise an explosive radiation correlated with shifts to specialized pollination. One diverse clade has evolved with extremely curved floral tubes and are predicted to be pollinated exclusively by one of two parapatric species of Sicklebill hummingbirds (<em>Eutoxeres</em>). In this study we focused on the floral biology of <em>Centropogon granulosus</em>, a bellflower thought to be specialized for pollination by <em>E. condamini</em>, in a montane cloud forest site in southeastern Peru. Using camera traps and a pollination exclusion experiment, we documented <em>E. condamini</em> as the sole pollinator of <em>C.granulosus</em>. Visitation by <em>E. condamini</em> was necessary for fruit development. Flowering rates were unequivocally linear and conformed to the ‘steady state’ phenological type. Over the course of >1800 hours of monitoring we recorded 12 <em>E. condamini</em> visits totaling 42 seconds, indicating traplining behaviour. As predicted by its curved flowers, <em>C. granulosus</em> 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.</span></p>