Bird pollination syndrome is the plant’s adaptation to ornithophily, but nectarivorous birds are not so selective

Many tropical plants are pollinated by birds and several bird phylogenetical lineages have specialised to a nectar diet. The long-assumed, intimate ecological and evolutionary relationship between ornithophilous plants and phenotypically specialised nectarivorous birds has nevertheless been questioned in recent decades, where such plant-pollinator interactions have been shown to be highly generalised.   

In our study, we analysed two extensive interaction datasets: bird-flower and insect-flower interactions, both collected on Mt. Cameroon, West-Central Africa. We tested if 1) insects and birds interact with distinct groups of plants; 2) plants with a typical set of ornithophilous floral traits (i.e. bird pollination syndrome) interact mainly with birds; 3) birds favour plants with bird pollination syndrome; and 4) if and how the individual floral traits and plant level nectar production predict bird visitation.     

Bird-visited plants were typically also visited by insects, whi...