The functional ecology of bat pollination in the African sausage tree Kigelia africana (Bignoniaceae)

Plants often interact with a wide range of animal floral visitors that can vary in their pollination effectiveness. Flowers of the African sausage tree Kigelia africana are visited by bats and bush babies during the night and by birds during the day. We studied floral traits (phenophases, scent, color, and nectar chemistry) and the visitation frequency and pollination effectiveness of different flower visitors to determine whether K. africana is functionally specialized for bat pollination. We found that flower opening corresponds with bat activity, flowers emit scent dominated by aliphatic esters and alcohols, and that nectar is produced in copious amounts accessible to bats. Pollen deposition on stigmas was twenty‐fold greater per visit by bats than it was per visit by birds, likely a result of the close morphological fit between snouts of bats and the flowers. However, bat visits appear to be rare at some sites and the delayed senescence of flowers that are open throughout the morning provides an opportunity for additional pollination by birds. We conclude that K. africana is primarily adapted for bat pollination, but is also able to exploit other animals for pollination.