There was an interesting article on bird-pollinated Babiana in the last Annals of Botany that (I think) is freely accessible: Caroli de Waal, Bruce Anderson and Spencer C. H. Barrett, "The natural history of pollination and mating in bird-pollinated Babiana (Iridaceae)," Ann Bot (2012) 109 (3): 667-679 http://aob.oxfordjournals.org/content/109/…