This investigation, dealing with wild todies, a family of tiny Caribbean birds, and concentrating on the Puerto Rican Tody (Todus mexicanus), is an attempt to document the natural history of the family Todidae, to determine the niches of each of the five species within widely differing communities, arid to postulate the pathways of tody evolution. The information gathered is also relevant to basic zoological problems such as populations regulation in tropical birds, species abundance within tropical habitats, generalization and specialization of birds on oceanic islands, and ecological equivalency.