Red-billed Tyrannulet has a broad latitudinal range but a restricted elevational distribution, and, as a very small bodied species that occupies the forest canopy, it often is difficult to observe. Consequently most aspects of its natural history are very poorly known. There is almost no information on its diet, and there is no information on its reproductive biology. There also are no quantitative data on population density or population trends. There also is no information on such topics as age at first breeding, life span and survivorship, dispersal, population regulation, molts, territoriality, and sexual behavior for Red-billed Tyrannulet.