Fruit in the diet of nestlings of the Puerto Rican Tody, a tropical insectivore

摘要

Many tropical frugivorous birds supplement the diet of their nestlings with insects, particularly in the early stages of development (Lack 1968, Skutch 1969, Morton 1973). In some of these cases, the nestling diet is exclusively insects (e.g., Skutch 1944). Although some frugivorous birds feed their young entirely on fruit as well (e.g., D. W. Snow 1962, B. K. Snow 1970), the growth rates of chicks of such species are relatively slow (Ricklefs 1976). Fruits are generally low in nutritional value, and the supplemental use of insects high in protein may enable tissue growth to proceed more rapidly (Morton 1973, Ricklefs 1976, Reinecke 1979). The opposite case, of birds which are insectivorous as adults feeding fruit to nestlings, is extremely unusual (Morton 1973) although not undocumented (e.g., Ligon 1970). Here I report observations of a tropical insectivorous bird, the Puerto Rican Tody (Todus mexicanus), supplementing the insect diet of its nestlings with fruit. I observed (through binoculars) a pair of Puerto Rican Todies feeding nestlings from 8 July to 16 July 1993 in the Maricao Forest Reserve, Puerto Rico (18°09′N, 67°00′W) The nest was a burrow beneath the roots of a tree in an embankment. I report here only feeding observations which I was able to record for at least 30 min without interruption, for a total of 7.5 h. Due to the abrupt angle of the tody's nest burrow, I was unable to determine either the number or age of the nestlings.