Ecology of a Snake Community in Northeastern Brazil

Nineteen species of snakes representing four families were simultaneously studied in a caatinga habitat of northeastern Brazil. Of these, 10 are terrestrial, 3 are terrestrial-aquatic, 1 is arboreal-terrestrial, 4 are arboreal, and 1 is terrestrial-fossorial. Four species are nocturnal, 5 species are nocturnal and diurnal, and 10 are strictly diurnal. Diets include mammals, birds, bird eggs, lizards, snakes, frogs, toads, and reptile eggs, with some snake species being food specialists and others being food generalists. Surprisingly, none of the species of snakes at the study site feed on invertebrates. A diversity of reproductive tactics is evident among the species in this snake community. There are oviparous and viviparous species, and clutch/brood size may be large or small depending upon the species. Both clutch/brood size and neonate (or egg) size were correlated with body size of female snakes. A principal components analysis (PCA) of morphological data revealed that two axes, one representing variation in body size and one representing variation in tail length and head size, explained 95% ofthe variation in the data. Portions of the morphological results corresponded well with ecological data. However, in some instances the morphological results were discordant with ecological results. Certain patterns, for example appear to have a phylogenetic basis. It is concluded that morphological analyses of snake communities cannot be adequately interpreted in the absence of ecological data.