DIET OF THE ATLANTIC FOREST MANED SLOTH BRADYPUS-TORQUATUS (XENARTHRA, BRADYPODIDAE)

The diet of maned sloths was studied throughout 14 months in an Atlant ic forest reserve of south-eastern Brazil. Three adult sloths were obs erved for a total of 680 h and located monthly by radio-telemetry. Dat a were collected on diet, recording the actual time the sloths spent e ating plant species. Overall, the diet was composed of 99% leaves, wit h young leaves (68%) preferred to mature ones (7%) throughout the year . A higher proportion of tree leaves (83%) than liana leaves (16%) wer e included in the diet. When analysed together, the diet of the three animals included a total of 21 plant species (16 tree and 5 liana), bu t each individual made up its diet with an even smaller number of spec ies (7-12) and with a particular subset of the local flora. This is a very small portion of the total number of tree and liana species avail able to the sloths; furthermore, the top species consumed were present at very low population densities in the forest. Thus, B. torquatus, l ike other congeneric species studied elsewhere in the Neotropics, is a strictly arboreal folivore with a highly selective diet, probably res ulting from evolving physiological adaptations to cope with a smaller range of plant secondary compounds. This is possible for the species o f this genus through a combination of low basal rates of metabolism, w hich enable the sloths to survive on an energy-poor diet, and a very l ong passage time of digesta, which, in turn, aids the digestion of a f ibre-rich diet while possibly contributing to the degradation of secon dary compounds.