These trapeze artists of the jungle prefer to eat a higher proportion of fruit in their diets than do other New World monkeys. In fact, the zoologist in Panama mentioned above reported that the monkeys he studied ate a diet consisting of about 90% fruits and nuts. They also eat leaves and young stems. However, spider monkeys are not entirely vegetarian. They have been seen reaching under tree bark and into rotten logs; in all probability, they do this to find bugs and larvae to eat. Some zoologists believe that they also eat small birds and even small mammals.