Mammals rustle through the undergrowth and swing along in the canopy, but not all are easily visible. Night hikes sometimes offer better opportunities for spotting forest mammals.

More than 20% of all mammal species are nocturnal bats. As you move closer to the equator from temperate regions (like that of the United States), bats make major contributions to the species richness among mammals. In the tropics, more food groups are available throughout the year, enabling bat species to specialize their diet around fruit, nectar, fish, blood, or meat.

Other than bats, mammals have ecological roles that are unparalleled in temperate zones. Mammals include monkeys, anteaters, sloths, lions, elephants, zebra and many rodents such as the agouti or paca. Some mammals, like the tapir and jaguar, are extremely shy creatures, and it is a rare event to see one.