There are over 260 species of mammals found in the Costa Rican rainforest. 50% of the mammals found in Costa Rica are bats. Bats are the only mammals that can fly, but since they are covered in fur, they cannot be classified as birds.

Bats are widely distributed around the world. In fact the only areas that bats aren't found are in the Arctic and Ataractic regions.

Larger bats eat fish, fruit, small animals, while other drink the nectar of flowers or animal blood.

The fruit-eating bats are the largest type of bats found in Costa Rica. In fact the Jamaican Fruit Bat can have up to a 16-inch wingspan. However, for their size don't weigh very much. Even though the Jamaican Fruit Bat is over a foot in length it weighs less than 2 ounces.

Bats are nocturnal. This means that they sleep during the day and are active during the night. During the day, bats roost hollow trees, under wooded roofs, or deep inside caves.

Some species of bats prefer to roost in communities. Communities of bats range in size from 50- 1 million! These bats are known as social bats. There are some bats, though, that prefer to live and hunt by themselves. These are known as solitary bats.

A common misconception about bats is that they are blind. Different species of bats have different types of eyes that range in complexity. Even though bats' eyes tend to be small, they are very well adapted to seeing at night.

Bats do however use high frequency sounds to help them to see better. The echo that they hear when the sound comes back is called 'echo-location'. When the sound that they send out hits the trees, ground, bushes, animals, insects, and other things around them, it bounces around in all different directions. But, the bats are able to tell the direction or angle that the echo is coming back from. This lets the bat know the direction that things are. Now, since sound travels very fast, the bat is also able to tell how long the sounds take to come back to them. So, now the bat knows where the echoes are coming from and how far away things are.

Another amazing bat species found in Costa Rica is the Fishing Bulldog Bat, which lives in the tropical lowlands near Tortuguero. This bat has an impressive 18-inch wingspan and hunts fish using radar. When fish get too close to the surface of the water, the ripples they cause send a radar signal to the bat. The bat then swoops down to the water's surface and catches the fish in its talons, much like a fish-eating raptor (like an eagle or osprey).