A greater sac-winged bat (Saccopteryx bilineata) smiles for the camera. An insectivore native to Central and South America, it is commonly found in or on the outside of hollow trees. The term "sac-winged" refers to small pouches on the bats wings that are used by males to attract females and to mark their harem territory. The males will fill these sacs with glandular secretions, and during mating displays the male will use his wings to fan the female vigorously and expose her to the scent mixture in the wing sacs. Males will also shake the contents of the sac towards bats outside of the male's harem territory to warn off intruders. Selva Verde Rainforest Reserve, Costa Rica.