A rhinoceros hornbill—one of 54 species of hornbills—perches on a fig tree in Gunung Palung National Park.
The casque, a protrusion on the upper bill that gives hornbills their name, may play a role in sexual selection or amplify the birds' calls. From loud barks to thunderous booms, hornbill cries resound across a range that extends from the dry savannas of sub-Saharan Africa to the lush forests of Melanesia.
(Text adapted from and photograph shot on assignment for, but not published in, "The Shrinking World of Hornbills," July 1999, National Geographic magazine)
