The eleventh installment of the Endangered Species Series was issued April 3, 2003, and celebrates the 30th anniversary of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). This issue focuses on endangered species of waterfowl.
The 37¢ stamps show the Great Hornbill, the Scarlet Ibis, the Knob-billed Goose, and the White-faced Whistling Duck. The Great Hornbill can be found in southern Asia. The bird is declining because of habitat destruction and the logging of large nesting trees.