The black-bellied tree duck (Dendracygna autumnal is) 1 is one of eight tree ducks (whistling ducks) in the genus Dendracygna . This group shares enough characteris tics--reticulated tarsus and symmetrical syrinx structure, among others--with the swans and geese Ia warrant a cam man subfamily, Anserinae of the waterfowl family Anatidae. De Iacour and Mayr ( 1945) make a tribal distinction, however, between the tree ducks (Dendracygnini) and the swans and geese (Anserini) based, in part, an differences in size, vertebrae number, and downy plumage . These same authors remark that the tree ducks are the leas t known of the waterfowl largely because there are no life history studies for any of the species. Of the two species found in the continental United States, the fulvous (_Q . bicolor) and black-bellied tree ducks , the ecology of the last named seemed singularly unknown.