 The duck was first described by Johann Friedrich Gmelin in 1789 and given the name Anas fulva but the name was " preoccupied , " or already used , by Friedrich Christian <unk> in 1787 for another species . This led to the next available name proposed by French ornithologist Louis Jean Pierre Vieillot in 1816 from a Paraguayan specimen as Anas bicolor The whistling ducks were moved to their current genus , Dendrocygna , by British ornithologist William John Swainson in recognition of their differences from other ducks . The genus name is derived from the Ancient Greek dendron , " tree " , and Latin <unk> , " swan " , and bicolor is Latin for " two @-@ coloured " . " Fulvous " means reddish @-@ yellow , and is derived from the Latin equivalent fulvus . Old and regional names include large whistling teal , brown tree duck , Mexican duck , <unk> and Spanish cavalier . 
