Mallard (Anas platyrhynchos) Science Article 11
abstract
Qualitative descriptive information on both vocal and visual displays of waterfowl is abundant (e.g., Heinroth 1910, 1911: Lorenz 1953; Weidmann 1956; Johnsgard 1965; McKinney 1965a, 1969, 1970, and quantitive data are available for visual displays of a few species of ducks
Abraham, R. L., The Condor 76(4):401-420