The behaviour of captive mallards (Anas platyrhynchos) and black ducks (Anas rubripes) was studied from the end of March to mid-June in 1991 and 1992 to determine the extent of interspecific aggression exhibited and the effect of sympatry and allopatry on interactions between the two species. / Mallards were more aggressive than black ducks regardless of sex and origin, though both species were equally attacked in both years, male ducks were more aggressive and more attacked than female ducks regardless of species and origin in both years, and ducks of sympatric origin were more aggressive than ducks of allopatric origin in 1991 regardless of sex and species while the opposite was true in 1992. / Site attachment was observed in 7 of 9 experiments performed in 1992. In the experiments involving site attachment, almost all of the activity centered around the feeding stations, not around the nesting platforms.

No description available.