Social behavior of breeding gadwalls in North Dakota

Responses of duck pairs encountering other ducks were categorized by McKinney (1965a) as displays, attack, escape and avoidance, sexual pursuit, and sociability. Gadwalls (Anas strepera) show all these responses on the breeding grounds, and characteristic behavior patterns occur depending on the reproductive state of the birds involved. The responses of paired ducks to unpaired males on the breeding grounds have not been described for the Gadwall or any other species. The function of aerial flights (McKinney 1965a) is also confused in the literature. The objectives of this paper are to describe the responses of paired breeding Gadwalls to other Gadwall pairs and unmated drakes and to dis- cuss the possible reasons for the type of spacing behavior Gadwall pairs exhibit.