Courtship of the Redhead (Aythya Americana)

Abstract

THE annual cycle of the Redhead (Aythya americana) has been studied more intensively than that of most North American ducks. The species winters mainly on the Gulf and east coasts and breeds in the prairie pothole region of the northern United States and southern Canada and in the large marshes of the arid west (Weller, 1964). It nests over water in emergent vegetation and is inclined toward parasitic-laying (Low, 1945; Weller, 1959). Its weight cycle and plumages have been described (Weller, 1957) and related to the chronology of pair formation (Weller, 1965). The present paper integrates my observations with those of previous workers on the courtship displays and pairing activities of the species, presents some quantitative appraisal of the frequency and sequence of displays, and discusses their possible role in the breeding biology of the species. The earliest reported observations of the courtship of the Redhead seem to have been made by Wetmore (1920: 243-244), but it was Hochbaum (1944: 38-43) who described most of their displays comparatively in his study of the closely related Canvasback (Aythya valisineria). The only more intensive studies of the courtship of a pochard (Aythyini) are those of Lind (1958, 1962) on the Red-crested Pochard (Netta rujina). Recently, McKinney (1965) discussed comfort movements and their use as displays in this and other species, and Johisgard (1965: 232-234) has described Redhead displays performed on water. General courtship activities of Redheads were outlined by Low (1945) who noted that courtship was prevalent on certain large water areas and occurred mostly in the morning and evening. The observations reported here were made on breeding grounds at Delta, Manitoba (1952-1954, 1956), and Utah (1955); on wintering areas in Texas (late December and early January, late February and early March, 1960-61) and Chesapeake Bay and Cayuga Lake (February and March, 1954); and on the northward migration route in Iowa (1961, 1962, 1966) and in Illinois (March, 1957). Observations on some captives of all ages were made at the Delta Waterfowl Station. Work in Manitoba, Utah, and on the east coast was sponsored by the Delta Waterfowl Research Station and the Missouri Cooperative Wildlife Research Unit. Studies in Texas were financed by the American Academy of Arts and Sciences, the Welder Wildlife Foundation, and Iowa State University.