Chronology of Pair Formation in Some Nearctic Aythya (Anatidae)

Abstract

Observations on 4 spp. of diving ducks demonstrated a general correlation between comparative chronology of pairing, acquisition of breeding plumage and nest initiation among most spp. The major exception was A. americana which normally follows A. valisineria in nest initiation but which preceded them in courtship. Aythya affinis was the last to start pairing and the last to nest. Data on 3 spp. of dabbling ducks of the genus Anas showed a considerably earlier pairing period in comparison with that of divers.