Harlequin Duck (Histrionicus histrionicus) Science Article 1
The timing of pair formation varies within and among species of ducks. In this study we documented the chronology of pair formation in a population of wintering Harlequin Ducks (Histrionicus histrionicus) in southwestern British Columbia. Harlequin Ducks began forming pair bonds in October and over half of the females were paired by December. This timing is much earlier than other ducks of similar size.
R. IAN GOUDIE AND W. SEAN BOYD, The Condor 100551-555, 1998