Long-term pair bonds in Harlequin Ducks

We documented the frequency of pair reunion in Harlequin Ducks (Histrionicu s histrionicus) on breeding streams in Alberta, and at a molting/wintering area in southwestern British Columbia. As long as their mate is alive, Harl equin Duck pairs reunite on the wintering area and return to the breeding s tream together. Pairs reunite even if the female is unsuccessful at breedin g the previous season, which suggests that reuniting with the same mate yea r after year is important. Some males that have lost their mate and fail to re-pair on the wintering area show fidelity to their former breeding site.