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.