Behaviour and chronology of pair formation by Harlequin Ducks Histrionicus histrionicus

Abstract

The chronology of pairing and behaviours associated with pairing were studied on a small population of wintering Harlequin Ducks. Research was carried out on 17 days between 19 September and 21 November 1995 on a 2 km rocky coastline in south-western British Columbia. The behaviours rushing, agonistic pursuits and head-nodding were found to be specific to courtship. Males performed more courtship behaviour than females. Males which had completed their pre-alternate moult exhibited courtship behaviours more often than moulting males. Pairing began in mid-September and continued to increase steadily to between 44% and 70% of females paired by 21 November. Three pairs identified during the 1994-1995 non-breeding season, re-united in the fall of 1995. Harlequin Ducks pair relatively early, probably because many pairs are re-uniting in the fall. The courtship behaviour shown by males is probably mate guarding by paired males and active courtship by bachelor males.