MOLT SPEED PREDICTS PAIRING SUCCESS IN MALE HARLEQUIN DUCKS

The bright plumage of male ducks in sexually dichromatic species is th ought to have evolved through intense sexual selection. This study exa mined the relationship between the timing and speed of moult into this bright plumage and subsequent mating success of male harlequin ducks, Histrionicus histrionicus. Males that moulted relatively slowly had a lower chance of establishing a pair bond than others. The timing of m oult was unrelated to whether a male obtained a mate. Moult speed and timing were not correlated within individual males, but were significa ntly repeatable in individual males over 2 years. Moult speed probably reflects the condition of males, whereas timing of moult is more like ly to be related to the distance to an individual's breeding area, whi ch determines the timing of arrival to the moulting grounds. In waterf owl species that have been studied, males usually form dominance hiera rchies before pairing and females tend to choose dominant males. We su ggest that male harlequin ducks that moult slowly are poor-quality ind ividuals, which are relegated to subordinate status and are unlikely t o attract a mate the following autumn. (C) 1998 The Association for th e Study of Animal Behaviour.