During prenuptial moulting, prior to the breeding season, the males replace their non-breeding feathers. Males that hold territory have shorter tails and carotenoid collars that are 40% larger than nonbreeding floating males . The red collar is for male-male competition, while female choice is based on tail length. Tail length is negatively correlated with carotenoid signal. Also, looking at body size and condition, this accounts for 55% of the variation in tail length. Body size may play a role in the variation of size and redness of both territorial and floater males.