TIMING OF PRENUPTIAL MOLT AS A SEXUALLY SELECTED INDICATOR OF MALE QUALITY IN SUPERB FAIRY-WRENS (MALURUS-CYANEUS)

Seasonally dichromatic male superb fairy-wrens (Malurus cyaneus) solicit extra-group fertilizations through displays of their brightly colored nuptial plumage during visits to females in neighboring territories. This ornamental plumage is lost at the end of the breeding season, and reacquired before the next breeding season after a highly variable period spent in a cryptic, female-like, ''eclipse'' plumage. Individuals start visiting females as soon as they return to nuptial plumage, often several months before the start of breeding. We examine variation in the timing of acquisition of nuptial plumage in relation to environmental conditions and the age, social status, and condition of males. We show that males undergo the prenuptial molt earlier as they age and when in superior condition, and that molt is delayed in years of more adverse winter weather conditions. We propose that the purpose of male displays may be to advertise their quality, and that females use this variation in the timing of acquisition of nuptial plumage to assess the relative quality of prospective extra-group mates. Molting earlier is apparently costlier, so this handicap would appear to be a reliable reflection of male quality.