Fitness Measures In Female House Sparrows: No Correlation With The Expression Of Two Plumage Ornaments

Abstract Male birds often possess conspicuous or colourful plumage traits which are thought to function either in mate choice or as status signals which indicate their competitive ability. Many studies have confirmed that the size or expression of these traits is positively correlated with their success at attracting mates, their social dominance, or their fitness. However, relatively few studies have examined plumage variation in females, likely because it is much less pronounced than in males. We examined whether female plumage is associated with fitness measures in the house sparrow (Passer domesticus). Male house sparrows have a conspicuous throat patch of black feathers that has been correlated with social dominance and fitness, and females also possess a variably-coloured throat patch, although the variation is much more subtle than in males. However, neither the timing of breeding nor reproductive performance was associated with throat patch colouration of female sparrows in any of three continuous study years, nor was it related to female age. The size of the other obvious female plumage trait, the wing bar, also did not predict fitness. We conclude that female plumage variation is not under sexual selection in the house sparrow.