摘要
Barn swallows Hirundo rustica have white spots on their tail feathers, and they have been hypothe-sized to be a handicap because white spots are prone to feather breakage, ectoparasites are dispro-portionately common in white spots, and size of white spots increases with tail length. Here I testfor attractiveness of narrow and long tail spots by manipulation of their shape while using com-plete painting of spots and an absence of treatment as a control. Female barn swallows are knownto differentially invest in reproduction when mated to attractive males. Spot manipulation tookplace during laying of the first clutch, and there were no effects of treatment on clutch size or broodsize of first or second broods. In contrast, the incidence of second clutches and the total number ofeggs and fledglings produced during the breeding season was larger in males with painting of theside of tail spots rather than painting of the tip of spots, painting of entire spots, or no treatment.These findings are consistent with the hypothesis that it is the shape rather than the size of tailspots that affects differential reproductive effort by female barn swallows.
