Foraging Cost of a Long Tail Ornament: An Experiment with Sand Martin Females

摘要: The handicap hypothesis assumes that sexual ornaments impose a viability cost upon the bearers. There have been few empirical tests of this assumption. Previous studies show evidence for tail ornament in male birds: negative relationship between an experimentally increased (long streamers) and efficiency at foraging nestlings. However, it must be admitted, apparent impairing effect elongated could result decrease parental effort response to increase female effort, which might occurred attractiveness (differential allocation effort). In study, differential expenditure was eliminated by lengthening female, rather than male, sand martins (Riparia riparia). Tail-elongated females decreased rate they fed nestlings, captured more but smaller insects. no simultaneous feeding males explain females. These results confirm existence birds flight, as is expressed terms impaired flight capacity.