Elaborate secondary sexual traits, such as the ornamental plumage of birds, may be favored by female choice because they serve as honest indicators of male quality. Elaborate traits are thought to be honest signals because they are expensive to produce and increase predation risk. Here we investigate another potential cost of elaborate traits, i.e., the time and energy required to maintain them in good condition. We tested the hypothesis that species of birds with ornamental plumage invest more time in maintenance behavior than do related species without such plumage. To test the hypothesis we quantified the maintenance behavior of nine ornamental and nine non-ornamental species in aviaries and zoos. To test the validity of using captive birds, we first collected data on 12 captive species for which data from wild individuals were also available. The maintenance times of captive and wild individuals were highly correlated across species. Maintenance time was also correlated with plumage length, independent of body size. Ornamental species had longer plumage than non-ornamental species, and they devoted significantly more time to maintenance. Time spent on maintenance cannot be devoted to other activities. This temporal trade-off reinforces the honesty of ornamental plumage. We suggest that high maintenance handicaps are present in a variety of animals.
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