What Determines Bird Beauty in Human Eyes?

Some authors have argued that human preferences for "beautiful" birds may skew the selection of species used to promote conservation programs. This evokes questions about the importance of color, shape, and other appearance traits of bird in affecting human preferences for birds. The aim of this study was to assess the traits affecting human preferences towards all non-passerine and five passerine bird families (n = 102), and to see whether such preferences correspond within a family or are species-specific. Using an Internet survey, we asked 200 human respondents to evaluate pictures of bird species, with two randomly chosen from each family, according to their attractiveness. The respondents were mainly from the Czech and Slovak Republics, but 67 came from other countries (the majority of which were English-speaking). An additional 100 respondents, exclusively from the Czech and Slovak Republics, evaluated the same pictures converted to silhouettes, to test the effect of shape versus color. We included various factors such as morphometric traits (i.e., measurements of body segments and the area the bird silhouette filled in the picture), body weight of the species, and colors, lightness, and saturation of the pictures in the statistical analyses, to help explain any variation in human preferences. We found that human preferences were significantly affected by bird morphology; however, the colors blue and yellow, as well as the overall lightness, were significant as well. The preferences for species belonging to the same family were positively correlated, possibly due to similarity in the body shape of related species. We suggest that finding the traits that determine human preferences toward birds may help conservationists promote a conservation program based on the selection of the correct, scientifically determined, flagship species.