Skip to content
Journal article

Colour polymorphism in birds: Causes and functions

Galeotti P, Rubolini D, Dunn P, Fasola M...(+4 more)

Journal of Evolutionary Biology, vol. 16, issue 4 (2003) pp. 635-646

  • 256


    Mendeley users who have this article in their library.
  • 131


    Citations of this article.
  • N/A


    ScienceDirect users who have downloaded this article.
Sign in to save reference


We studied polymorphism in all species of birds that are presently known to show intraspecific variation in plumage colour. At least three main mechanisms have been put forward to explain the maintenance of polymorphism: apostatic, disruptive and sexual selection. All of them make partly different predictions. Our aims were to investigate evolutionary causes and adaptive functions of colour polymorphism by taking into account a number of ecological and morphological features of polymorphic species. Overall, we found 334 species showing colour polymorphism, which is 3.5% of all bird species. The occurrence of colour polymorphism was very high in Strigiformes, Ciconiiformes, Cuculiformes and Galliformes. Phylogenetically corrected analysis using independent contrasts revealed that colour polymorphism was maximally expressed in species showing a daily activity rhythm extended to day/night, living in both open and closed habitats. All these findings support the hypothesis that colour polymorphism probably evolved under selective pressures linked to bird detectability as affected by variable light conditions during activity period. Thus, we conclude that selective agents may be prey, predators and competitors, and that colour polymorphism in birds may be maintained by disruptive selection.

Author-supplied keywords

  • Activity pattern
  • Comparative methods
  • Disruptive selection
  • Independent contrasts
  • Light levels
  • Morphs
  • Plumage colour

Find this document

Get full text

Cite this document

Choose a citation style from the tabs below