Ward J.M., Blount J.D., Ruxton G.D. & Houston D.C. (2002) The adaptive significance of dark plumage for birds in desert environments. ARDEA 90 (2): 311-323

Since Buxton's (1923) observation that many animals inhabiting desert environments exhibit black pelage, various hypotheses have been proposed to explain the evolutionary origins of this phenomenon. In this review, these hypotheses are examined for species of desert-inhabiting birds. Possibly, since dark feathers are more resistant to abrasion, they protect the inner organs from damage by ultraviolet radiation. Another physiological hypothesis states that radiative heat load at skin level and the risk of heat stress can be reduced in dark-coloured species. This could be modified by behavioural adjustments. Alternatively, dark plumage may facilitate social signalling. Black provides maximum contrast against the pale desert substrate during daylight, and may provide camouflage at night. These hypotheses are not mutually exclusive. However, we cannot exclude the possibility that dark plumage traits persist in desert species simply because of shared ancestry rather than adaptation. To disentangle the alternative hypotheses, and better understand the relative importance of different selection pressures in the evolution of dark coloration in desert birds, we suggest there is a need for further studies, including comparative studies that control for phylogeny