Adaptive significance of seabird coloration: the case of procellariiforms

The function of bird coloration has been debated over recent decades, but no general theory has yet emerged. Most studies have only analyzed the influence of a single factor, but multifactorial analyses may be required to understand the biological function of coloration. On procellariiforms (albatrosses and petrels), which comprise 105 seabird species, all with simple coloration (mainly black and/or white), correspondence analysis was used to find correlations between coloration and species body size, diet, feeding techniques, foraging group sizes, and climate at breeding localities. Correlations with taxonomic classification were also examined. No single factor played an overwhelming part in determining color patterns, but whereas diet, size, and climate had little effect, feeding techniques and foraging group sizes had important influences. Classification, at the genus or family level, and color pattern were also correlated. Clusters of species, whether derived from their color patterns or their feeding ecologies, were similar. Coloration may therefore be related to procellariiform life histories, possibly acting through competition and predation risk. Relative uniformity of procellariiform coloration, compared with other seabirds, may relate to their peculiar foraging techniques.