An Hypothesis for Seasonal Color Change in the Genus Sterna

In keeping with a recent and growing body of literature providing evidence for the functional significance of molt patterns in relation to other events in the annual cycle, I present and discuss an hypothesis for the adaptive significance of one aspect of seasonal color change in Sterna terns. After breeding, many adults molt a limited number of head feathers which results in a mottled aspect. I suggest that the post-breeding change in head color is a signal directed by nonbreeding species toward breeding congeners that may be encountered either during migration to winter range, or in the winter range. This advertisement of nonbreeding status should help members of migratory/wintering species to avoid costly courtship chases and aggression from breeding species.

An Hypothesis for Seasonal Color Change in the Genus Sterna Academic Article