EFFECTS OF SIZE AND MIGRATORY BEHAVIOR ON THE EVOLUTION OF WING MOLT IN TERNS (STERNAE): A PHYLOGENETIC-COMPARATIVE STUDY

Abstract

Abstract Approximately 60% of the 45 species of terns (Sternae) have an unusual form of wing molt in which a variable number of inner primaries and outer secondaries are replaced two or three times in a single year—a process that has been called “repeated molt.” Although several hypotheses have been proposed for the maintenance of repeated molt, few data exist regarding potential selective forces that may have favored the evolution of this molt strategy, and there are no explanations for the high degree of interspecific variation in the extent of repeated molt. Preliminary investigations indicated that large terns tended to have less repeated molt than small terns and that the presence of repeated molt appeared to be associated with migratory behavior. We examined these initial findings by combining data from the literature, from examinations of museum specimens, and from a recent molecular phylogeny of the terns to perform phylogenetic-comparative tests. First, we used independent contrasts to verify tha...