Mixed sexual dimorphism in Semipalmated Plovers

Abstract

Sexually dimorphic species generally are characterized by having one sex consistently larger, and often brighter, than the other. Semipalmated Plovers (Charadrius semipalmatus) exhibit a pattern of mixed dimorphism with females that are heavier and having longer wings than males, whereas males have longer toes and bills, and are more colorful than females. Although we found weak evidence that male and female plovers mate assortatively with respect to body size, this likely resulted from birds of certain phenotypes breeding at different times. The mixed pattern of dimorphism in Semipalmated Plovers has probably resulted from different selection pressures, ecological and sexual, operating on different characters.