MIXED SEXUAL DIMORPHISM IN SEMIPALMATED PLOVERS

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