Resumo

GOMEZ DEL ANGEL, Salvador; PALACIOS CASTRO, Eduardo  e  DE SUCRE-MEDRANO, Atahualpa Eduardo. Sexual dimorphism in size and forehead marking of the snowy plover (Charadrius nivosus). Huitzil [online]. 2015, vol.16, n.1, pp.21-27. ISSN 1870-7459.

Sexual dimorphism in birds is expressed in different forms such as size or plumage coloration. In shorebirds melanic marks differ between sexes and are highly variable, and it is believed that they play a disruptive role in the landscape. For the Snowy Plover (Charadrius nivosus) we analized the sexual dimorphism in body size and structure of the frontal bar. We found that the male is larger in the tarsus, wing chord, and the length and breadth of the frontal bar. In addition, we describe for the first time a horn-shaped ornament on the forehead bar, exclusive of males. Although other authors have reviewed the variability of these marks, its adaptive significance is poorly understood. We believe that dimorphism in the frontal bar is important both within and between sexes during the breeding season, playing a key role during courtship displays and male-male competition, where breast feathers contrast with this mark. Also a greater body size of males is consistent with polyandry and intense male-male competition.

Palavras-chave : morphometry; horn-shaped ornament; Mexican basin; Texcoco lake.