Diferencias entre sexos en el tamaño corporal y la dieta en el piquero de nazca (Sula granti): Sexual differences in body size and diet in the Nazca Booby (Sula granti)

Silvana García–R.; Mateo López–Victoria

doi:10.59517/oc.e178

Authors

Silvana García–R. Departamento de Ciencias Biológicas, Universidad de Los Andes, Bogotá, Colombia.
Mateo López–Victoria Instituto de Investigaciones Marinas y Costeras – INVEMAR, Santa Marta, Colombia.

DOI:

https://doi.org/10.59517/oc.e178

Keywords:

diet, dimorfismo sexual, Nazca booby, sexual dimorphism, prey size

Abstract

Differences in diet between individuals in sexually dimorphic seabirds have been attributed to differences in body size, and it has been stated that the sex with larger size consumes a greater amount of food as well as larger prey. To examine this hypothesis, we studied the trophic ecology of Nazca Boobies (Sula granti) on Malpelo Island (Colombian Pacific), where females are approximately 13% heavier than males. We collected regurgitation samples from individuals of both sexes and we measured and compared their total weights, as well as the size and weights of each of the items ingested by males and females. Females showed heavier regurgitations and consumed larger prey than males. There was a slight positive association between variables related to prey size and the body size of birds, regardless of sex. These results support the hypothesis that there is a relationship between diet and body size, but additional studies are necessary to determine whether differences in diet between sexes can be explained solely by differences in body size, or if they reflect other sex-specific characteristics.

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