Predicting the Sex of Kelp Gulls by External Measurements

Abstract

Male and Female of Kelp Gulls (Larus Dominicanus) are not clearly sexually dimorphic and are thus difficult to identify in the field. This paper evaluates sexual size dimorphism in this species and provides a reliable method for predicting the sex of measured individuals. Discriminant analysis of six morphometric characters of adult birds indicated that head lenght, bill lenght and bill depht were the most accurate variables for use in a discriminant function model, predicting sex with 97% accuracy.