Discrimination of sex in the White-bellied Sea-Eagle, Haliaeetus leucogaster, using genetic and morphometric techniques

Abstract

The White-bellied Sea-Eagle, Haliaeetus leucogaster, is monomorphic for adult plumage colouration, but in body size displays reversed sexual dimorphism, with female birds significantly larger. Analyses of morphometric data from 37 individuals from Australia and Papua New Guinea revealed a latitudinal cline in body dimensions, with individuals larger in the south. A discriminant function based on 10 morphometric characters was 100% effective in discriminating between 19 males and 18 females that had been sexed using molecular genetic methods. Reclassification using a jackknife procedure correctly identified 92% of individuals. The discriminant function should be a viable alternative to genetic sexing or laparoscopy for a large proportion of individuals within the Australo-Papuan range of this species; and can also be used to identify a small proportion of 'ambiguous' individuals for which reliable sexing will require those other techniques.