Morphometric and genetic sexing in the Gough Moorhen Gallinula comeri

To develop an accurate, low-cost method for sexing Gough Moorhens Gallinula comeri using morphometric measurements, twelve measurements were taken from 59 birds and validated against genetic sexing. The classification accuracy of variables was determined and discriminant analysis was used to test whether multiple variables improved accuracy. Males were larger than females in all dimensions. Head length reliably differentiated male and female Gough Moorhens. A threshold of 64 mm correctly classified 92% of the sample birds; adding other variables did not improve accuracy. Gough Moorhens can be sexed with an acceptable level of accuracy using a single morphometric variable, but genetic sexing is needed to confirm the sex of individuals that fall within the overlap zone (62-66 mm).