Sexing Common Snipe Gallinago gallinago in the field using biometric criteria

The Common Snipe Gallinago gallinago is a common inland wader caught at many ringing stations across Central and Western Europe during autumn migration. But sex determination is not easy in live birds because the species has no clear sexual dimorphism. This is an impediment to studies of its ecology. During 2005–2009, we measured various external features of 1,343 Common Snipes caught at Jeziorsko Reservoir in central Poland (51°40’N, 18°40’E), to determine the utility of measurements in determining sex. We chose a random sample of 284 birds for DNA sexing from blood samples. Discriminant analysis of their measurements showed that the length of the outermost rectrix was the most useful trait in sexing adult Common Snipes. Bill-length, the length of the outermost rectrix and the distance between the tips of the two outermost rectrices were helpful in sexing first-year birds. Discriminant procedures allowed for the correct sexing of about 80% of adult and immature Common Snipes.