Sex determination of Eurasian Woodcock Scolopax rusticola: A molecular and morphological approach

We used molecular sexing and morphological analysis to characterize sexual size dimorphism (SSD) in Eurasian Woodcock (Scolopax rusticola) wintering in central Italy. We analyzed SSD in 259 individuals (125 males and 134 females) sexed molecularly based on size differences in CHD-linked sequences from W- and Z-chromosomes. Females were significantly larger than males in bill measurements, tarsus and length of tarsus plus middle toe, while males had longer wing chord and ninth primary length. A discriminant function analysis was applied to a set of morphometric traits to study whether parameters of body size may be used to reliably sex individuals of this species in the field. We formed two equations, one for adults, which was 78.7% accurate, and one for juveniles, which was 76% accurate. Discriminant analysis showed that the length of the ninth primary, tarsus and nalospi was the most useful trait in sexing adult Eurasian Woodcock. Wing chord, nalospi and tarsus were helpful in sexing juvenile birds. Combining the results of DNA molecular sexing and several biometrics, would enable the development of easier sexing techniques. Our results will aid future studies looking at gender differences in the field.