Can Iberian Water Rail Rallus aquaticus be sexed reliably using simple morphometrics?

Abstract

In this paper we classified the sex of 39 Iberian Water Rails Rallus aquaticus using external morphometric measurements and genetic analysis. Logistic regression and classification tree model techniques (CART) were used to test whether simple morphometric measurements alone could classify sex correctly. For most of these measurements the overlap between sexes was too great to be of value. Bill length was the most relevant variable according to all the statistical analyses for the population under study. The applied combination of statistical techniques on biometric and genetic data correctly classify 80% of individuals. However, in view of the apparent variability in morphometric characteristics between populations, morphometric techniques to sex individuals from other populations should be validated using other criteria.