Sexing Mature Columbiformes by Cloacal Characters

Abstract

WHILE there is a pronounced sexual dimorphism or dichromatism in some species of the order Columbiformes, in most others there is not. Until recently we have known of no simple and reliable method for sexing living individuals of these latter species. Various techniques which have been used are: observation of slight quantitative differences in the coloration on the head, neck, and breast of the Mourning Dove, Zenaidura macroura (Petrides, 1951); slight differences in the contour of the head and neck of the domestic pigeon, Columba livia, (Levi, 1941); differences in behavior; and others. For a number of years, sexing by internal examination of gonads (by laparotomy) has been frequently used in the department of Genetics, University of Wisconsin. This is a delicate and time-consuming operation. Iwata (1926) described a method in which differences of the shape of the lips of the vent of Columba livia are used to distinguish the sexes. This technique has not to our knowledge been verifiable in this country (Levi, 1941). The objectives of this paper are three-fold: (1) to describe a simple method for sexing living adult doves and pigeons by cloacal characters and to present data on the reliability of the method; (2) to list the diverse species in which we have tried this method; and (3) to present data from brief experiments which indicate that the development of these characters is under endocrine influence. We believe the method to be quite reliable and as simple to use as the cloacal examination method for sexing ducks (Hochbaum, 1948) or the widely used method of determining the age of birds by the bursa of Fabricius (Gower, 1939).