SEX IDENTIFICATION IN PUREBREDSBARRED PLYMOUTH ROCKSIt had long been recognized that the size of the light headspots in Barred Plymouth Rocks varied in the two sexes. Themales tend to have larger headspots and the females to havedarker colored legs. However, this method has not been sufficientlyaccurate to be of much commercial value.Quinn and Knox (1939) attempted to separate the sexes of Barred Plymouth Rocks by means of the intensity of the blackpigment in the down and legs. In different lots of chicks they report 83.5, 86.1 and 91.8 percent accuracy.Jerome (1939) describes a method of sex identification in Barred Plymouth Rocks based upon the regularity of the outlineof the head spot rather than the size of the spot. Those chicks having headspots irregular in outline and scattered in appearanceare males while the females tend to have headspots withmore regular outlines. The author claimed an accuracy of 90percent or better when considering only the headspot and 95percent if the color of the legs was included in the consideration.The Canadian Department of Agriculture (Anonymous 1941)issues an excellently illustrated bulletin describing the method.It is stated in the bulletin that the method “is widely practicedin Barred Rock chicks by commercial chick sexers.” Sex identificationis based upon outline of head spot, color of legs andshade of down color. There are several types of male and female head spots some of which are shown in Figure 1.