When my BR's were about 4 weeks old, I could definitely tell the difference between cockerels and pullets. My roos had a much larger comb, wattles were appearing, and their body color was mixed black/white. Also, their legs were completely yellow.
My pullets were more black in color, and their legs were black on the front part of them. They had very small combs, and no wattles. Maybe I just got lucky, but my determination of their sex was 100% accurate.
Kansas Agricultural Experiment Station
SEX IDENTIFICATION IN PUREBREDS
BARRED PLYMOUTH ROCKS
It had long been recognized that the size of the light head
spots in Barred Plymouth Rocks varied in the two sexes. The
males tend to have larger headspots and the females to have
darker colored legs. However, this method has not been sufficiently
accurate 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 black
pigment 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 outline
of the head spot rather than the size of the spot. Those chicks
having headspots irregular in outline and scattered in appearance
are males while the females tend to have headspots with
more regular outlines. The author claimed an accuracy of 90
percent or better when considering only the headspot and 95
percent 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 practiced
in Barred Rock chicks by commercial chick sexers. Sex identification
is based upon outline of head spot, color of legs and
shade of down color. There are several types of male and female
Is a BR crossed with something else automatically a sexlink? ie- I have a mixed EE bantam roo and he crossed with my BR hen .... the chick definately had BR coloring (how I knew it was my BR hen) but had a white dot on it's head. Is it a sexlink therefore automatically a roo?