It is difficult for breeders to distinguish between the genders of young chickens; checking the vent, or genitalia, is not always accurate, and can be uncomfortable for the chick. Breeders therefore developed breeds that would cause differing feather colourings or other characteristics in male and female chicks which make the chicks easier to tell apart in the pen. Genetic traits which show up in one gender and not another are called sex-linked traits. Feather colours, leg pigmentation, and feather growth speed are some sex-lined traits in chickens which can be used to differentiate male and female chicks.
Cross black or red coloured males with fair hens. "Cross" is a genetic term that means "mate black or red coloured males with fair hens". This mating cross has to be a male chicken from a sex-linked breed with a pure breed fair hen. The results of this mating will produce reliably predictable gender specific colouring if you choose the right breeds: For example, Black Rocks or Black Stars are names for black sex-linked males with which you may initiate your cross. Most red chickens have sex-linked markings. The red males you may use to initiate your cross are Rhode Island Red or New Hampshire, or any of a number of Buff coloured males. Red males are generally referred to as gold. The females could be many of the white breeds, including Silver Laced Wyandotte, Delaware or Light Brahma.
The results of these crosses will produce male chicks with lighter markings and female chicks with darker markings. Double-check with a chicken farmer or the farmer's forum below, to make sure that your perspective cross will produce the gender-specific results you want. Offspring of sex-linked crosses are not reliable for future gender-selective crossings, unless you are an experienced chicken breeder and you are sure of your genetic lines.
Cross bar patterned females to solid coloured males. Bar-type pattern is an easy to recognise colour pattern that looks like evenly painted bars on the chicken's feathers. Offspring of this mating will all have a dark colour, but male chicks will also have a fair spot on the back of its head, whereas female chicks will be of a solid colour. Male adults which develop from this initial cross will grow into the bar type pattern whereas the females will not.
Plymouth rocks are a sex linked breed which has bar type females from which you can intiate this sex-lined cross.
Cross males with pigmented legs to light legged females. Male offspring will have light legs whereas female offspring will have pigmented legs. This method is not as reliable as the feather sexing methods, however.
Cross males that develop feather quickly to hens that feather slowly. The resulting males will feather more slowly than the females. Check these chicks as they hatch, because the feathers start growing quickly.
Please double-check your crosses with the breeds listed in the breeder's forum below to make sure that the crosses you plan to use will work.
Do not cross sex linked chickens with other sex linked breeds; the crosses will not work.