How to Sex a Chicken

A sexed chicken is simply one whose gender has been determined. Most mature chickens are easy to sex, but determining the gender of chicks is not always so easy. Learning how to sex a chicken depends a great deal on the bird’s age, breed and variety, and on the skill of the observer. 

Sexed chicks

Hatcheries offer most chicken breeds as both sexed and unsexed. Unsexed chicks, also called as-hatched or straight run, are the same mix of genders as they hatch from eggs. Theoretically, the gender ratio of unsexed chicks would be about 50/50, but that’s rarely true.

For example, sometimes I incubate eggs that hatch mostly cockerels (young males). Other times I hatch eggs that are nearly all pullets (young females). One awesome time I hatched out 100% pullets. It’s all just luck of the draw.

Sexed chicks are sorted by gender so you can get as many pullets or cockerels as you want. If you’re establishing a laying flock, for example, you can get exactly the number of hens you need.

Vent sexing

The traditional method for sexing chicks is vent sexing. This method, also called cloacal sexing, relies on identifying minor differences in the chicks’ tiny cloaca just inside the vent.

Vent sexing is typically a job for experts with extensive training. Accuracy, which requires keen observation that comes with lots of practice, tends to be about 90%. However, an experienced sexer can achieve a rate of 95% to 98% for some breeds.

Other breeds, however, are difficult to vent sex, resulting in reduced accuracy. Some hatcheries won’t vent sex those breeds at all. And bantam chicks are not often vent sexed because they are so tiny and delicate, they easily may be injured.

Sex linkage

Sex linkage is based on genes on a chicken’s sex chromosomes. A rooster has two identical sex chromosomes, designated as ZZ. A hen has two different sex chromosomes, designated as ZW.

The Z chromosomes carry most of the sex linked genes. A pullet gets her single Z chromosome from her male parent, so she inherits sex linked traits only from the father’s side. A cockerel, on the other hand, gets one Z chromosome from each parent, and therefore inherits sex linked genes from both father and mother.

Sex linkage can result in chicks that may be sexed by wing feather growth or by color. Two types of chickens sexed by color are sex links and autosexing breeds.

Sex link chickens

Sex link chickens, or sex links, are the result of mating a hen and a rooster of two different specific breeds. When the chicks hatch, the pullets and cockerels differ in their down color or pattern.

An example is the Black Sex Link, which results from a cross between a Rhode Island Red rooster and a barred Plymouth Rock hen. The little black cockerels have white spots on their heads, while the pullets are completely black. As they mature, the cockerels develop barred plumage, while the hens are black with brown neck feathers.

Sex linkage makes it easy to sex a chicken, with gender accuracy at 99 to 100 percent. However, since sex link chickens are crossbred, mating two sex links will not result in sex link chicks.

Autosexing breeds

The term autosex distinguishes sex link straightbreds (in other words, purebred chickens) from sex link crossbreds. Autosex chickens are the offspring of a hen and a rooster of the same breed and variety. Mating two autosexing chickens of the same breed therefore results in chicks much like their purebred parents.

Several breeds have been developed specifically for the autosexing trait. Their names combine the names of the original crosses. Legbar, for example, is a cross between Leghorn and barred Plymouth Rock. At hatch the down of cockerels is lighter than that of the pullets.

As with sex links, the intent of these breeds is to make it easy to sex a chicken. The color difference between genders persists into maturity and accuracy is 100 percent.

Some of our older breeds are naturally autosexing. The plumage color of males and females of these breeds stays quite similar throughout their lives and the differences are less obvious. Depending on the breed, the sexing accuracy rate for naturally autosexing breeds is 80 to 95 percent.

An example of a naturally autosexing breed is the barred Plymouth Rock. When they hatch, all chicks are black with white spots on their heads. The cockerels are a slightly lighter in color and their head spots are irregular and elongated or scattered. The pullets, by contrast, are a tad darker and their spots are rounder and more compact. At maturity, all genders are barred.

Feather sexing

In feather sexing, gender identification is based on the rate of wing feather growth in newly hatched chicks. This sex linked trait appears only if the chick’s father is of a breed that grows feathers rapidly and the mother is of a breed that grows feathers slowly.

When a rooster having both Z genes for rapid feathering mates a hen with a Z gene for slow feathering, all the offspring pullets will inherit a single rapid feathering gene from their father. The cockerels, by contrast, will inherit both a slow feathering gene from their mother and a rapid feathering gene from their father. Since slow feathering is dominant, the primary wing feathers of the cockerels grow more slowly than those of the pullets.

Feather sexing is used mostly for Cornish-cross broilers, to separate the slow-growing pullets from their faster-growing brothers. As with color sex links, you can’t get feather sex chicks by mating a feather sex rooster to a feather sex hen.

This method requires little training and has an accuracy rate of 90 to 99 percent, depending on the bloodlines used in the cross. And it works only during the first three days after hatching. After that, the cockerels’ wing feathers catch up with the pullets’ and they all look alike.

Wait and see

The easiest way for most people to sex a chicken is the wait and see method. This technique involves sexual dimorphism, or differences in the physical features and behavior patterns between roosters and hens.

These features can be clear in chicks as young as three weeks old, depending on the breed. Some breeds are difficult to sex until they’re nearly full grown.

As cockerels grow, they develop combs and wattles that are larger and more brightly colored than those of the pullets. Breeds with large red single combs usually develop early and are more obvious. At about the same time the roosters start crowing.

The males of nearly all breeds also develop longer or fuller tail feathers than the females. And the males of most breeds have pointed neck and saddle feathers. By contrast, females’ have shorter tails and rounded neck and saddle feathers. Roosters typically develop longer spurs, too, although some hens also grow spurs.

By seeing these clearly visible differences, the accuracy rate of sexing increases to nearly 100% as birds mature. So, if you are unsure how to sex a chicken, and you have lots of patience, simply wait and see.

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