Most hatcheries sell sexed chicks: You can buy all pullets (female) for the highest price per chick, all cockerels (male) for the lowest price, or “straight run” – a luck-of-the-draw mix of male and female as hatched – for a medium price. Some breeds are feather sexed while most are vent sexed. “Dirty Jobs” did half of an episode about chick sexing at McMurray Hatchery which can be seen on YouTube (part 1, part 2).
Feather sexing of 1 to 3 day old chicks is possible in crossbred chicks bred for that purpose. Chickens have a gene that determines how fast feathers grow in. A chicken can be slow-feathering (a dominant trait, K) or rapid-feathering (recessive, k). The trait is sex-linked because males carry two alleles for the trait and females carry one which they can give only to their sons. (If you are confused, do not despair. Check out the Sex Linkage article in my Genetics Mini-Series.) If you cross a slow-feathering breed female (K/-) with a rapid-feathering breed male (k/k), then the resulting females will be rapid-feathering (k/-) and males will be slow-feathering (K/k). Because of their rapid feathering, female chicks will have primary wing feathers that are longer than the covert feathers, and males will have short primaries the same length as their coverts.
For more information, see Missouri Animal Science, Feathersite, this YouTube video showing feather sexing, or part 1 of the “Dirty Jobs” show linked above. Down color can also be used to create sex-linked chicks, using the same procedure as above but with barred/nonbarred and silver/gold breeds. Some breeds are auto-sexing.
Vent sexing is an old Japanese technique also demonstrated in the “Dirty Jobs” video (best not to Google this one – there are some tough videos to sort through). Basically, the sexer scoops up a newly-hatched chick, squeezes the poop out of the vent, and spreads the vent with his thumbs to look inside. If he sees a shiny bump, or “eminence,” it is a likely male. If he sees an non-shiny flat area or very small bump, it is a likely female. There are many shapes, and vent sexers often have at least two years of training.
Several of my local poultry acquaintances have been keeping chickens for more than 50 years. They all say they are able to just look at a chick and make a very accurate guess as to whether it is male or female. They showed me their techniques on some of the chicks I was selling. The pullets, they said, had grown both primary and secondary feathers while the cockerels had less developed secondaries. The pullets had longer wings relative to their body length; the males wings were smaller and held tighter and higher on their body. They said they could tell the sex of a chick at any age – from a day old through maturity.
I had much less ease when I tried to apply their technique to my chicks at home. I think I might have these two Basques correctly sexed. I’ll let you know if I was right! (Update: Yes, I was!)
Another of the old-time poultry keepers said he could tell by their chirp. The males had a deeper, more guttural-sounding chirp while the females had a clearer, headier-sounding chirp. There are other old-fashioned techniques that rely on male chicks being more assertive and female chicks being more passive. You can read about and see pictures of these techniques in this article by Don Schrider over on Backyard Poultry Magazine.
- Article by Mother Earth News
- Poultrysite article
- Two Minds Scienceblog article (includes pictures of 4 vents)
- Ithica article – Sexing after a few weeks