When I order chicks from a large breeder, I can get chicks bases on gender (10 female and 2 male) in some cases, not straight run, and they know the gender. When I go to tractor supply or Big R they have pullets that are like 90% accurate they say to be female. Last year I got 5 easter eggers and got 4 pullets and 1 roo so 80% in that case but I digress.
How do they know that? I know some are auto sexing like my legbars and black sex linked and isa browns and such. But how do they know for the other breeds? Bared Rock or New Hamp Reds or Easter Eggers or whatever the breed.