Originally Posted by 16 paws
How do you tell if the legs are girls or boys?
It's not on all chicks, only barred/cuckoo varieties.
It's understanding the genetics behind the barring genes. A barred bird (black barred) is genetically a black bird, with a gene for the white "bars" of color.
A pure bred male barred bird has two genes for barring. A pure bred female barred bird only has one gene for barring. Each gene expresses as a specific amount of white. So, the males, having two genes, have more white bars than black base color on their feathers, giving them a lighter overall look. The two copies of the gene also give them a larger, messier head spot as chicks, and lighter, pure yellow legs.
One Oops cockerel in a group of females is usually pretty easy to spot as they feather out. Problem is when folks only have one or two barred birds, it makes it hard to use comparison for sexing. And, with some hatchery females, the quality of the barring can vary a lot and you can have very dark or lighter females.