Internet search finds.....
(1)I will take a questionable (sex) bird and put it in a pigeon crate with a known cock or hen and watch the reaction.
(2)Cradling the bird in both hands, run a forefinger along the keel bone (runs down the mid-linefrom the breast. At the end of the keel bone there's a space, then, toward the vent, 2 small thin bones will come together in a "V". If you can fit a small finger between where they come together, you have a hen(this is where the egg passes). If they are only 1cm-2cm apart, you have a cock. Older hens and cocks are easier to sex this way-it doesn't work well with babies.
(3)MOST hens look more feminine or fine around the head/necks & bodies are generally more compact. Cocks are thicker in the neck and are more masculine looking & generally a little bigger bodied.
(4)1 to 3 days after hatching: look at the sqeeker's ventwhile holding the little guy in your hand: a smile is a boy, straight or frown is a girl (don't ask me why, ask God!)
(5)Behavior: cocks are more aggressive, hens are usually more passive.
(6)Nesting: Cocks set from 9-10 a.m. to sunset (male is more aggressive, better to drive intruders away), Hens set through the night.