But they require space to live during that time, and food to eat, and someone must have enough time to butcher them on a different day.
Sometimes the extra meat from each individual bird just isn't worth it.
3rd from last, blue band, black bird: I'm leaning toward cockerel, but not positive. If you butcher it, definitely look for testicles to confirm. (Knowing what it really was takes away the "but what if it really was..." wondering after the fact.)
4th from last, red bird with some black: male.
Last one, Silver Laced: probably male. Check for testicles when you butcher him, to confirm that.
2nd to last, black with a yellow band: probably female, I'd leave her alive for now.