My guess is, they're in that "transition" period where Mother Nature adds yet another twist to the "inquisitive minds" of us Bobwhite lovers............(meaning.........."Quess what sex your birds are???).........LOL
I'm not in my right thinking mode right now (got walking pneumonia, and on some mind boggling meds), but when Bobs reach a certain age (right about the sex ID age), the males' beaks starts turning their "permanent" black color, and at some point, you can ID their sex more-so by comparing the beaks of the males and females by the color of the beak (mainly lower beak), and the male's beak will hold a "jet-coal-black" color moreso than than the female. I know it holds true with the mature birds.............just not sure tonight at what point that ID tactic can be used accurately........