I have 6 khaki camble ducks and they are about 2 and 1/2 months old. I think one of the has a tail fether turning up but i notice 2 of the 6 whick includes the one who's 1 tail fether looks to be turning up has a lighter colored bill with like a black spot at the end and the other 4 has a dark bill. Would the lightsr color bill be a sign of a male?