I bought 4 Barred Rock pullets in October - they were 17 weeks old at the time, and they all certainly looked like girls to me. Yesterday one started crowing. By my estimate they are 23 weeks old. Ummm..........is he a late bloomer or what????? I bought the 17 weekers because I figured we'd know for sure by then the roos from the girls. Must be something at my house - I have 2 cochin roos that didn't develop roo-ish traits until they were well over 20 weeks old as well. Should I stick to buying older birds or what???? I've got 5 roosters to 11 hens now!!!!