I have been looking at the tail feathers in all of my chickens to see the differences and similarities. I wasn't sure if there was any certain thing to look for other than the tail feathers that seem to go up and then curve downward in roosters. I have one that I was sure was a hen until it started crowing yesterday. Now I can also see that the tail feathers are curling downward. This one is the oldest of the 6. Now that he is showing signs of being a rooster, I wonder if the younger ones will be soon too? They are only about 2 weeks younger.