My chickens are about 20 weeks old, and my roosters are starting to grab the hens on the back of the neck and jump on their backs. I am starting to worry because they are walking around making a squeaky toy noise. The 3 roosters are doing it too but its a little deeper then the hens. Can someone please tell me why? At first i thought maybe they we're just sneezing but its just that now i don't think so.