The last few days my chickens are acting strange when I let them out to free range. They are all moving about in one tight clump. My 3 roosters, some half grown chicks, and the adult hens are all squashing themselves together and moving about as one unit. Its so funny to see. I have 14 chickens in total, with 3 hens that are sitting on eggs in the coop. Any ideas why they are doing this huddling together thing? Back in the coop they act normal again.