Hi Everyone, I received my 5, 3 week old Buff Orpingtons last night. All of the birds are behaving just fine, however I noticed that one of them is pretty much hairless underneath its tail feathers. The spot is about 1" in diameter. All of the other chicks have the typical blonde fuzz around the vent. Is this something I should be concerned with? The lady told me that 1 of the chicks is 4 weeks old, so I'm not sure if this is something that happens normally as they grow their "big girl" feathers. Please let me know your thoughts! Thanks!