Hi there... the last couple of days I've noticed my hens every once in a while will let out one short loud squawk for no reason. The other hens don't seem to notice or react and when it happens another hen is not close enough to have pecked her. I've seen/heard at least 2 out of the 3 do it. Maybe all 3. Not very often but here and there. Any reason for this? Thanks for any advice!