Occasionally, and especially if I have to house a chicken in a box or small wood pen, if it's sick or if I'm taking it somewhere, the chicken will peck like a woodpecker at the side of the box -- in short bursts of very fast pecking. I've had 2 or 3 different chickens do this. Anyone know what this is? One lame chicken that I treated for several months did this every evening when she retired into the wooden part of her pen. Is it a distress thing?