I didn't know either and was rather shocked to investigate the noise coming from the girls pen last week and discover the three of them arguing over a mouse! In the end one of them grabbed it, shot into the corner, threw her head back and swallowed it whole! I think it made them a little cocky that afternoon as when I let them out to free range that afternoon they decided that they were some kind of feathered mafia and declared a gang war on my neighbours St Bernard (who thankfully is very docile!) a cat and several times ran screeching at birds landing in the garden! They were like drunk football fans!