Those are chickens???

My friend's a roofer. He was working with a new guy he hadn't worked with before. They were up on a roof. There were chicken bones all over the roof. The new guy asks my friend, "How do you think all these chicken bones got up here?" My friend, who never speaks unless he has something important to say, just pointed up to the sky at the seagulls flying over the roof. The new guy looked up at the seagulls and said, "Those are CHICKENS?"