Even magical creatures need to poo, you know. But it's very difficult to actually see. During Hagrid's Care of Magical Creatures class, Buckbeak needs to go to the toilet and he doesn't care who is around to see it. So when nature calls, you have to go. And he does. It's a bit different to the colour that you're used to seeing (if you often take a look) as it's more orangey but it occurs just as Harry is about to approach Beaky for the first time.
