Painting area of a shape - Illustrator CS5

I'm very new to Illustrator, so please forgive me if this is a daft question. Trying to colour the chicken's feet black where they overlap the white cow's back. I've tried making the chicken a compound shape but a message pops up saying it can't do that. Same happens when I try to make a clipping mask. I'm certainly missing a vital step here. Any help, much appreciated.