Why does my dog like to chew on sticks?

My dog is a 1-yr-old fox terrier, and she is a power-chewer. We keep her stocked with rawhide bones, and she loves them (entertainment for hours), and she also has lots of toys, but nothing seems to beat a good stick from the backyard. She always wants to bring sticks inside, and on occasion has snuck them in and made a huge mess all over the couch or floor. Why is she doing this?