Caragors are the large beasts that you encounter around the world. Some of them are trapped in cages with doors that can be opened by using your bow to shoot the door side one or two times to break it open. These cages can also be open by attacking with your sword but that is not recommended as they will charge outside and attack you.
Mission 3 of the story involves a captain who is afraid of caragors and there a multiple cages within this area if you are having trouble finding cages on your own.