Predator or fur calling is my big passion. Anyway you basically have two different types of calls and they sometimes overlap. The food/distress calls and social calls. The food/distress calls run a wide range of mouse squeeks, screaming rabbits, wounded birds and the crying of the young. While social calls are usually howls, woofs, mating sounds & such. All have their purposes and their pluses depending on what critters that you are targeting. Fox & lynx tend to be a little more particular then coyote. Yotes come to almost anything where as wolf seem respond better to social calling then food/distress calls which bears prefer.