Facial gestures and body postures
Wolves use a variety of facial gestures and body postures to show where they stand in the pack's hierarchy. The position of a wolf's tail can be used to tell whether or not it is a dominant wolf or a subservient wolf. The alpha wolves of a pack generally hold their tails up very high, and the subservient wolves keep their tails hanging down. Very low ranking wolves will hold their tails between their legs or curved alongside their legs, and subservient wolves often tuck their tails between their legs when approaching an alpha wolf to show that they acknowledge the alpha wolf's place in the pack's hierarchy.
The position of a wolf's tail can also be used to tell what kind of a mood it's in. A confident wolf holds its tail up high, and a frightened wolf will hold its tail between its legs.