Wolves are, by nature, very shy creatures, avoiding all contact with humans if possible. Most all of the beautiful photographs you see in books are taken at captive facilities. There are relatively few wildlife photographers who are afforded many opportunities to photograph wild wolves. Playful wolves will often bow and stretch out in front while swishing their tails and back ends up in the air. Anger or fear, may be shown by flattening their ears to their head and exposing their teeth, coupled with a low growl.
Wolves have an excellent sense of smell.
Their olfactory system is about 100 times more sensitive than ours. They can distinguish between pack members by the scent of urine and scat, as well as sight. Wolves mark the outside of their territories not only by elimination but by vigorously scratching the ground, stimulating the scent glands between their toes - communicating another obvious mark to neighboring packs that this territory belongs to them . Howling is another obvious form of communication. Contrary to popular belief, wolves do not howl at the moon.