The sense of smell is a wolf's essential sense. Wolves use their nose to identify individuals and species and to determine age, gender, diet, social rank, emotional state, and breeding condition, according to Fred Harrington and Cheryl Asa in "Wolves: Behavior, Ecology, and Conservation." "To have a wolf's nose for only one day would surely reveal a whole new world," they add.
To estimate just how strong a wolf's sense of smell is, the author's compare wolves with dogs, a much more studied animal. They assume that a wolf's sense of smell is at least as strong as that of a dog. And dogs, they say, "are a hundred to millions of times more sensitive than humans in perceiving odors."
The odors that wolves perceive so well are honest communication that can't be faked, since a wolf has little control over the odors it leaves. Those revealing scents are also much longer lasting communication than howling, the topic of part one in this three-part series on how wolves communicate.
Harrington and Asa list a number of sources from which wolves produce scents: