"Fieldnotes," February 23rd & 24th, 2014: "Mule Deer Scent Behavior," by Beverly Dupree. http://www.montananaturalist.org/
"It would be easy to assume, looking at those ears, that the mule deer's most important sense is hearing. But then I noticed a curious behavior that led me to the conclusion that mule deer depend just as much on smell as on hearing.
At various times throughout the afternoon, I observed fawns approaching and immediately smelling the inside leg of mature deer. Temporarily lost fawns will run from deer to deer in an apparent search for their mothers, inspecting the tarsal gland of each doe and silently differentiating between the unfamiliar and the familiar. In cases where fawns sniff the wrong hock, they risk receiving an informative, albeit unexpected, kick."