Dr. Karl V. Miller
Daniel B. Warnell School of Forest Resources
The University of Georgia
There's little doubt that the most important sense to white-tailed deer is the sense of smell. Deer rely on their noses to warn them of the presence of predators and to help them find food. However, the most important function of scents is their role in communication with other deer. Simply through the sense of smell, deer can recognize other deer, learn about the other deer's sex, dominance status, reproductive state, and so on. Because we perceive our world primarily through visual means, it is hard for us to fathom the importance of odors in the world of other animals, such as whitetails. To just get a clue about what types of information deer get out of each whiff of air, we have to spend months, or years, in the laboratory working with highly sophisticated analytical equipment. Even after we identify a number of suspected compounds, we still only have a guess as to what these compounds tell the deer, if anything. We can test these compounds, and see how deer react to them. However, in many cases deer don't react to them at all. Does this mean that the deer didn't receive any information from them? Hardly! Just because the deer didn't give a behavioral response doesn't mean that it didn't learn something. On top of that, the context in which the scents are presented certainly influences how a deer may respond. What all this means is that until someone figures out how to wire up a deer's nose to a human, or to put a human's mind into a deer's brain, we will never be certain what a deer smells when it smells something.
Two Noses? Few hunters realize that a deer actually has two 'noses'. The second nose is technically not a nose, but it serves some of the same purpose. If you look on the roof of the deer's mouth you will see a diamond shaped structure with a small passage leading into the palate. This additional nose, called the vomeronasal organ (VNO), is similar to the Jacobson's organ that snakes use to 'taste' the air. Deer use the VNO exclusively to analyze urine. When a buck sees a doe urinate, he will often take some of this urine into his mouth and perform a behavior called flehmen, or lip-curl. This flehmen helps to introduce urine into the VNO. It is interesting that this organ is not connected to the same part of the brain that the nose is connected to. Instead it is connected to the part of the brain that controls the reproductive condition of the deer. What type of information the deer is getting is unknown, but it is likely that odors analyzed in the VNO help get the hormones pumping in the buck and bring him into rutting condition.