What is Rub Urinating
While I have witnessed deer urinating many times over the years, one time about 17 years ago I saw a mule deer buck do something very strange that I had never seen before. All deer squat when they urinate, like a female dog. But one day on a hunt I was watching a nice mule deer buck, and what he did was truly intriguing. After doing some research about it, I learned that what I witnessed is called rub-urinating, and both sexes do it.
What the buck did was as he was squatting, he brought his rear legs very far forward, pinched them together, and urinated on his own legs, with the urine running down onto his tarsal glands on the inside of his hocks. Then he began rocking his whole body back and forth, rubbing his tarsal glands together. It was actually quite comical to watch, and I figured it had something to do with the rut. When does or fawns do this, they may lick the urine off, but bucks don’t.
Bucks will perform this act primarily during the rut, and the more dominant bucks will do it more frequently, even with small amounts of urine. In the presence of a dominant buck, lesser bucks will not rub-urinate, they squat like they normally would.
The tarsal glands are an important form of recognition among deer. During the rut does and small bucks will sniff the hocks of larger bucks, determining their dominance by the scent of the tarsal glands. This behavior is five times more frequent at night according to biologist’s studies. When a buck stops rub-urinating, he is done with the rut, but he will resume this behavior after a period of time.
Studies have shown a diverse population of different species of bacteria living in the tuft of hair that makes up the tarsal gland. These bacteria interact with the compounds from urine in a way that creates the characteristic color and odor. Among the bacteria found in tarsal glands are species that can cause illness and infection in humans, so use rubber gloves or wash your hands thoroughly after coming in contact with the tarsal gland of a harvested deer. For these reasons, a lot of people believe that you must remove the tarsal glands immediately after harvesting a deer or they will taint the meat, but this has not been proven to be true. What taints the meat more is the amount of adrenaline a deer produces during the harvest, which is another reason for a swift, humane kill.