Tarsal Glands

I got up one morning determined to photograph some white-tailed deer.  I had seen one last fall, on the river, but had failed to get a clear shot of him.  I headed back to the same spot and walked along very quietly.  I was in luck!

I found three deer, feeding quietly in a marshy spot in the woods.  At first I only saw a big doe, but then I saw two others, further back in the trees.  They were very calm and looked at me as if to say, "Who in the world are you, and what are you doing here?"

When I got home and looked at the photos, I noticed an odd, dark mark on the inner "elbow" of the back leg of one of the deer.  Not being familiar with deer, I wondered if this was an infected wound of some kind.  (See below)

Looking at further pictures, I found that this deer had a matching spot on its other back leg.  I realized that these dark spots must be natural, and  I soon learned that they were tarsal glands.

Tarsal glands are areas of long hair on the back legs of deer, over sebaceous glands.  Deer urinate on them.  This is called rub-urination.  The secretion from the glands and chemicals in the urine combine on the hairs to create what is suspected to be a uniquely identifying scent for each individual animal.  All deer, old and young, male and female do this, but bucks are known to do it much more frequently during the rut.