Deer feed on hundreds of plants, but they are picky eaters. If a food does not taste just right, a deer will spit it out, along with any saliva that came in contact with it. This selectivity is important since deer will try to eat any foliage in an area. Deer have long tongues that contain many taste buds.
A deer's mouth has two sections. The front section, which contains canine and incisor teeth, is used for grabbing and breaking food. Teeth are located only in the bottom of the mouth. There is only a bony pad on top. Although the pad makes it hard to break plants, it provides protection from the rough edges of food. There is a gap between the front and back sections. The back of the mouth contains molars. These teeth are larger than the canines and incisors, and a deer uses them to chew its cud.
Most of a mature deer's teeth are big and fairly flat, ideal for chewing and grinding leaves, twigs, acorns and the like. Fawns have smaller teeth or "milk teeth". A deer's teeth grow and wear each year. Biologists and hunters age deer by examining their teeth.