Anatomy Whitetail Deer Anatomy

Digestive System

Deer are ruminants, meaning they are equipped with a four chambered stomach. An interesting characteristic about the ruminant's stomach is that it allows the animal to gather a lot of food at once and then chew and digest it later. The four chambered stomach is needed to process the large quantities of low nutrient food that deer eat.

Depending on the type and abundance of food, the deer can fill its stomach in about one or two hours. When a deer eats, food is chewed just enough to swallow. The food then passes down the esophagus into the stomach.

The deer has a four section stomach similar to that of cattle. The food goes into the first section which acts as a fermentation vat. Most of the digestion occurs in this area of the stomach. Deer depend on billions of microorganisms that live in its stomach to break down the fibers, cellulose,and other basic plant components, and convert them into materials that can be used by the deer's digestive system. Over 40 percent of a deer's energy is derived from the acids absorbed through the walls of its first stomach.

After the deer has filled its first stomach, it will lie down in a secluded place to chew its cud, just as cattle do. After chewing its cud for awhile, the deer re-swallows the food, which then passes to the second portion of the stomach. The food material then passes on to the third and forth stomach sections for more digestion and absorbtion. The food material then goes through the intestines and everything that isn't digested is passed off as waste droppings.

Deer Gestation

Does are bred during the rut which occurs from mid November to early December. This varies with location. The gestation period is usually about 200 days. The doe usually gives birth to a single fawn or twin fawns in late May or early June.

Deer Antlers

Usually only male deer (bucks) have antlers. Once in a great while female deer (doe) will also have antlers. Contrary to popular belief, antlers are live tissue, composed of bone. Antlers are the fastest growing tissue in the animal kingdom. They grow at an average of 1 to 2 inches per week during development. Antlers have a constant blood and nerve supply, which is inside the velvet antler covering, while growing. The antlers are covered in velvet from the time that the antlers start growing in the spring, until the antlers stop growing in the late summer to early fall. When the antlers stop growing, they start to shed this velvet covering. Bucks use trees and shrubs to rub their antlers on, to help rub off this velvet. This is where the term "buck rubs", comes from. Researchers agree that antlers have evolved as a weapon to gain dominance over other bucks during breeding season. After the breeding season, bucks will shed their antlers. Antlers are usually shed in January or February. Antler shedding usually occurs earlier in northern states than southern states. A new pair of antlers will start growing in the spring.

Another popular belief is that you can tell a deer's age by the number of points on each antler, this is not a good way to age a deer. The only true way to tell a deer's age is by its teeth. (See Age Determination )

  • Buck 1/2 year old - It will have small bumps for antlers, these are called button bucks.
  • Buck 1 1/2 years old - It will usually have one or two points on each antler, however they can have as many as 3 or 4 points on each side. The antlers are usually small in size.
  • Buck 2 1/2 years old - It will usually have 3 to 5 points on each side. The antlers will usually be small to medium in size.
  • Buck 3 1/2 years and older - It will usually have 4 to 6 points on each side. This is a mature buck and will usually have medium to large antlers.
  • Some bucks never develop large antlers. Antler size is influenced by genetics and diet.

Deer Sight

A deer's eyes are located on the side of their head, which has advantages and disadvantages. The advantage is, deer are able to view 310 degrees around itself. This wide view allows the deer to be totally aware of the surroundings, even when it is staring straight ahead.
The disadvantage is, deer cannot focus on one location with both eyes. This causes the deer to have very poor depth perception. Deer also see at a lower resolution than humans, and are believed to be color blind.

Deer are nocturnal animals. Nocturnal means that deer can see at night, which is one of the reasons they are more active at night. Deer have more light-detecting cells in their eyes than humans, which aids their nocturnal vision. Like other nocturnal animals, their eyes shine when exposed to light at night. This is due to a reflection off a special membrane in their eye.
It is believed that deer can also see in the ultraviolet light range, which is abundant during the earlier morning and late afternoon. This ability to see better, in early morning and late afternoon, helps to explain why deer are more active during these time periods.

Deer Hearing

A deer's hearing, being far superior to that of a human, can easily detect a faint sound. It is believed that a deer's hearing is so sensitive that it can determine how far away a sound was made. A deer's hearing is one of the reasons that it is so difficult to sneak up on it without being detected. The ears of a deer are vital in helping it avoid danger. When a deer hears a sound it will instantly turn its head and point its ears in the direction of the sound. The deer will focus all of its attention on smelling, looking and listening for any more signs of danger. If the deer doesn't smell, see or hear any danger, after checking the area several times, it will usually go back to its normal routine.

Deer Smell

Deer have a highly developed sense of smell, it is one of their best weapons for detecting approaching danger. The moist nose of a deer, similar to that of a dog, allows the deer to pick up the faintest of odors. The odor particles, drifting by on the breeze, stick to the moisture on the deer's nose and are then drawn into the olfactory organs. A deer can detect the odor of approaching danger several hundred yards away. This is why you should always try to hunt with the breeze in your face.