Deer are herbivorous animals whose primary diet consists of plant matter. More specifically, they are specialized herbivores as they are selective about the types of plants they eat.
Deer prefer to feed on plants with low fiber but high protein content and highly digestible. Therefore, they mostly feed on plant matter such as herbs, aquatic plants, woody shoots, buds, foliage, fruit, and lichens.
Carnivores are animals that primarily eat meat, and since deer eat onlu plants, they are not carnivores. Deer are not omnivores because omnivores rely on both meat and plant matter for food.
Even so, deer could arguably be seen as opportunistic omnivores because they are known to feed on meat occasionally. However, this is a very rare occurrence because their bodies are not adapted to chewing or digesting meat-based foods.
Why Are Deer Herbivores?
Herbivores are animals that rely on plants for food, otherwise referred to as primary consumers in the food chain.
There are two major types of herbivores- grazers and browsers. Grazers are adapted to eat grass, while browsers are adapted to browsing leaves and fruits of high-growing woody plants.
Herbivores have distinguishing features that enable them to chew and digest plant matter. They have large and ridged teeth, mobile lips, as well as anatomically complex digestive systems. For ruminants, the stomach is compartmentalized into four chambers to facilitate the thorough digestion of food.
Deer qualify as herbivores because their diet primarily consists of plant matter. They are browsers, so they eat twigs, forbs, and shrubs.
Related: Do Deer Eat Turnips?
How Are Deer Adapted to Eating Plant-Based Foods?
Deer have physical features of herbivores, such as specialized teeth built to chew plant-based food, and a compartmentalized stomach.
Deers’ physical features show that they have been herbivores for so long that they have evolved to specialize in eating plants. For one, their teeth are built in such a way that they can sufficiently break down plant matter before swallowing.
The molars are broad and flat, with rough surfaces for grinding up tough plant tissues.
The front teeth tend to be small and sharp to enable the animal to cut into twigs and small branches of woody trees.
Deer also have a gap between the front teeth and back teeth to provide space for the repositioning of plant tissue during chewing. This gap is called diastema.
Deer belong to a group of herbivores known as ruminants, alongside cows, sheep, and goats. Ruminants have compartmentalized stomachs with four chambers – rumen, reticulum, omasum, and abomasum.
These chambers ensure that the tough tissues and fibers found in plants are digested sufficiently before being released into the body cavity.
When a deer chews on its food, it first goes to the first chamber, the rumen, where it sits and softens up. The food then comes back into the mouth for further chewing, a process termed regurgitation. The second chewing of food is what we call chewing the cud.
At this point, the food then goes into the second and third chamber, respectively, where it is digested further.
The fourth chamber functions like the human stomach, and it is here that the nutrients found in the digested food are released into the body, and waste is turned into stool.
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Do Deer Eat Meat?
Scientists have observed that some herbivores indulge in the occasional meat-eating from time to time. In an unprecedented finding, researchers that were studying how human remains decompose in the wild fumbled upon a white-tail deer eating human remains.
This finding prompted a study to explain this behavior as the white-tailed deer is known to primarily feed on plant-based foods like fruits, nuts, twigs, and alfalfa.
Furthermore, they are not physically equipped to eat meat; for instance, they are unable to cut through thick skin with their teeth.
But in the study, scientists discovered that ungulates exhibit scavenger behavior by eating decomposing human flesh when it is available.
They do not hunt for meat, neither do they procure killings for meat – they only eat meat when they find it lying somewhere. This behavior has earned them the term ‘opportunistic omnivores.’
In other instances, deer have been observed to chase and even gobble down baby birds.
While it is not common for deer to portray carnivorous tendencies, different sources have reported sightings of deer eating carcasses of rabbits, fish that have drifted to shore, and birds.
Related: Do Deer Eat Rabbits?
Why Would Deer Eat Meat?
It does not make much sense for a specialized herbivore to eat meat-based food at whatever capacity. However, there are valid reasons as to why deer, and several other herbivores, eat meat once in a while.
One of the reasons deer eat meat is to be able to survive brief periods of starvation when there is a scarcity of plants. Since plants are rare in winter, you may likely spot deer nibbling away at carcasses left behind by carnivores.
This behavior makes the difference between extinction and survival in an emergency situation. Herbivores that depend on plants alone for food will be more likely than deer to die away during a scarcity of plant material.
Deer also eat meat because some nutrients are easier to get from animal parts. They mostly target bony areas because of their minerals, namely salt, calcium, and phosphorous.
Deer need these minerals for the development and strength of their own bones and the growth of firm antlers.
Also, as we have already established, deer are opportunistic omnivores. This means that while they don’t necessarily depend on meat for food, they will indulge if the opportunity presents itself.
However, this happens rarely and when it is absolutely necessary, like when there is starvation or when deer lacks essential minerals in their bodies.
Related Article: How Often Do Deer Have Babies?
Why Deer Are Not Carnivores
Carnivores are animals that primarily eat meat. Good examples of carnivores are members of the cat family like the lion, cheater, tiger, and jaguar. Their bodies are well-adapted to hunting and tearing meat off bones.
Deer do not have these qualities and are not even equipped to rip through the flesh of other animals. Besides, carnivores cannot eat plant-based foods as their bodies would not be able to digest them.
Read Also: Are Deer Dangerous?
Why Deer Are Not Omnivores
Omnivores are those animals that are adapted to eating both plants and animals, like bears and humans. This means that they can eat both plant-based foods and animal-based foods in equal measure.
Deer cannot qualify as omnivores because even though they eat meat, it is a very rare occurrence. They eat meat only when there is a scarcity of plants or when they lack certain minerals in the body.
Their tendency to eat meat-based foods when the situation calls for it earns them the term “opportunistic omnivores.”
Read Also: Are Deer Blind?
Deer are primarily herbivores, so they rely on plant matter for food. Their bodies are well adapted to chewing and digesting the hard tissues and fibers found in plants.
They have broad, flat, and rough teeth for grinding plants and four stomach chambers to ensure adequate and complete digestion of food.
Occasionally, deer consume meat-based foods such as small birds, carcasses left behind by carnivores, and decomposing human flesh. This only happens when there is a scarcity of plants and hence, the risk of starving to death.
It also happens when deer lack minerals found in animals’ body parts, such as calcium, phosphorus, and salt.
Joe is a freelance writer for FaunaFacts. Joe has written extensively about snakes for the site, but also contributes content about a range of animals.