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What Do Deer Eat (Guide)
In this article my aim is to give a fairly broad answer to the question, “what do deer eat”?
Deer have always fascinated me, having been brought up as a kid, close to a great forest full of legends and myths based around these majestic beasts. So I felt it was worth some of my time taking a closer look at what sustains these great beasts.
Deer are part of the Cervidae family that has around 55 species, which includes both elk and moose within the Cervidae family.
They are found in almost all parts of the world excluding Australia, Sub-Saharan Africa, and of course Antarctica.
The main focus of this article will be on North American Deer species. However, the eating habits and food types will generally apply to other parts of the world.
The exception being more northerly latitudes where lichens make up part of a deers regular diet.
The Digestive System of a Deer
A deer’s stomach has 4 chambers, this type of stomach configuration is known as a ruminant, whereas humans are monogastric with only a single stomach chamber.
In order for a deer to make use of the nutrients found in woody plants and fibrous leaves, they use a system of initially chewing the food then storing inside the stomachs first chamber. A process of regurgitating and chewing the cud follows in the second stage.
The first chamber of the stomach known as the rumen, adds natural bacteria secreted from inside the lining, starting the digestion process.
Digestion becomes a fermentation process, which breaks the fibrous material down into amino acids. After which, any remaining touger ingested material will need to be chewed again to complete the breakdown of the plant for maximum nutrition.
How Much Food Does a Deer Eat
This is, of course a fairly general estimation, but studies have shown an average healthy deer will need to eat around 5 to 8 pounds of food for every 100 pounds in body weight each day.
This ratio will ensure a healthy deer maintains its weight, ample fur covering and strong antlers.
In terms of water, deer need to supplement their food with extra water on top of the fluid contained in the fibrous plants that they eat.
Deer need around one and a half quarts of water per day to aid digestion and to provide enough hydration. A quart is around a quarter of an imperial gallon or roughly 1 litre in metric.
Classification of Herbivores in Deer
It is worth noting there are a number of different types of herbivore. The classification in which they fall dictates what each type of deer prefer to eat, plus the feeding patterns they adopt over the course of the seasons.
Feeding Types of Ruminants
There are 3 types of Ruminant herbivores
- Concentrate Selectors
- Intermediate Feeders
- Roughage Feeders or Grazers
Deer are both Concentrate Selectors and Intermediate Feeders, depending on the species. A Whitetail deer is the former.
A lot European deer species are intermediate feeders, such as red deer, reindeer and fallow deer.
Cattle and sheep etc, are categorised as roughage feeders or grazers, as they tend to eat mostly grass with a longer retention time inside the rumen section of the stomach.
Concentrate Selectors
The key feeding characteristic for concentrate selectors such as whitetails is they feed on smaller amounts but more frequently. They are browsers when it comes to food choice.
The plants they consume have a high cell content which is fermented in the rumen part of the stomach at a rapid rate.
Intermediate Feeders
This type is more of a hybrid, sitting in the middle of the categories. They can browse for their food or graze like cattle.
Feeding behaviour will tend to suit the availability of food sources throughout the year, switching from browsing to grazing for food sources.
Physical Characteristics
The mouth and head of each type of herbivore differ according to the feeding type. The University of Idaho [1] provides a PDF paper covering all the key physical characteristics for ruminants.
Types of Food Deer Eat
Unlike cattle who spend most their time eating grass, deer being browsers are far more selective in what they eat.
They do of course eat grass along with leaves, shoots of trees and woody plants. Fruit, mushrooms and berries are eaten too, depending on the time of year. Plus, nuts and even dead leaves when food becomes scarce.
Let’s take a look at each food type below in some more detail.
Forbs and Broad Leaf Plants
Forbs are generally considered broad-leaf flowering plants or more commonly known as weeds.
Some common forbs eaten by deer are bracken fern, jewelweed, ragweed, fireweed and so on.
This food source is more difficult to determine in regards to plant species. The QDMA have looked at food studies that have identified several hundred plant species that deer consume across the seasons.
If you take a look on the QDMA website [2] they have provided a fairly comprehensive table of herbaceous forages (forbs) consumed by whitetail across North America.
Sedges and Grass Like Flowering Plants
Grass contains a low amount of the required essential nutrients that deer need as part of a balanced diet.
Forbs have a much higher nutritional value in comparison to grass.
For this reason grasses only make up around 10 percent of the deer’s diet, this is particularly the case with the whitetail species.
When you see deer feeding on grassland, it’s the forbs and weeds they’re carefully browsing for amongst the grass. Forbs and sedges provide more proteins as well as minerals to a deer’s diet.
Nuts and Fruit
When available, deer will consume a variety of nuts and fruit. Acorns, hickory nuts, pecans on occasion and beechnuts are a popular choice with North American deer.
White oak acorns are preferred over their red counterparts as they contain more fructose giving them a sweeter taste.
In more rural forest areas deer consume apples, sumac heads and wild persimmons where possible.
The staghorn sumac grows mostly in the eastern part of the United States. The fruit is bright red with a hairy covering. The USDA [3] provides a data map for staghorn sumac in its most prevalent locations.
A large persimmon tree provides a lot of fruit for deer to eat. They will however only eat persimmon fruit when it’s ripe to eat [4].
Fruit like wild raspberry or strawberry plants that grow on the ground are on the menu too when it comes to whitetails.
Mushrooms
Mushrooms are very high in nutrition for deer but only make up a small part of their overall diet.
Even mushrooms that are toxic to us humans can be consumed by a deer with no adverse effect.
Expect to see deer eating mushrooms during wetter periods when mushrooms thrive in the moisture environment.
They will also eat fungi growing on trees during certain times of year.
Farmed Crops
The harvesting period is the time deer will enjoy many grown crops. Agricultural crops such as soybean, wheat, oats, corn and alfalfa provide a welcome boost to a deer’s diet prior to the colder months ahead.
They will also eat root crops such as carrots and potatoes, however this is less common compared to cereal based crops.
Final Thoughts
As you can see deer tend to be fairly particular when it comes to food choice. Browsing for their food instead of grazing large amounts of grass compared to other herbivores.
Having a basic understanding of how a deer feeds and what type of food is very useful for trail camera users and land managers alike.
I hope you’ve found this article useful, please drop a comment below if you have any suggestions in regards to a deers diet in general.
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