Deer generally will not eat mice unless they are desperate. Thus, technically, they could eat mice, albeit on very rare occasions.
Deer are designed to eat grasses, wheat, and foliage. Nevertheless, as opportunistic meat-eaters, deer do not actively hunt for mice. Instead, they eat them when the chance presents itself, for instance, when they chance upon a dead or injured mouse.
Primarily, deer are specialized herbivores who feed on parts of woody plants. Their bodies and anatomy are adapted to chewing and digesting plants, which is what they eat 90% of the time.
Thus, they cannot consume a lot of meat-based foods because their digestive systems are not built to process them.
Why Do Deer Eat Mice?
Deer are more adapted to eating plant matter than meat. Their bodies and digestion system are not built to eat animals.
Furthermore, they lack the hunting skills required to catch and subdue prey. However, they indulge in occasional meat-eating, where they consume meat in small quantities that their bodies can process.
One of the main reasons deer tend to eat mice is the scarcity of their usual food, introducing the risk of starvation. During certain periods, such as winter, there are very few plants left that deer can consume.
Therefore, the animals will resort to eating flesh such as mice for survival. During these moments of food scarcity, dietary flexibility can mean the difference between survival and extinction.
At times, plants lack the proteins and minerals that deer need to grow and develop. For instance, antlers require minerals like phosphorous and calcium to grow strong and healthy. Deer get these proteins from eating mice and other animals.
Since these minerals are mostly found in the bony parts of animals, deer concentrate more on these bony areas while nibbling at meat.
Another reason why deer would eat mice is that the opportunity has presented itself. Deer are opportunistic feeders. They are not built to be predators, so they can’t chase down a mouse and kill it. Therefore, they normally eat injured, dying, or dead mice.
Additionally, adult female deer, such as the black-tailed deer, tend to eat mice during the deer’s birthing period.
This is because when they are lactating, mother deer do not get enough nutrients from browsing. Thus, they supplement their food with nutrients found in mice.
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How Often Do Deer Eat Mice?
Deer do not indulge in mice-eating often, especially if they are getting enough nutrients from their primary sources of food.
Deer are browsers who prefer to eat foliage, and they primarily feed on the leaves and fruit of woody plants.
Normally, it is uncommon to find deer actively looking for mice to eat. The only instances deer will go around looking for mice to consume are when there is a scarcity of plants or when they have a deficiency of certain minerals in their body.
Both of these instances are rare, meaning that deer will eat mice once in a long time. Besides, their bodies are not built to sustain large amounts of meat in their stomachs.
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Do Deer Eat Any Other Animals?
Apart from mice, deer also eat other small animals such as baby birds. Baby birds are a favorite to many deer species because they are easy to catch and soft enough to chew and swallow without complications.
Baby birds are not the only other animals that deer tend to eat. They have also been caught eating other small animals like squirrels and rabbits.
However, it is highly unlikely that the deer hunt down the squirrels and rabbits themselves. The most likely scenario would be the deer fumbling upon sickly, injured, or dead rabbits and squirrels.
Deer have also been seen nibbling away at the remains of humans decomposing in the wild. Similarly, they do not pass up the opportunity to help themselves to carcasses when they come across them in the wild.
Mostly, deer focus on the bony areas of the meat because they are highly concentrated with the minerals like calcium and phosphorous. Male deer are especially in need of these minerals because of their growing antlers.
Additionally, deer occasionally feed on snails, slugs, and insects when they bump into them.
Still, it is not common for deer to eat meat-based foods. Their bodies are not built to accommodate or digest large amounts of meat, so they can only eat it in small portions.
Furthermore, they are unable to bite through the thick skin of animals with their small front teeth and broad molars. They can only munch on the soft parts of the animals, like the limbs.
What Happens When Deer Eat Meat?
The body of deer is built to digest and process plant matter. As ruminants, they have four stomach chambers with which they thoroughly digest tough plant tissues and fibers.
Even so, they can consume small quantities of meat-based foods without suffering any negative effects.
The only time the consumption of meat would be problematic for deer is if the animal consumes more meat than the body can accommodate.
This is especially if it neglects its usual diet, which is essential for its ultimate survival and good health. Meat is only good for deer when taken as an occasional supplement to the nutrients provided by plant matter.
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Does Eating Mice Affect the Health of Deer?
It is possible that eating mice can affect the health of deer, but it is difficult to see the extent of these effects. Scientists worry that the mouse-eating habit of deer may cause contagious illnesses like the chronic wasting disease.
Abbreviated as CWD, chronic wasting disease is a fatal neurological sickness that affects ungulates, including elk and moose.
Also, eating a lot of mice becomes inefficient and may cause malnourishment for the deer.
Normally, herbivores cannot digest meat-based diets. Therefore, eating a lot of meat may cause organ diseases, growth abnormalities, and, if nothing is done about it, eventual death.
While they are herbivores, deer sometimes eat meat. Thus, they tend to feed on mice when the opportunity presents itself. Normally, deer turn to meat diets when there is a scarcity of their primary food source or when they are lacking essential minerals like calcium and phosphorous.
Since deer are not adapted to hunting, they take advantage of injured or dead rats. For this reason, they qualify as opportunistic feeders.
Even so, deer cannot take large quantities of mice because their bodies are not built to digest and process meat. Too much meat in their bodies could cause diseases and even death.
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.