Hunters, conservationists, and the general public are familiar with deer. However, not everyone knows that many deer species are spread across several continents. Neither do many people know whether deer are nocturnal or diurnal. And because people mostly see deer in their natural surroundings during the day, they don’t question their sleep patterns or other behaviors. So, are deer nocturnal or diurnal, or do they exhibit other unusual sleeping patterns of which we are unaware?

What Are Deer?

Contrary to popular belief, deer are not nocturnal animals but are crepuscular.

iStock.com/Dan Richards

There are approximately 43 deer species distributed worldwide. These animals have hoofs and are ruminants, meaning they chew the cud like buffalo, cows, sheep, and goats. Deer have four compartments in their stomachs, with the first and largest known as the rumen. Being ruminants, deer swallow their food, regurgitate it, and then continue chewing it to ease the digestive process.

These ruminant animals belong to the Cervidae family and are part of the Artiodactyla order. Other ruminants in the Ruminantia sub-order include okapis, giraffes, antelopes, pronghorns, and chevrotains. Next, we cover some basic information about deer species before discussing their sleep behavior.

Deer Species

Although there are over 43 deer species worldwide, the following are some of the more familiar types:

  • White-tailed deer: With their scientific tag, “Odocoileus virginianus,” this deer species is a common sight in North America. Their name comes from the beautiful white hair on the underside of their tail. A fully-grown white-tailed deer weighs about 150 pounds.
  • Red deer: These deer thrive in Europe, Northern Africa, and Asia. They have a reddish-brown coat, stand about 4 feet high, and weigh approximately 440 pounds.
  • Mule deer: Mule deer are also known as migrators. These tiny deer only weigh between 50 and150 pounds and are famous for migrating in winter.
  • Elk: The elk or wapiti is one of the largest members of the deer family. This animal weighs about 700 pounds and can reach running speeds of up to 40 miles per hour.

It may be helpful to go over these terms so that it is easier to understand what we mean when talking about the deer’s sleeping pattern.

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  • Nocturnal. Nocturnal behavior means the animal is active at night, which some people believe is the deer’s sleep pattern.
  • Diurnal. Diurnal sleep and waking patterns mean the creature is most active during the day.
  • Crepuscular. Crepuscular behavioral patterns are present when the animal is active, primarily during the twilight hours around dusk and dawn.
  • Metaturnal or cathemeral. These activity patterns mean that the creatures sleep and wake at regular or irregular hours during the 24-hour cycle, whether day or night.

Are Deer Nocturnal?

Deer are not nocturnal, although people occasionally mistake some species for showing signs of nocturnal behavior. However, people often confuse nocturnal behavior with crepuscular sleep patterns. And displaying nocturnal behavior is out of character for this animal species. Nevertheless, they may resort to nocturnal grazing to avoid predation. Still, most deer species are primarily crepuscular.

Deer Are Crepuscular and Not Nocturnal

Sika deer
Deer are pretty adaptable in their sleeping pattern as they can shift to more diurnal and nocturnal activity as the need arises.

Martin Mecnarowski/Shutterstock.com

Deer are active during twilight, rather than specifically diurnal or nocturnal, which explains the prevalence of vehicle-deer collisions in twilight hours. Twilight hours occur before the sun goes down, and shortly after, the sun rises above the horizon. Deer sometimes sleep during the day and at night, exhibiting nocturnal and diurnal characteristics, but these animals are crepuscular. But deer are pretty adaptable in their sleeping pattern as they can shift to more diurnal and nocturnal activity as the need arises. The need to alter their sleep behavior may be due to weather and seasonal changes and the mating season.

Factors Influencing Sleep Behavior

Many factors affect how and where deer sleep, including but not limited to food availability and a change in weather conditions. For example, deer change their habitats and sleep patterns based on weather conditions. These animals may choose to be active at night during summer to obtain relief from the daytime heat. So, dusk and dawn are convenient foraging periods that support their safety from predators and their comfort.

High heat levels in the summer will also drive deer to take shelter during the day to avoid heat stress. Similarly, deer will alter their sleep and activity patterns to avoid extremely cold weather conditions. Because deer are so adaptable, they will change their foraging habits according to the seasons, environmental conditions, and food sources. Besides the cold and heat, these animals will seek shelter in forests and thickets for protection from the weather and predators.  

Studies indicate that crepuscular behavior is associated with anti-predator tactics. Since deer are primarily crepuscular, this behavior suggests that most of their predators are either nocturnal or diurnal. So, these animals take advantage of their predator’s sleep patterns to protect themselves by engaging in crepuscular activities. 

The moon phases also influence the movements of deer. Nighttime visibility differs according to the moon’s phases, encouraging deer to adapt their behavior accordingly. Consequently, deer tend to thrive in conditions where they more easily spot and avoid danger with as little risk as possible.

Sleeping Positions

Deer have a distinctive approach to their sleeping positions that depends on their surroundings. Most deer sleep on their sides and support their heads in the recumbent position. Deer do not sleep while standing up because they will fall over. However, they can rest while standing with their eyes open in a semi-sleep state.

Besides, deer never enter a state of deep sleep, with most only sleeping for a brief period at any one time. This minimum sleep is because they must remain vigilant for predators, supporting a quick escape.

Research confirms this light, minimum sleep pattern in the lesser mouse-deer. These deer rest in a recumbent position characterized by primarily slow wave and paradoxical sleep states.

Deer also often position their heads to keep their body as warm as possible. To achieve this extra level of comfort, they prefer resting on a south-facing slope that offers the maximum warmth of the sun.

Co-Sleeping Behavior

Axis Deer in Park
Deer often live in herds, making resting easier as their numbers promote safety.

iStock.com/Alberto Carrera

Deer thrive in numbers, so it makes sense that they rest in numbers, especially since they must be light sleepers to survive. Also, sleeping in groups means more deer are in various sleep states, which helps spot predators. Additionally, the younger deer are vulnerable to harsh weather conditions. Extra protection from each other’s body heat helps keep them warm, promoting their survival in adverse conditions.

Interesting Deer Facts     

  • Deer predators and threats. Deer are necessary meals for the survival of many predators in the wild, including coyotes, jaguars, mountain lions, bears, tigers, wolves, and other large raptors. Small mammals and birds also feed on deer carcasses. Young fawns are particularly susceptible to predation as they are defenseless against predators. Likewise, people are one of the deer’s most dangerous predators. People hunt deer for sport and their meat. And since hunters understand deer sleeping patterns, this knowledge makes them even more vulnerable. Hunters also take advantage of their co-sleeping behavior for easier and more frequent kills.
  • Deer lifespan and reproduction. Male deer begin to grow their antlers in the first year of their life. Deer can live for up to 12 years in the wild. But some factors, such as predation, vehicle collisions, and hunting, can significantly interfere with their lifespan.
  • Reproduction. Deer reproduction takes place every year for a short time. Most deer species engage in polygenic reproduction, where a single male will have multiple female partners. Still, the females only have one male partner. Only a few deer species are monogamous.

Nocturnal vs. Diurnal: What’s The Difference?

Navigate to Nocturnal vs. Diurnal: What’s The Difference? for further information about the nocturnal and diurnal phenomenon in various living creatures.

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