Why Reindeer Are One of the Least-Studied Animals in the World

With their beloved place in holiday lore and popular culture, reindeer are some of the most recognizable animals on the planet. Yet despite their fame, there is little research about these extraordinary animals. Here at A-Z Animals, we were fortunate enough to sit down with one of the world’s few reindeer specialists, Dr. N. Isaac Bott, to uncover some of the most fascinating and little-known facts about these incredible creatures. From their unique adaptations to the extreme conditions of the Arctic to their surprising abilities, here are 10 noteworthy facts about reindeer that you probably didn’t know!

1. Very Few People Study Reindeer

Reindeer are a familiar sight in popular culture, but you may be surprised to learn that very few people study them scientifically. Dr. Bott is a reindeer specialist and is widely recognized as one of the only veterinarians in the world who offers reproductive services specifically for reindeer.

As a specialist in theriogenology (the study of animal reproduction), Dr. Bott met his first reindeer in 2010. He had been called to assist reindeer in labor. The newborn calf was also sick, and Dr. Bott spent the next few weeks visiting and caring for it. During that time, the owner revealed that he had spent a decade searching for someone to help with artificial insemination in reindeer.

Dr. Bott happily took on the challenge. Within a year, they had successfully produced the world’s first female reindeer through artificial insemination. Dr. Bott told A-Z Animals, “I learned that [reindeer] were unique. For the most part, they are very docile, and they have personalities, just like a dog or a cat or a horse. They are unique in tons of different ways.”

2. Reindeer and Caribou Are Not the Same

Although the terms are often used interchangeably, reindeer and caribou are not the same animal. Many well-respected organizations have used the wrong term, which is understandable given the lack of research until recently. However, according to Dr. Bott, while they are closely related, reindeer (Rangifer tarandus tarandus) and caribou (Rangifer tarandus granti) are two different subspecies.

Caribou crossed the Bering Land Bridge thousands of years ago and evolved in North America. The name “caribou” comes from the Mi’kmaq Nation of Canada and means “snow shoveler,” a fitting name for an animal known for digging through snow to find food.

Reindeer, in contrast, are Eurasian. Originally from Siberia, reindeer were utilized for milk and transportation, particularly in frigid, remote areas. The Nenets people of the Yamal Peninsula, for example, are well-known for their reindeer-herding traditions, following the animals’ natural migratory routes. Even today, reindeer herding continues to be an important aspect of life for many in these Arctic regions.

In the 1890s, they were brought by boat from Siberia to Alaska. As for the name “reindeer,” the name has nothing to do with Santa’s sled. It comes from the Old Norse word hreinn, which simply means “deer.” So when you say “reindeer,” you’re essentially saying “deer-deer”!

3. Reindeer Can Tweak Their Internal Clocks

Reindeer live in the Arctic, a region of extreme light and darkness where summers have nearly 24 hours of daylight and winters are plunged into months of darkness. For most animals, these extremes would disrupt their circadian rhythm, or internal body clock, which regulates everything from sleep patterns to metabolism.

Reindeer, however, have uniquely adapted to these harsh conditions by essentially turning off their circadian clocks. This allows them to maintain a consistent routine of grazing and resting throughout the day, regardless of the season or the amount of light available. They can continue this cycle—munching on grass, lichens, and leaves for a few hours, taking a nap, and then returning to grazing—even in the dead of winter without any sunlight.

4. Reindeer Conserve Energy and Heat with Their Nose

Beyond their unique circadian clocks and thick fur, reindeer also have a highly specialized nose that aids in their survival amid the harsh Arctic climate. A reindeer’s nose contains a complex structure of scrolling bones, cartilage, and soft tissue, all lined with lots of blood vessels. This incredibly vascular nasal turbine acts as a natural heat exchanger. It helps them to stay warm in the winter and cool in the summer.

As a reindeer breathes in frigid air, this structure quickly warms the air before it reaches the lungs. When the reindeer exhales, the process reverses: the warm, moist air from the animal’s lungs cools as it passes through the nose, causing the water vapor to condense, allowing the body to reabsorb it.

By warming the air as it is inhaled and reclaiming heat as it is exhaled, the reindeer’s nose prevents body heat from escaping into the cold. This is why, unlike humans, you won’t see a reindeer’s breath on a cold day. Additionally, the reabsorption of water vapor during exhalation helps reindeer stay hydrated.

5. Santa Might Have an All-Female Reindeer Team

Reindeer are the only species of deer where both males and females grow antlers. Male reindeer begin growing their antlers in late February, and they can grow up to two inches each day. Initially, a soft, sensitive “velvet” layer covers the antlers. Once the antlers fully calcify and turn into solid bone, the reindeer rub off this velvet. Though it may look gruesome, it isn’t painful for the reindeer, as the antlers have no feeling once they’ve hardened.

Unlike other deer, reindeer use their antlers for more than just sparring during the rut. Reindeer also use their antlers for defense, to forage for food, and to remove snow. According to Dr. Bott, “They have what’s called the ‘shovel’ — the lowest forward projection on the antler that helps clean snow when they’re foraging during winter months.”

Although both male and female reindeer have antlers, a key difference is when they shed them. Intact males lose their antlers by early December, while females keep theirs until later in the winter or even early spring. Dr. Bott says, “Antlers also serve a purpose in this species for protecting their offspring.”

Interestingly, reindeer are the only deer species in which even castrated males grow antlers, although they do not shed them until early spring. Thus, if intact male reindeer shed their antlers before Christmas, then Santa’s sleigh could only be pulled by female reindeer, castrated males, or perhaps even a mix of both.

6. Reindeer Eyes Change Color and Can See Ultraviolet Light

Even reindeer eyes have evolved to thrive in Arctic environments. They can see ultraviolet (UV) light, which is invisible to humans without the aid of a black light. While our vision cuts off around 400 nanometers (nm), reindeer can see up to 320 nm. This unique ability gives reindeer a considerable advantage. Things that are difficult for us to see, like urine or white fur against a snowy landscape, glow in high contrast to a reindeer’s eyes.

According to Dr. Bott, a reindeer’s eyes also change color with the seasons. “The cells along the retina — what’s called the tapetum lucidum, a reflective surface in the posterior aspect of the eye that facilitates night vision — those cells actually change color from summer to winter.” In the summer, they’re green, and in the winter, they’re blue. This helps reindeer with their vision during the long and dark Arctic winters.

7. Reindeer Produce Supercharged Milk

Reindeer calves grow exceptionally fast — an important trait for a species constantly on the move. According to Dr. Bott, baby reindeer can be weaned from their mothers in just three to four months. Calves are born weighing around 12 pounds in the spring, but by the end of the year, they weigh over 150 pounds.

This rapid development comes from the incredibly rich milk that female reindeer produce. Dr. Bott explains, “The initial milk, that first colostrum, can contain up to 24% milk fat.” To put that in perspective, a Jersey cow — a dairy breed known for having the highest milk fat content — produces milk with only around 4% fat.

8. Reindeer Reproduction is a Miracle of Perfect Timing

In reindeer, successful reproduction hinges on perfect timing. Other deer species have a breeding window of 12 to 24 hours. Reindeer, in contrast, have a much narrower window of around one hour.

This tight schedule becomes even more challenging with the unique properties of reindeer semen. Dr. Bott explains, “Reindeer semen is less motile and prolific compared to that of other species. So, you can collect semen from a male, but freezing it in liquid nitrogen is incredibly difficult. Then thawing the semen — and having it remain viable long enough to fertilize an egg within that short one-hour window — makes it even more challenging.”

This is why artificial insemination in reindeer was unsuccessful for several decades. Intriguingly, Dr. Bott found success by looking to an unlikely source: sheep. Instead of using semen extenders designed for deer or cattle, as others had tried, he used special sheep extenders from France. This approach enabled him to successfully freeze reindeer semen for the first time.

9. Reindeer Can Alter Their Gestation Time

Female reindeer have a unique ability to synchronize their births. This means their gestation period (how long they are pregnant) can vary by as much as 40 days, but the calves are all born around the same time.

For example, a female that breeds in early September will have a longer pregnancy compared to one that breeds later in the year. As Dr. Bott puts it, “When it’s time to have babies, they all do.” This ensures that all the calves in a herd are born within the same week.

In the lower 48 states, the average gestation period for reindeer is around 220 days. Although there is variability in this number by as much as 40 days, calves conceived later in the season may have a much lower chance of survival, particularly if they are born after around May 15. Dr. Bott told A-Z Animals about a premature calf born in his herd just this year. The calf was born on June 30 with a gestation of only 199 days, and sadly, it only survived for a few hours. “When they’re premature like that, it’s so hard,” Dr. Bott says. “We don’t understand what drives it, although we think it has to do with predators, and also plants blooming.”

10. Reindeer Are in Trouble

Reindeer have a perfectly timed, inborn instinct that tells them when to migrate. This instinct ensures they arrive at their destination when one of their vital food sources, cotton grass, is ready for nursing mothers.

However, climate change and human activity are disrupting this delicate balance. According to Dr. Bott, even a slight change in temperature can be catastrophic. If the grass is a week late, for example, it can lead to an extremely high mortality rate for the herd.

This is one of the many reasons that Dr. Bott’s research on reindeer reproduction is so vital to the species’ survival. He explains, “The advantages of artificial insemination mean that you can bring in genes from anywhere. You can freeze semen in liquid nitrogen and ship it anywhere in the world.” This helps to combat the detrimental effects of genetic bottlenecking caused by dwindling populations.

Dr. Bott further emphasizes that humans have a unique responsibility to protect these animals. “There are so many millions of species, and we’re the only species that has the intellect and capacity to protect the other species,” he says. “Any time a species becomes extinct, the world becomes a lonelier place.”

Dr. Bott further explains, “We need to take into account animal migrations and animal well-being in any of our projects; certainly, we’re making our own lives easier, but if we’re doing it at the expense of others, it really needs to be evaluated.”

About Dr. N. Isaac Bott

Dr. N. Isaac Bott has a bachelor’s degree from Southern Utah University and is a 2009 graduate of Washington State University’s College of Veterinary Medicine. He owns and operates Mountain West Animal Hospital, a mixed animal veterinary facility in Springville, Utah. He is a past president of the Society for Theriogenology, has served as a council member and chair of the American Veterinary Medical Association’s Council on Veterinary Service, and as the co-chair of the Utah Veterinary Medical Association’s Legislative Committee. In 2023, he was awarded the Dr. John Steiner Award for Practitioner Excellence, and in 2024, he was given the Utah Veterinarian of the Year Award. He has authored over a dozen peer-reviewed scientific articles. He is the proud father of three children: Kaycee, Kayden, and Kendyn.

The post Why Reindeer Are One of the Least-Studied Animals in the World appeared first on A-Z Animals.