(Reindeer) Caribou: Antlers Aren’t Just for the Males, Females Own Them Too

We all know that Santa Clause rides reindeer (caribou) to deliver presents. But what do you know about caribou – Santa’s trusted allies? Join us on the journey to the north to uncover the astonishing facts about Santa’s loyal companions – the caribou.  

Scientific name: Rangifer tarandus
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Cervidae
Genus: Rangifer

1. They’re covered in hair

The caribou or reindeer is a member of the deer family. There’re about 6 caribou species, including barren-ground caribou, mountain caribou, woodland caribou, Southern mountain caribou, Peary caribou, and boreal caribou.

The reindeer, which are robust even-toed mammals, exhibit remarkable adaptations to survive in the tundra.

These Arctic animals boast a complete covering of hair, extending from their snouts down to their feet. This coat is short and dense with 2 distinct layers. The outer layer is tough and provides protection, while the undercoat is soft and wooly, offering warmth and insulation. This uniqueness also helps them buoyancy during swimming.

The male caribou

In summer, their coats take on a brown hue, which gradually transitions to grey during winter. Their rumps and chests are grey.

With their broad, fur-clad paws and flattened hooves, these creatures are equipped to withstand cold temperatures and traverse diverse landscapes, such as snow, mud, and water. The hollow structure of these hooves allows them to effortlessly dig through the snow while foraging for food.

Their blunt muzzle is also covered with hair. Caribou is the only deer member that has this characteristic. They possess a special Nasoturbinal bone that serves two important functions. Firstly, it warms the air they breathe before it enters their lungs, which is very helpful in cold environments. Secondly, it enhances their sense of smell, enabling them to detect potential dangers, locate food hidden beneath the snow, and navigate their direction.

The female caribou

The reindeer possess dual circulatory systems within their bodies, whereby the circulation in their long legs can be up to 50 degrees colder compared to the rest parts. Their hollow hairs that are embedded in a dense layer of fat retain heat in extremely cold environments.

These creatures have a size ranging from 4 to 7.25 feet (1.2 – 2.2 m) in length and stand at a shoulder height of 4 to 5 feet (1.2 to 1.5 m). The male caribou, often called bulls, weigh approximately 150 kg, while the females, known as cows, are smaller with less than 100 kg. During the mating season, the males’ necks undergo an enlargement, accompanied by prominent, expanded white patches surrounding the neck area.

Interesting fact:
The animal known as reindeer and caribou is essentially the same. In Europe, it is commonly referred to as reindeer, whereas in North America, the terminology differs based on their nature. When found in the wild, they are called caribou, while those under domestication are known as reindeer. (Reindeer were domesticated around 2,000 years ago).

2. Their antlers grow back

What makes reindeer different from other deer species is that both males and females have antlers. In other species, only the males come with this feature. However, not all female caribou have antlers. Besides moose, caribou have the largest antlers.

The males possess larger and more intricately branched antlers, extending up to 51 inches in length. On the other hand, female antlers are relatively straighter and smaller, about 20 inches long.

Antlers emerge directly from the caribou’s skulls and are encased in a thin skin known as velvet. During September, the velvet covering male antlers vanishes. Some reindeer even their antlers against branches and rocks to speed up the process.

The reindeer is shedding his velvet

When the velvet is actually living skin, and when it is off, the antlers unveil a pink hue caused by the blood flowing through it. Once the shedding process is complete, the antlers harden and transform into a bone-white color, losing their blood supply entirely.

These antlers lose and grow back every year. The males shed their antlers after the breeding season and get them back in February. On the other hand, the female antlers are kept until after they give birth for a while. Smaller males and females that are not pregnant don’t shed their antlers until April.

Caribou use their antlers for different purposes: to protect themselves from predators, to clear snow from the ground to reach food sources, and to fight for the right to mate.

Fun fact:
The Mi’Kmaq people, an indigenous First Nations group in Canada, have contributed to the naming of the caribou. The term “Caribou” originates from the Mi’Kmaq word “qualipu” (pronounced: KAL-i-bu), which translates to “one who paws.”

3. Diet

Caribou are herbivores, they mostly eat vegetation with different types. During the summer, they feed on a diverse range of plants including leaves, grasses, berries, and seeds. However, in the winter when food becomes scarce, these deers primarily depend on lichen, with reindeer moss being their favorite variety. They also consume dried grass and willow twigs during this season.

With a remarkable enzyme known as “Lichenase,” they can convert lichen into glucose or sugar, giving them enough energy to endure harsh winters. Because their diet mainly includes plat matters, they need to eat substantial amounts of food. This generates internal heat at higher levels, protecting them against freezing temperatures.

These species possess a distinct digestive system akin to cows, consisting of a four-chambered stomach, enabling them to effectively process their food. They chew food, regurgitate it, and then eat it again. The food goes to their first stomach, where it undergoes a process of mashing into small pieces known as cud. This cud is then stored for future meals. This unique double digestion system plays a crucial role in breaking down resilient plant materials.

Thanks to their distinctive diet and digestive system, caribou can survive well in the environment with fluctuating seasons.

4. Caribou vs moose vs elk

These three species are all members of the deer family. However, there are still differences between moose, elk, and caribou.

Coat colorGrey, light to dark brownDark brownGrey or red with white hair on the rump
AntlersBoth males and females have antlers
Large and tall with branches
Only males have this feature
Large, wide, and flat
Only males have this feature
Long and tall with points
HabitatArctic tundra, and boreal forests, reaching far to the northBoreal forests and Arctic tundra, although their extent does not reach as far northMeadows and forests
AggressivenessRarelyAggressive and territorialAggressive and can attack without a sign

5. They’re vulnerable to insects

In their native environment, reindeer encounter significant obstacles. They are hunted by formidable predators such as Arctic wolves and human hunters. The calving season presents additional challenges as the vulnerable or newborn calves become targets for various predators, including golden eagles, brown bears, wolverines, sea eagles, and even polar bears.

To safeguard the entire herd, reindeer possess a remarkable gland positioned at their ankles. This gland emits a distinct scent when a caribou is attacked by predators. This scent acts as a warning signal to other members, urging them to maintain a safe distance and adopt protective measures for their lives.

Besides this, they have a better weapon – the ability to see ultraviolet light. Reindeer are the sole known group of mammals on our planet with the remarkable ability to perceive ultraviolet light visually. And how this helps to protect them from the wolf? You’ll see on the video below:

Besides these natural predators, these reindeer are also attacked by insects like horseflies, botflies, deerflies, warbleflies, black flies, and mosquitoes. To protect themselves, they instinctively seek shelter by moving to higher altitudes and coastal areas.

They even strategically plan their pregnancies, selecting the optimal time for their offspring to enter the world. This way, they can make sure that their young are strong enough to endure the ceaseless assaults from the relentless flies that inundate the tundra in late June every year.

6. Habitat

Caribou can be found in the northern and Arctic regions of North America, Europe, and Asia. It is estimated that there are around 2.8 million caribou worldwide. They are located in some countries like Russia, Alaska, Canada, and Scandinavia (including Greenland).

Their habitats encompass mountainous regions and subarctic boreal forests where northern pine trees prevail. They also live in the arctic tundra, which is known for its permanently frozen soil and limited vegetation

7. They have the longest migrations

Caribou embark on immense yearly migrations throughout the summer season as they look for food. Their migration stands out as one of the most challenging voyages undertaken by any land-dwelling mammal.

Thousands of individuals come together to create vast herds, undertaking an extensive round trip that spans over 5,000 kilometers (3,100 miles). This remarkable journey encompasses various destinations, including spring calving regions, as well as summer and winter eating grounds. The migration commences as female herds embark on their journey several weeks before the males. The males, accompanied by the yearling calves born in the previous birthing season, follow suit and join the migration.

These tenacious animals often traverse rivers and lakes while embarking on their migratory journeys, employing their broad hooves as paddles and their coat as buoys. While on the move, the herds can achieve remarkable speeds of up to 50 miles per hour.

These herds tend to expand during the spring migration towards the north, as it is a time for birthing. They disperse into smaller groups across the tundra during the summer to graze, and their numbers gradually decrease in autumn when mating occurs.

During the winter months, caribou migrate to subarctic boreal forests, in which conditions are more favorable and the snow cover is also less thick than in the harsh and barren tundra. This migration enables them to access lichen more easily.

8. Behavior

Caribou live in groups. In the wild, they form expansive herds that can range in size from 100 to 250,000 individuals. However, domesticated reindeer herds are typically smaller, consisting of 50 to 1,000 members.

Compared to females, male caribou generally display more aggression. While females prefer living in larger herds, males can become aggressive when surrounded by other fellows. This is a threat because they can be unpredictable and pose a threat. They possess powerful hooves that can deliver lethal blows when they sense danger.

A porcupine caribou herd

Furthermore, certain subspecies possess leg joints that generate a unique clicking sound when they move. This sound is a communication signal to other members of the herd, indicating the reindeer’s whereabouts and activity, such as feeding or running. The loudness of the click is proportional to the size of the reindeer, allowing other caribou to recognize other herd members in close proximity.

Although reindeer are typically calm creatures, they occasionally produce a resounding snort that resembles a gathering of pigs, especially when they gather with cows and newborn calves.

9. Reproduction

The autumn season marks the mating season for caribou, usually occurring from late September to early November. Throughout this period, males participate in intense competitions called ruts. During ruts, they charge at each other and interlock their antlers in order to assert dominance and get the females’ attention.

The battles carry the risk of causing significant harm, including cuts and bruises, to the participating males. However, the most dire outcome of these conflicts is when the antlers become entangled, rendering the caribou unable to free themselves. This can cause them starve to death.

The winning males exhibit dominance by mating with a significant number of females within their group, usually ranging from 15 to 20 individuals. As polygynous animals, these creatures can mate with different females in their lives.

The gestation period of the females is about 45 days. They give birth to a single calf (twins are rare) in May and June. Despite their small size at birth, weighing only around 10 pounds, they can find their footing and start moving. Within just 3-6 hours, these little ones can even muster the energy to run alongside the herd.

The young nurse for a few weeks and then start to graze at 3 weeks old. As fall approaches, these young become self-reliant and independent. Female caribou typically reach full maturity around 2.5 years old. However, they can breed as early as 16 months.

The young can get up and run after a short time of being born

Following the birth of their calves, reindeer form groups referred to as post-calving aggregations, aiming to shield themselves from predators and bothersome insects. As the summer goes by and the insect population diminishes, they disperse and forage on willow leaves and mushrooms in order to replenish their body weight.

In the wild, the lifespan of caribou is about 15 years.

10. Conservation Status

Caribou are currently classified as “Vulnerable.” Their global population has witnessed a concerning decline of 40% over the past 3 generations, dropping from nearly 5 million to approximately 2.8 million.

According to recent research, it has been found that among the 51 herds present in Canada, a minimum of 20 herds are currently facing a decline in population. None of them are exhibiting any signs of growth.

Overhunting is a primary factor contributing to this decline. In the 1800s, their warm, waterproof, and soft fur was in great demand and commanded substantial prices in trade. Their decline is also attributed to habitat loss, fragmentation, degradation, and predation. Their slow reproduction rate further hinders their ability to recover from population decline.

The creatures are also affected by climate change. Increasing wildfires are depleting lichen, a crucial food source for caribou that requires several years to regenerate. The onset of climate change is causing winter icing, which traps food and leads to malnutrition and mortality among caribou.

The warmer temperatures brought about by climate change also facilitate the proliferation of mosquitoes and flies, posing a threat to caribou due to blood loss and infestation. Furthermore, shifting ice patterns disrupt the traditional migratory routes of caribou across frozen water bodies.



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