# Caribou (*Rangifer tarandus*)

Caribou, also known as reindeer, are majestic animals with large antlers. They roam the cold Arctic regions and are known for their long migrations in search of food.

- **Category:** [Mammals](https://www.snappit.app/explore/categories/mammal)
- **Rarity:** Common
- **Danger:** 2/5 · Low
- **Snaps:** 2
- **Habitat:** Tundra
- **Also known as:** Reindeer

![Caribou](https://res.cloudinary.com/drieglelr/image/upload/v1771424587/objects/5966.jpg)

## Appearance

The Caribou has a dense, shaggy coat, often grayish-brown to nearly white, with a distinct white mane and rump. Their large, crescent-shaped hooves are a key visual feature, helping them traverse diverse terrains. Antlers, often wide and complex, are typically grown by both males and females.

## Taxonomy

- **Kingdom:** Animalia
- **Phylum:** Chordata
- **Class:** Mammalia
- **Order:** Artiodactyla
- **Family:** Cervidae
- **Genus:** Rangifer

## Caribou, up close

The caribou or reindeer (Rangifer tarandus) is a deer of the Arctic and subarctic: tundra, mountains and northern forests across North America, Greenland, Europe and Asia. Wild herds in North America are called caribou, while in Europe and Asia the same species is called reindeer, and millions of reindeer are herded by northern peoples. It is the only deer in which females normally grow antlers, and some herds make the longest known migrations of any land animal.

Also called: Wild reindeer.

Antlers on the cows too, eyes that turn blue in winter and the longest migrations on land. Spin it, tap it, then test yourself.

### Special abilities

- **Antlers for All** (Both sexes grow antlers): Caribou are the only deer in which cows normally grow antlers too. Big bulls drop theirs after the autumn rut, but pregnant cows keep theirs all winter. [2][1][14]
  - New antlers start in spring and are finished by late August. Big bulls rub off the velvet in late August and early September, just before the rut.
  - The biggest bulls shed their antlers from late October to December.
  - Young bulls and cows that are not pregnant keep theirs until about April. Pregnant cows usually keep theirs until their calves are born in late May or early June.
- **Shifting Mirrors** (Gold → blue eyeshine, summer to winter): A reindeer’s eyeshine changes colour with the seasons: golden in the endless summer light, deep blue in the long winter twilight. [4][5]
  - The mirror behind the retina is made of tiny collagen fibres. In winter they sit closer together, so the mirror reflects bluer light.
  - The blue mirror sends less light back out of the eye, and the retina becomes more sensitive in dim light.
  - Scientists think pupils that stay wide open all winter raise the pressure inside the eye, and this squeezes the fibres closer.
  - Reindeer are the only mammal known to retune their eyes to the season like this.
- **UV Eyes** (UV light reaches the retina; still debated): A reindeer’s cornea and lens do not block all ultraviolet light, and its retina responds to it. What reindeer use this for is still an open question. [6]
  - Both rods and cones respond to UV, even though reindeer have no special UV-sensing cells.
  - The Arctic is rich in UV light, scattered by the sky and bounced off snow and ice, especially in the long twilights of spring, autumn and winter.
  - Scientists suggest UV vision may help reindeer pick out things that reflect UV differently from snow, such as some plants. This has not been tested in the wild.
- **Clicking Walk** (Click with every step; still debated): Walking reindeer make a loud clicking sound with each step, and both bulls and cows do it. [10][15]
  - Park rangers in Alaska say tendons in the feet click as caribou walk.
  - Scientists call it a “knee-click”. Reindeer are one of only a few hoofed animals that click loudly and regularly, along with Père David’s deer, white-lipped deer and eland.
  - Exactly where the sound comes from is not proven. A 2022 study found a small oval opening in a tendon sleeve of the front leg that might play a part.
  - In eland, clicks tell rivals how big a male is. Whether reindeer clicks help a herd keep together has not been tested.
- **Snow Shovel** (“The one who paws” possible meaning of “caribou”): In winter, caribou dig through the snow with their broad hooves to reach the lichen underneath. [2][16][13][17]
  - Their concave hooves work as scoops as they paw through snow to uncover lichens and other plants.
  - The name “caribou” may come from the Mi’kmaq word xalibu, “the one who paws”.
  - Winter is the hungriest season. Caribou move less then than at any other time of year, saving energy.
  - When rain falls on snow and freezes, an ice crust can seal the food away. In winter 2013–14 this starved 61,000 herded reindeer on Russia’s Yamal Peninsula.
- **Heat-Swap Nose** (+6 °C breath out when the air is −45 °C): A reindeer’s nose and coat are built to keep heat in. At −45 °C, its breath leaves the nose at only about +6 °C. [8][9][10][11]
  - Arteries and veins in the nose lining run side by side in opposite directions, so heat from outgoing breath is caught and kept in the body.
  - In summer the system can switch to get rid of heat: on a +29 °C day, breath left the nose at +38 °C.
  - The hair is hollow and holds heat, and the thick coat even helps a caribou float.
- **Marathon Migration** (≈1,350 km longest round trip, straight line): Some caribou herds make the longest known migrations of any land animal: about 1,350 km in a straight line between their summer and winter ranges and back. [18][1]
  - A 2019 study compared migrations of big land mammals. Caribou and reindeer herds took the top six places; the Bathurst and Porcupine herds were longest, at about 1,350 km.
  - That is the straight line. Following every twist and turn, caribou in northern North America moved up to 4,868 km in a year, though grey wolves moved even more.
  - Once on the move, caribou can travel up to 50 miles (80 km) in a day.
  - The Bathurst herd used to migrate up to 1,500 km; as the herd shrank, so did its journey.
  - Longest round-trip migrations: Caribou (Bathurst herd) ≈1,350 km; Grey wolf (Northwest Territories) ≈1,016 km; Mule deer (Wyoming) ≈772 km; Wildebeest (Serengeti) ≈650 km; Moose (Alaska) ≈392 km
- **Seasonal Hooves** (2 seasons long rims in winter, worn down in summer): Caribou hooves change through the year. In winter they grow long, with sharp edges that bite into crusty snow and ice; in summer, rocks wear them down again. [2][12]
  - The sharp hoof edges give a firm grip on ice and smooth rock.
  - Wide-splayed toes and big dewclaws spread the weight on snow and boggy tundra.
  - Hooves are made of keratin, the same stuff as your nails, and the pads and hooves flatten with each step to cushion it.

### Body parts

- **Antlers** (≈1 m tall: 3 ft or more) [1][2][3]
  - Caribou are the only deer in which both sexes grow antlers. A bull’s are large and massive; a cow’s are shorter, thinner and more irregular.
  - Antlers grow from spring to late August under a fuzzy skin called velvet, full of blood vessels that carry food for growth.
  - In Denali National Park, antlers of both bulls and cows can stand 3 feet (about 1 m) or more high.
- **Eyes** (Gold → blue eyeshine, summer to winter) [4][5][6][7]
  - Behind the retina is a mirror layer, the tapetum lucidum. In summer it shines gold; in the dark Arctic winter it turns deep blue.
  - The blue winter mirror goes with a more sensitive retina, which helps in the long blue twilight of the Arctic winter.
  - A reindeer’s cornea and lens let some ultraviolet light through, and its retina responds to it.
  - Reindeer may not need a strong daily body clock: in their cells two key clock genes barely keep a daily rhythm, and the sleep hormone melatonin simply follows light and dark.
- **Nose** [8][9]
  - Inside the nose, networks of arteries and veins run side by side, so heat from each breath out is caught before it escapes.
  - In a winter test at −45 °C, a resting reindeer’s breath left its nose at only about +6 °C. That saves heat and water.
  - In warm weather the blood flow switches round so the nose can get rid of heat instead.
- **Mouth** (Lichen main winter food) [10][1]
  - In summer caribou eat grasses and other low-growing plants. In August they feed heavily on willow leaves and mushrooms to put weight back on.
  - From September they switch to lichens (“reindeer moss”), dried sedges and small shrubs such as blueberry.
  - By grazing and browsing, caribou help shape the plant and lichen communities they live in.
- **Mane** [2][1]
  - In autumn a bull has a rich brown or grey and white coat and a fringe of white hair flowing from throat to chest.
  - Bulls only call during the rut, and their voice is more “airy” than a cow’s.
  - Cows and calves are the chattiest, calling to keep in touch, especially around calving.
- **Coat** (Hollow hairs that hold heat) [10][11][1]
  - Caribou hair is hollow and holds heat well.
  - The thick, many-layered coat keeps out the weather and even helps a caribou float when it swims.
  - Newborn calves have dark chocolate to reddish-brown hair.
- **Hooves** (4 toes on each foot) [1][2][12]
  - Large, concave hooves splay wide to carry a caribou over snow and soft tundra, and work as paddles when it swims.
  - In winter the hooves grow long, with sharp edges that grip crusty snow, ice and smooth rock. In summer, rocks and hard ground wear them down.
  - Each foot has 4 toes: 2 big hoofed toes and 2 large dewclaws set far back, which spread the weight even more.
  - With every step, the foot pads and hooves spread and flatten to cushion the blow.
- **Stomach** [2][13]
  - Caribou are cud-chewers, like cows. Their food is fermented in a big first stomach called the rumen.
  - Ground and tree lichens are their main winter food. Living on lichen sets caribou apart from all other large mammals.
  - Lichens are easy to digest and rich in energy, and this lets caribou survive on harsh northern ranges.

### Stats

| Stat | Value | Notes |
|---|---|---|
| Bull weight | 159–182 kg | average adult bull; up to 318 kg recorded [1] |
| Cow weight | 80–120 kg | average adult cow [1] |
| Weight at birth | 6 kg | and doubles in 10–15 days [1] |
| Antler height | ≈1 m | 3 ft or more, in bulls and cows [3] |
| Longest round-trip migration | ≈1,350 km | Bathurst and Porcupine herds, straight line [18] |
| Distance in a year | up to 4,868 km | caribou in northern North America, every step counted [18] |
| Distance in a day | up to 80 km | 50 miles a day when migrating [1] |
| Breath temperature | +6 °C | leaving the nose when the air is −45 °C [8] |
| Wild tundra caribou and reindeer | 2.1 million | down 56% from 4.7 million in about 20 years (2018) [20] |
| Herded reindeer | ≈3.4 million | kept by about 24 peoples in 10 countries [21] |

### Photos

- [A bull caribou in Alaska](https://commons.wikimedia.org/wiki/File:Caribou.jpg) (photo: Dean Biggins, U.S. Fish and Wildlife Service, Public domain)
- [A cow, still wearing her antlers, and her calf on the winter solstice, Brooks Range, Alaska](https://commons.wikimedia.org/wiki/File:Caribou_at_Chandalar_Shelf_(53452255339).jpg) (photo: BLM Alaska, Public domain)
- [A female reindeer with antlers near Lake Khövsgöl, Mongolia](https://commons.wikimedia.org/wiki/File:Reindeer_of_Mongolia_04.jpg) (photo: Bernard Gagnon, CC0)
- [Peary caribou on Bathurst Island, Nunavut, Canada](https://commons.wikimedia.org/wiki/File:Peary_caribou_-_Bathurst_Island.jpg) (photo: Paul Gierszewski, CC BY-SA 4.0)
- [A Peary caribou swimming the Thomsen River, Aulavik National Park, Canada](https://commons.wikimedia.org/wiki/File:Aulavik_swimming_caribou.jpg) (photo: Paul Gierszewski, CC BY-SA 4.0)
- [Part of a herd of about 60,000 Porcupine caribou in the British Mountains, Yukon, 1972](https://commons.wikimedia.org/wiki/File:Porcupine_caribou%2C_1972.jpg) (photo: Lee E Harding, CC BY-SA 4.0)
- [A reindeer in the Kebnekaise valley, Swedish Lapland](https://commons.wikimedia.org/wiki/File:20070818-0001-strolling_reindeer.jpg) (photo: Alexandre Buisse (Nattfodd), CC BY-SA 3.0)
- [A wild caribou in Denali National Park, Alaska, late August](https://commons.wikimedia.org/wiki/File:Carib%C3%BA_(Rangifer_tarandus)%2C_Parque_nacional_y_reserva_Denali%2C_Alaska%2C_Estados_Unidos%2C_2017-08-30%2C_DD_39.jpg) (photo: Diego Delso, CC BY-SA 4.0)
- [Herded reindeer at Ljungris, Härjedalen, Sweden, in October](https://commons.wikimedia.org/wiki/File:Reindeer_Ljungris_October_2014_01.jpg) (photo: Arild Vågen, CC BY-SA 4.0)

### Questions

- **Are caribou and reindeer the same animal?** Yes. Both are Rangifer tarandus. North Americans call wild ones caribou; in Europe and Asia the same species is called reindeer, and many reindeer are herded. Some scientists propose splitting the group into several species, but that is still debated. [22][18][23]
- **Do female reindeer have antlers?** Yes. Caribou and reindeer are the only deer in which both sexes normally grow antlers. Cows’ antlers are smaller, and pregnant cows usually keep theirs until their calves are born in late May or June, long after big bulls have dropped theirs. [1][14][2]
- **How far do caribou migrate?** The longest migrations, by the Bathurst and Porcupine herds, are about 1,350 km there and back in a straight line, the longest known for any land animal. Counting every twist and turn, caribou can walk up to 4,868 km in a year. [18]
- **Why do reindeer eyes change colour?** The mirror layer behind the retina, the tapetum lucidum, is gold in summer and deep blue in winter. The winter version makes the eye more sensitive in the long blue twilight of the Arctic winter. [4][5]
- **What do caribou eat?** In summer they eat grasses and other low-growing plants, then willow leaves and mushrooms. From September they switch to lichens (“reindeer moss”), dried sedges and small shrubs, and in winter they paw through snow to reach lichen. [10][1][2][13]
- **Are caribou endangered?** The IUCN lists the species as Vulnerable. Wild tundra caribou and reindeer fell from 4.7 million to 2.1 million in about 20 years, and some herds have dropped by more than 90%, though a few, like the Porcupine herd, have grown. [30][20]
- **Why do reindeer click when they walk?** Walking reindeer make a loud click with each step. Park rangers say tendons in the feet make the sound, and scientists are still working out exactly where it comes from and whether it helps a herd stay together. [10][15]
- **Can reindeer see ultraviolet light?** Their eyes let some ultraviolet light through and the retina responds to it. Scientists think this may help in the UV-rich Arctic winter, but what reindeer actually use it for has not been tested in the wild. [6]

### Caribou and reindeer: myth or fact?

Tap Myth or Fact for each claim, then check the answer.

- "Caribou and reindeer are two different animals." **Myth!** They are one species, Rangifer tarandus. In North America wild ones are called caribou; in Europe and Asia they are reindeer, and many are herded. Some scientists now argue the group should be split into several species, so this may change. [22][18][23]
- "Female reindeer grow antlers too." **Fact!** Caribou are the only deer in which both sexes grow antlers. Cows’ antlers are shorter and thinner than bulls’. [1][2]
- "Reindeer can fly." **Myth!** Sorry, Santa: no reindeer can fly. On the ground, though, they are champions. Some herds travel about 1,350 km there and back each year, and they swim well, using their hooves as paddles. [18][1]
- "Santa’s antlered reindeer must all be girls, because males lose their antlers before Christmas." **Myth!** The biggest bulls do drop their antlers between late October and December. But young bulls keep theirs until about April, so a Christmas team with antlers could include young males as well as cows. [1][2]
- "Reindeer eyes change colour with the seasons." **Fact!** The mirror layer behind the retina is gold in summer and deep blue in winter. Reindeer are the only mammal known to do this. [4][5]
- "Walking reindeer make a clicking sound." **Fact!** Both sexes click loudly as they walk. Park rangers say tendons in the feet make the sound; scientists call it a knee-click and are still working out exactly where it comes from. [10][15]
- "“Reindeer moss” is a moss." **Myth!** Reindeer moss is really a lichen. Lichens are caribou’s main winter food. [1][2]
- "Caribou make the longest migrations of any land animal." **Fact!** Measured as the straight-line distance between summer and winter ranges and back, yes: caribou and reindeer took the top six places in a 2019 study, up to about 1,350 km. Over a whole year, though, grey wolves cover more ground. [18]

### Caribou records

Superlatives and record holders, each checked against its source.

- Longest land migration: Caribou (Bathurst and Porcupine herds), ≈1,350 km (round trip, measured in a straight line between the two ends) [18]
- Only deer with antlered cows: Caribou and reindeer, Both sexes (the only member of the deer family in which both sexes grow antlers) [1][2]
- Only mammal that retunes its eyes: Reindeer, Gold → blue (the only mammal known to adapt its eyes each year to the blue winter twilight) [5][4]
- The only domesticated deer: Reindeer, ≈3.4 million (semi-domesticated reindeer, herded in 10 countries) [22][21]
- One of the farthest walkers: Caribou, 4,868 km a year (one of only 4 species in the 2019 study to pass 3,500 km in a year, with grey wolves, khulan and Arctic foxes) [18]
- Smallest North American caribou: Peary caribou, Small and pale (lives only on the islands of the Canadian Arctic) [19]

### A caribou’s year

Calving, bugs, the rut and a long winter on lichen. Dates are for Alaska and northern Canada and shift a little from herd to herd.

- **Late May–June**: Calves are born. Herds return to the same calving grounds year after year. Cows give birth to one calf each, almost all within a short time, so predators cannot eat them all. [1]
- **Late May–June**: Cows drop their antlers. Pregnant cows, who kept their antlers all winter, shed them around the time their calves are born. [14]
- **June–July**: Insect season. Huge groups gather on windy mountains and coasts, where wind and cool air keep mosquitoes and warble flies away. [1]
- **August**: Feasting. As insects die back, caribou spread out and feast on willow leaves and mushrooms. New antlers are finished by late August. [1][2]
- **Late Aug–September**: Velvet off. Big bulls rub off their velvet, and the autumn migration begins. Bulls may carry more than 3 inches (7.6 cm) of fat on the back and rump for the rut. [1]
- **September–October**: The rut. Bulls spar, then fight for cows. In Alaska’s Western Arctic Herd the main rut is in mid to late October. [1][3]
- **Late Oct–December**: Bulls drop their antlers. The biggest bulls shed their antlers after the rut. [1][2]
- **Winter**: Lichen and low power. Caribou paw through snow for lichens and move less than at any other time of year to save energy. [2][13]
- **April**: A new start. Young bulls and cows without calves shed their antlers, and new antlers begin to grow in spring. [1][2]

### The great caribou migration

Many big herds walk between calving grounds on the tundra and winter ranges, often in the forest further south. Smaller herds may not migrate at all.

- **≈1,350 km** longest round trip. The Bathurst herd (Canada) and the Porcupine herd (Alaska and Yukon), measured in a straight line between the ends of their migration. [18]
- **Top 6** places for caribou and reindeer. In a 2019 comparison of land migrations, caribou and reindeer herds held the top six. Next came a grey wolf population that follows caribou, at 1,016 km. [18]
- **4,868 km** walked in a year. The real path, with every twist and turn, is far longer than the straight line. [18]
- **>500 km** winter range shift. Between 2012 and 2020 Alaska’s Western Arctic Herd moved its main winter range more than 500 km, from coastal tundra to mountains further east, in one of the fastest-warming places on Earth. [24]
- **1,500 → 1,250 km** shorter trips for a smaller herd. The Western Arctic Herd migrated about 1,500 km at its peak of nearly 500,000 animals around 2003, and about 1,250 km once its numbers had halved. [18]

Each herd is defined by its own calving ground, though different herds may mix in winter.

### Reindeer and herding peoples

Reindeer are the only deer that people have domesticated. Herding is a way of life, a source of food and clothing and a deep part of the culture of many northern peoples, from the Sámi of Norway, Sweden, Finland and Russia to the Nenets, Evenki and Chukchi of Siberia and the Dukha of Mongolia.

- **≈3.4 million** semi-domesticated reindeer. Kept by about 24 herding peoples in 10 countries: Norway, Sweden, Finland, Russia, Mongolia, China, Greenland, Canada, Alaska (USA) and Scotland. [21][25]
- **2 origins** for domestic reindeer. DNA shows reindeer were domesticated separately in Fennoscandia, by the Sámi, and in Russia. [26]
- **Wild and tame** still side by side. Reindeer are still early in domestication: wild and herded reindeer live alongside each other across Eurasia. [26]
- **61,000** reindeer lost to ice. After rain froze on the snow in November 2013, Nenets herders on the Yamal Peninsula lost 61,000 of about 275,000 reindeer to starvation that winter. [17]

Herders and researchers say losing pastures to other land uses is the biggest challenge reindeer herding faces.

### Caribou vs moose vs elk

Three big North American deer. Only one of them has antlered cows.

| | Caribou | Moose | Elk |
|---|---|---|---|
| Scientific name [27][28] | Rangifer tarandus | Alces alces | Cervus canadensis |
| Adult male weight [1][29][28] | 159–182 kg (up to 318 kg) | 408–635 kg | ≈318 kg |
| Adult female weight [1][29][28] | 80–120 kg | 318–499 kg | ≈227 kg |
| Antlers on females [1][29][28] | Yes, normally | No | No |
| When bulls drop antlers [1][2][29][28] | Late October–December (big bulls) | Early winter | March–April |
| Young per birth [1][29] | 1 calf (twins very rare) | Often twins, sometimes triplets | — |
| Longest migration (round trip) [18][28] | ≈1,350 km | ≈392 km (Alaska) | Seasonal moves to lower winter ranges |

Moose are the largest members of the deer family. Caribou are the only deer whose cows normally grow antlers.

### Are caribou endangered?

Worldwide, caribou and reindeer are Vulnerable. Millions remain, but many wild herds have shrunk fast since the 1990s.

- **IUCN Red List:** Vulnerable (VU) (Population decreasing). Migratory tundra caribou and wild reindeer fell by 56%, from 4.7 million to 2.1 million, over about two decades. In 2018 only 2 of the 22 herds monitored were still at their peak. [30][27][20]
- IUCN Red List, 2016 assessment
- **Threat: Herds in steep decline** (>90%): Five herds in the Alaska–Canada region have fallen by more than 90% and show no sign of recovery. [20]
- **Threat: Rain on snow** (61,000): Rain that freezes on snow locks lichen under ice. Icing caused a Peary caribou crash in the 1990s and starved 61,000 herded reindeer on Yamal in 2013–14. [19][17]
- **Threat: A changing climate**: Scientists link falling survival of calves and adults to changing climate. Alaska’s Western Arctic Herd has moved its winter range by more than 500 km. [20][24]
- **Threat: Lost pastures**: Herders and researchers say the loss of pastures to other land uses is the main threat to reindeer herding. [21]
- **Helping: Counting and tracking**: Biologists count herds each summer, when caribou gather in big groups, and follow them with GPS collars. [1][18]
- **Helping: Some herds bounce back** (+44%): The Porcupine herd grew 44% between 2001 and 2016, and Peary caribou recovered from 5,400 in 1996 to about 13,200 adults by 2015. [20][19]
- **Helping: Herders’ knowledge**: Fieldwork with Nenets herders has helped scientists understand how ice, weather and sea-ice loss affect reindeer. [17]
- **Peary caribou** (NE): In Canada, COSEWIC lists it as Threatened (2015): about 13,200 adults, down from 22,000 in 1987 after icing die-offs. [19]

### Caribou sounds and signals

- Cow and calf calling back and forth: Keeping in touch. Cows and calves are most vocal around calving and in early summer. [1][2]
- Huffs and snorts from a herd: Everyday herd sounds; a snorting herd can sound like pigs. [1][2]
- A bull calling in autumn: The rut has begun: bulls only call in the breeding season. [1]
- Bulls clashing antlers, rearing up and pawing: Fighting over cows during the rut. Most fights are short, but some are serious. [3][1]
- Packed into huge groups on windy ridges and coasts: Escaping mosquitoes and warble flies in summer. [1]
- Clicking with every step: A walking reindeer. Whether the clicks help herd mates keep track of each other is not yet proven. [10][15]

### Herd

- **Bull**: Adult male, 159–182 kg on average (up to 318 kg recorded), with large, massive antlers and, in autumn, a white fringe from throat to chest. (Drops his antlers after the autumn rut) [1][2]
- **Cow**: Adult female, 80–120 kg, with shorter, thinner and more irregular antlers. (Pregnant cows keep their antlers until their calf is born) [1][14]
- **Cow with calf**: Calves are born dark brown to reddish brown in late May or June, weighing about 6 kg, and double their weight in 10–15 days. (One calf a year; twins are very rare) [1][14]
- **Peary caribou**: The smallest North American caribou: mostly white, with a slate-grey back and a grey stripe down the front of the legs. Some look almost all white in winter. (About 13,200 adults; Threatened in Canada (COSEWIC 2015)) [19][2]

### Caribou quiz

1. Which caribou grow antlers? **Both bulls and cows.** Caribou are the only deer in which both sexes grow antlers. [1]
2. What colour is a reindeer’s eyeshine in winter? **Deep blue.** The mirror behind the retina is gold in summer and deep blue in winter. [4]
3. About how long is the longest caribou round-trip migration, in a straight line? **1,350 km.** The Bathurst and Porcupine herds migrate about 1,350 km there and back. [18]
4. What do caribou mainly eat in winter? **Lichens.** Ground and tree lichens are their main winter food. [2]
5. What is “reindeer moss” really? **A lichen.** Reindeer moss is a lichen. [1]
6. When do the biggest bulls drop their antlers? **Late October to December.** Big bulls shed their antlers after the autumn rut. [1][2]
7. Who usually keeps their antlers until spring calving? **Pregnant cows.** Pregnant cows usually keep their antlers until their calves are born in late May or early June. [14]
8. About how much does a newborn caribou calf weigh? **6 kg.** Calves weigh about 6 kg at birth and double that in 10–15 days. [1]
9. Which kind of light can reach a reindeer’s retina? **Ultraviolet.** A reindeer’s cornea and lens let some ultraviolet light through, and its retina responds to it. [6]
10. At −45 °C, about how warm is a resting reindeer’s breath as it leaves the nose? **+6 °C.** The nose catches heat from each breath, so the air leaves at only about +6 °C. [8]
11. What may the name “caribou” mean in the Mi’kmaq language? **The one who paws.** It may come from xalibu, “the one who paws”, for the way caribou dig through snow. [2]
12. Roughly how many semi-domesticated reindeer are there? **3.4 million.** About 3.4 million reindeer are herded by about 24 peoples in 10 countries. [21]

### Sources (checked 2026-10-16)

1. [Alaska Department of Fish and Game. Caribou (Rangifer tarandus granti): species profile.](https://www.adfg.alaska.gov/index.cfm?adfg=caribou.main)
2. [Hinterland Who's Who (Environment and Climate Change Canada and Canadian Wildlife Federation). Caribou.](https://www.hww.ca/en/wildlife/mammals/caribou.html)
3. [U.S. National Park Service, Denali National Park and Preserve. Caribou: the Denali herd.](https://www.nps.gov/dena/learn/nature/caribou.htm)
4. [Stokkan KA, Folkow L, Dukes J, Neveu M, Hogg C, Siefken S, Dakin SC, Jeffery G (2013). Shifting mirrors: adaptive changes in retinal reflections to winter darkness in Arctic reindeer. Proceedings of the Royal Society B 280:20132451.](https://doi.org/10.1098/rspb.2013.2451)
5. [Fosbury RAE, Jeffery G (2022). Reindeer eyes seasonally adapt to ozone-blue Arctic twilight by tuning a photonic tapetum lucidum. Proceedings of the Royal Society B 289:20221002.](https://doi.org/10.1098/rspb.2022.1002)
6. [Hogg C, Neveu M, Stokkan KA, Folkow L, Cottrill P, Douglas R, Hunt DM, Jeffery G (2011). Arctic reindeer extend their visual range into the ultraviolet. Journal of Experimental Biology 214:2014–2019.](https://doi.org/10.1242/jeb.053553)
7. [Lu W, Meng QJ, Tyler NJC, Stokkan KA, Loudon ASI (2010). A circadian clock is not required in an Arctic mammal. Current Biology 20:533–537.](https://doi.org/10.1016/j.cub.2010.01.042)
8. [Blix AS, Johnsen HK (1983). Aspects of nasal heat exchange in resting reindeer. Journal of Physiology 340:445–454.](https://doi.org/10.1113/jphysiol.1983.sp014772)
9. [Johnsen HK, Blix AS, Jørgensen L, Mercer JB (1985). Vascular basis for regulation of nasal heat exchange in reindeer. American Journal of Physiology 249:R617–R623.](https://doi.org/10.1152/ajpregu.1985.249.5.R617)
10. [U.S. National Park Service, Gates of the Arctic National Park and Preserve. Caribou.](https://www.nps.gov/gaar/learn/nature/caribou.htm)
11. [U.S. National Park Service, Bering Land Bridge National Preserve. Caribou.](https://www.nps.gov/bela/learn/nature/caribou.htm)
12. [Wells J, Watson K, Daniel CR, Brodell RT, Nahar VK (2022). Holiday reindeer trivia for physicians who like hair and nails. Skin Appendage Disorders 8:314–316.](https://doi.org/10.1159/000521326)
13. [Joly K, Cameron MD, White RG (2025). Behavioral adaptation to seasonal resource scarcity by caribou (Rangifer tarandus) and its role in partial migration. Journal of Mammalogy 106:96–104.](https://doi.org/10.1093/jmammal/gyae100)
14. [Alaska Department of Fish and Game. Caribou. Wildlife Notebook Series (PDF).](https://www.adfg.alaska.gov/static/education/wns/caribou.pdf)
15. [Pyszko M, Němeček P, Horák O, Páral V, Kotrba R, Hoffman LC, Robovský J (2022). Newly described anatomical opening on forelimb tendon in the artiodactyls and its relation to knee clicks. Scientific Reports 12:4362.](https://doi.org/10.1038/s41598-022-08303-z)
16. [Canadian Museum of Nature. Caribou.](https://nature.ca/en/caribou)
17. [Forbes BC, Kumpula T, Meschtyb N, Laptander R, Macias-Fauria M, Zetterberg P, et al. (2016). Sea ice, rain-on-snow and tundra reindeer nomadism in Arctic Russia. Biology Letters 12:20160466.](https://doi.org/10.1098/rsbl.2016.0466)
18. [Joly K, Gurarie E, Sorum MS, Kaczensky P, Cameron MD, Jakes AF, et al. (2019). Longest terrestrial migrations and movements around the world. Scientific Reports 9:15333.](https://doi.org/10.1038/s41598-019-51884-5)
19. [COSEWIC (2015). COSEWIC assessment and status report on the Peary caribou Rangifer tarandus pearyi in Canada. Committee on the Status of Endangered Wildlife in Canada.](https://www.canada.ca/en/environment-climate-change/services/species-risk-public-registry/cosewic-assessments-status-reports/peary-caribou-2015.html)
20. [Russell DE, Gunn A, Kutz S (2018). Migratory tundra caribou and wild reindeer. NOAA Arctic Report Card 2018.](https://arctic.noaa.gov/report-card/report-card-2018/migratory-tundra-caribou-and-wild-reindeer/)
21. [International Centre for Reindeer Husbandry. What is reindeer husbandry?](https://reindeerherding.org/what-is-reindeer-husbandry)
22. [Hull E, Semeniuk M, Puolakka HL, Kynkäänniemi SM, Niinimäki S (2021). Tendons and ligaments of the Rangifer tarandus metapodial and hoof. Polar Biology 44:1803–1816.](https://doi.org/10.1007/s00300-021-02919-z)
23. [Harding LE (2022). Available names for Rangifer (Mammalia, Artiodactyla, Cervidae) species and subspecies. ZooKeys 1119:117–151.](https://doi.org/10.3897/zookeys.1119.80233)
24. [Gurarie E, Beaupré C, Couriot O, Cameron MD, Fagan WF, Joly K (2024). Evidence for an adaptive, large-scale range shift in a long-distance terrestrial migrant. Global Change Biology 30:e17589.](https://doi.org/10.1111/gcb.17589)
25. [International Centre for Reindeer Husbandry. Herders.](https://reindeerherding.org/herders)
26. [Røed KH, Flagstad Ø, Nieminen M, Holand Ø, Dwyer MJ, Røv N, Vilà C (2008). Genetic analyses reveal independent domestication origins of Eurasian reindeer. Proceedings of the Royal Society B 275:1849–1855.](https://doi.org/10.1098/rspb.2008.0332)
27. [Wikidata. Rangifer tarandus (Q39624).](https://www.wikidata.org/wiki/Q39624)
28. [U.S. National Park Service, Yellowstone National Park. Elk.](https://www.nps.gov/yell/learn/nature/elk.htm)
29. [U.S. National Park Service, Denali National Park and Preserve. Moose.](https://www.nps.gov/dena/learn/nature/moose.htm)
30. [Gunn A (2016). Rangifer tarandus. The IUCN Red List of Threatened Species 2016: e.T29742A22167140.](https://www.iucnredlist.org/species/29742/22167140)

## Measurements & details

- **Length:** 120-220 cm
- **Weight:** 60-318 kg
- **Lifespan:** 10-15 years
- **Litter Size:** 1-2
- **Gestation:** 228-234 days

## Diet & Feeding

Caribou are herbivores that mostly munch on lichens, grasses, and small shrubs to survive.

- **Primary Foods:** Lichen, Grasses, Sedges, Willow, Birch, Mushrooms
- **Foraging Method:** Foraging

## Ecological connections

- **Eaten by:** Grey Wolf (*Canis lupus*) — Main predator, often targeting calves or weaker individuals.
- **Eaten by:** [Grizzly Bear](https://www.snappit.app/explore/grizzly-bear) (*Ursus arctos*) — Opportunistic predator, especially on calves or during migrations.
- **Eaten by:** [Wolverine](https://www.snappit.app/explore/wolverine) (*Gulo gulo*) — Preys on calves and scavenges caribou carcasses in winter.
- **Depends on:** [Reindeer Lichen](https://www.snappit.app/explore/reindeer-lichen) (*Cladonia rangiferina*) — A critical winter food source, dug from under the snow.

## Traits

- [Social](https://www.snappit.app/explore/traits/social): Social animals live in organized groups, cooperating for survival benefits such as foraging, defense, and raising offspring.
- [Antlered](https://www.snappit.app/explore/traits/antlered): Antlered describes animals possessing antlers, which are bony, branching growths found predominantly on male deer and related species.
- [Herbivorous](https://www.snappit.app/explore/traits/herbivorous): This trait characterizes organisms whose diet consists entirely or primarily of plant material.
- [Thermoregulating](https://www.snappit.app/explore/traits/thermoregulating): Thermoregulating organisms maintain a stable internal body temperature despite fluctuations in the external environment.
- [Tundra](https://www.snappit.app/explore/traits/tundra): This habitat trait refers to species inhabiting tundras, which are treeless biomes characterized by permafrost, cold temperatures, and low-growing vegetation.
- [Ancient Lineage](https://www.snappit.app/explore/traits/ancient-lineage): This trait signifies organisms belonging to a very old evolutionary group with ancestors dating back millions of years.
- [Longevous](https://www.snappit.app/explore/traits/longevous): This trait characterizes organisms with an exceptionally long lifespan compared to others of their kind.
- [Migratory](https://www.snappit.app/explore/traits/migratory): Migratory animals undertake seasonal movements from one region to another, typically in response to changes in climate or food availability.

## Collections

- [Mammals](https://www.snappit.app/explore/collections/mammals)

## Safety

**Danger:** 2/5 · Low

Admire caribou from a safe distance and never approach them in the wild.

## Frequently Asked Questions

### How to identify Caribou?

Compare ears, muzzle, tail, feet and coat markings. Size is hard to judge without something nearby for scale, and young mammals may not have adult coloring yet. Mammal Identifier: upload a photo and compare the visible details.

### How long is Caribou?

120-220 cm

### How much does Caribou weigh?

60-318 kg

### How long does Caribou live?

10-15 years

### What does Caribou eat?

Caribou are herbivores that mostly munch on lichens, grasses, and small shrubs to survive.

### Where is Caribou usually found?

Tundra

### How many babies does Caribou usually have?

1-2

## Where to spot

- [Northwest Trek Wildlife Park](https://www.snappit.app/guides/places/northwest-trek-wildlife-park) — Washington, US · Zoo
- [Alaska Wildlife Conservation Center](https://www.snappit.app/guides/places/alaska-wildlife-conservation-center) — Alaska, US · Zoo
- [Mount McKinley National Park Headquarters District](https://www.snappit.app/guides/places/mount-mckinley-national-park-headquarters-district) — Alaska, US · National Park
- [Skandinavisk Dyrepark](https://www.snappit.app/guides/places/skandinavisk-dyrepark) — Central Denmark Region, DK · Zoo
- [Thüringer Waldzoo Gera](https://www.snappit.app/guides/places/thuringer-waldzoo-gera) — Thüringen, DE · Zoo
- [Cougar Mountain Zoo](https://www.snappit.app/guides/places/cougar-mountain-zoo) — Washington, US · Zoo

[View all places to see Caribou](https://www.snappit.app/guides/where-to-see/caribou)

## More Mammals

- [Eastern Fox Squirrel](https://www.snappit.app/explore/eastern-fox-squirrel) (*Sciurus niger*)
- [Eastern Cottontail](https://www.snappit.app/explore/eastern-cottontail) (*Sylvilagus floridanus*)
- [Eastern Chipmunk](https://www.snappit.app/explore/eastern-chipmunk) (*Tamias striatus*)
- [California Ground Squirrel](https://www.snappit.app/explore/california-ground-squirrel) (*Otospermophilus beecheyi*)

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Source: [Caribou: Characteristics, Facts & Places to See — Snappit](https://www.snappit.app/explore/caribou)