Caribou – Truly Arctic Vegetarians?
So you think it’s hard to be a vegan in Texas, where you’re shunned if you don’t consume a cow a year to support the local economy?
Imagine being a vegetarian in the Arctic. The bigger animals, like moose, musk oxen and caribou, must cover a lot of territory to find enough greens to survive. Grazers and browsers in the Arctic have a difficult life – it’s all about staying warm and finding enough food to survive.
Reindeer Don’t Fly
Contrary to myth and Santa stories, reindeer don’t fly but instead roam the Arctic in great herds.
Reindeer – called caribou in North America – seem to be the most social of all the northern herd animals. The eight largest caribou groups in North America gather in huge bands of up to 50,000 to 500,000 during spring migration. Their herd size is seasonal, and they basically travel between their birthing grounds and winter feeding range. After the big spring migration, the herds split into smaller groups for calving. They reconvene for their migration south before breaking up the party for winter, when they scatter into the woods just south of the Arctic. They diversify their humdrum diet of lichens and grasses to include
some twigs, leaves and trees.
Of the north-dwelling grazers and browsers, the North American caribou is the only truly Arctic species. There are many sub-species of reindeer, and most of them are sub-Arctic.
With all the variations on the reindeer theme, it’s hard to generalize their lifestyles. Wild reindeer basically live in North America, Greenland and Iceland (where they were introduced in the 1700’s). Domesticated reindeer live in northern Scandinavia and Russia.
Caribou Stomachs, Fur and Feet
Caribou have a four-chambered stomach, which makes them ruminants, or cud-chewers – similar to our domestic cattle but certainly not to be confused with them. Like other Arctic animals, a caribou’s ears and tails are short to reduce heat loss. Most caribou are gray to brown with even lighter undersides. In the winter, caribou coats get much thicker and they tend to turn much lighter in color. In fact, their fur comes in two layers – a dense and wooly undercoat covered by longer, hollow, air-filled hairs that trap warm air to retain heat. That double-coat technology might also keep them warm and dry when fording rivers and surfing off the coast. Caribou are excellent swimmers for land mammals.
The caribou’s nose features another interesting adaptation. Their nasal turbinate bones are designed to increase the surface area inside the animal’s nostrils and pre-warm the Arctic air. Cold air comes in and it’s warmed by body heat before entering the lungs. Warm air leaving the lungs is briefly captured in the nostrils, where it condenses water. The exhaled breath moistens the incoming dry air so that it might be more easily absorbed into the blood through the mucous membranes.
Caribou feet are also well adapted to the Arctic environment. Their hooves are broad with deep clefts, and they change with the season. In the summer, their hoof pads are spongy to provide more traction on soft, wet tundra. In the winter, their pads shrink and harden while the hoof rim expands to cut into ice and keep them upright on the slick stuff – their hooves act like caribou crampons.
North American caribou males can weigh up to 250 to 300 kg (550 plus lbs) and can be 1.5 meters (5 feet) tall. In most cases, females are significantly smaller than the males. Both male and female caribou have antlers that are covered in velvet (thin fur) while they grow.
The bull’s antlers are impressively large for his body size, though the girls’ antlers are much daintier and less significant. After males rut in the fall, they shed their antlers while the females keep their antlers through the winter and lose them after giving birth.
Mating is a fall affair (September through October), when the bull with the biggest antlers typically wins a harem of five to 15 females. The female has her single calf in the spring (May to June). During the next three months, the calf relies on its mother’s milk and her ability to ward off predators.
Even North American caribou come in different flavors – such as Peary, Barren-Ground, and Woodland – with different adaptations for their specific geographic locations. For example, the Peary Caribou in Arctic Canada are the smallest of the North American caribou at 100 kg (243 lbs) for males and 60 kg (132 lbs) for females. They don’t migrate, while other caribou groups can travel up to 3000 miles per year. Reindeer are fast – they can run up to 50 mph – but Peary Caribou can outrun Arctic wolves.
Though we consider caribou to be herbivores, they’ve been known to eat a few birds, eggs, Arctic char, and even lemmings. Fortunately for tourists and the Chukchi people, these desperate carnivorous experiments are rare incidents in the animal’s ongoing struggle for survival.
[TRIP TRIVIA: If you ever visit the Chukotski Peninsula in Russia, don’t be surprised if you see the locals (Chukchis) practicing a little reindeer roping. Chukchi means “rich in reindeer,” and that indigenous inland community has been managing reindeer herds for centuries.]