10 things you didn’t know about reindeer

by ZSL on

With Christmas just around the corner, Donovan Glyn, Team Leader of Deer and Antelope at ZSL Whipsnade Zoo, shares the secrets of a seasonal specialist, and explains why Rudolph is actually female. 

Heidi the reindeer at ZSL Whipsnade Zoo


1.    Reindeer aren’t only found in Lapland 

Reindeer and caribou (as these animals are known in the US) are the same species, Rangifer tarandus. Widespread across the northern hemisphere, wild reindeer can be found in Alaska, Canada and the northernmost states of the US, as well as Russia, Greenland, Iceland, Mongolia, Norway and Finland. 

Reindeer subspecies range in size from the tiny Svalbard reindeer of the High Arctic, at around 60kg, to the forest-dwelling American caribou, which can weigh in at more than 300kg!

2.    They’re very well-insulated 

Reindeer live in some of the coldest places on Earth, so it’s no surprise that they have some pretty clever ways of keeping warm. In winter, they grow a thick coat with an outer layer composed of hollow hairs. That final layer traps the air and provides brilliant insulation. It’s so effective at keeping in heat, reindeer can reportedly even lie down in the snow and not cause it to melt. 

3.    Reindeer have distinctively shaped skulls

Their skulls have a broader, flatter muzzle than most deer. This allows time for the air they breathe in to be warmed up by their sinuses. By the time the air hits their lungs, it’s still pretty cold by our standards, but it’s a lot warmer than it was. This helps them to maintain their core body temperature. 

Flora the reindeer at ZSL Whipsnade Zoo

4.    It’s a year of two halves for reindeer

In summer, they’ll spend up to 20 hours a day eating, and pretty much double their body weight in preparation for the colder months. They can live almost entirely off those fat stores during the winter months, eating only the odd bit of lichen or moss. They become very static in the winter, keeping still as much as possible to conserve precious energy. We see the same pattern in reindeer at the Zoo. They don’t exactly shut down, but they’re definitely on a go-slow. 

5.    Their eyes change colour!

It’s not just a reindeer’s weight that changes dramatically over the year. Even their eye colour shifts from yellow-green in summer to dark blue in winter. In the darker months, their eyes tend to be more sensitive to pick up the limited amount of light available. Their feet adapt too: in summer, the footpads on their wide, splayed hooves are thick and spongy, helping them keep their footing on soft tundra. In winter, the pad shrinks back, leaving a rim of hoof that grips the slippery snow and ice, and helps them dig for food. 

6.    Their navigational skills are incredible

Some reindeer are migratory with herds – which can contain up to 500,000 animals – travelling some 5,000km each year in search of food and shelter (the longest journey undertaken by any land mammal). 

One theory about why young reindeer retain a close link to their mothers, long after they’re weaned, is that it allows these routes to be passed on from generation to generation. 

7.    Reindeer can sprint at up to 80kmph

We’re all familiar with images of Santa’s sleigh being pulled through the sky by reindeer on Christmas Eve. The legend of flying deer is surprisingly ancient, with 3,000-year-old strong carvings from Mongolia depicting antlered beasts in flight. The reindeer’s agility and speed could provide a possible inspiration for such images. Reindeer can sprint at up to 80kmph and run for extended periods at more than 30kmph. Compared with plodding over the snow on foot, being pulled by reindeer must have felt like flying. 

Flora and Heidi the reindeer enjoy some browse in their paddock at ZSL Whipsnade Zoo

8.    Reindeer have evolved to get maximum nutrients

Reindeer make the most of every scrap of nutritious material available to them, from fresh green leaves and branches in the spring to lichen and mosses in winter. The challenge with our reindeer at the Zoo is to recreate that varied diet, and make sure they’re getting all the trace minerals and micronutrients they have adapted to take advantage of. Ours get a special pellet, developed by researchers around 30 years ago, based on their natural die, which dramatically improved the health and wellbeing of reindeer in zoos. 

9.    Rudolph is female 

Reindeer are the only deer species in which many females have antlers, as well as males. Even babies grow a small set before their first winter. Male reindeer will use their antlers to tussle with rivals – quite why females grow them is unknown, but it may help them defend feeding spots. Males lose their antlers around November, while females keep theirs through to January and February before shedding them. This can only mean one thing. Santa’s reindeer are definitely female. 

10.    Wild reindeer used to live in Britain – and now they do again!

Reindeer roamed Scotland until around 8,000 years ago, when they went extinct either as a result of overhunting or climate change. In the early 1950s, a small herd was introduced to the Cairngorms and has since prospered. 

Our two reindeer at Whipsnade, Heidi and Flora, will be giving Santa a helping hand this Christmas. If you can't spot them in their usual paddock, they'll be next to our Meet Santa area - or you may even find them going on their regular walks around the Zoo! 

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