When you think of reindeer, you probably picture Santa’s sleigh‑pulling crew, but there’s a trove of little known quirks that make these Arctic deer truly fascinating.
Little Known Reindeer Secrets
10 Domestic And Wild Differences
Estimates for when humans first tamed reindeer vary wildly. In Eurasia, some scholars argue the process began around 7,000 years ago, while others place it closer to 2,000–3,000 years ago.
Even after millennia of interaction, reindeer are still considered only semi‑domesticated. Two main reasons: they haven’t undergone intense artificial selection until very recently, and most herds aren’t fully confined, allowing domestic animals to mate freely with their wild cousins.
Physical differences are subtle but noticeable. Semi‑domestic reindeer tend to be a bit smaller, sport shorter snouts, and display a broader palette of colors—including the occasional pinto pattern—whereas wild populations show more uniform coloration.
In a region west of Lake Baikal, researchers once milked reindeer intensively and found that the domestic stock boasted udders about 25 % larger than those of nearby wild individuals.
Behaviorally, domesticated reindeer give birth and mate roughly a month earlier than their wild relatives, are less ambitious during migrations, and have reduced endurance on long treks. Most strikingly, they’re far tamer, more tolerant of humans, and readily trainable.
9 Hot And Cold In The Arctic
Reindeer sport long legs that help them sprint across the tundra and evade predators, but that length also threatens heat loss. A clever network of blood vessels solves the problem: warm blood flowing out to the legs runs side‑by‑side with cold blood returning, allowing a heat‑exchange that cools the outgoing blood and keeps the legs from draining body warmth.
Inside their noses, reindeer have a set of bone‑and‑cartilage structures called conchae that look like rolled‑up scrolls. These are wrapped in a richly vascularized mucous membrane.
When cold air rushes in, it passes over the warm mucous layer, heating up to body temperature and becoming saturated with water vapor before reaching the lungs. The moisture then travels into tiny folds that funnel it toward the back of the nose and down the throat.
Exhaled air then slides over the cold mucous surface, cooling rapidly and condensing its water vapor. The result is that, unlike most mammals, the air exiting a reindeer’s nose is relatively cold and dry.
8 Flies In Reindeer Noses
During July and August, reindeer can be seen shaking their heads, stamping their feet, and dashing across the tundra for no obvious reason. They’re actually trying to dodge parasitic flies, especially the bot fly Cephenemyia trompe, which doesn’t lay eggs but instead squirts tiny maggots straight into the nostrils.
The larvae develop inside the nasal passages, eventually burrowing deeper into the sinuses and throat. By spring, a heavy infestation can produce a mass large enough to impede breathing, and in extreme cases the reindeer may suffocate.
When the larvae mature, they crawl back into the nasal passages, where the host sneezes or coughs them out. The maggots then hit the ground, overwinter, and emerge as adult flies.
These flies are adept trackers: their antennae are tuned to the scent of reindeer urine and the pheromones secreted between the animal’s toes, allowing them to follow a trail for more than 48 km (30 mi).
7 Antlers
To sport antlers in December, a reindeer must be female, castrated, or still a youngster. Mature, intact males shed their antlers in autumn, while the other groups keep theirs through winter.
Reindeer are the only deer species where females grow antlers, a fact that has puzzled scientists for years. The prevailing theory is that female antlers help them compete for food during the harsh winter months.
Reindeer dig pits in the snow to uncover lichen, their staple winter fare. Females use their antlers to defend these lichen pits from other herd members, especially larger, antler‑less mature males.
Meanwhile, males benefit from shedding early because many females are pregnant in winter and need extra nourishment. With females monopolizing food resources, the developing calves have a better chance of surviving to spring.
6 Birth Control Shots For Male Reindeer
Male reindeer, or bulls, go into a fierce rut each year, becoming aggressive, destructive, and hazardous to both handlers and fellow herd members. The mating frenzy can cause a bull to lose up to 35 % of his body mass.
To curb these extreme behaviors, producers inject bulls with the birth‑control drug Depo‑Provera, ideally on the first day antler velvet begins to shed—a clear sign that rut is approaching.
Bulls on Depo‑Provera still mate but are generally less aggressive. Moreover, the hormone‑modulating injections seem to extend their lifespan: while untreated bulls typically live 7–8 years, those receiving the drug have been recorded reaching 12 years.
5 Reindeer Noises
Male deer often produce distinctive calls during breeding season, but reindeer take it a step further with a specialized air sac located near the windpipe. When a bull wants to attract a female—or warn off a rival—he inflates this sac, producing a guttural, rattling bark.
Reindeer are born without air sacs; they develop later. Both sexes grow the sac similarly at first, but around ages 2–3, growth stops in females while it continues in males until about six years old, creating a marked size difference.
The male’s air sac is asymmetrical, extending to either the left or right side of the neck. At the start of the rut, the neck muscles swell dramatically, and a beard‑like mane grows around the sac. When the bull calls, the mane fans out, providing a visual cue to nearby reindeer.
4 Eating Lichen
Reindeer are among the few mammals that rely heavily on lichen, which makes up 60–70 % of their winter diet. Depending on the lichen species, they can extract 40–90 % of its organic matter—far more efficiently than sheep or cows.
Like other ruminants, reindeer have a multi‑chambered stomach. Bacteria thriving in the rumen, together with the animal’s own enzymes, break down the tough lichen fibers.
Lichen is rich in carbohydrates but low in protein and minerals. In captivity, without a nitrogen supplement, reindeer will lose weight on a lichen‑only diet.
To compensate, reindeer recycle urea—a major component of urine—back to the rumen. The kidneys concentrate urea, and the rumen microbes use it along with fermentable carbohydrates to synthesize protein. Approximately 71 % of winter‑produced urea is reclaimed for this purpose.
3 A Diet Of Droppings
Spitsbergen, the lone inhabited island of Svalbard, endures eight months of winter, forcing its resident reindeer to subsist on sparse mosses and low‑quality plants. Remarkably, they supplement their diet by munching on goose droppings.
During summer, barnacle geese graze the lake shores, consuming most of the available grass and some moss. Their digestive systems aren’t efficient at breaking down cellulose, whereas reindeer excel at it thanks to specialized stomach microbes.
Studies show reindeer prefer droppings that contain grass fragments over those with moss. When geese form piles of six to eight droppings, researchers have observed reindeer chasing the birds away to get at the nutrient‑rich waste.
Rough calculations suggest that six to eight reindeer could survive on goose droppings alone for the two months the geese are present, highlighting the importance of this unconventional food source.
2 Reindeer Are Fond Of Their Own Urine
Reindeer, like many deer, use urine as a social signal. Both sexes rub their hind legs together while urinating, spraying the air and coating their hocks with urine‑derived chemicals for later scent communication.
During the rut, a male’s urine‑coated legs act as a scent beacon, marking his moving territory and signaling dominance to rivals.
Reindeer also engage in “urine‑digging”: a bull will excavate a shallow pit, urinate into it, and then rub his nose in the liquid for ten minutes or more. Females sometimes follow suit, sniffing the same spots.
1 Reindeer Love Human Urine
Reindeer diets lack sufficient salt. Coastal individuals can lick salt deposits or sip seawater, but inland herds must find alternatives. Like many deer, they’re drawn to salty sources, and oddly enough, they’re especially attracted to human urine.
In Alaska, the Inupiat people exploit this by using human urine as bait in pitfall traps. The scent lures curious reindeer, which wander into spiked pits.
In Russia’s Tuva region, the Tozhu people rely on the same attraction. Their semi‑domestic reindeer forage independently, yet they’re offered salt and human urine to encourage them to return to camp. Men often urinate near a hollow stump or purpose‑built urinal; the urine freezes in winter, providing a lasting snack for the curious animals.
These practices underscore how a simple compound—urine—can become a powerful tool for managing and taming reindeer.