Each winter, when the temperature drops, and we start reaching for our big coats and gloves. It always amazes me how comfortable the reindeer are in these conditions. It’s not a surprise really, being an arctic animal, they have evolved to cope with some of the coldest temperatures on the planet. Reindeer don’t show physiological signs of being cold until -35°C and have been known to survive right down to -72°C in Siberia. So how do they do it? I thought I would write a blog describing some of their incredible adaptations that keep them snug in the winter.
Coats
Reindeer have an incredibly insulative coat with hairs all over their body, in their ears, up their noses, between their toes. The only part of a reindeer without hair is their eyeballs! Their winter coat is so insulative that they lie on the snow without melting it. Their winter coat is formed of two layers, long guard hairs with a fine downy layer underneath. The long guard hairs are all hollow, with a honeycomb structure inside trapping pockets of warm air – an excellent insulator. They are also triangular allowing them to fit closely together without gaps to let the cold in.
Clicking
A question that we are regularly asked on Hill Trips is: what noise does a reindeer make? In the spring mothers and calves call out to each other by grunting and in the rut a bull reindeer will grunt to his females. During the winter though, reindeer don’t make many vocal noises. Instead, they make a clicking noise. This comes from a tendon sliding over a bone in their back legs with every step they take. This allows the reindeer to stay together as a herd during a blizzard when they can’t see each other without having to vocally call out to each other, which would lose body heat.
Nose
Reindeer noses are amazing, definitely one of my favourite reindeer adaptations for the cold. During the winter time, reindeer generally keep their mouths closed, keeping the heat in, and instead breath through their noses. Inside their noses are amazing scroll structures which increase the surface area between the cavities where the air they are breathing in and the air they are breathing out are stored. This means heat exchange can occur and the air they are beathing out can warm the air they are breathing in, essential when the outside air is well into the minuses. Back in 2018, Ruth wrote a fantastic blog explaining in detail how amazing the nose of a reindeer is, it is well worth a read for more information, click here to see!
Feet
Reindeer have huge feet which serves two purposes: snowshoes and snow shovels. By being so big it spreads their weight out on the snow, stopping them sinking too far into the snow. Their back feet also step into the prints of their front feet and they will move as a herd in a single file line, stepping in the prints of the first reindeer, this makes walking through snow incredibly efficient. Sometimes when it’s really snowy here, we put out skis on to go and find the reindeer, in that case they will walk in our ski tracks instead. They can also their feet as big shovels to dig through the snow. Reindeer can smell lichen through a meter of snow and will dig through the snow to get to it.
Antlers
Last but certainly not least…. antlers! Antlers are absolutely amazing and definitely could be an entire blog by themselves (in fact I have linked some previous blogs about antlers below). They are made of bone and grow and fall off again every year and then regrow the following year. They grow each year during the spring and summer, and whilst the bone is growing it is encased in a specialised skin called velvet. The velvet provides the blood supply that feeds the bone as the antler is growing. Once they finish growing, the velvet strips off and the antlers can then be used as weapons! The males use them to fight with each other during the rutting season over the right to breed with the females. Once the rut is over, their antlers will fall off, they are too heavy on the males to keep them all winter. Our heaviest set weighed a whopping 8.9kg. So, what do antlers have to do with the cold? Well, during the winter, once the males have lost their antlers it’s only the females and the calves who still have them. This gives the females a physical advantage whilst they are pregnant and makes sure they get plenty of food to eat during the harshest time of the year. The females loose them too, in the spring, as the new antler grows through underneath.
Lotti
