Due to what today is, it only felt appropriate to talk about one of the more famous animals around this time, and that is the reindeer, or caribou, as it is called in North America. They have a circumpolar distribution, which means they are found throughout the northern part of the northern hemisphere, from North America to northern Europe to Siberia and northern Asia. 

There are 12 current extant, or living, subspecies recognised, some of which are sedentary, meaning they stay in the same area, and some of which are migratory. The migrations of the Porcupine caribou herds are among the longest of any mammal; some are even longer than the great migrations of African animals. Some herds in Labrador, for example, can migrate up to 5000 km (3000 mi) in a year, making it the longest migration of any mammal. The Taimyr herd of caribou is among the largest in the world, with the herd numbering between 400 000 and 1 million individuals depending on the year. 

Caribou are part of the cervidae family, which means, like other deer, the males grow antlers. However, unlike other cervidae, caribou females also grow antlers. If you listen to Ep 3 of the Biome Podcast (click here to listen), we talk about the ins and outs of antlers. There is a lot of size variation between the males of different subspecies, but on average, the male caribou has the second largest antler size after the moose. Generally, the caribou antlers living in open areas are larger than those of the subspecies living in woodland areas, which makes sense as the larger they are, the more likely they are to get caught on trees and branches. 

Something that isn't as well known about reindeer is that they have developed adaptations to maintain efficient metabolic activity regardless of the season. For example, breeding females can weigh as much as 10 kg (20 lbs) more than non-breeding females at the same time. During the winter, the caribou mainly feed on lichen, which is high in carbohydrates. As the babies are born around the middle of summer to early autumn, the lichens play an important part of the newborns' diet throughout their first winter. 

Interestingly, there is evidence to suggest that in late winter, when the reindeer are stressed and extremely hungry, they might feed on lemmings, which are small rodents, char, which is a type of fish, and even birds' eggs.

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