These supreme winter survivors were hunted to extinction in Scotland some 800 years ago, but reintroduced by an enterprising Sami herder called Mikel Utsi in 1952. He had spotted that for reindeer, the Cairngorms had the right ingredients for a desirable homeland: bitterly cold winters and plenty of tasty lichen.

https://www.theguardian.com/travel/2020/nov/07/best-places-to-spot-uk-wildlife-in-winter