The Cheviot fauna are a mixture of native species and imports.
Among the latter are the Cheviots goats, descended from stock brought over by Neolithic farmers. The Romans probably brought rabbits, but they only became common much later. They may also have introduced the pheasant.
The grey squirrel is the best known of the newer arrivals, starting as a 19th century novelty. Then there are minks and rainbow trout, both 20th century incomers.
Many of the original native animals have died out. Elk, one of the largest members of the deer family, disappeared from Britain about 4000 years ago; aurochs, the ancestors of modern cattle, went about 1000 years later. Lynxes and bears may have lasted into Roman times or even a little later, while the wolf was still going strong in the 13th century. The last record of them being killed in the Borders was in 1458.
The last beaver probably died around the same sort of time, while wild boar persisted a little longer, although the native stock was sometimes replenished by imports for hunting purposes.
Golden eagles only stopped nesting in the Cheviots in the late 19th century.