Exmoor Ponies, Rammamere Heath SSSI, Bedfordshire. Rare, Endangered Breed of Horse, Equus ferus caballus, Equidae. The Exmoor pony is the oldest and most primitive of the British Isles native ponies, as well as the purest, and some still roam as semi-feral livestock on Exmoor, a large area of moorland in Devon and Somerset in southwest England. The Exmoor is one of the British Isles mountain and moorland pony breeds. These ponies are being used for conservation grazing on Rammamere Heath SSSI, Bedfordshire.