Thanks for your comment, Marijke. That is, in fact, one of the criticisms the couple who run the farm have faced. This is their response:

'While predators do not, as is commonly believed, directly regulate herbivore populations through predation (essentially, food resources do this), they do clearly affect the behaviour of grazing animals. How much influence apex predators bring to bear on the ecosystem is still hotly debated by ecologists. Some insist that in a ‘landscape of fear’ grazing animals would be constantly under stress and on the run, seeking the more inaccessible and possibly less fertile areas to live and breed, and this would have a huge impact on vegetation succession.'