Surely birds that are ground foragers must be more alert to danger and more aware of what is behind and around them. It pays in terms of staying alive to be aware of their surroundings and to be sensitive to the watching eyes of a predator. Jean Pattison, the African Queen, made a quite original observation that supports this. If all these eggs hatched and the babies lived to adulthood, Africa would soon be covered in African Greys. In nature, species with a high death rate produce many more young than those which have fewer predators and a lower death rate.
Parrots are prey animals.
The unique responses by prey animals to outside stimuli are very different than the responses of predators such as humans, dogs or cats. Being part time ground feeders, Greys are even more at risk than many other species of birds. It is almost impossible for humans, as predators, to understand the stresses which prey animals experience. Actions by a pet owner, which are similar to those of a predator in the wild, can unintentionally trigger high levels of stress in a bird. Greys are not like dogs or horses or other domestic animals that accept the dominance of humans.