If someone wanted to raise Feather Dragons outside the foreign realm, it would be very difficult. One reason was because of the environment and the other was because of the person's ability.
The Feather Dragons were very famous for their pickiness of their habitat.
The main reason for their pickiness was because of their own physique.
The Feather Dragons were one of the first groups of mutated beasts to arrive on the Wasteland Continent. At that time, the Wasteland Continent was filled with Spiritual Energy and their bodies had been transformed, giving them the ability to produce Spiritual Energy.
Later on, the continent continued to expand and there was less Spiritual Energy. The Feather Dragons that had a smaller number could only release Spiritual Energy passively, but couldn't absorb enough Spiritual Energy. This made them slower and easier to be hunted by other beasts.