Rare animals can be found during "Path of the Hunter" quests. To play these quests you need to liberate Outposts. The spawn area of the animals will be shown during the quests. You can see a red "Rare" stamp on the hunter posters if the quest features rare animals.

One of these quests can be started at the coordinates X: 428.9, Y: 694.3 (see to right corner of the world map).
 

Poacher Video Guide