While this creature lives in the Southern Serendia mountains, in the region 'Southern Neutral Zone' near the Serendia Western Gateway, it does *not* appear in the Ecology tracker for Serendia nor Calpheon nor Drieghan. It appears to be 'hidden knowledge' (on BDO Console - May 2026)

Its ecology knowledge can still be learned, along with that of its offspring 'Young White-Tailed Dear':
https://bdocodex.com/tw/npc/20560/

There is a title 'White Tailed Enchanted' for killing 440 of them.