Items, NPCs, quests, objects and spells of patch 1.12.1, read live from the realm itself.

Roc Gizzard

NPC	Level	Zone	Chance
Roc	41 - 43	Tanaris	80.0%
Fire Roc	43 - 45	Tanaris	80.0%
Searing Roc	47 - 49	Tanaris	80.0%