Parrot Cage (Hyacinth Macaw)

Parrot Cage (Hyacinth Macaw) teaches you how to summon Hyacinth Macaw, a parrot companion. It is the only epic-quality companion obtainable outside of the World of Warcraft Trading Card Game.

Source
Parrot Cage (Hyacinth Macaw) has a small chance of dropping off any mob in Northern Stranglethorn and The Cape of Stranglethorn. The drop rate has not been published, but it is estimated to be extremely low.

History
This companion used to only drop from the various Bloodsail pirates in Stranglethorn Vale. Its drop chance was extremely low—some estimated it to be as low as 1 in 10,000. Because it dropped only rarely from a limited pool of mobs, it was notoriously difficult to farm and could sell for tens of thousands of gold on some realms (new players sometimes mistakenly sold it for a low price on the auction house; it was later changed from common to epic quality to help prevent this). In patch 4.0.3a this companion became a zone drop, presumably making it easier to obtain and lowering its value.