The Black Moa allegedly assaulted four young men who were traveling in Ferndale. So bloody and terrifying was the assault that most of them could not even remember where it actually took place. Finding and dealing with the "elusive, mysterious, cunning, devious, and despicable" Black Moa is the objective of the quest The Beak of Darkness.
The Black Moa can be found in Ferndale, southwest of the Kurzick Aspenwood Gate outpost. Beware of the large number of Dredge patrols in the area, including the boss Mungri Magicbox.
Charming the Black Moa, rather than killing it, will fulfill the final objective of the quest.
The Black Moa will spawn whenever you enter Ferndale as long as any character in the party has completed the quest.
In the wild, the Black Moa always has an "elder" evolution, even though the creature's name does not indicate this. To obtain a fully evolved Black Moa, you must either death level a Black Moa at the Zaishen Menagerie Grounds or pay Helena to unlock the last tier.
Other species of Moa can be found throughout the world:
Nehdukah claims Zho lost her left eye to a Black Moa while he was saving her from its grasp. Zho confirms she lost her eye to the Black Moa in her journal and in an idle quote on Shing Jea Island.
Approaching Nehdukah and his company in Plains of Jarin with a Black Moa will cause them to shout and run in terror.