Harper Bird is a quest item which is needed during Find out What Happened to Montaron in Baldur's Gate II: Shadows of Amn and Baldur's Gate II: Enhanced Edition. The bird is added to the inventory of a character who interacts with the cage on the first floor of the Harper Building in Athkatla Docks. This needs to be brought to Xzar.
In-game description
| “ | From what the Spectral Harpists have said, you gather that this bird was once poor Montaron. This would be what Xzar is looking for. | ” |