The mechanical nightingale is a wind-up nightingale from the Pawn Shoppe in the Village of the Crown.
Background[]
It is made of plain tin painted dreary shades of brown to match the coloring of a real nightingale. A small key emerges from its back. It sings a sweet song barely distinguishable from the real thing. Its hard tin body doesn't feel anything like a real bird's soft feathers. When it's wound up, it plays a sweet, sunny tune. Alexander is able to trade for it with a copper Daventry coin or for one of the other small items in the shop. He later uses it to trick the sense gnome of sound on the Isle of Wonder. It is also used to befriend Sing-Sing.
It can also be used to trick the guards in the Castle of the Crown on the short path. In this case, the mechanical nightingale is taken away to Captain Saladin and not seen again.
Behind the scenes[]
This item is known as the "wind-up nightingale" in the KQ6 hintbook.
Although Hakim describes it as "barely distinguishable from the real thing", it does not sound at all like Sing Sing. This makes her and the sense gnome rather easily convinced.