Muggles' Guide to Harry Potter/Magic/Jobberknoll

Overview
The Jobberknoll is a tiny, largely mute, blue-speckled bird that eats insects.

Extended Description
According to "Newt Scamander", the Jobberknoll makes no sound until its death, at which time it releases a long scream composed of every sound it has ever heard, in reverse (and presumably sped up).

Analysis
"Scamander" also says that the feathers of the Jobberknoll are used in truth serums and memory potions. Presumably this is because of the Jobberknoll's ability to recall and replicate sound heard during its lifetime.

There is no mention of this creature in the seven main books of the series, and apart from its possible use as a potion ingredient, it does not play a role in the series at all.