Coalsprite

 Bloody pain in the arse they are. Can 't even do my damn job with those nuisances around. They take pleasure in misplacing our tools, or pretending like a shaft is haunted. 

-A miner from the Westenwolds

Coalsprites are small, black winged creatures the size of a small pidgeon. They have four small legs, but spend most of their short lives in the air and thus rarely use them. They inhabit mineshafts, and spend most of their time bothering the miners by misplacing their tools or flying around the head of a miner in large swarms, making their work near impossible. They can be forced away by shouting Nyrreid gwhyl nar dumthry which is a dialect of the Tongue of Nature. The coalsprites, upon hearing the words, will stop bothering whoever spoke the sentence.