A black colored avian.
The black on its feathers are darker than the long nights of Teyvat. When many of them circle in the sky, they can create the illusion of a solar eclipse. Some locals consider them inauspicious, while others consider them a symbol of good fortune. As the saying goes, that's how traditions work.
Rumors abound among adventurers from various nations concerning a giant talking crow raised by a young female investigator from Mondstadt...in-game description from the Archive
Killing one for the first time will add this creature's entry into your in-game archive.