Whether or not you're a heavy metal fan, you're aware enough of the genre, I'm sure, to know it involves liberal amounts of headbanging on the part of both fans and performers, and -- more specific to death/black metal -- a peculiar kind of long, guttural scream that's apparently words being sung. If you've ever wondered where people came up with these bizarre forms of musical expression, I say to you now: I've found the answer. Look no further than the animal kingdom.

Exhibit A is this angry rooster, whose lungs must hold an unbelievable volume of air.

I've never seen any creature, human or animal, headbang with such conviction. He's even got a mohawk! As one YouTube commenter put it: "Why isn't this video ten minutes long?"

Though this clip doesn't use any of the original video's sound (a cat making strange noises), the intense-but-glazed expression on the cat's face is classic metal.

On the other hand, there's a slight possibility that the death metal style of singing may have been inspired by Cookie Monster.

Animals aren't content to stop at death metal, though. This parrot can beatbox.