Sky burial isn’t a burial at all, of anything. It’s the act of leaving a corpse exposed to the elements, often in an elevated location, and only a few different cultures do it, for different reasons and in different ways.
The concept's been on my radar for a few years thanks to happening upon the Vajrāyana Buddhist bya gtor practice primarily found in Tibet —and less so in China and Mongolia. It can be shocking to see — ex-human beings being dispassionately dragged up a mountain, chopped up, and thrown to a venue of waiting vultures.
But then I started to think (and read) about it. One of the main tenets of Buddhism is compassion, which includes kindness toward all animals. So the idea at work here is that, if your body is just a shell for your spirit, which will be reincarnated anyway, and if your spirit has left it and it could nourish another creature, then it should. Bya gtor literally translates to "alms for the birds" in Tibetan. It’s considered important to not waste the opportunity to help another living thing.