Watch: Hummingbird 'Snores' in Its Sleep

Hummingbirds are known for living fast, flitting around between flowers as their wings flap up to 200 times per second. But they still have to sleep, as this video shows:

The clip above was posted to YouTube in December, but suddenly went viral in recent days thanks to Reddit. It stars a female amethyst-throated sunangel, native to the Andes, and was filmed at a research facility in Peru. According to uploader forrestertr7, the bird is in a machine that tests oxygen intake. (As forrestertr7 also admits, "I know it's not actually snoring, it just kinda sounds like it.")

For anyone worried about the bird's well-being, forrestertr7 offers reassurance:

"This experiment was performed with the guidance and supervision of some of the top experts in tropical ornithology. The investigation was fully permitted and performed in a world renowned research facility. This bird was not harmed whatsoever, it was fed with sugar water throughout the experiment and was released safely. We know this bird was not stressed because it was consuming a very stable amount of oxygen."

Due to their small size, hummingbirds burn lots of energy just to keep a constant body temperature — a problem that's alleviated by their high-energy nectar diet. But since they can't drink nectar while asleep, they sometimes enter brief states of "torpor" to reduce their metabolism. This is like mini-hibernation, leading to lower heart and breathing rates. The sunangel in the video may have been in torpor, forrestertr7 says: "All of the hummingbirds measured like this consumed a very low amount of oxygen at a very stable level as compared to other, larger birds, which means that they were in torpor, or a state close to torpor."

To see how hummingbirds nap in more natural settings, check out these two videos: