This hummingbird is sleeping in a specialized research container connected to a machine that measures how much oxygen it is breathing. According to forrestertr7, who posted the video to YouTube, this experiment was part of research aimed at understanding the differences between the metabolism of hummingbirds and that of larger species. After its nap, the hummingbird was released back into the wild.

But what about the snoring? Does the hummingbird really need a tiny, little beak strip, or what? I asked science blogger Joe Hanson, who posted this video to Twitter earlier today, and he did some research. Turns out, it's not totally unreasonable to call that adorable little wheeze a "snore". But, at the same time, hummingbirds have very different biology than we do. A snore for them isn't the same as a snore for us.

Hummingbirds have incredibly high metabolic needs. To do all that buzzing around and to keep their tiny bodies warm, they eat the human equivalent of a refrigerator full of food every day, mostly in the form of high-energy nectar and fatty bugs. Because of their small size, they also lose a lot of body heat to the air. In order to preserve energy on cool nights, they have the ability to enter a daily, miniature hibernation called torpor.

...Just before morning, their natural circadian rhythms kick in and they start to thaw out, like heating a car engine on a cold day. What we see in the video is probably a bird coming out of torpor (which is what the scientists in the video were studying), starting to breathe in more oxygen to raise its body temperature, and making that adorable snoring noise.

Read the full story at Joe Hanson's blog, It's Okay To Be Smart