"The bird is in a container that is attached to machines that measure how much oxygen the bird is consuming. The noise you are hearing is the hum of the machines in the background. The noise is actually a lot more quiet than it seems, for whatever reason my camera picked it up and made it sound a lot louder. 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. 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. After the experiment was done, I watched the bird fly away myself, it was fine. And yes, I know it may not actually be snoring. Even the supervisors of the project are unsure why it is making that noise. I have asked them to look into it since this video has received so much attention. I have been studying ornithology for years and am currently a Masters student studying birds. The welfare of birds means the world to me, and I am dedicating my career to their conservation."