Monarch butterflies have disappeared from some parts of the U.S., but there are plenty of the winged creatures at Mexico’s Monarch Butterfly Biosphere Reserve. In a video spotted by The Kids Should See This, entomologist and conservationist Phil Torres pays a visit to the UNESCO-protected butterfly sanctuary in Michoacán, which is located northwest of Mexico City.

Beginning each fall, millions of the butterflies—which could soon be labeled an endangered species, depending on the U.S. Fish and Wildlife Service’s forthcoming decision—migrate from the U.S. and Canada to the forests of Michoacán. Once there, they completely cover the pine and oyamel trees they land on, creating fluttering branches that look like a strange species of tree at first glance.

“It’s not just visually stunning. It’s not just emotionally stunning … It sounds absolutely magic[al],” Torres says, “because you’ve never heard before the sounds of tens of millions of butterflies flying around you, because it only happens here. It’s one of the rarest sounds on Earth and you’re about to get a listen.”

At around the 5:40 mark in the video, you can hear the low buzzing sound of the butterflies—a surprisingly soothing ambient noise that’s best heard through headphones. Check out Torres’s video below, and visit his YouTube channel, The Jungle Diaries, to see more nature videos like these.

[h/t The Kids Should See This]