The Mayan city of Chichen Itza is full of architectural and engineering marvels. Every equinox, an enormous snake born from the shadows slithers down the side of the Temple of Kukulcan. But the pyramid does more than put on this biannual light show.
Clap your hands at the base of the stairs, and an echo will ring through the air. It isn’t an ordinary booming echo, either. It sounds like the song of a ghostly flock of birds, a chorus of chirps that crescendos before fading into silence.
The birdsong may be no coincidence. According to some acoustic specialists, it mirrors the call of the resplendent quetzal, a gorgeous bird cloaked in an opulent array of green and red feathers. Like the snake, the quetzal was considered divine by the Maya. This “god of the air” was a symbol of goodness and light. Its tail feathers adorned the headdresses of many a noble (no birds died during the creation of the headdresses, as killing a sacred quetzal was forbidden).
The warbling echo was first studied in 1998 and has been intriguing scholars ever since. It’s unclear whether the Maya intentionally crafted the pyramid with such an effect in mind. Some argue they did in fact begin building the stone behemoth knowing its tiered stairs would manipulate sounds and let it sing the song of their sacred bird. Others speculate they stumbled upon the acoustic marvel by accident, then later tweaked the architecture to enhance the effect.
Sadly for the quetzal, increasing habitat loss and illegal trafficking is threatening the magnificent species. Fragmented pockets of their population have already been extirpated, and their future as a whole remains uncertain. Should the species perish, their song will still linger within the jungle, thanks to the eerie chirps echoing up the stairs of the Temple of Kukulcan.