The male white bellbird. (Credit: Anselmo d’Affonseca)

Visitors to the mountains of the northern Amazon can get unusually close to the white bellbird. Ornithologists have long suspected that this bird’s call is the loudest in the world, but a recent trek into the mountains and some careful measurements confirms that male White bellbirds do indeed have the loudest birdsong ever recorded.

The observation, published Monday in the journal Current Biology, comes with some unanswered questions