Deep in the evergreen forests of Vietnam, curious little green-blooded frogs spend monsoon nights performing vocals, improvising new melodies each time they sing.
Known popularly as “frogs that sing like birds”, male Gracixalus treefrogs perform to attract females and to ward off other males.
But these are not your average frogs, croaking out the same old tunes. Gracixalus frogs shuffle notes to compose a new melody every single time they sing.
To human ears, songs of the three related species – G. quangi, G. supercornutus and G. gracilipes – sound like birds chirping.
They randomly mix high-pitched, long notes called “whistles” with short, sharp “clicks” to compose new tunes.
Each song is unique in its complexity, duration, amplitude, frequency and structure, as opposed to being specific to an individual or a species as it is in most frogs.
Photo credit: Jodi Rowley