This album, recorded by celebrated ornithologist Johan Dalgas Frisch, (and first released on the Sabia label in 1961), was once in the Top 50 of Brasil's popular record sales. President João Goulart actually gave JFK a copy when he came to visit (click on thumbnail below for photographic evidence). Talk about a country with its musical priorities in the right place!
This collection of recordings isn't readily available in the states, but if you can't track down a used LP or torrent, it looks like you can buy it from this site in Brasil.
This post is a special 'avian edition' of a series about music that disorients the senses. I've found that some of the most amazing and jarring auditory illusions are not the usual scientifically distilled or synthesized ones, they're often found in folk music and made by people's voices. Of course, in a way, it makes perfect sense - the vocal chords are some of the most complex and advanced musical instruments in existence. They are ubiquitously available, and we've been experimenting with them for longer than any other sound-making implement.