"He and I recognised right off the bat that this was something very peculiar," recalled Mr Ridgely, director of the Center for Neotropical Ornithology at the Academy of Natural Sciences in Philadelphia.
What Mr Ridgely, 52, and the Ecuadorean expert, Lelis Navarrete, heard and eventually saw high in the Andes mountains, was a new bird species.
Once he saw the large bird with the unusual white facial markings, he knew that it was "one of the most distinctive new birds to be found in a while".
The academy was to formally announce the discovery yesterday, and soon will submit a description of the bird to a leading ornithological journal, The Auk. The scientists will also name the bird. They have determined it is a species of the genus Antpitta, a group of very reclusive, long- legged, non-migratory birds.