To some its warbling is like the sound of a beautiful mysterious instrument, while to others it seems like the singing of a blithe-hearted child with a highly melodious voice.

I had often heard and listened with delight to the singing of the rialejo in the Guayana forests, but this song, or musical phrase, was utterly unlike it in character.

It was pure, more expressive, softer--so low that at a distance of forty yards I could hardly have heard it.
But its greatest charm was its resemblance to the human voice--a voice purified and brightened to something almost angelic.

Imagine, then, my impatience as I sat there straining my sense, my deep disappointment when it was not repeated! I rose at length very reluctantly and slowly began making my way back; but when I had progressed about thirty yards, again the sweet voice sounded just behind me, and turning quickly, I stood still and waited.

The same voice, but not the same song--not the same phrase; the notes were different, more varied and rapidly enunciated, as if the singer had been more excited.