Musician Wren whistles perfect octaves

The Musician Wren (a.k.a. Cyphorhynus arada) whistles melodies that sound 'human'. Musicologist Emily Doolittle and biologist Henrik Brumm found that Musician Wrens preferentially produce successive perfect octaves, fifths, and fourths; the basics of human harmony.

Their paper was published in the very likeable Journal of Interdisciplinary Music Studies. In the archives of this journal, you will find some great research on extraordinary subjects:

The Australian pied butcherbird and the natureculture continuum - Hollis Taylor and Dominique Lestel

Imitations of bells: Correspondence between bell acoustics and onomatopoeic texts - Rytis Ambrazeviius and Renata Balsien

Searching for the `natural` origins of the symmetrical scales: Traditional multipart Setu songs - Rytis Ambrazeviius and Žanna PŠrtlas

The reception of overtone singing by uninformed listeners - Marie-Cécile Barras and Anne-Marie Gouiffès

The xeno-canto website has many more of recordings of the Musician Wren. The Australian Butcher Bird is another excellent whistler.