The Baka Pygmies famously yodel to stunning effect:

http://www.youtube.com/watch?v=98Xj_oLkRT4

As did the Dezurik Sisters, aka The Cackle Sisters on account of the dazzling virtuosity of their singular cunning, especially with respect of farmyard sounds:

http://www.youtube.com/watch?v=6uvKXEz2V3Q

As for birds, I often wonder what songs we humans sang in the wild - & how close those primal songs remain to our inner-dreaming with respect of music as a whole.