Imitating human sounds is a lot to ask of a bird. We form vowels and consonants with our lips and our tongue, among the most supple, flexible, and indefatigable parts of the human body. For birds, with no lips and with tongues that generally aren’t used for making sounds, it’s a tall order to take on the nuances of human speech. This may explain why only a handful of species have accomplished the skill. Parrots are unusual in that they use their tongues while calling and can manipulate them to articulate vowel sounds, talents that probably underlie their ability to mimic speech.
