Complex sentence: A classical example of vocal learning is birdsong in the bird species whose repertoire is not entirely innate, but besides songbirds, parrots and hummingbirds, seals and cetaceans have been found to have this capacity as well.
Split into simpler sentences: A classical example of vocal learning is birdsong in the bird species whose repertoire is not entirely innate--songbirds, parrots and hummingbirds. Besides them, seals and cetaceans have been found to have this capacity as well.