The impact that wiped out the dinosaurs also wiped out all songbirds, except for in (ark) Australia. Australian songbirds then spread out to rest of the planet.
The closest living descendents (aka basal lineages) are the Lyrebird and the Rufus scrub bird. The lyrebird’s song is a mixture of its own song and other birds songs. They have been also been known to mimic chainsaws, car alarms, camera shutters, and human speech.
So, what about Australia made all the birds sing?
screaming out of anxiety at all the stuff that can kill them.
but in a pretty soprano voice