Entire flocks of wild cockatoos are starting to become vocal in Sydney. It is believed that escaped pet cockatoos are joining the Sydney flocks and teaching them how to deal with humans. Which includes the phrases taught by the ex-owners.
A naturalist from the Australian Museum said they have an influx of people thinking their crazy when they go outside to see a flock of cockatoos and have the whole flock pronounce a chorus of "who´s a pretty boy then".
Cockatoos are smart, social birds and communication and contact is important. A decade long drought inland originally brought the birds to the coastal city, it seems they have decided to stay and are now breeding in Sydney.