© PerthNow Corellas are among the wild birds which have begun to talk.
The wild birds are being taught by pet birds that have escaped or been released by their owners and joined the flocks.
"We have had people call us thinking they are going mad or had something put into their drink because they've gone out to look at the flock of birds in their backyard and all the birds have been saying something like: 'Who's a pretty boy then'?" the Australian Museum's naturalist, Martyn Robinson, said yesterday.
Mr Robinson said Sydney was home to large numbers of galahs, sulphur-crested cockatoos and corellas that had fled New South Wales' far west during the decade-long drought.
"They've decided to stay and even begun to breed in the city, and if a pet bird of their species escapes their cage or is released because their owner's moving or whatever, they naturally join the wild flocks," he said.
"These birds are very smart birds and very social and communication and contact is important between them.
"So the pet bird begins to say things it's been taught by its owner and the rest of the flock learns and starts speaking too, to mimic the pet bird," Mr Robinson said.
"I just hope a pet that's been taught dirty words doesn't join a flock."
Mr Robinson said all three species were noted for their ability to learn behaviour rather than rely on innate traits.
He said the wild birds decided to stay in Sydney - a sort of avian sea-change - because it provided a fantastic habitat.
video for YouTube... should get alot of hits.