Cacatua sanguinea

Until a few years ago, these birds were found only well inland, across the mountains.
But now quite often large noisy restless flocks descend on Richmond and Windsor.
These are in a neighbour's tree; several other trees in the street were just as full.

See 112 of them here: http://www.pbase.com/image/173616276
And even more here http://www.pbase.com/image/63889190