Swift parrots are an endangered bird with only ~2000 birds left (which is why you're getting this low-quality photo - it's likely the only one I'll get...). They breed on the east coast of Tasmania and migrate across the Bass Strait to the Australian mainland in the winter, feeding from flowing gums as they move up the east coast as far as Brisbane. They are quite small birds at 25 cm, of which a large amount is the long, thin tail. They are noisy in flight and make quiet noises to each other when feeding.
1: Royal Park, Melbourne, Vic., 06/06/2011.