Little Pied Cormorant
Phalacrocorax melanoleucos

Something you notice when birdwatching in Australia is the variety of cormorants you get. These are one of the smallest species and seem to fairly common and moderately approachable. The first two are adults amd the last a juvenile.
 

1 and 3: Royal Botanic Gardens, Sydney, 06/12/2009. 2: Victoria Park, Sydney, 26/09/2009.