Spotting

Most ducks people see in parks have gotten use to people. These maybe real wild ones. Looking at the sizes of some of these I would say some are immature and this maybe a new home to them or a stop over from another location. It may take Liam to see if they maybe Teals or Mallards.

Black ducks are eastern ducks.
http://www.allaboutbirds.org/guide/ameri...

Any possibility at all that they are American Black Ducks?

Probably immatures, male may have left the area. I was just at a pond in our area and less males.

Jellis, I agree, they are probably female mallards. The only reason I would doubt that is that I watched this group of ducks for about a week and there were none that looked like male mallards. These ducks were very wary of people and would not let me approach them. I have actually never seen ducks in the lakes of the blue mountains and I have been going there every summer for my entire life so I was especially curious about these.

Looks like female Mallards. But not positive cause they could be Teals. The behavior in image 3 is that of type of duck, Dabblers as opposed to Diving or Sea ducks.
http://birding.about.com/od/birdinggloss...