Thanks Melanie. No, they're not very common here. I only saw one pair at the University Park yesterday and have sometimes seen one or two pairs at a Nature Reserve. The sort we see here everywhere in large numbers are the bigger and less colourful Canada geese.
I think it is a goose rather than a gander. If geese are like ducks, the male will have a curly feather on their tail. Next time you are walking around the lake, notice the male ducks.(curls).