There are several thousand Plumed Whistling Ducks on the local sewerage ponds in town. They fly out every night to feed. I drive around the rice paddocks with the spotlight before I go to bed to make sure they are not at my place.
I was in town after dark a few days ago and the ducks were flying over about 100 at a time. I heard the whistling and looked up and could see them silhouetted against the sky before it was totally dark.