This video from Florida in the USA says about itself:
22 November 2016
Three cute Black Bellied Whistling Ducklings with their proud mother and father guarding over them make for a beautiful family. The ducklings have just finished a swim with mom and are drying off in a nest bowl made in grass. To have flightless ducklings in late November is unusual for ducks in general, but not the Black Bellied Whistling Ducks who are year-round residents of central Florida.
To here a flock of these ducks giving their signature “whistle call” check out below here.
This video from Florida in the USA is called Black Bellied Whistling Duck Flock Calls.