Why does my duck make this noise?

[Wifezilla]

Yeah those little grunting, snuffling sounds as they root around in the dirt are happy ducks noises.

 

[70%cocoa]

Mine grunt as they snuffle around in the garden (happy noises) and they make high-pitched noises like a single note played hard on a flute (don't know what this means) and they make a harsh staccato noise while holding their head in and moving it from side to side. The last one seems to be "get out of my way" or " I'm warning you!". Plus a few varieties of quack: "You're home from work now so let us out of the pen NOW", "Oh good, here's the peas!!", "Hi everyone, here I am", "Oh, there you are, where did you get to? Glad you're back". That's the ducks. My drakes seem to have a smaller repertoire than the ducks.