is it true that only female ducks quack
A noisy species, the female has the deep quack stereotypically associated with ducks. Male mallards make a sound phonetically similar to that of the female, a typical quack, but it is a deep and raspy and can also sound like breeeeze. When incubating a nest, or when offspring are present, females vocalise differently, making a call that sounds like a truncated version of the usual quack. They hiss if the nest or offspring are threatened or interfered with. When taking off, the wings of a mallard produce a characteristic faint whistling noise.
Mallard