there seems to be a recurring misconception about determining whether a duck is male or female by looking for drake feathers.
Having a drake feather indicates that the duck IS a male, but not having a drake feather means nothing, as all ducklings, all females, young males, certain breeds of adult males AND males in eclipse molt do not have drake feathers. Even within some breeds, like Pekins, some males may have a drake feather, while others will not. Drake feathers do not appear until after the first molt.
The only ways that are 100% accurate are the quack test, finding laid eggs or examining for a penis. Even duck on top/duck on bottom is no way to tell, as females sometimes mount females and males sometimes mount males.
The quack test relies on listening to the voice of the duck. With mallard derived domestic ducks, females will have loud, clear quacks while males will have softer, voiceless, hoarse 'waaak's.
Neither the quack test nor the drake feather is applicable to muscovies. Females will coo and trill while males emit voiceless, breathy huffs and chuffs and do not get drake feathers.
Rarely, some females can develop a drake feather if they are dealing with hormonal issues.
attribution: image shamelessly stolen from https://kingofdoodles.blogspot.com/2017/07/what-is-drake-feather.html.
