https://karuna-nature.com/en/observe-identify/mallard
Mallard fact sheet: how to recognize males and females, the speculum, calls, habitat, diet, and simple tips to observe it better without disturbance.
the mallardanas platyrhynchos
https://www.usgs.gov/publications/body-mass-dynamics-wintering-mallards-anas-platyrhynchos-lower-mississippi-alluvial
Body mass in overwintering waterfowl is an important fitness attribute as it affects winter survival, timing of spring migration, and subsequent reproductive...
body massanas platyrhynchosdynamicswinteringmallards