They look less than a week old to me. So sweet and tender and FUZZY!!!

I have a bunch that hatched 4/24-26. They're nuts, sleek and athletic, running all over their very large brooder. You can vent sex them. Search YouTube for a video on vent sexing ducklings put out by Meyer Hatchery. I thought about trying with mine, but they looked so tiny and delicate I was afraid. I tried some yesterday though, and am pretty sure I could tell the males. Now awaiting the arrival of red and blue small zip ties from
Amazon so I can mark their little ankles and see later on whether I was right.
Waterfowl are difficult to sex just by looking until they mature. Once mature, drakes have a "sex feather"-- a feather on the top of their tail that makes a little curl. Many breeds also display nuptial plumage during breeding season. Sooner than that however, you can sex them by their voices. Females have a harsh quack which they will treat you to, should you dare to pick them up. Males have a cute little raspy voice.
Geese are harder (unless you have vent sexed them accurately--do it young!

) I didn't have mine figured out until one of them started breeding the other three. Now I can tell--he has a different stance--more sort of stretched up tall--and he's the only one with feathers on the back of his neck. (Hair-pulling is apparently an important part of the whole mating thing.

A guy needs a little help maintaining his balance, I guess.