Not that I am aware of, but I'm no expert on them. The boys start getting the ring around their necks, but that's not super duper early. It is before their tails curl, though.
I went out and took pics and posted with just the pics as there were quite a few. :-)
https://www.backyardchickens.com/forum/viewtopic.php?pid=1379607#p1379607
No clue on the hens. The drakes all look very similar except the head color, in my experience. (I had one of each.)
I'll see if I can bribe my son to go out and take pics of mine in a bit. ;-)
I have a quad of Australian Spotteds that I plan to sell eggs and maybe ducklings from this year, but wouldn't know the first thing about sexing them so that WON'T be happening! hehe
I have three females, two look similar to the mallard, but lighter. My other is more of a peachy color. I had...