Definitely hens, I've had them for almost two years and they just started doing it a few months ago.
I can't get them to stop! It's so frustrating. I tried to find a video on YouTube of what they sound like and I can't really find anything like it, but one of them is definitely attempting to crow and she does it every morning until about noon. Aside from the crowing, they both do a crazy loud, drawn out SQUAWWWKKKKKKKK constantly.
Mine do "Bawk, bawk, bawk, bawk, BAWK!!!" Which, is the egg song.