Yeah its very scary to watch them mate. Except right before they do it, they initiate it by bobbing their heads up and down a few times. I'm sure there's a video on youtube somewhere. That part is funny. Water is what turns them on 99 percent of the the time. They always did it in the pool or at their water bowl. I didn't know any of that at first, and was confused for a month or so, haha. My boy always looked like he was surfing on my girl. It was weird. And I also learned ducks have one of largest genitals of mammals, and it looks like a cork screw or a pigs tail. It just coils up in there. Very gross. But yes some green poop is bad. It usually is bright neon green and watery. I guess it mostly means they're not eating and usually is for a serious reason. They should also show other signs too though, and it is continuously green. I wouldn't worry if its one semi-green poop once in awhile with no other symptoms. That seems normal. But all 3 times I've seen the neon green liquid poop it was serious, and a different reason each time, but it also involved them mostly laying down, with their tail down, and u could just tell. Once amelia swallowed a penny, which is toxic and kills ducks, she survived though, the second she was egg bound and died, and the third is dw currently which is getting better and still an unknown reason.