Greater Scaup

On November 30, 2019 I did a post on the greater scaup, a bird I'd seen at Antelope Island in the Great Salt Lake. When I joined iNaturalist some time later I submitted photos of those birds and was informed by a number of identifiers that the birds were actually lesser scaup. 

Note the green sheen on the head of the male to the left and the yellow eyes of the females in the middle. They are greater scaup.

Several weeks ago I was at the Salton Sea SRA and got photos of birds I submitted to iNaturalist as lesser scaup (see above). Again I was wrong, identifiers came back with the identification of greater scaup.

These males, photos taken last Saturday, have a greenish sheen on the back of their heads and are greater scaup. 

This female has an amber iris, rather than a yellow iris, and I believe is a lesser scaup. 

I've decided I need to learn the difference. The male lesser scaup has a purple sheen on its neck and the female has an amber iris. The male greater scaup has a green sheen on its neck and the female has a yellow iris.