You're scoping the birds out on the far side of the lake and you see some birds that you are pretty sure are Goldeneyes, but which is it...Common or Barrow's?
As I have seen and terribly digiscoped both in the last few days, I've been able to relearn the difference myself. I thought I might share them with you in case you have the same memory recall issues that I have.
But what if you can't see the facial patch? The amount of white shown as well as the black and white color pattern both are clues. Common Goldeneyes show much more white even at great distances. Barrow's Goldeneyes have white stripes surrounded by black feathers as can be seen in the photo above.
For females, it is a little more difficult to tell at a distance. Female Common Goldeneyes have mostly black bills, while Barrow's have mostly yellow-orange bills. Good luck!