Bear River FWMA, Box Elder County, Utah, 5/24&25/08. These images contain a nest of both Western and Clarks Grebe's. I find the easiest way to tell the differnece during breeding is that the Clark's has white extending all the way up behind and encampasing the eye. The Western does not, evident in these images. I don't know if you noticed or not, but both birds are attending the same egg, different lighting and perspective.