Snow Geese are mostly white (white morph), but some only have a white face, with the rest of their bodies dark brown and dark blue. They are not too rare, as I usually can see at least one or more in any flock of Snow Geese.
When still immature, the blue morph colors are less pronounced while the face has not turned white yet.
There were several thousands Snow Geese at the refuge while I was taking the above photos. Suddenly they shouted to one another and rose up in the sky.
Perhaps they were wary of some Bald Eagle, for they soon settled back on another part of the refuge.