blue morph snow goose

I was at Whitewater Draw at dawn to photograph sandhill cranes. A group of snow geese flew in and landed and I took a few shots. This one is not good and not a keeper, except I noticed something unusual on review. One of them appeared to be dark, so I thought perhaps melanistic? According to this site they call it blue morph: Snow Goose Identification, All About Birds, Cornell Lab of Ornithology

@Arizona Docent I’ve seen them up here in Alaska. The first time I’d thought I’d be naming a species after myself!!