Immature Glaucous Gulls are pretty much all white
Both the aptly named Black-legged and Red-legged Kittiwakes breed in the Pribilofs. The Black-legged Kittiwake has a wide distribution all around the northern hemisphere, while the entire world population of Red-legged Kittiwake breeds only here or nearby.
Guess which Kittiwake species this one is?
How about this one?