black to bill in basic plumage is a much variable feature, especially in subadults. this is not a ring-billed gull for many reasons, especially structure and size, best seen on shape of bill. it is a subadult or adult american herring gull. note for instance the rather narrow and blurry black mark to bill, different to adult ring-billed gulls. also the nature of head streaking is different being rather blotchy very dense around neck sides etc. plus the pinkish legs!
ok, and the other 3 are also american herring gulls, two first cycles and a second cycle (to the right, = now 1,5 years old)