Laughing gulls (Leucophaeus atricilla) in winter plumage. In summer, the gray, mottled hood becomes solid black.http://www.allaboutbirds.org/guide/laughing_gull/id
5. If I remember correctly, this one is a little more brownish and not as much white, indicating he was a juvenile.
6. People visiting this park frequently feed the birds (probably not a good thing) but it does guarantee quite a show when the food comes out. This family was tossing bits of food in the air and I was able to catch the action at just the right moment with them nicely framed among the flock, everyone engaged with the action, and the little boy excitedly pointing to them.
Everything shot with 5DIII and 70-200 2.8L II IS. Because they are so used to people, they let you get pretty close so I didn't have to do any cropping on these close ups.