The young Herring Gulls have fledged and now there are lots of them flying around.
They’re following the adults around and begging for a free meal. The adults are trying to ignore them as best they can. This little Herring Gull was walking around making a soft peeping sound. The juveniles will be mostly dark their first year, then their plumage changes as they get older and they don’t get their complete adult plumage until they’re 4 years old. Just try looking in the Sibley Guide to Birds http://www.sibleyguides.com/about/
to see that he uses 2 pages to cover all the plumage differences. And you thought fall Warblers were confusing!