In the 1980 version of Birds of the Carolinas, LBBG was noted as "very rare" in the winter along the, mainly, North Carolina coast, with a few scatted into northern SC. While now fairly common and expected all along both coasts in the winter, this species if still fairly uncommon, but regular, in the Piedmont at that season, usually at large reservoirs (and feeding at municipal landfills).
Here in Wake County, NC (and adjacent Chatham) it still rates a flag on eBird, although a few can usually be found daily in the gull roosts at Jordan, Falls, and Harris Lakes.
The (fairly recent) exception to this has been in March. For the last couple of years, large numbers of LBBGs have been seen on Piedmont reservoirs in mid to late March. Presumably these are Bahamas/Florida/Caribbean (where they are fairly easy to find in winter) and Southeastern wintering birds that are migrating back north. Mark Montazer estimated 1,000 at Jordan Lake this morning. I arrived a bit after he did, but still had many hundreds. They were the most common gull species on the lake.
This March Madness of LBBGs seems like a fairly recent phenomenon, I don't recall such aggregations not that long.
While most of our wintering birds are first or second cycle, these March birds are mostly adults.
If you are on or near one of the big Piedmont lakes in the next week or two, keep an eye out for this impressive flotilla.
