They’re almost big enough.
Or maybe a pair of Southern Pileated Woodpeckers (Dryocopus pileatus) on a longleaf pine (Pinus Palustris).
I got pretty close; they just laughed. Eventually I walked away to do something else, and they flew into another tree directly over my head, where you see them in this video:
Pileated Woodpeckers, Dryocopus pileatus, Lowndes County, Georgia.
Pictures by John S. Quarterman, 7 November 2011.
-jsq