Stumped By Woodland Warblers at Croatan NF

I spent my last full day on this Out East birding mission at Croatan National Forest, a huge expanse of protected land between New Bern (NC) and the Atlantic Ocean. There's no hope of seeing but the smallest fraction of that territory, so I explored two pockets. One, on the north end (Island Creek Trail) and one on the southeast side (Nesiok Trail.) These two sites allowed for a good mix of habitats, although they're predominantly woodlands. And my attention was given, appropriately enough, to woodland warblers and vireos. Some I can pick out by song (Northern Parulas, Prothonotary Warblers, Red Eyed Vireos, Pine Warblers, etc.) Some... (sigh)... No chance today. And as birders know, warblers and vireos can be darn near impossible to find in the bright green treetops. I spend half an hour on one character who sounded near enough to me to touch and yet managed complete invisibility. But one persists. Unless a more knowledgeable tutor is at hand, brute force is the way to learning. And today, I learned some, and learned what I still need to learn.