We had a major incoming flight of warblers Friday night, so Sat. morning was full of warbler calls. I only know the calls of the most common warblers, but it is better to learn their calls rather than straining your neck for an hour to peer into the treetops.
Interestingly, that same flight left last night and there is nary a warbler this morning. Birders love those big flights that arrive overnight.
If you have poor memory for bird song, there is an iPhone app for that: Merlin Bird ID. It is not 100% accurate - but what is?