@hightor,
This is that critical two weeks in the US. Birds that live in deep forests are heading north through mid May and its the best time to see these rarer species. We put out raisins and orange slices for the baltimore orioles. Ive seen quite a few orioles this year, and two scarlet tanagers.
Now Its a bunch of solo gigs of uncommon tunes sung by these visitors and usually the mockingbirds pick up the main melodies and keep em going through summer.
We see oriole nests in the woods nearby .They build these things that look like "caterpillar nests" which hang from high poplar trees. Bt end of August, theyre all gone.
BUT I dont think Ive ever seen any bobolinks. Ive heard em , but never seen em.