I'll kill several birds with one stone here (metaphorically, of course). Of Sondheim's "Greenfinch and Linnet Bird, Nightingale, Blackbird, How is it you sing? ..." I saw three of these four birds. No nightingales. Not bad, though the sightings were a little unsatisfying since the Greenfinches and Linnets were pretty far away.
And if I ever heard them singing, I didn't know it. I think a cicada sound I heard over and over may have been the buzzy call note of the Greenfinch, but I never heard it do much of a song in late July. The ones in this photo are at a feeder at Rural Roosts, the amazing rural pine cabin retreat where we stayed in Lincolnshire. My Linnet photo was far away and blurry, but it at least allowed me to get an ID. Here's my fellow Catholic University alumna, the great Harrolyn Blackwell, singing Sondheim's song:
And, speaking of birds that are green in color - something rather unusual in the U.S. (the only ones I can think of without looking it up are the female Painted Bunting and the Black-Throated Green Warbler, though those really look yellow to me) - there was another bird on my list to see even though I don't know any songs or poems about it. That's the Green Woodpecker.
I encountered these excellent birds, which are similar to our (tan-colored) Northern Filckers in the U.S., on Cycle Route 1 between Lincoln and Bardney. Spectacular birds, and they let me get close enough to observe the male (right) feeding the juvenile (left).
Finally, the Blackbird. I've sung about them in a song by Amy Beach, and just slightly more famously, the Beatles have sung about them a bit. I'd venture to say that most Americans have no idea which bird to picture when they hear the birdsong on the recordings (if many have even given it a thought at all). The Blackbird that that Paul McCartney sings about is a kind of thrush, related to the American Robin (which has nothing to do with the European Robin except that the breast is about the same color of red). I heard them on country roads in Lincolnshire and have heard them in the spring in Rome, where their haunting, otherworldly song can fill up a city park or echo off the buildings of the city, and they are known to sing at night like the song says. It reminds one of the American Robin's song in that it features upward-moving outbursts punctuated by brief pauses, but its song is much more varied and wacky. Bonus points: the guitar accompaniment of the Beatles song was based on a piece by J.S. Bach. Here's one video of one singing. Stick around because it just keeps going with multiple variations. I was so glad I got to hear some in Lincolnshire!