Birders have a lot of mnemonics to help them remember birdsongs, but no doubt the most memorable is "If I sees you; I will seize you; and I'll squeeze you till you squirt." The idea is that the Warbling Vireo is making that taunt to his prey. Now, we are pretty sure birds don't sing to their supper, but that mnemonic has done its job for a long time. Herb Wisner told me he learned it from the legendary Arthur Allen in an ornithology course at Cornell, so we know it has been around for at least 70 years, more likely many more. Now you can even buy a t-shirt with the phrase emblazoned on it at https://www.birdergifts.com/designs/warbling-vireo. (this is not an endorsement.) By the way, I think "sees" is a nice touch, a way to get another burry note in there. I found that one at the Standford.edu website; most versions use "see."
This particular Warbling Vireo in North Carolina sounded like no other Warbling Vireo I had heard in my life. That's probably because I have very little experience with this species in eastern North America. The eastern and western populations barely interbreed and their songs are a little different, different enough for me to (1) tell them apart, despite (2) recognizing all as Warbling Vireos. The mnemonic captures two key characteristics shared by both populations, a syncopated rhythm and a few buzzy notes, as in "seize" and "squeeze."
Interestingly, and quite coincidentally, yesterday's song has both characteristics as well. Does the Rubythroat sound like a Warbling Vireo? No, but they have one more common feature. Each song is different from its predecessor. Tomorrow could bring something entirely different, but today's challenge is the same as yesterday's. How do they make a series of songs that all sound alike and yet are made up of entirely different parts? I wager a catalogue of each tiny note-type in those songs would run into the dozens, and yet, I predict, they are not invented on the spot, but instead reside in the memory of that little bird.