Listening to a Continent Sing

This white-eyed vireo begins with four normal-sounding songs in A B A B sequence, the alternating sequence already indicating that he's a little worked up about something. Then he launches into a muted tirade in which he's deconstructed all of his songs into a stream of mimicry. The best I can do is to pick out the whit whit calls pilfered from the wood thrush, at 0:12, 0:31, 0:41, and more.

I don't know what's in his head, what caused all of this. Perhaps he had just encountered another male on his territory? I wish I knew.

Background

Yellow-throated and blue-headed vireos

Photo by John Van de Graaff