Cowbird? No. Grey Catbird!

This creature was singing by itself in a tree along 40th Street, between my errand to the Post Office and my errand to the library, which was just before a heavy rainstorm.

I don't know what it is, but it might be a cowbird.

[EDIT: A naturalist friend nearby saw this pic when I posted it on facebook, and he quickly identified it as a [url=https://en.wikipedia.org/wiki/Grey_Catbird]Grey Catbird.[/url] What a delightful thing that is!]