Chimney Swifts may be heard more than seen. Especially from the sidewalk, with its narrow view of the sky. But that chittering call of their’s is here, there, everywhere.
They’re quite a challenge to photograph. 
Even more difficult is catching one entering or departing the chimney they are roosting/nesting in. 
Here’s the second Swift-active chimney within two avenue blocks of the homestead.
From last summer. I haven’t yet confirmed that this one is being used this year. A trio around it isn’t proof enough for me; need to see one enter or emerge.
On Swift culture (no Jonathan here).
There Are a few swifts in Greenwich Village. Not nearly as many as there used to be.
Yet another species in decline… their unique need for chimneys is literally cut off by newer chimney designs and caps on chimneys. The emptying of the air of insects is another big factor, of course.