Yes, they do!

Those are the sounds of squirrels. I have tons of them since my neighbors have a walnut tree.

Yes they do. My mon once fed a squirrel once (I told her it's a bad idea). It started clicking at me when I was sitting on the porch (no doubt looking a handout).

Paul

Thanks everyone,
But I found out something very interesting......it was crows! I saw a couple flying over the field and this clacking sound was moving with them. Then I saw a show on Crows recently on PBS and they showed them making the sound.
I had no idea! I guess they make this sound when they're talking to family, as opposed to the caw...caw...sound they make to a larger group.
Another interesting thing I learned on this PBS show was that when there is a crow's death, the group gathers on a tree near where it died and sit there quietly for awhile. (like they're having a funeral). Then they fly off quietly.
Ain't nature grand?!