@Matthew
Matthew,
Yeah, I guess that's what I'll do for this year. I've removed that nest every day for about a week and a half, and it's rebuilt within a few hours - they are stubborn and industrious little buggers! It's kind of my fault anyway. When I put up the shelf for the swallows (they originally were building on top of a light fixture, which I couldn't let happen), I inadvertently left enough space behind one of the ceiling joists that I attached the shelf to for these other guys to work. I'll let the chips fall where they may for this year, and try and remedy things in the fall. Thanks for your input and the links.
Jim