In response to Tom Beal's question about Tree Swallows (July 7, 2006).

I also monitor a bluebird trail (of about a dozen boxes), where half are
occupied by Tree Swallows at the beginning of the season. I have also
experienced very messy boxes that need to be cleaned out before my bluebirds
can do a second nesting in them. My theory is: the TS's are not planning to
come back to re-nest, so just let the "maid service" take care of it! :-)
But seriously, regardless of "why," we need to clean these boxes as best we
can. I wipe them out with a product called "Poop-off" (used by pet bird
owners) that contains a non-toxic, bio-degradable enzyme. I buy the
"Anywhere Wipes," which come in a plastic pop-up canister like "Wet Ones."
If you neighborhood pet store doesn't carry it, go to
www.lifesgreatproducts.com <http://www.lifesgreatproducts.com/> .