Thank you to Eddie Callaway re: the various cites you referred me to re: sparrow control for bluebird boxes. I have obtained some sparrow traps from Gilbertsonnestbox.com - which work great. These are small little traps, easy to install in boxes that have been taken by sparrows. I have trapped and dispatched 8 sparrows, just in the past 1 1/2 weeks. Now all of my boxes (at least for the present) are empty, and hopefully some bluebirds and tree swallows will get a chance to move in.