susanmcrae's Identifications

The last time a bluebird pair set up in this birdhouse (the rest of this sentence is sad) House Sparrows came in and killed their five hatchlings. I've been keeping up with removing the House Sparrow nests from the one birdhouse they keep trying to use...even removing a few eggs in the process...but I've seen the male House Sparrow landing on this bluebird nest and vocalizing territorially. Is there anything else I can do?