Keep Out Sparrows

I'd appreciate any suggestions about keeping house sparrows out of my bluebird houses.

—Ginnie Bowling, Lawton, Michigan

George: You can discourage sparrows from using bluebird houses by locating the houses at the edges of open fields. That's where the habitat is more suitable to bluebirds than house sparrows. Make sure the entrance holes are no larger than 1-1/2 inches in diameter for eastern bluebird houses, and 1-9/16 inches for mountain and western bluebirds. Also, because house sparrows aren't protected native birds, you can legally remove their nesting materials.