Look at what I read at Wikipedia about the House Sparrow………….it is very interesting!!
In the United States and Canada, the House Sparrow is one of only three birds (the other two being the European Starling and the Rock Pigeon) not protected by law. As an invasive non-indigenous species, it is legal to kill House Sparrows and destroy their eggs at any time in most places in the United States. These three introduced species are now each more widespread and common on the continent than are any other birds. House Sparrows kill adult bluebirds and other native cavity nesters and their young, smash their eggs, and take over their nesting sites, and as such are major factors in the decline of bluebirds and other native cavity nesters in North America. Because the House Sparrow is smaller than the less aggressive native birds with which it competes, it is impossible to keep them out of nest boxes built for many native birds. Attempts to counter the effects of the House Sparrow on native bird populations include the trapping and shooting of adults and the destruction of their nests and eggs.