Last year I put up this Marten house and sparrows immediatley moved in. Purple Martens are very polite and private birds and will not nest with other species of birds. This spring I took the house down and cleaned it hoping to remove any trace of sparrow nest. Guess what! The Martens laid claim to the house first this year and are defending it with all their might. Not only are they pretty birds with a melodic trill, but they have a reputation for consuming huge amounts of mosquitoes. I hope so.