- Use a larger opening: Bluebirds prefer nest boxes with smaller holes (1.25 inches), while sparrows often require larger holes (1.5 inches). Installing a predator guard with an appropriate entry size can prevent larger birds, including English house sparrows, from entering your box.
- Install a metal baffle below the entrance: Sparrows don’t like to land on flat perches, so you can put up a metal baffle to deter these invaders. The baffle should be about 1 to 2 inches wide, and start 2 inches below the entrance hole and extend away from the box at least 1 inch.
- Use a sparrow trap: Sparrow traps are designed to capture sparrows and deter them from returning to your nest boxes. These traps can be baited with feed, and are an effective way to capture pesky house sparrows.
- Block off the entrance: If you have an empty nest box during the winter months, you can temporarily block the entrance to prevent sparrows from roosting in the box when temperatures drop. Leaving a small gap at the bottom will permit bluebirds to enter during nesting season.
- Remove perches: Sparrows like to perch on your bluebird houses. Eliminate that option as much as you can.
- Relocate your bluebird box: If there is a tall tree or other elevated structure nearby, move the bluebird box to reduce accessibility for sparrows. You may also want to clear brush, shrubs, and other hiding spots near the nest box as they make it easier for sparrows to reach the nest.