Bluebirds, purple martins ... Consult this helpful birdhouse hole size chart for guidelines. House wrens require the smallest entrance, only 1-1/8 inches. This will also keep out competing ...

It has an opening precisely sized for bluebirds ... x 2-1/4-in.) entry hole. You can use a variety of woods and plywood to build this birdhouse, as long as they’re weatherproof and not pressure ...

If you should happen to have a hammer and saw, you can easily construct a birdhouse that is especially designed for overwintering bluebirds. The important thing is to position the box's entrance hole ...