What Size Birdhouse Opening for a Finch?

Deciding on an opening size for your birdhouse means deciding what sorts of birds you hope to encourage to move in.

Species

The House finch is the most common North American finch.The House finch is the most common North American finch.
A small variation in opening size, from 1 inch to 2 inches, can greatly impact what sorts of birds to which you play host. Typically, a House finch will prefer an opening of 2 inches in diameter. When building a birdhouse for a finch, however, there are a few things to keep in mind when determining the size of the opening to cut.

Finches are a type of bird that ranges in size from the 2-inch Siskins to the 9-inch Grosbeaks. Most birdhouses built for finches will be built to accommodate the House finch, a small, seed-eating finch that is common throughout North America. The House finch prefers a 2-inch opening in a house raised off the ground, out of the reach of predators.

Go Perchless

The House sparrow is an introduced species that has reduced House finch numbers throughout much of its range by taking nest sites and even destroying eggs and young. House sparrows require small perches in order to gain entrance to a birdhouse, so cutting your birdhouse opening and neglecting to install or removing the perch will allow the House finch to gain access without admitting sparrows.

Wood Choice

If you construct your birdhouse out of hardwood, such as oak or maple, consider using a softer wood for the front panel, where the opening will be. This enables a House finch to widen the opening if need be. If you use a soft wood, such as pine, for your front panel, make your opening slightly smaller -- in the vicinity of 1 3/4 inches in diameter should be sufficient. If you use hardwood for the front panel, make the opening the full 2 inches, as the finch will not be able to easily widen the opening.

Trial and Error

Successfully housing a specific species of bird can be difficult and may take several seasons. Many birds have similar needs when it comes to openings and house locations, so you may find you are housing a family of chickadees, rather than House finch. Tweaking with the hole opening from season to season can help you zero in on your target species. A hole that is too large can easily be remedied by wood-gluing a small square piece of wood over the hole in the off season and cutting a new hole through the square with the desired diameter.

About the Author

Andrew Leahey has been a writer since 1999, covering topics as varied as technology how-to guides and the politics of genetically modified organisms to African food supplies. He is pursuing his J.D. while renovating an 1887 farmhouse located in the New Jersey Pine Barrens.