How To Determine The Perfect Size Hole For Your Birdhouse

Birders around the U.S. know that birdhouses are the ideal way to get their favorite birds to stop and stay awhile. Simple methods for attracting more songbirds to your yard and garden include adding bird feeders and birdhouses. Birdhouses come in all shapes, sizes, and colors, but there's one aspect that is perhaps the most important: the size of the entrance hole. The right sized hole can make or break your birdhouse. If it's too small, then the birds will not be able to come inside, rendering the house a useless lawn decoration. But if the hole is too big, you might be creating an unsafe environment for nesting birds. Consider the fact that all manner of predators and invasive birds can get into a birdhouse if the entrance hole is too large! When in doubt about how big or small to make the entrance, go for a hole about 1.25 inches big to allow the most beneficial birds in without inviting the ones you would rather not.

Putting up several birdhouses may seem like a simple hack to get birds to flock to your yard, but think carefully about their design. Perches are typically not recommended for the entrance to a birdhouse. Instead of being useful for the birds, they become a useful tool for predators to hold onto to get into the birdhouse. Birdhouse entrances also have an optimal position when hung. Though it could change depending on your location and the location of the birdhouse, the best direction for an entrance hole to face is northeasterly. 

It may come as a surprise that the size of the entrance hole can actually limit admittance to some birds. Some non-native species, like house sparrows and European starlings, exhibit aggressive behavior towards other birds. Limiting these bird's presence in your yard can be good if you want to encourage more native birds, like purple martins and bluebirds. But if you size the entrance hole exactly on your birdhouse, you can completely bar them. To ensure house sparrows can't get inside your birdhouse to destroy eggs, make the hole smaller than 1 ¼ inch. To limit European starlings, the hole can be a little bigger, as long as it's smaller than 1 9/16 inches. If you're trying to protect purple martins, use a crescent-shaped hole that starlings cannot fit through.

Sizing the hole of your birdhouse just right can also invite the right type of feathery guests. When determining the best size hole for a DIY birdhouse, pinpoint the species of birds you would like to provide a home for in your yard. You can try to attract birds that serve as little helpers in your garden, like chickadees, or birds that are declining in your area. Chickadees, for example, prefer a 1.125 inch entry hole, one of the smallest. If you're still unsure what size hole is best, remember that 1.25 inches is typically the sweet spot for your friendly feathered friends.