The Troyer Bluebird House

One of the bluebird house designs I build is known as the Troyer model. It’s often described as being sparrow-resistant, which naturally raises the question: what makes this design different from traditional bluebird houses?

To understand the Troyer design, it helps to know a little about one of the biggest challenges bluebirds face—competition from House Sparrows.

The Challenge: House Sparrows

House Sparrows are an introduced species in North America and are very aggressive cavity nesters. They often compete with bluebirds for nesting sites and will sometimes take over traditional birdhouses.

Because of this, bluebird enthusiasts and conservationists have experimented with different birdhouse designs that help discourage sparrows while still being attractive to bluebirds.
The Troyer bluebird house is one of those designs.

The Slotted Entrance

The most noticeable feature of the Troyer model is the horizontal slot entrance instead of the traditional round hole found on most birdhouses.

This slot allows more light into the nesting cavity. Bluebirds generally tolerate brighter nesting spaces, but House Sparrows tend to prefer darker, more enclosed cavities. By allowing more light inside the box, the Troyer design can make the nesting space less appealing to sparrows.
Another benefit of the slot is that it makes it more difficult for a House Sparrow to guard or block the entrance. House Sparrows are known to defend nest boxes aggressively, sometimes preventing bluebirds from entering or escaping. The longer slot opening reduces the ability of a sparrow to control the entrance in that way.

Interior Space Matters

Many Troyer-style boxes also use a smaller nesting cavity or interior tray.
House Sparrows prefer larger spaces where they can build bulky nests made of grasses and debris. The more compact interior of a Troyer box can make it less attractive to them while still providing enough space for bluebirds to nest comfortably.

Sparrow-Resistant, Not Sparrow-Proof

It’s important to understand that no birdhouse design is completely sparrow-proof. House Sparrows are adaptable birds and may still attempt to use almost any nesting cavity.
For that reason, most bluebird experts describe the Troyer box as sparrow-discouraging rather than sparrow-proof. Its design simply makes the box less appealing to sparrows and can give bluebirds a better chance of successfully nesting.

A Design Built for Bluebirds

Like all of the birdhouses I build, the Troyer model follows recommended guidelines used by bluebird organizations and conservation groups.

While many birdhouses are designed mainly for decoration, bluebird houses must meet very specific requirements in order to work. Features like proper entrance design, ventilation, drainage, and easy clean-out access all help create a safe and comfortable nesting environment.

For people who struggle with House Sparrows in their area, the Troyer design can be a helpful option when trying to attract bluebirds.

Supporting Bluebirds in Your Backyard

Eastern Bluebirds rely on cavities to raise their young, and in many areas natural nesting sites are limited.

Installing a properly designed nesting box—whether it’s a traditional round-hole house or a Troyer model—can make a meaningful difference in supporting these beautiful birds.

And if you’re lucky, the house you install may soon become the place where a pair of bluebirds raises their next family.