Will chimney swifts use a birdhouse? Tower size that works

Part of our guide on sparrow nesting house

Most birdhouses fail chimney swifts as they need a tall, narrow, rough-walled tower, not a box with a hole and perch.

Why chimney swifts avoid standard enclosed birdhouses

Say you hung a typical birdhouse with a small hole and a perch on your porch. The chimney swifts will ignore it. They do not use occupied cavities or boxes with external holes and perches.

Swifts need a vertical enclosed space with no flat floor or perch to land on. They cling to rough walls inside narrow shafts. The wide openings and perches of standard birdhouses do not suit their flying and nesting style.

The key is the behavior of chimney swifts. They roost and nest by clinging vertically on rough surfaces inside chimneys or hollow trees. A box with a hole disrupts this and makes them vulnerable to predators.

What a swift tower is and how its open vertical shaft differs from a box

Picture a tall, narrow wooden tower with an open vertical shaft instead of a hole. This is a swift tower. If that sounds like your situation, read up on robin nesting box guide next.

A swift tower is a vertical box about 4 to 5 feet tall and 18 inches wide. It mimics the inside of a chimney with rough sides. The opening is a vertical slot running the tower's height, not a single hole.

Unlike a standard box, the tower’s vertical shaft allows swifts to fly straight up inside and cling to walls. It also offers protection from weather and predators while matching their natural nesting environment.

The vertical slot opening usually runs the full height of the tower. This design lets swifts fly straight in and out without needing a perch. The opening width often ranges from 3 to 4 inches, narrow enough to keep out predators but wide enough for agile swift flight. We cover designer luxury birdhouse in its own article.

Some swift towers have an exterior door or panel for maintenance. This door is usually camouflaged to avoid disturbing swifts. After installation, check the tower regularly but avoid opening it during nesting season to prevent stress to the birds.

• Shape: tall, narrow, vertical shaft
• Opening: long vertical slot, not a small hole
• Interior: rough surfaces for clinging
• Height: 4 to 5 feet for secure nesting space

Inside dimensions, height and surface texture a tower needs to hold a nest

Imagine measuring a swift tower’s insides before building. The ideal inside width is about 18 inches. Too narrow and swifts can’t maneuver. Too wide and they lose the vertical surface to cling to.

Height matters. The tower should be 4 to 5 feet tall inside. This length provides enough vertical space for the nest and the birds’ movement. Shorter towers often fail to attract swifts. The other half of this decision is best place for bird nesting boxes.

Surface texture is critical. Swifts cling best to rough, unfinished wood or a surface with vertical grooves. Smooth painted or sealed surfaces repel them because they cannot grip to build nests.

If the tower’s interior is too smooth, swifts fail to grip and abandon nesting attempts. Builders sometimes add vertical grooves about 1/8 inch deep and spaced one inch apart to improve grip. Another option is attaching rough strips of wood or mesh to the inside walls.

An inside width less than 16 inches can cause swifts to collide with walls during flight. Towers wider than 20 inches lose the vertical wall effect, making it hard for swifts to cling and nest properly. The ideal height of 4 to 5 feet ensures room for nests stacked vertically and swift movement. Before you commit to anything, it is worth looking at bedding for bird house.

For example, a 4.5-foot tall tower with an 18-inch inside width and interior grooves saw multiple swift pairs successfully nest over several seasons. Checking the tower after the season confirmed intact nests and no damage to the interior surfaces.

Where to place a tower and when it needs to be up for nesting season

You want to place your swift tower 10 to 30 feet above the ground. The height gives safety from predators and mimics real chimneys. Towers placed too low usually fail to attract swifts.

Put the tower near chimney openings, old swift roosting sites, or open areas with clear flight paths. Swifts hunt insects on the wing and prefer open airspace near water or trees.

Install the tower before early April, as swifts arrive from migration then. Late installation reduces chances swifts find and use it that season.

Wind exposure matters too. Towers placed on leeward sides of buildings or poles have calmer air, favored by swifts. Avoid locations where prevailing winds slam directly into the tower opening, which can deter nesting.

Avoid placing towers near bright artificial lights. Swifts prefer dim or natural light environments for roosting. An ideal spot combines height, open flight paths, and some shade during peak sunlight hours.

Installing a tower in late March or early April gives swifts time to look at and settle before egg-laying begins in May. Past this window, swifts may settle elsewhere due to competition or missed cues.

• Height: 10 to 30 feet above ground
• Location: near chimneys or open flyways
• Timing: install before early April

1. Choose a location near an existing chimney or open flyway.
2. Mount the tower securely 10 to 30 feet high on a pole or building.
3. Install no later than early April to catch swift arrivals.

What to do if swifts are already in your chimney and why active nests cannot be removed

If swifts are nesting in your chimney, do not remove the nest. Active swift nests are federally protected under the Migratory Bird Treaty Act.

Disturbing or removing an active nest can result in legal penalties and harm to the birds. Swifts choose chimneys because they closely match their natural nesting conditions.

Instead, monitor the nest until the season ends. After the swifts leave in late summer, you can clean and block the chimney if needed to prevent future nesting.

Consider building a swift tower nearby to offer an alternative nesting site and encourage swifts to move there naturally next season.

Will chimney swifts use a birdhouse? Tower size that works

Will chimney swifts use a birdhouse? Not if it’s a standard box with a hole and perch. They need a tall, narrow tower with a vertical opening about 18 inches wide and 4 to 5 feet tall inside.

The tower's smooth walls won’t attract them. Rough wood with grooves lets swifts cling and build their nests. The vertical shaft matches their natural chimney homes and flying habits.

Place the tower 10 to 30 feet high near existing swift activity. Put it up before their arrival in early April to stand a good chance of attracting them.

This tower size and orientation meet the swifts’ requirements, increasing the chance they’ll use it for nesting instead of a chimney.

Questions people still ask

I've built swift towers that attracted nesting swifts by matching their natural chimney preferences.