How Do I Attract Swifts to My Nest Box?

The swift is a remarkable bird that spends the majority of its time in flight, including when they are sleeping (!). Indeed, pretty much the only time they aren’t flying is when they enter a nest to breed, lay eggs or feed their young.

Unfortunately the Common Swift is struggling in Ireland: recent data showed a 57% decline in numbers between 1998 and 2016, with the swift on the red list as a bird of ‘high conservation concern’. Much of this decline is down to loss of nesting sites, which can happen due to renovations of buildings old or new.

Built-in Swift Nest Box - IB GZ 03

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Swifts can be selective about where they breed, but when they trust a nesting location they are highly loyal to it. Installing a swift nesting box or space is a great way to do our bit for swift conservation, but there are some key guidelines to keep in mind if you want your nest box to be attractive to swifts.

The first guideline is to be patient: it can take time for swifts to find a nesting space and come to trust it. Don’t be discouraged if you don’t have success in the first year.

Nesting Preferences

Ireland’s sole swift species is the Common Swift or ‘Apus apus’. The Common Swift prefers to nest under building eaves, in roof spaces or in crevices in older buildings.

Nest Box Types

Nest boxes can come designed with single, double or triple entrance holes, with each entrance leading into its own brood chamber. Swifts are colonial birds, so you are increasing your chances of successful occupation if you have multiple nest boxes at one site (note: two triple entrance boxes = 6 nesting chambers).

Triple Swift Nest Box - 17A (Irish Spec)

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Nest Box Guidelines

Entrance Size

The entrance hole of any swift nesting box should be designed in such a way to make it accessible to swifts but also to discourage other species from occupying the box. Swift Conservation Ireland recommends dimensions of 29mm (Height) x 65mm (Width).

If it is any less than 28mm, swifts likely won’t be able to get in. Similarly, if it is more than 30mm then starlings - who can aggressively take over the nest - will be able to enter.

The entrance hole should be situated 5-6 cm from the floor of the box; this is to safeguard against chicks accidentally falling out.

Interior Dimensions

Both external and internal (i.e. built-in nest boxes or bricks) nests should have a minimum size of: 16 H x 16 D x 32 cm L.

Swift Facade Nesting Box - NKGZ10

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This is to provide enough space for 2 adults and 3 chicks. Swift chicks need enough space to stretch out their wings for push-up exercises; this is important because they need to build upper body strength so that they can take flight from the nest successfully.

Tips on Swift Box Placement

Installation under eaves or soffits is best. This will have a number of benefits:

• helps to prevent the nesting box from overheating
• making the nest box more secluded from predators
• protection from wind, heavy rain

Further Tips:

• The nest box should be situated at least 5 metres (or 16-20 feet) off the ground
• Avoid a south-facing aspect, which can lead to too much direct sunlight. North or east facing is preferable, providing a measure of shade during the day.
• When leaving their nest, swifts will habitually swoop downwards: therefore it is important that there are no major obstructions or protrusions directly under the swift box which could potentially cause injury.
• Birds can be dazzled by bright light, so avoid placing the nest box in the glare of outdoor lighting, lamp posts etc
• If it is not a built-in swift box or one designed to be tucked in under eaves, a sloping roof can be beneficial as it discourages predators from perching on the box.

Common Swift Built-in Nesting Box - IBGZ4

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Using Swift Calls

Swifts will naturally seek out locations with established colonies, so this presents something of a challenge if you are trying to attract a pair of swifts to a newly established nest box. This is where a ‘swift call’ comes in.

Swift call systems encompass an electronic device which mimics the sound of a busy, established colony. The noises that these devices emit are ‘thrilling screams’, played at an appropriate volume using a mp3 or USB recording, an amp and speaker.

Swift Bird Call Sound System

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The best time to play these sounds is at dawn or dusk from May (arrivals) through June (generally the main time for egg laying) through July (incubation and chick-rearing). The device is best placed very near your nest box, or even inside it. According to BirdWatch Ireland, playing these calls with regularity greatly improves your chances of successful occupation.

Bear in mind also that there is no use playing the calls in cold or wet weather, as swifts will not be seeking out nests in these conditions.

Do You Need a License to Play Swift Attraction Calls?

Not any more! There used to be a requirement to haare ve an NPWS (National Parks & Wildlife Service) license in order to play swift attraction calls. This was removed in February 2024.

Guidance from Swift Conservation Ireland says that it is better to play the calls at a low volume (not more than half volume), as this is shown to be more effective for helping swifts to locate boxes. If you can hear the calls from 5 meters away, this should be plenty loud.

Single Swift Box 17B (Irish Spec)

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Keep your neighbours in mind. If you live in close proximity to other houses you may have to strike a balance; inform them of why you’re playing the calls. In a lot of cases the swift calls can fade into natural background noise, but people can be sensitive to the sounds as well. You could offer to turn down the volume or change the direction of the speakers, for example.

What are the Best Times to Play Swift Attraction Calls?

You could play the calls from dawn until dusk every day, but it’s more efficient to set up a timer to play calls at optimum times. These optimum times are generally:

• 8 to 11am
• 2 to 4pm
• 6 to 11pm (or until dark)

Do Swifts Return to the Same Nest Every Year?

Swifts are ‘site-faithful’: this phrase refers to when animals or wildlife will return to the same location or site for breeding, foraging, nesting or overwintering. When swifts trust that an area is safe and suitable for nesting, they will return in the following years.

This puts a responsibility on us to ensure that the nest box is kept in good condition and safe from predator access. Schwegler swift nest boxes will need very little in the way of cleaning or maintenance; swifts are a tidy species when it comes to nesting.

Bear in mind the importance of not disturbing an active nest, which can lead to it being abandoned. Swift nesting season in Ireland runs from late April to early September.