Guidelines for installing Swift nest boxes in church belfries

20th February 2024
A guest blog from our friends at Action for Swifts , first published in 2020. They have produced an excellent PDF which can be downloaded here, complete with illustrations and photographs for anyone who is interested in installing nest boxes in their local church belfry. With their permission the content is reproduced below.
action for swifts

Nest boxes in church belfries have proved to be very successful, resulting in some substantial new colonies. There are about 16,000 churches and chapels in England, many with a suitable belfry. So there is an opportunity to make a significant contribution to halt the decline of Swifts.

The advantages of church belfries are that they are high, out of the way, and Swifts seem to like nesting there. One of the things that Swifts like is a degree of seclusion. The louvres in front of a Swift box in the belfry provide this.

Getting a church project started

The prerequisites for embarking on a project like this are a team with energy and enthusiasm as well as a sympathetic vicar, bell captain, church wardens and Parochial Church Council (PCC).

The first thing to do is to visit the belfry to check that such a project is feasible. An exploratory visit should only require the permission of a church warden or vicar. If basic measurements, and photographs (with flash) can be obtained, then custom boxes can be designed and these designs incorporated in a submission to the PCC.

The illustration right shows which measurements are needed (click the image to expand it). Although louvres are usually equally spaced it is a good idea to check this by measuring every individual louvre spacing. The direction in which the louvres face is not an issue, as, even on a south facing aspect, the boxes will not overheat.

Getting Permission

There was a time that, provided certain common sense rules were obeyed, swift boxes could be regarded as de minimis , and approval by the PCC would be sufficient. The ‘common sense’ rules include no interference with bell ringing, no screws into ancient stonework, though stainless screws into mortar between stones is acceptable, and no impact on the external appearance of the church.

Following a period when a faculty was required, in April 2020 the rules changed so that bird boxes have been added to ‘List B’. This means that, in addition to the agreement of the PCC, the archdeacon needs to be consulted to decide whether a faculty is needed. The archdeacon should give notice in writing that the matter may be undertaken without a faculty. The archdeacon may impose additional conditions in the written notice. In making your case, you can say that Swifts are declining at 5% per annum, they are classified as ‘Endangered’. They make a fantastic show in the summer screaming around the church tower . Unlike some species that nest in buildings, they make little or no mess . However, it may take 2 or 3 years to attract the first swifts.


Provided the boxes can be designed, constructed and installed by volunteers, costs can be kept down. The carpentry involved is not difficult. A small project, say 8 boxes behind one set of louvres would cost less than £100 for materials.

Nest box design

Most experience has been with tailor-made box-shaped cabinets, containing multiple nest chambers. Typically, the floor of each nest chamber is between 350 sq cm and 500 sq cm with a height determined by the spacing between the louvres. The internal height should be more than 8.5cm, ideally above 10cm.

Most louvres are wide enough (often about 45cm) to accommodate 2 boxes side by side. The entrance should be 65-75mm x 28mm positioned near the floor of the nest chamber and towards the side. Entrances can be positioned anywhere in the gaps between louvres. A good idea is to make cardboard templates of your design to test fit before cutting any plywood.

Frequently there are wooden battens surrounding the louvres that can be used to support the boxes. Should there be no wooden battens, then you can either install battens with stainless screws into mortar (not into stonework) or with bracing bars spanning the reveals. Swifts prefer nest boxes containing a nest platform which can be as simple as an 85mm hole in a 12 cm square of 9mm or 12mm plywood glued to the floor at the furthest corner from the entrance..

Access for inspection can either be carried out after the end of the breeding season by removing the whole back, or with simple access doors.


Most belfries have wire mesh netting on the inside to exclude starlings and pigeons. Either the netting can be replaced with Swift boxes, or holes can be cut aligned with every nest chamber entrance. Cut 3 sides of a rectangle about 10cm x 7cm then fold the rectangle inwards about the bottom uncut side. With deep louvres it may help the Swifts if a small tunnel is added outside the netting in front of the entrances. After installing nest boxes, ensure that Swifts and other wildlife are excluded from all sides of the belfry.

St Mary’s Newmarket

Battens each side of the louvres are far enough apart (about 50cm) to support 2 columns of nest boxes. The height of the boxes is dictated by the louvre spacing. Access doors with a hinge and simple catch are for inspection and simple maintenance. Swifts tend to prefer the higher louvres, so these boxes occupy the top 4 louvres. The single box on top takes advantage of an entrance at the top most point of the opening.

St Mary the Virgin, Santon Downham

This belfry has wide louvres allowing 3 boxes across the width of the opening. Rather than building 1 large cabinet, it was implemented as 3 cabinets of 3 boxes each. This made installation more manageable.

Deep louvres
Sometimes with deep and irregular louvres, a single cabinet is not appropriate. This is one way that swift boxes could be implemented in such a situation.

St Mary the Virgin, Santon Downham
swift boxes inside church window

Special situations
Some belfries are not louvred, in which case some creativity may be needed. St John’s Bury St Edmunds has a kind of trellis in each opening. These model drawings show what was implemented with small canopies indicating the position of nest box entrances. This has proved to be very successful with over 20 pairs of Swifts in 60 boxes.

No battens?
If there are no battens at the sides of the louvres and it is not practical to fit any, then a bracing bar could be the solution. The spring and tightening nut is only needed at one end of the bracing bar.

Attraction calls
Playing attraction calls will increase the chances of success and reduce the time taken to attract the first occupants. For this reason there must be an accessible power socket with a way to route speaker cable to a tweeter near the nest boxes. Make sure that all sides of the belfry are Swift-proof before starting to play calls.

Frequently asked questions
Q: Will Swift boxes dampen the sound of the bells?
A: As Swift boxes usually do not cover all of the louvres and as they are normally made of 12
mm plywood, attenuation of the sound of the bells is minimal.

Q: Can you see the boxes from outside the church?
A: If a dark stain is applied to the boxes, then they are virtually invisible from outside the
church. The external appearance of the church will not be affected.

Q: Will Swift boxes allow bats or other wildlife to enter the church?
A: As the nest boxes are sealed on the inside, no wildlife can get into the church.

Q: Do Swift droppings foul the church?
A: Unlike Starlings and House Martins, Swifts do not produce large amounts of ‘white-wash’.
Swifts are clean birds, the adults consume the chicks droppings, and very little in the way of
droppings would be produced outside.

Q: Do boxes need to be cleaned out at the end of the season?
A: Swifts use minimal nesting material. Invertebrates reduce the material through the winter.
It is not necessary, indeed it is bad practice, to clear a Swift’s nest at the end of the breeding
season, they need it for breeding the following year. However, if tits or sparrows have
occupied the box, then it is a good idea to clear it out outside the breeding season.

Q: Does playing attraction calls disturb neighbours?
A: As the belfry is so high, most people do not even notice it and the calls will cease when
the colony is established .

Q: Are Swifts affected by bell-ringing?
A: Swifts have been observed on video being momentarily startled when bells start to ring,
they then soon settle down. Often they do not react at all.

Case studies
For examples of details of church projects and other stuff about Swifts and churches see
Action for Swifts, April 2020
[email protected]

Download the full PDF file here – Swifts in church belfries

Skip to content