Thursday 3 December 2020

Swift Bricks - the 'universal' nest brick

The SLN Swifts & Planning Group has produced a paper advocating the provision of Swift bricks as a preferred solution for a range of small cavity-nesting species. It comes from a realisation that this will have better outcomes for these species than trying to satisfy all species independently.

The paper makes the points that integral or internal nest boxes are:
  • more aesthetically pleasing
  • maintenance free
  • long lasting
  • less prone to predation
  • less prone to temperature variations
The paper does not address species that prefer open-fronted nest boxes or nest boxes suitable for mounting externally.

Photo: Hugh Hastings and the Duchy of Cornwall
The main thrust of the paper is to counter the current tendency to provision large numbers of sparrow terraces. There is mounting anecdotal evidence that they have very low occupancy rates and that House Sparrows prefer Swift boxes.

A one-size-fits-all policy is not only more effective, it simplifies things for ecologists, planners and builders.

Further, whereas Swift boxes can accommodate House Sparrows, Tree Sparrows, Blue Tits, Great Tits, occasionally House Martins and, with a larger entrance, Starlings, sparrow terraces cannot accommodate Swifts.

You can download the paper here: PDF
There is an extended version of this blogpost on Mark Avery's blog

Tuesday 15 September 2020

Carlton Marshes Nature Reserve

Suffolk Wildlife Trust have built a new visitor centre at Carlton Marshes Nature Reserve. 8 S Bricks have been built in to the timber-frame construction, by making entrances in the wooden cladding.

Steel plates surround the entrances to deter woodpeckers and starlings from attempting to enlarge them. The nest chambers penetrate 50mm into the insulation which is insufficient to cause any heat loss problem.

From their website: "Carlton Marshes lie in the Waveney Valley at the southern tip of the Norfolk Broads and is part of the Suffolk Broads. It comprises a jigsaw of grazing marsh, fens, peat pools, short fen meadow, tall fen (called 'tall litter fen'), dykes, pools and scrub. Mostly man-made, these habitats have developed over hundreds of years of traditional management and now host specialised wildlife."

S Brick dimensions. The opening is enlarged to allow some positioning tolerance

Computer model showing S Brick embedded in insulation

Photo credits below to Steve Aylward, Head of Property & Projects:

S Bricks installed waiting for cladding

Cladding installed with entrances in place

Steel entrance plates installed

Entrances to 8 S Bricks

Sunday 23 August 2020

Effect of nest box width on wing bending

A swift's wing length is about 170mm, thus any box with a minimum dimension less than 170mm will require the swift to bend its wings in order to turn. This post is a brief analysis of just how much a wing needs to bend for a range of box widths.

A number of nest boxes on the market have a minimum dimension of 100mm, which requires a wing to bend over 180° in order for the bird to turn.

The following charts illustrate the relationship between. box width and degree of bending. These are calculated with an idealized assumption that a straight wing would bend into a circular arc. Of course, most of the bending and wear will be concentrated nearer the wing tip which might be worse than it being uniformly distributed along the wing length.

Swifts will nest in boxes 10cm wide, but the wear to their wingtips after a whole season of turning in such boxes is unknown.

Relationship between box width and bend angle
The range of shapes for different box widths. All of these lines are the same length, 170mm.

Thanks are due to Mark Smyth for these videos showing a Swift turning in a 10cm wide nest box:


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Sunday 2 August 2020

Swifts inside PVC soffits

Open eaves, with breeding Swifts, are frequently turned into closed eaves with PVC soffits. This is an example of such a project in Cambridge in 2020.

The pictures below show 5 neat holes in the Soffit of Gray House, a block of flats in Cambridge. Holes 1, 3 and 5 have an S Brick eaves box above them which contain any birds that enter these holes and they act as a barrier for any birds that might enter holes 2 and 4. There is a total of 8 S Brick eaves boxes in this building with 10 spaces for swifts.

You can read about the S Brick for closed eaves here:

This includes a link to instructions on how to make a neat entrance in a soffit

5 neat holes (click to enlarge)

There is an eaves box above the left hole,
nothing above the right hole

Thursday 23 July 2020

Lancaster Royal Grammar School

Paul Worden  (@paulworden2015) is employed as a site manager at Lancaster Royal Grammar School where there is a wide range of buildings dating from 1852 to 2011. Paul has sent us a simple way to install Swift boxes in an old stone building. There are often situations where no off-the-shelf swift box product is suitable, and a custom design is needed. This is an example of one such case.

Back in 2017 we were approached by a local member of @LancasterSwifts to see if we would be interested in installing external nest boxes in the hope of attracting swifts to our site, although no expert I have always had a keen interest in birds so I soon took up this offer of help from the local group who arranged the supply of the boxes.

The eight boxes were installed immediately along with a speaker and MP3 player so we could hopefully attract the birds for 2018, but although many swifts entered the boxes none have nested in them as far as we know but starlings have occupied a few of them.

Last year 2019 we had a major refurbishment of our 1852 building that required scaffolding to be erected in order to carry out some of the work so while this was in place I took the opportunity to provide more nest sites in the hope of attracting more birds.

Scaffolding provides a perfect opportunity
I  looked at many external boxes but I came up with a much simpler and cheaper idea that would last indefinitely.

I simply removed some stones from under the eaves that were not load bearing by drilling around the motor joints and pulling them out, removed all the rubble from inside, inserted a budgie nest bowl along with a small camera in one of the boxes and then boarded up the front with some external plywood held in with some clear silicone. I also moved the MP3 player to this building and played recordings that almost instantly attracted many birds to have a look.


Then this year as the birds returned and the MP3 player was turned back on I noticed the birds were soon flying up to and on occasions into the nest site. Then in May the first egg could be seen on camera soon followed by a second one but sadly that must have remained unfertile but today we have a very healthy looking bird that I’m sure is going to fledge in the next day or so. I’m also confident the other 4 nests have young given the activity in and around them.

I never thought such a simple and cheap job can bring so much reward so I will be adding more around the site when I can.

The following pictures describe how it was done:

Select a stone for removal

Furnish the inside with nest form and camera

Provide a front with an entrance

First happy occupants

Saturday 11 July 2020

Rutland Swift Boxes

Tim Collins lives in a village just 3km from the shores of Rutland Water. In the last 17 years, he has built a thriving colony of 26 pairs of swifts in DIY nest boxes of his own design.

Tim's success is down to a combination of his proximity to a major source of food, and clearly the Swifts like his nest boxes. Tim's nest boxes are notable for their extreme simplicity - a simple box with a bottom entrance next to the wall. It is not even a complete box as it has no back. The version that goes under the eaves has no roof either.

While Tim’s boxes are all bottom opening, the design could easily be adapted to be front opening if you believe the swifts in your area prefer that design. An interesting experiment for a new colony would be to install a mix of front and bottom opening boxes and see which are occupied first.

In Tim's own words:

The 'Rutland' Swift Box
Unlike most other swift nest boxes the 'Rutland' swift box has its entrance hole in the floor of the box. This may look odd to human eyes however people don't think like swifts or know what swifts are looking for when searching for a nest site. The design has been developed from experience gained since 2001 at a growing nest box colony in a village close to Rutland Water. Our swifts really seem to like these boxes; the more we put up the more breeding pairs we attract.

The Rutland Swift  box (click image to enlarge)

The box is designed to mimic the appearance of many 'natural' nest sites in older buildings, such as the gap between fascia boards and the walls of the house, that require the swift to make a final upwards approach to the entrance hole. It initially drew on some suggestions in an old edition of the British Trust for Ornithology (BTO) nest box guide however we have evolved the design as we expanded our own swift colony (all in nest boxes). In 2020 we had 24 pairs breed in these bottom opening boxes, so in this part of the country it is clearly a design liked by swifts!!

The Design
The nest boxes are simple to make and install under the eaves of a house. The basic design is effectively only a 'half box', sealed at both ends and makes use of the wall of the house and the existing soffits to form its back and roof. Our own boxes are made from planed softwood timber however you could also use marine plywood. Once built the exterior of the box is painted, ours are white as this matches the colour of our house's fascia boards and soffits. White is also the best colour to use if the box will be exposed to direct sunlight as it helps reflect light and so reduces the risk of overheating. If you do decide to paint your boxes it is also worth using good quality exterior grade primer, undercoat and gloss as experience shows that this wears better and so reduces repainting requirements.

Basic materials:
A planed softwood plank 19 x 144mm x 1800mm (readily available at most DIY stores)

Panel pins - 40mm - used to do the initial fix as the box is assembled, can either be removed or driven home with a nail punch and the hole filled with wood filler.

Brass screws - to hold the box firmly together
Right angle brackets (ideally plastic coated or brass to avoid rusting)

Cutting List (all cut from the 19 x 144mm wide plank)

1 x 500mm
1 x 540mm
2 x 144mm

The precise length of the box is flexible and individual boxes should be tailored to match the available spaces. It is however worth remembering that prior to fledging young swifts like to stretch out and exercise their wings; as swifts have a wingspan of 42 - 48cm a box length of about 50cm is a good choice. It is perfectly acceptable to make the box smaller if that is the available space; Swifts often nest in really small spaces. The images below show both the basic design and a variation on it.

The size of the entrance hole is important (to avoid other species such as starlings intruding), we've tried various shapes and have now settled on a 28 x 65mm slot; this is easily cut with an electric jigsaw (but can be done by hand with a fretsaw). The entrance hole is placed at one end of the box, we find it best to locate it so as to maximise an open approach to the box (away from any drainage pipes or chimneys)

Once finished the box is fixed to either the wall or the soffits with right angle brackets.

Rutland Wall Box
This variant is for cases where there are no suitable eaves. It is a good idea to give the roof a water-proof coating of some sort.

Rutland Wall Box

Tim Collins
June 2020

Thursday 18 June 2020

Swavesey Memorial Hall

Swavesey Memorial Hall was built in 1919. It has a number of Swifts and House Sparrows breeding under open eaves. As part of the Over and Swavesey Swift Conservation project, we devised a way of adding more nest boxes on the gable.

The gable faces NW
The challenge is to do something that does not compromise the appearance of the building. The eaves of the gable are about 170mm wide and over 200mm deep, so there is plenty of space to hide some nest boxes out of sight.

4 double boxes
The design is a simple shoebox, installed sloping parallel to the eaves, but with a horizontal nest platform at the bottom of the slope. 4 double boxes were built, 2 for each side of the apex.

The slope is grooved to give the swifts some grip. The result is not unattractive and achieves the goal of preserving the appearance of the building.

The team was Bill Murrells, Bruce Martin and Dick Newell, with John Stimpson helping with minor adjustments.

8 nest chambers ready for Swifts or Sparrows

Design drawing

Wednesday 10 June 2020

A neat renovation in France

Some time ago, we sent some half-brick entrance pieces to Carolyn Knowlman ( for a project in Amboise. Following this, an opportunity arose during a renovation, where some existing swift nest sites were under threat.

Offcuts used to make entrances
Rather than use entrance pieces cast out of concrete, the stone mason used offcuts to make his own entrance pieces.

The nest sites inside were preserved with a very acceptable end result on this beautiful house.

House Sparrows have already moved in to two of the entrances, but it is not known yet if the Swifts have returned to the 2 nest sites that they previously occupied.

Before and after the renovation

Close up of an entrance piece

Another close up

Spot the boxes

Tuesday 2 June 2020

Eight S Bricks in 6 hours

Century House, Swavesey was reroofed 2 years ago. As a result a number of Swift nests were lost, and the roof was left in a state that Swifts could get into the roof space, resulting in some fatalities.

As part of the Over & Swavesey Swift Conservation Project, organised by Helen Pletts, it was decided to insert 8 S Bricks in the gable. It is a solid wall with no access inside, so everything had to be done from the outside. The bonding was somewhat irregular, so we had to make sure we chose stretchers to be removed which had a good chance of being aligned with the stretcher behind it. This was achieved by choosing stretchers adjacent to a header.

It was straightforward removing the outer stretcher, as the wall was constructed with soft lime mortar. In order to get hold of the inner stretcher, a handle was screwed into it to enable pulling it out. We had to be careful that nothing would fall onto the false ceiling inside.

Tailored S Bricks were made to fit this non-standard (Imperial) brick size. The backs of the boxes were coated in a layer of silvered insulation material to give some level of protection from heat from an uninsulated roof. For this project, the brick slips were  made by the Swavesey Sheddit group, a volunteer mental health workshop support project.

No other product on the market would have been practical in this situation.

The cherry picker was hired from Anglia High Access Ltd, who did a great job removing the bricks, with Bill Murrells, Action for Swifts, installing the S Bricks. From start to finish it took 6 hours

The project was funded by South Cambs District Council.

8 tailored S Bricks

8 bricks removed ready for 4 S Bricks

Bill Murrells fitting an S Brick

8 S Bricks installed

Overview shot

Sunday 5 April 2020

Shepcot House Swifts

There is very little research on acceptable parameters for Swift nest boxes, so we have to rely on anecdotes. This is an example of Swifts nesting in a very small space indeed, perhaps giving a lower bound on what Swifts might find acceptable.

We are grateful to Catherine Day for talking about Shepcot House at the Bristol Swift Conference, Nov 2019 and to Mike Priaulx for the pictures and the information below.

Andy Potter - local Swift enthusiast

Shepcot House in Enfield is due for renovation, but it already housed a thriving colony of 27 pairs of Swifts. These birds have lost their nest sites, but 68 Ibstock Swift bricks in the new development have been provided, installed with the guidance of an ecologist (Middlemarch Environmental) during 2019
(see and search for 'shepcot')

The Swifts have been nesting in spaces 4cm high x 6.5cm deep x 26cm long behind the panels. They nested in the slots from the 2nd slot up in the picture on the left. The lowest slots with breeding Swifts are estimated at a little over 4 metres.

One of the slabs has fallen off allowing close inspection of the space behind, as in the pictures below.

Some of the panels have swifts nesting at both ends of the panel. Others are not used, and may have less space behind.

Most of the occupied panels face due south, so the panels must provide a degree of thermal insulation. The south elevation has the most open aspect and the unhindered flight line seems to be a factor.

There seemed to be no record of this Swift colony prior to it being highlighted during the construction works, so it is not known how soon these buildings were colonised after their construction during the 1960s.

There was a planning condition for nestboxes but the new provision by Countryside Properties has been voluntary, based on the ecologist's advice.

Here is a link by the developer:

[Also of relevance is this post about Swifts breeding in a House Martin's nest :]

The Swifts did not nest in this slot, as the front slab had fallen off
Slot height is a little over 4 cm
Slot depth is about 6.5 cm

Saturday 4 April 2020

Face-plate Swift box

Swift boxes are normally thought of as 'external' or 'internal'.  John Crowther of Stroud wanted to retrofit swift bricks into his stone walls.

When John removed a stone, he found that there was no cavity and the space created was L 290mm x D 125mm x H 100mm. First thoughts of fitting an S Brick would have reduced the 125mm depth to about 100mm, which might have been enough space, but a 10cm depth for a bird with 175mm wing-length is a bit of a squeeze, though Swifts can nest in a space this small.

As we wanted to give the Swifts a little more space, and John preferred not to install another external box, we compromised by making 2 face-plates to close off two spaces. At the same time we added 12mm to the 125mm giving an internal depth of 137mm. Though not as unobtrusive as an internal Swift brick, it resulted in a neat solution.

To keep water out of the nest chamber, there is a layer of sealant between the face-plate and the wall

The material, 12mm MgO board, was left over from the stand we shared with Genesis Nest Boxes at Futurebuild - now a 4000-bed hospital.

The following pictures illustrate the concept:

2 face-plates showing outside and inside

One stone removed and face-plate installed

Wednesday 12 February 2020

S Bricks in a rendered wall

This is the end result of the project reported here: 

S Bricks do not have enough headroom to house a camera, which is why 4 out of the 10 Swift bricks in this project are a custom design.

The 'before' picture: the hip roof in the middle is to be converted into a gable

S Bricks installed
4 custom camera boxes installed
The 'after' picture: 6 S Bricks and 4 custom camera boxes installed

Sunday 9 February 2020

A solution looking for a problem

This is a bit of fun. We were presented with the problem of a building in Swavesey with Swifts nesting on top of the wall in a high gable. The Swifts are sometimes getting into the building, occasionally found dead.

The owners do not want to lose their much-loved Swifts. There is no way to get at the inside of the gable to block their entry. So the solution seems to be to provide alternative nest sites in the same gable, then block the entrances on the outside.

It is a solid wall, with headers and stretchers. So we came up with the idea of removing a header and then inserting a configurable nest box as described in this animation:

                  [Hit (ctrl) > loop to make it loop] 

The overall dimensions of the nest box, with the slider retracted is 30cm x 12cm x 8.3cm.
A simple box this size would give an internal floor area larger than an Ibstock Swift brick, but slightly smaller headroom. Although this would have been an option, we wanted to give the Swifts more space.

Having built a working prototype, we have now discovered that there is no insulation beneath the recently re-tiled roof, which means the roof space would get dangerously hot.

We are thus reverting to a plan B, which will probably be S Bricks with an insulated back embedded in the wall.

Saturday 11 January 2020

Modified Schwegler 1MF

The Swifts Estate nest boxes in Fulbourn Cambs are one of the most successful projects in the UK: 276 nest boxes in 250 dwellings are home to 100 pairs of Swifts, together with House Sparrows, Great Tits, Starlings and House Martins.

The nest boxes comprise 168 custom made internal boxes and 54 Schwegler 1MF double boxes (108 nest chambers). However, 90% of the Swifts are in the internal boxes with only a handful in the Schwegler 1MF's. (See here for internal nest box design).

2 internal entrances near the top of the gable
and the modified Schwegler 1MF. The other side
of the gable is a mirror image (click to enlarge)
So we mulled the idea of modifying the entrances of the Schwegler 1MF's to be more like the internal boxes.

Andrew Tristram, who lives in another part of Fulbourn also had 2 Schwegler 1MF's on his gable, which attracted breeding Starlings. He reduced the entrance size and played Swift calls, but still no Swifts. We then installed 4 Cambridge System internal boxes inside the roof space, and 2 pairs of Swifts moved into them.

As an experiment we then made 2 new entrance plates for the 1MF's with horizontally facing entrances, with a similar appearance to the Cambridge System entrances.

Although it is too early to draw firm conclusions, 1 pair of Swifts moved into 1 of these modified boxes. We intend to replace more of the 1MF entrances, but we need to wait another season to get any more data, so we thought we would publish this now.

Saturday 4 January 2020

The Swift Micro Caller

Graham Fell of Kendal Swifts has discovered some amazing new technology: an MP3 player costing less than £1. 

Together, and with others, we have been trialling it and so far we believe that it is a viable, very low cost solution. There are many vendors selling this piece of kit; try googling "TF card U disk MP3 Format decoder". It comes as a printed circuit board, there is no housing, you need to supply your own.
You can plug calls in on a USB memory stick to the U disk port, or on a Micro SD card into the TF card port. The tweeter should be connected to the 3W Speaker port. The system is powered with a Micro USB cable compatible with a mobile phone or Kindle charger (not iPhone).

Our analysis so far:
1. Volume is not quite as loud as Cheng Sheng/Kinter type systems at maximum volume, but it is loud enough for most situations. Usually one turns the volume down on these other systems.
2. Sound quality is good, with no distortion at maximum volume.
3. Control buttons not as convenient as control knobs, but not difficult to use.
4. There is only one speaker port (2 on a Cheng Sheng). We have not tried connecting 2 tweeters in parallel to this port.
5. We don't know yet what the Swifts might think of it [Update: we have attracted Swifts into boxes.]
6. It seems to consume a very low amperage, so we are testing to see whether it is feasible to run for a whole season on a single battery charge, without solar panel.

For a complete system, you need:

The TF card
USB memory stick or Micro SD card with calls in MP3 format
Micro USB cable (£1 from Pound shop)
USB mains plug 
Tweeter and speaker cable

You can probably buy all this for  less than £10

And you need a 240 volt timer. We recommend a digital timer as it does not need resetting after a power outage.

As an interim we have made some housings on a laser cutter. as in the following pictures. For this illustration we have a short speaker cable, you may well need 6 metres or more:

Micro Caller with Micro SD card
Micro Caller with USB memory stick
With power on and a USB memory stick or MicroSD card inserted, the Micro caller will start to play, cycling indefinitely through all the tracks.
To increase volume: continuously depress the Next/V++ button
To decrease volume: continuously depress the Prev/V-- button
To move to the next track: short press on Next/V++ button
To move to the start of the current track: short press on Prev/V-- button
To stay on the current track: press Repeat
To revert to cycling through all tracks: power off and then power on again.