Threats & Mitigation

The success of mitigation measures depends largely on the ability to retain existing nest sites or to recreate nest sites in exactly the same position as those lost


Threats to nest sites may be temporary or permanent.

Temporary threats usually take the form of scaffolding or disturbance during the nesting season.  While swifts can negotiate open scaffolding if it is constructed with them in mind, netting prevents all access.  

Permanent threats range from the complete destruction of the building where they nested to minor repair work like repointing stonework or repairing loose tiles. Although complete destruction is usually non-negotiable, demolition can at least be timed to avoid loss of active nest sites. The swift species action plan requires that demolition should not take place between May and August where swifts are known to be or suspected to be nesting.

Other threats can be either designed out altogether or mitigated by replacing lost nest sites as close as possible to those lost.

The scale of the threat in any one instance varies depending on whether the buildings are in public, corporate or private ownership. Huge areas of redevelopment pose a greater single threat but are easier to identify and to mitigate by dealing with one or two key people. Piecemeal repair and development by individual house-owners offer a less serious immediate threat but may be harder to identify and mitigate unless the owner is sympathetic.


The success of mitigation measures depends largely on the ability to retain existing nest sites or to recreate nest sites in exactly the same position as those lost. Recreating nest sites even six inches away from the originals, fails to keep the swifts.

Here's a selection of common threats with mitigation measures:


This 1940s tenement block in Gartloch Road Glasgow was demolished in late July.

Demolished during the swift season
There were swift nest sites here and it had been promised that demolition would be left until mid-August at least.

As this was before the passing of the Nature Conservation (Scotland) Act 2004, we could not take action. Under the previous Wildlife and Countryside Act, “intention” to destroy would have had to have been proven. There was however a visit from the police to the company.

row  of house due for demolition
The end of a colony in Port Glasgow, 2016. There's been no sign of them in adjacent buildings
Demolished buildings
There was no threat to “live” nest sites as demolition took place in early spring. As a result, returning swifts had nowhere to nest and are now gone from the area.


It is possible to install swift nest sites on adjacent buildings and hope that the swifts find them. However, unless someone is prepared to play swift calls for at least one season this has not yet been known to work (around Glasgow at least).

Install swift nest sites in new buildings on the site. Of course there will be a time-lapse and to have any chance of swifts using them, it will be necessary to play calls, so unless it is either a publicly-owned building or a new resident is interested in helping out, this will not work.

An unsuccessful case

four swift box embedded in the brick work
Swift bricks installed in Scotsburn Road, Barmulloch, in 2012, after buildings which contained swift nest sites were demolished. No swift sitings to 2017.

A successful case

Swift boxes attached to new building
Due to the commitment of the manager of Pentland Housing Association at the time, these nest boxes were placed on a building replacing a demolished building in Thurso, and calls were played the following season. Some boxes were used by swifts (and some by sparrows).  

( see also "some of the best")

Complete Renovation - building conversion (e.g. from older building to flats)

This can be a temporary threat if managed properly.

The biggest renovation threats are often carried out by Local Authority Housing or by Housing Associations and involve new roofs, fascias, windows, harling and rough casting.

During conversion, usually all pointing is renewed with enthusiasm, all old gaps in stone or brick-work filled, roofs are renewed and pipes replaced, leading to total and permanent loss of nest sites.

Conversion mitigation

With some forward planning, mitigation measures can be successful and exisiting nest sites retained.

Any building should have been thoroughly surveyed for bats and birds in any case. If not, ensure that this is done in the appropriate season (conversion projects do not happen urgently!). Swift nest sites can be noted, marked and retained within the conversion and, if possible, new ones created too!

Simple plywood nest boxes might be provided inside if internal works are likely to change the space inside the building.

See also Linlithgow distillery site.

Complete renovation, building conversion (e.g. from older buildings to flats, can be temporary if managed properly)

converting old building into flats

Kilpair Street in Haddington - where by accident or design, gaps in pointing were left under the eaves. We do not know if swifts still nest there however.


This style of tenement is typical of the peripheral estates of many Scottish cities, and I believe that we have lost hundreds of nest sites due to their renovation over the past 15 years, and the covering of the concrete lintel with PVC fascias. The irony of course is that the demolition of the old tenements which these buildings were built to replace probably destroyed even more swift nests – but we do not have records of that period.

local authority flats in Drumchapel
Castlemilk Drive before renovation, with swift nest sites over concrete lintels
local authority flats after renovation
Same street after renovation: new roof and PVC fascia = no swifts
Retro-fitted swift box
Provision of retro-fitted “shoe-box style" nest boxes. So far provision of this style of nest boxes on these schemes has not been successful. Glasgow Housing Association (GHA) has installed in the region of 70 nest boxes over the past ten years. So far none have been used (by swifts).

Renovation - roof repair/replacement - Pantiles

Apart from disturbance during work pantiles are now normally blocked at the ends with a lump of mortar precisely to prevent birds and insects getting inside the spaces.

scaffolding blocking swift nests
Roof renovation in St Andrews. The contract specified that all ends were to be sealed.


It is possible to leave at least some ends open. We have no examples of this being done intentionally.

Swifts under the pantiles
I believe that the open ends at this scheme in Haddington are an accident rather than intentional but swifts were happily nesting there in 2015.

Renovation - roof repair with flat tiles

This is is a common cause of loss of nest sites on the continent, when pantiles are relpaced with flat tiles .
swift nest tiles
The Dutch manufacture these purpose-made tiles which come with a nest box at the back of them.

Repairing broken roof tiles

A frequent cause of loss of swift nest sites, where swifts have been gaining access via broken or displaced tiles. This happened in Motherwell when some four-storey 1950s tenements were renovated.


Unfortunately there's no known measures as no one wants to leave broken or displaced tiles on a new roof. The Dutch tiles (above) incorporating swift nest sites are not yet available for purchase in the UK either.

Renovation, repair or replacing of ridge tiles

Swifts have been seen often nesting under ridge tiles where they were made of clay, and where gaps were sealed with mortar, which wore away over time.

Loose mortar opens doors
There was a swift nest site under the ridge tile here but it was lost when the buildings were renovated.

A successful case

bespoke swift nest solution from end capping
One project successfully retained a long-standing nest site by cutting out a slot in the end capping tile – the Marley tile is especially well adapted for that as it has a moulding of exactly the right dimension.
The bespoke solution in place
Clearly it is important to ensure that there is a large enough space behind the capping tile and below the ridge tile for swifts to nest.

Renovation and repair of guttering and rone pipes

If gutters or rones are being replaced, there is no need to lose nest sites, as long as work is carried out outwith the nesting season. Simply ensure that the new ones are placed in the same positions as the old ones.

roof view of flat in Glasgow
Roof repairs on Edinburgh Road, Glasgow, where the original concrete soffits had been painted and not faced with PVC. There were still two swift nest sites there in 2016.

An unsuccessful case

On this site, in Barmulloch, where there had been probably six nest sites and where I thought we would keep the swifts as the concrete lintel was simply painted (2014), we lost them. I think it is because the new gutters are placed slightly lower down than the old ones and so restrict the spaces too much – as shown below. With forewarning and care and a good contractor, it would be possible to check the eaves before the new gutters were fixed and to mark and slightly carve out the concrete at the sites of existing nests.

UPDATE 2021: 3 nest sites were seen to be being used again and swifts were managing to get in under the new soffits.

After the roof repairs flats in Barmulloch
Even choosing to paint soffits rather than clad them in PVC doesn't work if the gutters are moved
Close-up shot of tiny gap underneath a gutter
The gap beneath the gutter is now too small for swifts to access

Cladding soffits and gable ends

This is a common reason for loss of nest sites. During renovation, miles of the concrete soffits constructed in the 1930s to 1960s have been covered over with PVC fascias, eliminating the swift nest sites.

An unsuccessful case

This example shows the before and after of a gable end soffit that was clad in PVC during building re-roofing works. The original mortar pointing previously allowed swifts access beneath the tiles. Four nests were lost.

Re-roofing in itself need not threaten swift nest sites, if done outwith the nesting season, as long as the eaves are not altered. But where the fascia is clad with PVC, then the nest sites are inevitably lost.

before renovation
Soffits before being clad in PVC
After renovation
Soffits after being clad in PVC

This new PVC fascia in Barlanark covers the older concrete lintel at the eaves where swifts nested, and is a standard detail in renovation or re-roofing projects.  This is common practice, and is possibly the single most common cause of loss of nest sites (in Glasgow at least), even though the PVC fascia is not essential, as pictures of other projects above show.

Window repairs

Generally this is not a problem as long as the scaffolding does not blocks nest sites and the nest access was originally in a gap at the window ledge.

Mitigation. Leave the nest site unless it has been the cause of water ingress.


Repointing is a major factor in loss of nest sites in older and historic buildings. It is a grim thought to think how many swifts have been walled up in these repairs.

recently repointed stone building
Plugging up all the gaps leaves little opportunity for swifts to get in (or out)

An unsuccessful case

A beautiful job but the swifts have been overlooked
Repointing at Selkirk Museum. Sparrows nest in the adjacent building, so perhaps swifts do too.


Note and retain swift nest sites and create a few extra possible ones. There is no need to repoint the top course of stone-work too rigorously. It is usually protected from weather by an overhanging eave or gutter. A few gaps in the stonework do not interfere with the integrity or weather-proofing of the building.

top course of wall
The top course was left alone on this renovation of Stanley Mills, in Tayside, with the agreement of the architect for Historic Scotland. 

Addition of an internal nest box may be preferred as here at Inchture church. See also Broughton House and Haddington, Kilpair Street.

swift nest box
This swift box was installed inside the Inchture church. Photo by D.Muir, Tayside Swifts

An unsuccessful case

All the gaps are plugged and another colony is lost
Swifts nested in Dundee gaining access under the fascia which had originally been filled with chicken wire, which had rotted allowing access to the roof space for both swifts and starlings. When the houses were re-roofed, the internal gaps were sealed with foam and another colony (in Dundee) was lost.

Renovation - minor works. New windows, rough casting, harling and painting

These works in themselves need not remove swift nest sites, so long as the entrances are not blocked off as part of the work or by new facing materials (but note also notes on scaffolding).

New buildings with special exclusion netting

Some people will go to great lengths to ensure that swifts do not get in to the building!

chicken wire over a gap in a roof
Chicken wire on a building (in Selkirk) blocks gaps previously used by swifts.


Install / create new nest sites or leave spaces for swift access.


Scaffolding can be a temporary threat as it prevents swifts getting to their nest sites. There are examples of swifts deserting due their nests to (temporary) scaffolding, but also of swifts returning after being unable to get access for a season where the sites are retained.

Scaffolding can be a temporary threat
This site lost about six nest sites due to the new fascia. Although one or two swifts hung on in other adjacent sites for a few years, there are now none nesting in the vicinity.

Loft insulation

Filling the loft space with insulation can make it impossible for swifts to nest if the material is laid right up to the eaves. Insulation should leave about 200mm clear at the edges.

loft insulation can block access
The picture shows loft insulation cut back to leave plenty of space around a nest site, which is no more than an accumulation of bits and pieces after many years. Photo taken by D.M. Insulation ltd, a company which was keen not to disturb the swifts.

However, presence of the insulation may well deter swifts from using other sites in the building. Should we be placing plywood boxes at intervals along the wall-head to enable swifts to explore alternative nest sites in the future?

Retro-fitted external insulation

Climate change politics has hastened the application of external insulation panels to existing properties.

Pic of housing type being insulated in Dundonald.
Photo of housing type being insulated in Dundonald

The application of external panels to eaves level blocks access to the swift’s original nest sites below the faschia.

Discussion is, at this time (November 2023), ongoing regarding recent projects in Dundonald and Kilmarnock managed by the Energy Agency on behalf of the Local Authorities. The Scottish Government provides substantial grant funding to enable mixed tenure External Wall Insulation projects. The council and housing associations fund work to their own housing stock and grant aid provides financial assistance to homeowners. A contribution is paid by other housing agencies or private owners. The level of contribution influences the rate of uptake.

Pic of original and insulated walls next to each other
Photo of original and insulated walls next to each other.