Swifts and bats are particularly susceptible to how human behaviour affects their breeding sites, which are very often on or in older buildings. There has been a marked decline in the number of swifts in Scotland and expert opinion suggests this is in large part due to the way new buildings are built and how older buildings are maintained, depleting nesting opportunities.

It is possible to make provision for swifts to nest in or on a building without compromising the building’s ability to withstand the Scottish weather and without any known health or hygiene issues arising. Swifts do not make a mess like house martins and swallows, or in any other way cause problems for buildings or for their occupants. White marking can sometimes indicate where a nest hole is located on a building but there is usually very little nest fouling, rarely any streaking down walls and no piles of guano below, as commonly found with hirundine species.

Sadly, the common swift is host to a biting flat fly or ked which will move quickly over the body of swifts and swiftlets and draw blood in parts which are not well feathered. Although keds can be vectors for other parasitic organisms, none is known to be able to transfer to humans or domestic pets, even if opportunity were there. The main culprit is Cratærina pallida and also c.melbae. There is another, the c.acutipennis which is found in the Congo and other parts of Africa which affects swift species but is not reported to have apus apus as a host.

As people, for various reasons, fail to maintain their buildings, they allow swifts to take advantage of missing stones and pointing or of broken timber fascias. Therefore, late repairs to building defects can make swifts homeless, unless measures are taken to provide the same accommodation as the building is made secure and weathertight. This can often be done quite easily and it should only be a last resort to fit swift boxes on the outside of the building.

Mitigating repair work for swifts can become complicated when dealing with a listed building or with buildings in a conservation area. The cost of making a planning application to permit the installation of boxes can be a deterrent to building owners and there is no guarantee that any application will have a successful outcome. The objective would be to provide a lasting breeding site, so winning a temporary consent or providing a box which is not durable is counterproductive. In urgent circumstances, "something" is better than "nothing" but, generally speaking, it is better to try to address the problem without adding to the building. Each situation needs to be taken on its own terms and we want to help people tackle these problems. To embrace life with swifts and to try to stop the decline.

The time it takes to make a planning application and a listed building consent application can work against the swifts' interests. We hope local authorities will be persuaded to take a proactive stance in situations requiring compromises and quick decisions; when there is a need to come up with a solution which fits the swifts' calendar. It would also be good to see the planning fee waived where an application is solely for the mounting of swift boxes or other mitigation works which require consent.

Last year we advised on a situation with a listed building when there was not enough time to go through the process of applying for consent and we advised cutting a "standard" swift door in the replacement soffit boards. The returning swifts will have access to their original nest, albeit by a slightly different opening and we hope this will be enough. Making an opening in a fascia or soffit means a risk of weather ingress but it can be minor or manageable, depending on the circumstances.

The particulars of every situation need to be carefully worked through, to make sure people are not creating as many problems as they solve, which includes trying to help construction professionals to understand what they are dealing with and the implications of their interventions, however well intended. Ongoing research and monitoring of individual situations will, we hope, enable building owners, surveyors and architects to be equipped to understand the particular problems they face, in order to get the best outcome.



© A. P. Rodger 2018

On wallheads like this, the timber wallplate lies more or less centrally on top of the thick stone wall and the rafters bear on this plate. The roof is closed by the timber sarking boards, nailed to the tops of the rafters. The bottom row of slates is nailed to the sarking and they rest on the outside edge of the wall with a cantilever over the rones for effective drainage of rainwater.

Note how the top of the wall head tends to be irregular, because of the nature of the rubble stonework. Also it is common to find a lime or cement render coating or harling on the outside surface of the wall, which forms a pie-crust edge at the top of the wall, on which the slates lie.

Very often the top edges of wall rendering become ragged and, if a piece of harling or render comes away, where a slate bridges the high points, it can form an opening the right size and shape for a swift to enter while not offering enough purchase for most other bird species to use the hole. These openings can seem unsightly, even if in the shadow of the eaves or rones but the people who maintain buildings often wrongly assume they present a risk of weather or creatures getting inside the building. As you can see from the diagram, anything which goes on in this space between the outer wall head and the underside of the bottom slate is outside the building envelope and, even in Scotland (famous for its horizontal rain) the weathering risk is minimal provided the rones / gutters are properly maintained.

Above is a photograph of such a nest hole. Note the chalky scuffs on the rone underside, caused by young swifts firing faeces pellets out of the nest, which can be a tell tale for established swift breeding activity.

A problem for swifts can arise when a roof is re-slated, especially when a roofing felt is used. For a number of reasons, it is not always good to use an impermeable bituminous felt but there are many builders or roofers who still do. The roofer will reslate or tile the roof in the same way as before except they will lay a roofing felt over the timber sarking before fixing the slates or the tile battens. This felt will be laid so that its bottom edge will drape into the rone. Between the sarking boards and the rones, roofing felt will sag into the space, previously available to the swifts and the felt's weight and coarse texture will prevent access.

This does not mean that felt cannot be used when reslating. However, we would prefer to see roofers use a breather membrane which is designed for situations where slates are nailed directly through the membrane such as Roofshield. This breather membrane is lighter and requires an edge support to allow it to dress properly to the rones. This edge support should be stout enough to keep the gap free for swifts. However, if it is not sufficient in the particular circumstances or if heavy felt has been used, a thin slate or a shim of metal can be slipped between the wallhead and the membrane to hold it up, off the nest cavity, as was used to good effect at Glenhead. [NB: When using Roofshield or other similar membrane, care should be taken not to leave loose and draping sections in which swifts (or bats) can catch their claws and get stuck.]



© A. P. Rodger 2018

As well as the widely available commercial products, some people interested in the conservation of swifts are designing and making nest boxes which can be used to mitigate the destruction or limiting of available breeding sites. Swift box designs are being made to suit different building types and we will try to monitor how well they work. We are also trying to develop a flat pack design based on the Zeist nest, using laser cut weather resistant Medite. One of the problems we are finding with commercially available boxes, apart from their considerable cost, is their availability. So a home grown, on demand supply will be a boon, especially when a quick response is needed. We want to run durability tests with the product first but it looks promising.

The pair of terracotta boxes made for the Glenhead byre (in collaboration with Errol Brickworks - now sadly no more) are suited to building into the masonry walls of agricultural buildings and it would be good to trial more, in more accessible locations, if a new source of clay components and willing farm owners with tall buildings can be found.

A rule of thumb for siting a box, in terms of a minimum height above ground level, is about 5m though I have seen established "natural" sites which work well at just under 4m from the ground. When planning a new site or box location, it is probably better to err on the side of caution and make it as high as possible. 5m + puts the nest above the height of most vehicles and well out of reach from the ground, except by tall ladder.

More box designs will be tested and news on these will appear in a future postings on this site.


© A. P. Rodger 2018