Nest boxes for Common Swifts
Common Swifts are cavity nesters. They are in Germany roughly from the end of April to August, in individual cases until September. Their nesting sites are legally protected all year round. Common Swifts are synanthropic birds, which means they nest in human settlements, often unnoticed. "Naturally" they breed in niches in buildings, which means that their natural breeding sites are mainly on tall, old buildings and industrial premises, since new buildings and buildings that have been given energy-efficiency refurbishment have too few natural openings. They breed in dark cavities in the roof cornice, under or behind gutters, in holes in walls, under window sills, in leaky roller-shutter boxes (with the shutters still in use or not), but also behind facades or roof cladding, for example on flat roofs. Their entrance holes can be very small, and they are not always visible from below. Often you can only spot them by watching the birds approaching and entering in the evening hours. Natural breeding opportunities are dwindling more and more: refurbishment work, re-roofing, so-called pigeon repellent paste, pigeon spikes and a lack of knowledge of the law as well as a lack of awareness of the problem make it ever harder for building-nesting species such as Common Swifts to find a nesting site, lay eggs and hatch and raise their young. Common Swifts live to a great age – the fact that they are no longer there in summer is only noticed once the swifts have died and no young have grown up to replace them.
Common Swifts are birds that feel at ease in a group. They like to fly in flocks and to breed in colonies. It is no problem for them, and rather an advantage, if several nesting sites are available close together. As a general rule: Common Swifts can only be settled where swifts are already flying. After all, they also have to be able to discover a breeding site.
They prefer dark cavity entrances (no Common Swift, however small, can resist a "cavity"), they prefer nest sites with dark hollow spaces, and they need to be able to fly in directly. Common Swifts will only approach a site where there is a way in from below or from the front.
Common Swifts fly up to the nest entrance directly from below, so there should be a clear approach height of at least 5 metres.
If you want to install new nest boxes, you should bear the following in mind.
As a basic principle: to avoid soiling of the facade or keep it to a minimum, the entrance holes should be at the front and not underneath the nest box. The Common Swifts need at least 5 m of clear space below in order to be able to fly in. It should be possible to observe Common Swifts in your neighbourhood. The ideal nesting site faces east, north-east or north, so that the sun does not beat down too strongly in summer and the temperatures inside the box remain bearable. Many different models are commercially available, suited to the various possibilities a house offers. You can also build a box yourself, or deliberately create a nesting site in a new build or conversion.
Nest box mounted externally under the eaves © C. Haupt
Nest box mounted externally on a flat roof © C. Haupt
Artificial nesting sites should not be too small!
Bear in mind that Common Swifts have a wingspan of around 40 cm. They can raise 1 to 3 chicks. Young Common Swifts look out of the nest box at the world below them. They also do "sit-ups": they push themselves up with the help of their wings and thus train their breast muscles. That means they need a certain amount of space. The fact that Common Swifts today also breed in very small nesting cavities is partly because we are taking more and more space away from them. Small nesting sites store more heat, and in great heat young Common Swifts are then presumably more likely to jump out. So choose spacious nest boxes.
Common Swifts breed in the rear part of the cavity corner, i.e. in a box in the diagonally opposite corner. They prefer plain nests; a nesting hollow about 1 cm deep and 10 cm in diameter helps them make a start. They carry hardly any nesting material into the breeding site; instead they glue the small nest together from material collected in the air. Please do not put artificial wooden nests into the nest boxes.
© Eva Brendel
Make sure that sparrows and starlings (likewise specially protected bird species and building nesters) cannot occupy the boxes first; they build different nests from different materials, and Common Swifts can get caught in the nesting material brought in this way and strangle themselves. A starling guard is useful here. If you are able to reach the nesting sites, it makes sense to close them in autumn after the birds have left and to open them again only at the end of April. We recommend installing the nest boxes in such a way that you can reach them.
It makes sense to open and check the nest boxes after the Common Swifts have left. Remove all material that Common Swifts do not use for nest-building and that is filling up the box. Above all, remove plastic, string, eggs and dead birds. However, no toxic substances against parasites should be used to clean the nest box. A natural Common Swift nest is spartan. They collect exclusively material that is carried to them in the air and glue it together with saliva into small, hard nests that are used year after year.
This is what natural Common Swift nests look like:
© Eva Brendel
Corvids are increasingly specialising in Common Swifts arriving at and leaving their nests. Make sure that corvids such as magpies cannot land directly on the swift box, for example by giving it a sloping roof.
Earlier recommendations that Common Swift nest boxes should not or need not be cleaned can no longer be upheld. Every year we care for strangled Common Swifts; every year there are reports of nest boxes so clogged up that Common Swifts can only lay their eggs in the area of the entrance hole; every year there are reports of birds found dead in swift nest boxes because they could no longer free themselves from the material that had been brought in. The shortage of nesting sites for building nesters is severe – they now compete for every spot, including unsuitable ones.
Together with a woodworking workshop we have developed a nest box for Common Swifts; you can find details here: Nest boxes from JVA Heimsheim
"Villa Apus" weighs 5.8 kg, is solid and sturdy and is made of solid timber sourced exclusively from sustainable forestry. © C. Haupt
The interior. "Villa Apus" is supplied with an integrated starling guard (front left), with ventilation openings (top) and with a milled nesting hollow (back right). © C. Haupt
Building instructions can be found on the internet.
Further nest boxes are also available from Holzwerkstatt Sassen.
In new buildings, discreet hollow blocks can be incorporated into the wall, creating a swift home very easily © C. Haupt
An opening through the wall can also be made afterwards, with a nest box fixed behind it © C. Haupt
Death trap loft: 2 Common Swifts that died of thirst; they found a way into the loft, but not a way out again. © C. Haupt
But: never simply install ventilation tiles, never simply create an opening for birds to fly into without fixing a nest box behind it! By doing so you turn the space behind that opening into a death trap which Common Swifts can get into but can no longer find their way out of.
In new builds, conversions and energy-efficiency refurbishments you can also, with timely planning, deliberately replace nesting sites in such a way that from the outside only the entrance hole is visible. There are special boxes that can be fitted beneath the insulation, but it is also possible, for example, to use special hollow blocks.
If you already have Common Swifts on your building and now want to have the roof re-covered, or carry out a facade refurbishment, or are planning an energy-efficiency refurbishment, you must bear the following in mind:
Common Swift nesting sites are legally protected all year round. This means that even if you have the work carried out between September and April (when the Common Swifts are not in Europe), you need a permit (in Hesse: from the lower nature conservation authority). During the breeding season such work is out of the question in any case. A Common Swift brood is protected by law. Common Swift nesting sites must also not be filled with construction foam, closed off with wire baskets, obstructed by scaffolding or destroyed by other means. In summer it is not an abstract date that counts, but the actual presence of Common Swifts. Not all Common Swifts have finished raising their young by the end of July or mid-August!
If you want to or have to create replacement nesting sites, note the following: Common Swifts are extremely site-faithful and very conservative. They use a breeding site all their lives and find it very hard to adapt if they lose it. Every year breeding pairs fly to exactly their own entrance. If in doubt, they will neither see nor take any notice of a box three metres away. Unfortunately this also means that, if in doubt, they notice too late that the long-established entrance is closed and injure themselves as they fly in. Common Swifts fly very fast, including when approaching the nesting site. The resulting approach injuries are correspondingly severe.
A way in at the very spot where the entrance used to be is ideal. Otherwise, give preference to corners and niches that Common Swifts readily accept: under the roof overhang; where gutters meet the downpipe, …
When choosing a nest box, please base your decision on the conditions on site. Otherwise, what was said above applies.