One of the simplest ways to help swifts is to keep your eyes open.
Is scaffolding being erected somewhere in your neighbourhood between May and the beginning of September? Perhaps it is even being draped with netting?
This may be a death sentence for young swifts!
Watch out for parent birds desperately trying to reach their nest – blocked by the scaffolding and netting – in order to feed their young! If this is the case, you must intervene at once. First of all, speak to the construction workers calmly and politely and ask them to remove the netting along the roof cornice. Often this is enough on its own to make access possible again. In some cases, however, scaffold boards may also have to be removed if they are obstructing the birds' entry.
Should your request be refused, contact the local nature conservation authority (Untere Naturschutzbehörde). Insist that staff come to the site without delay to assess the situation and order the necessary measures.
But things need not be that dramatic at all. Perhaps you will simply spot an ideal place to create a nesting site.