Good intentions gone bad

Common swift entering a roofing tile

Common swift entering a roofing tile


When working on biodiversity the power of the sum of efforts that individuals put in, matters a great deal to the outcome. There is however a chance for these good intentions to turn out bad, resulting in a negative influence on exactly that what was supposed to be facilitated.

Examples of this can be found in your local garden center. The increasingly popular roofing tiles used to facilitate the common swift (Apus apus) in its nesting preferences, ask for a more thought through placing than one might expect. Numerous fatalities have been reported as a result of overheating after use of the tiles. Modern rooftops are often much less steep than rooftops which used to serve as the swifts nesting spots, the tiles are laid tighter and ventilation is too low. Roofing tiles that are placed in this way, can result in overheated nests up to over 60°C on a sunny day. It kills the young swifts, or it gets them to flee which also results in death most of the time.

So how should these tiles be used to actually serve their purpose? Only use them on roofs facing north and angled over 45°. Place them in the middle of the roof to facilitate entry and to reduce chances of overheating. Make sure no vegetation or other objects are blocking the flight route to- and from the entry. Don’t place the tiles when a flat surface is present less than 3 meters below the tiles, birds flying out often lose altitude before reaching speed. Place multiple nesting tiles in close proximity to facilitate colonies and ventilation. Place the tiles in an irregular pattern, this makes the entries easier to find. And finally, provide nesting material to gain maximum efficiency.

Cases like this underline the importance of research on the efficiency of methods which are used to facilitate nature. Without sufficient knowledge not only money will be wasted, but also lives and biodiversity.

More information (in Dutch)
Bouwen voor gierzwaluwen. Informatie voor de bouwwereld.