Nest box for alpine swift

The common swift ( Tachymarptis melba ) is the largest swift species found in Spain. Its crossbow-like shape—hence its Catalan name, "ballester"—is characterized by long, narrow wings and legs so short they prevent it from landing on the ground. It is easily recognized by the white markings on its belly and throat, separated by a brownish collar.

This bird is present on the peninsula during the summer, arriving in March from Africa, where it spends the winter, and leaving in October. As an efficient insectivore, it plays a key role in biological pest control. It nests in crevices and cavities in rocks and buildings, reusing the same sites each year and rebuilding its nests when necessary.

Since modern buildings offer few suitable nesting options, installing nest boxes makes it easier for the common swift to find safe havens for breeding and raising its chicks.