In 2012 Ferrovial signed an agreement for construction of the Padornelo Tunnel, in Zamora, as part of the high-speed rail line (AVE) project linking Madrid and Galicia. This section is one of the most complex of the high-speed Madrid-Galicia line because of the rugged landscape and the unspoilt nature of the area. So much so that building works have uncovered another site of some 20 nesting pairs of sand martins in a sandy embankment. Ferrovial Agroman is experienced in this type of situations, and works with the Spanish Ornithological Society (SEO/BirdLife) to protect this species. With this aim in mind, the company has kept works within the vicinity of the colony to a minimum. This trans-Saharan migratory bird establishes its busy colonies almost exclusively on the embankments of rivers or gravel, where it digs tunnels for nesting. Populations are currently dropping, and the sand martin is now protected at an international level, having been added to the List of Wild Species of Special Protection Regime.