A twig snaps, a crow calls, but nothing moves in the dense pine forests of Spain's Guadarrama mountains. Vultures and eagles soar over the snowcapped peaks and wild boars roam the valleys below, as they have for centuries. But for the farmers who work this land, a threatening and worrying comeback is taking place in this timeless landscape, home to Spain's newest national park.

After an absence of 70 years, the wolf is back in the Guadarrama hills and breeding just 60 km from Madrid.

There have been sightings for several years of lone males, but camera traps recently picked up a family of three cubs, two adults and a juvenile. To the consternation of the farmers who believed that this ancient foe had left the hills forever, breeding packs are expected to follow. The bloody results are plain to see. In the past two months around 100 sheep and cattle have been killed near Buitrago, in the northern foothills of the Guadarrama mountains, says Juan Carlos Blanco, a wolf specialist and adviser to the Spanish Environment Ministry.