Effect of proximity to ski slopes on nest predation risk of the Pyrenean Western Capercaillie (Tetrao urogallus aquitanicus)

Abstract Mountain tourism has shown a strong increase over the last decades. One of the most important activities is skiing, which has a great economic impact on these traditionally less developed areas. However, the massive arrival of people in these habitats can have negative repercussions on the fauna of these ecosystems. An example is the highly endangered Spanish population of Western Capercaillie ( Tetrao urogallus ), which occupies a habitat that often competes with ski facilities. In view of this negative situation, nest predator control is sometimes proposed by managers as a tool to improve the populations of the endangered species. However, experiments assessing the effect of these actions have led to uneven and generally ineffective results. Furthermore, most of the Western Capercaillie's nest predators are also protected species and their lethal control poses ethical and legal limitations. We assessed the relationships between habitat structure and proximity to Nordic ski slopes with Western Capercaillie nest predation rate by monitoring 57 artificial nests in the Pyrenean population (N. Spain). Nest predation rate was estimated as 35.1%, being the corvids the most frequently identified predator (60% of the predated nests), followed by the Red Fox ( Vulpes vulpes ; 20%), the Beech Marten ( Martes foina ) and European Pine Marten ( Martes martes ; 10%) as well as the Wild Boar ( Sus scrofa ; 5%). The distance to ski slopes and to roads were the only variables that showed a significant relationship with nest predation probability, reaching 60% in the area around the ski slopes and less than 10% for nests at distances above 2.5 km. We discuss how this result could be related to a greater presence of generalist predators near the ski slopes attracted by the remains of garbage and what could be the guidelines to follow to reduce this risk of predation.