Bird Collisions with Overhead Ski-Cables: A Reducible Source of Mortality

With the expansion of resorts for winter sports, the number of ski lifts has increased dramatically. The overhead cables of these structures are dangerous for birds, particularly for grouse and partridges living in the mountains, and cases of collisions are frequently reported. In 1997, the Mountain Galliformes Observatory (OGM) initiated a survey of sections of cables where dead birds had been discovered in all French ski areas in the Alps and the Pyrenees. The aim was to identify avian collision mortality sites in ski areas and to provide recommendations for reducing cable collisions in respective habitats. During the 1997-2009 period, 835 mortality events were identified on 137 of the 225 ski lifts investigated. The collisions involved six species of Galliformes present in the mountains of France. The species suffering the highest losses were the black grouse (Tetrao tetrix) in the Alps and the capercaillie (Tetrao urogallus) in the Pyrenees (capercaillie disappeared from the French Alps early in the decade; black grouse is not present in the Pyrenees). The collisions were mostly due to button lifts. It is possible to reduce mortality by installing marking devices on the more dangerous sections of cable. Collection and analysis of the type of data presented here can facilitate the characterisation and visualisation of potentially dangerous sections of existing and future installations.

Keywords: Black grouse, capercaillie, french alps and pyrenees, marking devices, ski-lifts, tetraonids, impact, collision, bird mortality, visualisation, button lifts, overhead cable, grouse, partridges, ski areas, floaters, mountain galliformes observatory.