It is essential for grass livestock farming to cope with climate variability and, particularly, drought. A potential solution is to use collective mountain pastures, which are colder and wetter, in the summer. However, there is little knowledge on such collective pasture management. Therefore, we surveyed three collective sheep summer mountain pastures and three small and one large cattle summer mountain pastures in 2012 in the Auvergne region, France. Farmers using and managing the pastures were interviewed. We also analysed regional statistics, an economic report and a shepherd journal. Our results show that drought has incited farmers to use collective pastures. Beginning and ending dates of the summer grazing season and animal transfers have been modified by collective decisions and individual farmer strategies. We conclude that collective summer mountain pastures is a unique source of flexibility for livestock farming.