Between 1998 and 2011 we monitored the winter ranging behaviour of eight female Saker Falcons Falco cherrug fitted with satellite-received transmitters. Our tracking revealed that the winter home range area occupied by individual Saker Falcons varied greatly (median = 166 km2, range = 5-18,469 km2). A random forest model showed that Saker Falcons wintering on the Qinghai-Tibetan Plateau preferentially occupied areas with rich grassland (cover > 50%) on high altitude plateaus (4,000–5,000 m asl) with low levels of anthropogenic influence. Plant biomass in rich grasslands can support high winter densities of plateau pikas Ochotona curzoniae, which likely explains the preference exhibited by Saker Falcons for grassland cover > 50%. Factors influencing the abundance and distribution of this ‘keystone’ prey species are likely to have an effect on Saker Falcons and other predatory species. A key element of rangeland management on the Qinghai-Tibetan plateau has been the establishment of extensive protected areas as part of a strategy to balance economic and social development with the requirement of sustainably managing water resources, maintaining rangelands for pastoralists and conserving biological diversity. Wide ranging predatory species, such as the Saker Falcon, can be useful indicators of biodiversity in protected areas and act as ‘sentinels’ for anthropogenic changes that may impact many different taxa.