The demise of the guanaco in the Andes of central Chile after hunting and livestock competition peaked 50-70 years ago in the Mediterranean ecosystems of Chile. Hares became the predominant wild herbivores besides domestic livestock in this mountain range. The Río Cipreses Natural Reserve was established to protect a small population of guanacos in 1984. Cattle were removed and guanacos recovered from the brink of extinction. We studied how hares and guanacos overlapped in space and time (Co-occur and overlap packages in R) and determined their ecological role for puma subsistence. A camera trap study (n=5,008 trap-nights) between 2013-2015 and puma scat collection since 2012 (n=107 scats) showed that hare-puma and hare-guanaco co-occurred spatially and time overlap was only significant between puma-hare. Hares' percentage of occurrence in the diet was 71% and hares accounted for 85% of the relative biomass consumed by pumas. Our results indicate that the hare continues to be the most important prey item in the diet of the puma, despite guanacos 1,000% increased population to about 250 animals in the study area (8,372 ha). We discuss the ecological role of hares as exotic prey for the survival of pumas.