The males are released into a caged section of the orchard that contains the grapevines. Corrugated iron has been dug in all around the base of the cage so that the guinea pigs have a hard job to escape. Here they can eat the greenery that grows under the vines but will not eat the grapes (as the chickens used to do). Their numbers are stable as they are all male. The tunnels between the clumps of grass are cool and secluded so they should be able to survive hot weather. The only need for human intervention is to keep up the water supply.
Guinea pigs are among the only animals that cannot regulate their body temperature through making their own Vitamin C. This means that they are prone to death in heat or cold. However our guinea pigs seem to adapted very well to the challenges of cold. All survived outside last winter with only each other and some straw to keep them warm. It snowed three times but they were fine. It slows the reproduction down, though!