Red deer run rampant across the high country in New Zealand, causing extensive environmental damage. A 50-year effort to control the invasive animal gets underway.

By the 1930's the deer population in New Zealand was out of control and causing serious environmental damage through grazing, severe soil erosion and slips from the thousands of hooves ripping up the ground. Even today you can find deer trails several feet deep crossing major passes.

The Department of Internal Affairs creates an ambitious program to drastically reduce the deer population, run by World War I veteran Captain George Yerex, aka "The Skipper". The programme hires men, mostly experienced shooters, as cullers. Their job is simple; to kill as many deer as possible, leaving the bodies where they fall and cutting off the tails as proof of kill.

There are no huts. Cullers stay in tent camps or rock bivouacs, spending up to nine months at a time in the field, often without seeing another person.

This is some of the toughest, most remote country in New Zealand. The men are working above the bush line in snow and ice, fording dangerous rivers and negotiating ravines. With no radio communications, they have to be totally self-sufficient.

The job attracts a mixture of applicants. Some are experienced bushmen but others are enthusiastic teenagers and overseas immigrants with no idea of New Zealand's harsh, mountain conditions. All of them are thrown in at the deep end with very mixed results.

Go to this episode on rnz.co.nz for more details