The world's largest ecological reserve behind a pest-proof fence lies south-east of Cambridge, New Zealand, close to Hobbiton and the Waitomo glow-worm caves. It's the Maungatautari Reserve, also known as Sanctuary Mountain. All kinds of ancient and endangered species now have a chance to thrive on this island in the sky, rising up above the intensively-farmed plains of the Waikato. I went for a ramble on the mountain with the Auckland meetup group, Feet First.