Heading down the path, suddenly two bright blue birds the size of turkeys appear, all aquamarine plumage and bright red beaks. These are two Takahēs, and, nodding like chickens, they creep around, glancing over from time to time. They only head off into the high grass when I tiptoe up towards them and come within 20 metres of them. I’m on a hike in New Zealand, heading along the Heaphy Track with a group and my fellow walkers don’t believe when I tell them what I saw later on, as I don’t have a picture to prove it. That’s because among all the rare and wonderful birds New Zealand boasts, the t…