This seemed rather odd behaviour from Mark, who was usually a man of mild and genial manners, and I asked him what was up. He muttered something briefly about birds and continued to ignore us.

I looked around again. There certainly were a lot of birds in the garden.

I have to make a confession here, and it's going to sound a little odd coming from someone who has travelled twelve thousand miles and back to visit a parrot, but I am actually not tremendously excited by birds. There are all sorts of things about birds that I find interesting, I suppose, but the things themselves don't really get to me. Hippopotamuses, yes. I'm happy to stare at a hippopotamus till the hippo itself gets bored and wanders away in bemusement. Gorillas, lemurs, dolphins I will watch entranced for hours, hypnotised as much as anything else by their eyes. But show me a garden full of some of the most exotic birds in the world and I will be just as happy to stand around drinking tea and chatting to people. It gradually dawned on me that this was probably exactly what was happening.

`This,' said Mark at last in a low, hollow voice, `is... '

I waited patiently.

`Amazing!' he said at last.

Eventually Gaynor prevailed on him to bring himself back from his trance and he started to talk excitedly about the tuis, the New Zealand pigeons, the bellbirds, the North Island robins, the New Zealand kingfisher, the red-crowned parakeets, the paradise shelducks, and the great crowd of large kakas which were swooping around the garden and jostling each other at the bird bath.

I felt vaguely depressed and also a little fraudulent at being unable to share his excitement, and that evening I fell to wondering why it was that I was so intensely keen to find and see a kakapo and so little bothered by all the other birds.

I think it's its flightlessness.

There is something gripping about the idea that this creature has actually given up doing something that virtually every human being has yearned to do since the very first of us looked upwards. I think I find other birds rather irritating for the cocky ease with which they flit through the air as if it was nothing.

I can remember once coming face to face with a free-roaming emu years ago in Sydney zoo. You are strongly warned not to approach them too closely because they can be pretty violent creatures, but once I had caught its eye, I found its irate, staring face absolutely riveting. Because once you look one right in the eye you have a sudden sense of what the effect has been on the creature of having all the disadvantages of being a bird - absurd posture, a hopelessly scruffy covering of useless feathers and two useless limbs - without actually being able to do the thing that birds should be able to do, which is to fly. It becomes instantly clear that the bird has gone barking mad.

Here, to digress for a moment, is a little known fact: one of the more dangerous animals in Africa is, surprisingly enough, the ostrich. Deaths due to ostriches do not excite the public imagination very much because they are essentially so undignified. Ostriches do not bite because they have no teeth. They don't tear you to pieces because they don't have any forelimbs with claws on them. No, ostriches kick you to death. And who, frankly, can blame them?

The kakapo, though, is not an angry or violent bird. It pursues its own eccentricities rather industriously and modestly. If you ask anybody who has worked with kakapos to describe them, they tend to use words like `innocent' and `solemn', even when it's leaping helplessly out of a tree. This I find immensely appealing. I asked Dobby if they had given names to the kakapos on the island, and he instantly came up with four of them: Matthew, Luke, John and Snark. These seemed to be good names for a group of solemnly batty birds.

And then there's the other matter: it's not merely the fact that it's given up that which we all so intensely desire, it's also the fact that it has made a terrible mistake which makes it so compelling. This is a bird you can warm to. I wanted very much to find one.

I became increasingly morose over the next two or three days, because it became clear to us as we traipsed up and down endless hills in the rain, that we were not going to find a kakapo on Little Barrier Island. We stopped and admired kakas, long-tailed cuckoos and yellow-eyed penguins. We endlessly photographed pied shags. One night we saw a morepork, which is a type of owl that got its name from its habit of continually calling for additional pigflesh. But we knew that if we were going to find a kakapo we would need to go to Codfish Island. We would need Arab the freelance kakapo tracker, and we would need the freelance kakapo tracker's kakapo-tracking dog.

And all the signs were that we would not get them. We flew off to Wellington and moped about.

We understood the dilemma facing the Department of Conservation. On the one hand they regarded protection of the kakapos as being of paramount importance, and that meant keeping absolutely everybody who was not vital to the project away from Codfish Island. On the other hand the more people who knew about the animal, the better the chances of mustering more resources to save it. While we were mulling all this over we were suddenly asked to give a press conference about what we were up to and happily agreed to this. We talked earnestly and cheerfully to the press about the project. Here was a bird, we explained, that was in its way as extraordinary and unique as the most famous extinct animal of all - the dodo - and it was itself poised on the brink of extinction. It would be far better if it could be famously loved as a survivor than famously regretted, like the dodo.

This seemed to cause some movement within the Department of Conservation, and it transpired that those within it who supported us won their case. A day or two later we were standing on the Tarmac of Invercargill airport at the very south of South island, waiting for a helicopter. And waiting for Arab. We had won our case, and hoped, a little nervously, that we were right to do so.

Also in our party was a Scotsman from DOC called Ron Tindal. He was politely blunt with us. He said that there was a lot of resentment among the field workers about our being allowed to go to Codfish, but a directive was a directive, and we were to go. One man, he said, who was particularly set against the whole idea was Arab himself, and it was just as well that we be aware of the fact that he was coming under protest.

A few minutes later Arab himself arrived. I had no idea what I expected a freelance kakapo tracker to look like, but once we saw him, it was clear that if he was hidden in a crowd of a thousand random people you would still know instantly that he was the freelance kakapo tracker. He was tall, rangy, immensely weather-beaten, and he had a grizzled beard that reached all the way down to his dog, who was called Boss.

He nodded curtly to us and squatted down to fuss with his dog for a moment. Then he seemed to think that perhaps he had been a little over curt with us and leant across Boss to shake our hands. Thinking that he had perhaps overdone this in turn, he then looked up and made a very disgruntled face at the weather. With this brief display of complete social confusion he revealed himself to be an utterly charming and likeable man.

Nevertheless, the half-hour helicopter trip over to Codfish Island was a little tense. We tried to make cheerful small talk, but this was rendered almost impossible by the deafening thunder of the rotor blades. In a helicopter cockpit you can just about talk to someone who is keen to hear what you have to say, but it is not the best situation in which to try to break the ice.

`What did you say?

I just said, "What did you say?...

'Ah. What did you say before you said, "What did you say?...