In a secret spot, restricted to visitors, Jim Eagles marvels at the elegant, isolated beauty of NZ's only flock of endangered white heron.

From behind the wooden shutters of the observation hide, all we could hear was a rather ugly chorus of "aaaak, aaaak, aaaak", a few fluttering noises and the sound of running water.

But when Dion Arnold, our jetboat driver and guide, opened the shutters we found ourselves facing dozens of magnificently regal white herons, surrounded by their royal spoonbill and little shag retainers, nesting in the shelter of a row of kahikatea trees on the other side of the Waitangiroto River.

It was like opening a pair of battered wooden doors and finding behind them a gloriously decorated medieval cathedral filled with the aura of centuries of prayer.

I don't think it's an exaggeration to say that this single nesting site of the kotuku - surely our most elegant bird - in the spectacular forests of south Westland is one of New Zealand's sacred sites.

Like many people I have occasionally seen kotuku, at places like Miranda and Kaiaua on the Firth of Thames or Matata in the Bay of Plenty, as they lead their mostly solitary lives.

But I have also heard the legend of how each summer every kotuku in the land - about 170 of them - must gather in a secret spot to court, mate and raise their young.

Now, just across the river from me, was that mysterious nesting place, occupied not only by the country's 50 or so nesting pairs but also by an equal number of fledglings from this year's brood, already almost as big as their parents and learning to fly, but still demanding noisily to be fed (hence the cries of "aaaak, aaaak"). It was a remarkable sight.

Even getting here had been like a mystical quest. It's widely assumed that the nesting site is on the beautiful Okarito Lagoon. But, while the lagoon is an important feeding area for the white herons, the clump of kahikatea trees under which they nest is in fact some 10km away on the Waitangiroto River, with access only by water.

The only way to get there is to make your way down the wild West Coast, along one of the most beautiful roads in the world, State Highway 6, to the little settlement of Whataroa, 32km north of Franz Josef.

Whataroa is home to Arnold's parents, Shirley and Ken Arnold, who some 30 years ago came up with the idea of running carefully controlled tours to the nesting site. After some years of negotiation they got approval and today still hold the only Department of Conservation concession to enter the nesting sanctuary. Numbers are strictly controlled and the birds are there only from September to early March so it remains a spectacle that few people get to see.

From Whataroa you take a short bus trip to a jetty on the Waitangitaona River, then board Arnold's jetboat for a 20-minute ride to the river mouth, through a small estuary and up the Waitangiroto River - a pleasant journey, past lovely old trees, the occasional angler, a few kingfishers and shags, and a couple of white herons feeding on the river banks - until you reach a small jetty where a 500m boardwalk leads to a small, two-storey hide. And, of course, when the shutters open ... there are the birds.

It's a place that has always drawn superlatives. Maori used the kotuku in oratory as a figure of speech for a significant event or a great person. The first European known to have visited was Westland's first district surveyor, Gerald Mueller, who in 1865 paddled up the river in a canoe and in a letter to his wife described the nesting herons as "the crowning beauty" and "a glorious sight".

Unfortunately, that beauty was almost the heron's downfall, because their elegant white plumes became fashionable in women's hats and by 1877 there were only six breeding pairs left.

But the colonial Government did eventually take action, the birds were protected and in 1924 the nesting site was declared a sanctuary. Numbers have slowly increased and are now thought to have stabilised at around the 170 mark.

As I watched the amazing interaction between the adults and their huge offspring, with much spectacular dancing on branches and flapping of wings, Arnold pointed out a couple of adults which were still showing their breeding plumage.

When the birds gather here in September they grow long showy plumes, which they display like peacocks as part of their mating ritual, making them even more beautiful than the solitary figures we see round the country.

Once they've selected a mate, nested and produced chicks the plumes start to disappear, so this late in the season I was fortunate to see them.

The white heron nests are large, rather clumsy collections of sticks running midway along the line of kahikatea on the river bank. But, adding to the fascination of the scene, high above them in the tops of the trees are the nests of several royal spoonbills, their elegant feathers and peculiar bills reminding me of a collection of bulbous-nosed butlers. And dotted around among the heron nests are those of the little shags who appear, in this refined company, like a bunch of scruffy page boys.

At the time I was there the young herons were just learning to fly, their inexperience resulting in many a clumsy course change and near crash, but by now they will be ready to fend for themselves. Indeed, just last week at Kaiaua I saw a kotuku feeding on the shore, indicating that the birds have now left the nesting site and resumed their lonely lives spread out across the country.

So the Waitangiroto River will have once more lapsed into a restful green silence ... until next September when the herons start to gather again.

CHECKLIST
* Getting there: Air New Zealand flies to Westport and Hokitika. See airnewzealand.co.nz

Thrifty Car Rentals can deliver cars to both airports and several other points down the coast. See thrifty.co.nz
* Where to stay: Franz Josef Country retreat is a grand country lodge facing Lake Mapourika and close to both Franz Josef and Okarito. See glacier-retreat.co.nz
* What to do: White Heron Sanctuary Tours are on State Highway 6 in Whataroa. See whiteherontours.co.nz
* Further information: For more about visiting the West Coast see westcoastnz.com
Jim Eagles went to Whataroa with help from Tourism West Coast and Air New Zealand.