Travel blogger Jill Worrall encounters soap opera-worthy drama at South Westland's kotuku colony.

There was some sex, a little violence, home improvements and some intimate dining-in - it could have been any night of reality television but in fact these scenarios were being played out among the kotuku colony of South Westland.

Kotuku, or white heron, can be seen feeding as solitary birds throughout New Zealand but they nest in only one place -in a bend of the Waitangiroto Stream just north of the Okarito Lagoon.

No-one knows why the birds choose this one small grove of treeferns, kiekie and lower-growing native trees to mate, make their nests and raise their chicks. This small stretch of river seems identical to others both up and downstream but it is here the birds return between August and September for the breeding season. They are joined by a small colony of royal spoonbills who favour nests perched precariously in the towering kahikatea behind the stream and little shags who build nests often just a beak or two away from the much large kotuku.

This year there are about 38 breeding pairs of kotuku - they are rare birds but not nearly as endangered as they were in 1875, little more than 10 years after the first European found the nesting site. By 1875 there were only six nests left because the kotuku's beautiful feathers became all the rage for ladies' hats.

Protection for the birds began in 1924 and today the bird and their streamside sanctuary are administered by the Department of Conservation. Access is by permit only and just one company has a DOC concession to run tours in the reserve.

White Heron Sanctuary Tours are based in Whataroa and the journey to the colony begins with a van ride across the fertile Whataroa plain to the Waitangitaona River. To most visitors this is probably the least interesting part of the journey but only recently I have discovered that my maternal ancestors were among the first Europeans to settle in this area in the mid-1800s. Appropriately perhaps their name was Bird - there's even a Bird Road and Mount Bird.

At the river, which runs crystal clear with a mix of spring and mountain-fed water, we board a jetboat. Driver/guide Dean navigates us downstream through a series of lazy meanders until we reach the lagoon, protected from the pounding Tasman Sea waves by a long gravel spit. Somewhere here there was a now long-vanished settlement where my great grandfather married my 16-year-old great grandmother.

We turn back inland here into the Waitangiroto Stream and Dean cuts the engine. We glide between kowhai and kahikatea and into a landing stage. There's a 500-metre boardwalk to the hide directly across the stream from the birds. Through a gap in the trees along the way we get our first glimpse of the spoonbills - plump piles of white feathers sitting high in the trees like pillows wedged in the branches.

From the hide almost the entire colony is in view and at the start of the breeding season it's a hive of activity. Kotuku, legs trailing and necks tucked in, fly past with pieces of twig in their beaks which they then present to their mates. One bird lands with an enormously long and rather rigid branch. Its mate looks less than impressed. I can imagine it saying "What on earth am I supposed to do with this?" But they both take one end each and poke it into place in the rather ramshackle nest.

One pair, which is standing precariously on top of a kiekie plant are mating, wings flapping to maintain their balance while the plant sways dangerously. Other birds are still in the courtship stage - displaying their lacelike breeding plumage like peacocks. During this part of their lifecycle the birds' beaks change colour - from yellow to blue-green.

Along a small stretch of muddy beach there seems to be an avian domestic going on - a trio of male spoonbills are scrapping over the attentions of a lone female, which eventually seems to get fed up and strides off into the undergrowth abandoning all three.

No-one is sure why the little black shags choose to nest within this colony of much larger birds but the theory is that the one-metre tall herons with their sharp beaks provide a measure of protection from predators such as harrier hawks and even stoats which are capable of climbing up into the nests.

We spend about 40 minutes watching the birds, following the nest-building and the inbound/outbound flights. Dean tells us that chicks could arrive any day and then the adult birds become even busier feeding their brood. Kotuku usually lay about three eggs but usually only one, maybe two, of the chicks reach maturity. The birds grow quickly - becoming fully fledged after only about seven weeks.

As we zip along the estuary on our way back Aoraki-Mt Cook and Mt Tasman come into view behind the forest and a lone kotuku picks its way among the shallows. I wonder...did my great grandmother have a kotuku feather in her hat the day she got married?