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Miranda - The Refuge of Migrants

Gordon Ell reports on the Miranda Naturalists Trust. Photography by Geoff Moon

The birds fly in flocks of many hundreds, twisting and turning en masse, wings almost touching in close formation. The high-speed beating of their wings thrums the air, not so much with noise as with a wave of pressure, pushed on the wind. More birds skein the sky in loose lines. Twice each day, driven to shore by the rising tides, the migrant waders of the Thames estuary come to rest at Miranda.

The Firth of Thames is one of the best places to watch birds in New Zealand and the Miranda Naturalists' Trust provides a framework of facilities and field work to enrich the experience. The trust's buildings, facing the shoreline shellbanks, provide low-cost accommodation and an education centre which hosts visiting bird-watchers from all round the world. It compares more than favourably with more famous centres, such as Slimbridge or Minsmere in England, both for the facilities and the experience of wild nature.

For Miranda is the resting place for up to 39 species of migratory birds, some from as far away as the high Arctic. The birds flock here in thousands to feed while their breeding territories are frozen in the tundras of north Asia and the Americas.

The godwit are the famous ones, an icon species, celebrated in New Zealand literature as a symbol of a restless people dwelling culturally in two hemispheres. Along with lesser-known species of migratory birds, the godwits gather in great flocks through autumn for their journey back to the tundra to breed. In spring, they- and their young - return to Miranda to recover their strength and feed through summer on the rich mudflats of the Firth.

Their departures and arrivals are celebrated at Miranda in special functions which approximate seasonal festivals. The Departure of the Birds in late March draws hundreds of enthusiasts to witness the growing excitement as the flocks gather to migrate.

Then it is that masses of birds join in sweeping flocks, rising suddenly from their shoreline roosts in practice flights. Male godwit, in particular, take on a ruddy complexion - their generally fawn colouring turns to russet in late summer, signalling readiness to breed.

Similar changes can be seen affecting breeding birds of other species: the russet male knots which mix among the godwits but are only about half the size; turnstones, assuming a tortoiseshell effect; golden plover; tiny red necked stints, small as sparrows; or the heron sized eastern curlew, standing head and shoulders above other roosting birds.

The human visitors to Miranda take their telescopes and binoculars down to the shellbanks and specially built hides to observe the birds. Generally, the time to enjoy them is when the rising tide drives the birds in off the mudflats. They conic in small groups at first, flushed from some distant mudbar by deepening water. Often they join growing groups of their own species, gathered on the foreshore; so there may be an area of godwits and another of resident birds, such as shags, white-faced heron, white fronted terns or gulls. In the last minutes of the rising tide even larger groups of birds arrive, flocking together from the shallowest shores where they have fed until the last possible moment.

For a couple of hours the birds roost, often on one leg, to reduce their resistance to the coastal wind and perhaps retain body warmth. There is the occasional local disturbance among the thousands of waiting birds but generally they are quietly at rest.

Then, as the tide falls, they begin to move out again. Some fly en masse to feed far out in the Firth; others simply wade into the adjacent tidal guts to probe the mudflats between the shellbanks.

Dick Sibson was one of the founders of the Miranda Naturalists' Trust. expounding the idea of a field studies centre in the Forest & Bird journal of August 1988.

Support came widely from members of Forest and Bird and the Ornithological Society, and also the local community. One farmer, the late Allan Lane, provided access over his farm to the foreshore for bird-watchers.   The bulk of the 750 plus members live in the surrounding regions of Waikato and Auckland, many having membership both in Forest and Bird and the Trust. Additionally, Forest and Bird branches from the Far North to South Canterbury and North Taranaki have visited.

The Trust has a broad brief in natural history - its founders also wanted to use the field centre to study natural history in general.  On open days there are field trips not only to see the birds but to study the plants and even the archaeology of the area. (Miranda Redoubt on the hill behind was one of a chain across the south Auckland hills, protecting the infant capital during the wars in the Waikato).

'We may have focused overly much on birds to date,' confesses the centre manager, Keith Woodley, explaining a broadening events calendar. 'We'd also like to offer visitors the opportunity of walks in the Hunua Ranges, native fish studies and botanising'.

The centre itself is one of few unnatural features on a strip of low-lying coast built of shellbanks. This 'chenier plain', built by successively advancing shellbanks, is said to be a 'world class' example of this kind of geological feature. The banks of shell have built up over some 4000 years through coastal drift, gradually encompassing more of the tidal flats, a dynamic process which brings continuing change to the edge of the sea. There are 13 known shell ridges, marking the advance of the land into the mudflats.

From inside the field centre, broad windows look across the chenier plain with its marginal pastures and shallow pools where many birds roost and feed. Closest by the windows is Widgery Lake, an artificial pond named for another founder. Here visitors have seen wetland birds, as unusual as bittern and banded rail, feeding just metres away. In the middle distance the latest white shellbanks mask the mudflats where the birds feed. Over all is the ever-changing pastel light of a vast skyscape, frequently swept by the restless flocks, backed by the solid horizon of the Corornandel Ranges on the far side of the Firth.

Identifying the birds of Miranda can be a challenge. One pioneer of ornithology in New Zealand, the late R.B. (Dick) Sibson, used to speak of the difficulties of recognising what he called 'little brown jobs'. Birdwatchers, including Sibson, explored this coast, starting in the 1940s. (Once they rode their bicycles 5Okms or more through the ranges from Auckland to reach Miranda). On these field trips they identified several migratory species till then unknown in New Zealand including the terek sandpiper. Fittingly, Dick Sibson is remembered in the Sibson Room at Miranda, comprising a social centre for interpretation displays, lectures and public gatherings, along with a living area and kitchen.

The first stage of the low but expansive buildings was opened in 1990, with a wing of two bunkrooms and self-contained manager's flat added in 1991. Additions in 1993 included a new flat, the Wrybill Room which serves as a classroom and library, a meeting room and functions centre. In 1998 the Trust is buying a property next door to house its manager, thus increasing visitor accommodation in the centre itself, and providing more parking. One week this autumn there were 1000 visitors.

'This is a place for members to gather,' says Keith Woodley. 'Nevertheless, visitors come from all round the world, 60 percent of them from Britain. A good number of them are 'twitchers' keen to add New Zealand waders, especially wrybill plover and New Zealand dotterel, to their bird lists.' This ecotourism' helps fund the operation.

A blackboard at the entrance to the centre lists birds recently seen and where to look. The names are frequently evocative, often of faraway places: the Hudsoman godwit; Asian dowitcher, Mongolian dotterel, Pacific golden Plover, red-necked stint, greenshank, and various other species of sandpiper and tattler.

'Miranda is an educational centre,' says Keith Woodley. 'Community groups and schools come here by the busload to see the sights.'

Until now we've focussed on building,' says Keith Woodley 'but now we're moving to a research base.' There is plenty to do.
'The centre is making contacts with universities to study the marine environment. It's ironic but we presently know more about the birds, than the creatures they eat out there on the mud.'

To have the Ramsar designation, as a wetland of international significance, the area had to meet various criteria, including being home to one percent of the population of a particular species: Miranda is the winter home of more than half the population of New Zealand's endangered wader, the wrybill plover. These birds breed on the shingle riverbeds of the South Island in early spring, then migrate north. On the northern harbours their numbers swell through December and January, the birds feeding on the tidal flats before returning south to breed in August.

South Island pied oystercatchers migrate here in huge and growing numbers too. A bird count on June 14, 1998, recorded some 28,500 South Island pied oystercatchers visiting the Firth of Thames.

The oystercatchers generally breed in the braided rivers and higher country of the South Island, migrating to coastal harbours, particularly in the north, in late summer. The oystercatchers at Miranda are largely those which breed on farmland in Otago and Southland. This migratory population is growing as the nesting habitat of pied oystercatchers extends. The oystercatchers return south to breed, mostly in late July and August but some of the immature birds stay over summer at Miranda.

Pied stilt are another locally migrant bird which swell the resident populations during winter when 5000 have been recorded on the Firth of Thames. Many of the North Island population of banded dotterel, breeding inland from July, visit the coasts from January-February, joining those which are resident at Miranda. Kingfishers become conspicuous in autumn for they favour life by the coast in colder months. Winter flocks of white-faced heron frequent the saline ponds along the shore.

As the birds which breed in the north depart in the autumn, the 'internal' migrants take their place on the mudflat foodstores. Also wintering over are smaller populations of northern hemisphere birds not yet ready to make the migration back to the Arctic. Their numbers include substantial populations of godwit, a thousand or more, which retain the fawny feathers of non-breeding birds and may indeed be some of the young born in the previous northern summer. In wintertime the serious birdwatchers record a broad range of visiting species alongside the resident New Zealanders.

Miranda is by no means the only habitat frequented by migrating wading birds. Shallow harbours and estuaries throughout the country all attract substantial numbers of godwit, knot and other species, including dotterel and other local birds in season. The nearby Manukau Harbour, for an outstanding example, is a major wader feeding ground. It has more birds but they are harder to find on this more private coast.

The distinctive feature of Miranda is its accessibility. The opportunity for enthusiasts to experience and study the ebb and flow of birdlife constitutes the popular appeal of Miranda.

©   1999, Gordon Ell

Gordon Ell has produced a television feature, with photographer Geoff Moon, about the birds of Miranda.

Geoff Moon is a freelance natural history photographer and author.  An Honorary Fellow of the Photographic Society of New Zealand, he is the author of eight major books.