Nature and conservation
IntroductionRead about some of the conservation work being undertaken in the Heaphy Track area.
Trees and plants, east to west
The first section of the track climbs through a beautiful forest dominated by red and silver beech. Tiny orchids grow on the forest floor, many of them flowering in summer. At higher levels the trees are stunted and mountain beech appears near Perry Saddle.
Beyond the saddle are the Gouland Downs, a remnant of an earlier New Zealand, eroded to a nearly flat surface known as a peneplain. At 500 million years, the rocks here are among New Zealand’s oldest.
The rolling areas of red tussock with occasional patches of stunted silver beech are a spectacular sight, and somewhat eerie when the clouds lower. Flax, stunted shrubs and small herbs live among the sheltering tussocks. In boggy places, tiny sundews catch insects on sticky droplets, absorbing valuable nutrients from their quarry. Several plants found on the downs occur nowhere else, including a yellow-flowered lily and a small native foxglove.
Beyond Gouland Downs, the track skirts the Mackay Downs through more tussock fields and patches of beech. The bedrock here is glistening pink granite with large black and white crystals of mica and quartz.
From James Mackay Hut the track descends, passing initially through beech. Below an altitude of about 300 metres, the forest changes and podocarps — the fleshy-fruited New Zealand “pine” trees — appear, often emerging high above their neighbours. The most common is rimu, but miro, kahikatea and matai will also be seen. Beech is no longer the main canopy species at this level. Other broad-leaved species, such as rata, mahoe, kamahi, pigeonwood, hinau, pokaka and pukatea, appear, adding diversity to the forest. Undergrowth is generally richer than at higher altitude too. Kiekie and supplejack twist their way upwards, while many small shrubs jostle for light near the forest floor.
At the Lewis River junction the first nikau palms appear. The track continues through a bright and vine-festooned forest, following the naturally tannin-stained Heaphy River to its mouth.
The final section of the track skirts the beach and has both a subtropical and a sub-Antarctic feel to it, while the forest is very lush with many large-leaved glossy plants and vines, the cold sea is far from inviting, running far up the beaches and pounding the rocky points. Tight clumps of wiry shrubs huddle together, their form testifying to the wind’s strength and direction.
Weka, tūi, bellbird, pigeon and robin are a few of the native birds which are readily seen. You may also see the large parrots – kea and kākā, the smaller parakeet and the blue duck. With luck and a bit more commitment it is possible to see, or at least hear, the great spotted kiwi.
Gouland Downs could be the home to the first wild population of takahē outside of their Murchison Mountain refuge.
Long-tailed bats are seen more rarely coming out at dusk to feed in the open on insects. They locate their prey using echolocation, sending out sound pulses inaudible to humans, which bounce back off anything in their path. This bat and the rarer short-tailed bat were New Zealand’s only land mammals before the arrival of people. Both are now threatened by destruction of their habitat and introduced predators, such as rats and stoats. Any bat sightings should be reported to DOC.
Kahurangi National Park harbours half of New Zealand’s 40 species of carnivorous land snail (Powelliphanta). Several may be seen along the track, particularly near limestone outcrops where there is enough calcium to nourish their sizeable shells. They shelter during the day and come out on damp nights to feed on native worms, which grow up to a metre long.
A number of animals brought to New Zealand by European settlers have become established in the national park. Deer numbers are low, while pigs (which eat Powelliphanta), goats and hares have yet to spread to the west of the park in any numbers.
Damage to forests near the track is minimal except on the West Coast, where the impact of possums on mature rata trees is becoming severe. Possums are also known to feed on Powelliphanta. All native wildlife in the park is protected. Taking live snails or their empty shells is prohibited.
Great spotted kiwi
Kiwi surveys occur every five years at Gouland Downs and have now taken place three times. The good news for the great spotted kiwi is that this species appears to be holding its own.
Kiwi numbers and population densities have remained much the same over the past 15 years. The recording of the presence of young kiwi is an encouraging sign that the population is renewing itself.
Great spotted kiwi live within Kahurangi National Park in the area around Gouland Downs. You may hear the birds calling at night from the Perry Saddle, Gouland Downs and Saxon huts. Kiwi are most likely to be heard after dark. Male and female make different calls. Male great spotted kiwi make a shrill, repeated, drawn-out whistle “kiwi”. The female great spotted kiwi makes a harsh, low “churr”.
Keep an eye out for kiwi feathers caught in vegetation along track edges, kiwi footprints in snow, probe holes where the birds have been digging with their powerful beaks in search of grubs and worms, and kiwi poo, which resembles extra large (up to 5 cm) bird droppings.
Before your trip, you can hear the noise of a female great spotted kiwi on the What Bird? website.
Kiwi were once widespread throughout New Zealand in the time before Maori and Europeans arrived with their rats, dogs, cats, stoats and other mustelids. Kiwi evolved for thousands of years with little competition for the ground space of the forest. And back then there was plenty of forest! When mammals turned up, hunting with sound and smell, kiwi had no defences to deal with them.
The result is that today all kiwi are classed as threatened species. In some area, kiwi are managed very intensively – eggs and chicks are removed to pest-free zones, raised and returned to the wild when strong enough to survive on their own. To date, Kahurangi’s great spotted kiwi do not need this kind of attention.
Most Powelliphanta species are in North-west Nelson and north Westland but, despite their diversity within Kahurangi National Park, you will be very lucky to see one alive.
They are nocturnal creatures but occasionally venture out on a rainy day. Their most active forays for food will be on warm, moist nights, especially those following a long, dry spell.
It is more likely that you will come across snail shells but remember – collecting Powelliphanta shells is illegal.
The largest species is Powelliphanta superba prouseorum, found in Kahurangi National Park and measuring about 90 mm across. These are the Sumo wrestlers of the snail world, weighing in at 90 grams, or the equivalent of a female tui.
Powelliphanta land snails are under serious threat. Habitat loss and predation are the main problems. As a result of major habitat loss in the past, many snail populations are now restricted to tiny pockets of native forest.
If the forest is removed, opened up or dried out, many isolated populations could be gone forever. Domestic cattle, feral pigs, deer and goats trample the ground, which removes cover and causes drying – snails must have dampness. Possums, pigs and rats eat and crush the snails, as do weka, thrushes and hedgehogs. Possum control, rat control, weed control, revegetation programmes, habitat protection and wetland restoration are all conservation measures that are currently being carried out to give Powelliphanta a chance for survival.