Banks Peninsula is an ecological island of considerable size, ruggedness, diversity and distinction. Not so long ago it was an actual island, but is now firmly moored to the mainland by a great fan of glacial outwash material. Founded on two complex volcanoes active until about 6 million years ago, it has a finely dissected landscape with myriad nooks and crannies. It has several endemic plants and an endemic bird (white-flippered penguin). It lies at the southern limit for many warm-temperate plant species, and at the northern limit for a smaller number of southern species. It has strong lowland elements, but above about 500m is montane. It has a maritime climate, particularly exposed to the south, and is gnawed at by the sea around two-thirds of its perimeter.
Since human arrival (about 1200-1300AD), the primeval cover of dense forest, abounding in birds, lizards, bats and big invertebrates, has been almost totally annihilated. With it has gone most of the fauna. Around the coast too, the losses have been huge: seal rookeries, sea bird colonies (shearwaters, petrels, penguins, shags, gulls, terns, etc), native sand flora and lush herbaceous communities.
Enough remains though to be excited about. Over recent decades there has been steady regeneration of native bush and shrublands and recovery of populations of birds such as bellbird, brown creeper (pipipi) and kereru. The white-flippered penguin has been rescued from oblivion by determined efforts. Botanical surveys have revealed remnant populations of notable plants, several ranking as nationally threatened. Unexpected lizard populations have been discovered. At least one population of pikao (pingao, golden sand sedge) has been restored on the coast. Many blocks of land – both private and public – have been formally protected for conservation reasons. Most exciting of all is Hinewai, a private reserve that began as an ecological restoration project on a small farm but has grown to over 1000ha and has captured the imagination of many, both in Canterbury and further afield. Hinewai lies in the heart of the “Wild Side”.
The “Wild Side” and its natural heritage
The portion of Banks Peninsula that has become known as the “Wild Side” is the south-eastern corner (see maps). It extends from the outer eastern shores of Akaroa Harbour to the northern side of Le Bons Bay, taking in the series of indented bays, their entire catchments and the skyline ridge with its rocky peaks and knolls (the highest of which are Flag Peak, 809m, and Stony Bay Peak, 806m). Like most of the peninsula, it is abrupt country, with steep slopes rising from a radiating array of fairly gentle valleys. The bays have beaches of sand, gravel or boulders, whilst the rest of the coast is cliff-bound. There are numerous near-shore rock stacks. At about 12,500 ha, the “Wild Side” occupies a little less than a third of Akaroa Ecological District. It is an area larger than Campbell Island.
The reason for focussing conservation attention on the “Wild Side” is that it retains a larger diversity of native vegetation, flora and fauna than elsewhere on the peninsula and therefore has better prospects for protection and restoration. It is no accident that Hinewai is at its centre. In addition to Hinewai (protected private land), there are quite a few formally protected natural areas, including scenic reserves managed by the Department of Conservation, QEII National Trust Open Space Covenants, Banks Peninsula Conservation Trust Covenants and land (Misty Peaks Reserve) acquired by Christchurch City Council for conservation and recreation. These areas combined protect about 2000 ha of land, or about one-sixth of the “Wild Side”. They are complemented by Pohatu Marine Reserve at Flea Bay, and there is a proposal for another marine reserve near Akaroa Head.
About 6,000 people visit Hinewai each year, such is its reputation as an area specialising in ecological restoration. The Banks Peninsula Track, which takes in the heart of the “Wild Side”, lures a stream of interested walkers. Many others visit the public reserves or drive out to the accessible bays. The recent amalgamation of Christchurch City Council and Banks Peninsula District Council has opened the way to increasing recognition of the peninsula as a cherished hinterland for Christchurch people. There are therefore excellent opportunities for public education about the natural heritage of the “Wild Side” and for public participation in conservation projects.
The following is a brief description of the natural biological attributes that make the “Wild Side” special. It is based on Hugh Wilson’s wonderfully comprehensive Banks Ecological Region Protected Natural Areas Programme Survey Report (Wilson 1992), but with updates from a variety of other sources.
Topography and substrate
There are a great variety of aspects, microsites and base materials, from the shore to the peaks (over 800m). The coast has beaches, scarps and cliffs. The valleys have flattish alluvial bottoms but steep incised heads with cascades, waterfalls and pools. The slopes have steep rocky aspects and run up to a network of ridges and spurs. There are numerous rock outcrops, a few screes and substantial colluvial deposits. The underlying rocks are volcanic, ranging from basalt to trachyte, but are overlain with a mantle of loess. Therefore there is a geological and topographical basis for a wide range of natural habitats and vegetation types.
The area has retained more native forest cover than elsewhere on Banks Peninsula. Some fragments of the primeval forest remain, including beech forest (red beech and black beech, found nowhere else on the peninsula) and lowland and montane podocarp-broadleaved forest. The lowland forest fragments contain remnant matai and lowland totara, whilst in the uplands are Hall’s (mountain or thin-barked) totara and the only pahautea (cedar) on the peninsula. Otherwise, there is an extensive regenerating mosaic of native vegetation: broadleaved forest (mahoe, broadleaf, five-finger, kaikomako, pigeonwood, tree fuchsia, etc), kanuka forest (dominant in many places) and shrubland. In sheltered warm microclimates by the sea are remnant nikau, kawakawa, akeake and titoki. At higher altitudes are snow tussock, speargrass, mountain flax and neinei. Rock outcrops are refugia for several endemic plant species.
Parts of the “Wild Side” have extensive shrublands of gorse, a legacy of marginal farming. However, where protected from stock, fire, herbicide and mechanical clearance, the gorse is acting as a nursery for rapid native forest regeneration. This is nowhere better demonstrated than at Hinewai, which has 20 years of recovery from farming, much of the gorse already replaced by native vegetation. Therefore the “Wild Side” already has considerable diversity of native vegetation, and much extra potential for restoration through regeneration.
The native flora is remarkably diverse. Hugh Wilson reported a total of 464 native vascular species in Akaroa Ecological District (Wilson 1992). Most would occur within the “Wild Side”. He has subsequently found more species. Hinewai alone has at least 56 species of ferns, which is astonishing. In the 1992 report Hugh listed about 70 native plant species of particular interest and concern in Akaroa District, most of which occur in the “Wild Side”. They include those that are nationally threatened, such as Banks Peninsula sun hebe (Heliohebe lavaudiana), gossamer grass (Anemanthele lessoniana), fierce lancewood (Pseudopanax ferox) and native verbena (Teucridium parvifolium); those that are rare in the ecological region, such as mountain cabbage tree (Cordyline indivisa), raukawa (Raukaua edgerleyi) and pahautea (Libocedrus bidwillii); those endemic to the ecological district, such as Akaroa daisy (Celmisia mackaui) and Akaroa harebell (Wahlenbergia akaroa); those at southern limits, such as nikau (Rhopalostylis sapida) and puka (Griselinia lucida); those at northern limits, such as fragrant tree daisy (Olearia fragrantissima); and those uncommon in the ecological region, such as red beech (Nothofagus fusca) and shore puha (Sonchus kirkii). There are also plants endemic to Banks Peninsula, such as Hebe strictissima, Leptinella minor and Banks Peninsula sun hebe.
Long-tailed bat was formerly present on Banks Peninsula but has not been reported for some time. Short-tailed bat would probably also have been present in the past. Both could be re-introduced.
In the past there would have been abundant colonies of New Zealand fur seal and New Zealand (Hooker’s) sea lion. Sea elephant and leopard seal would have been regular visitors. There has been some recovery of New Zealand fur seal but the other seals are rarely seen. Banks Peninsula is a key area for nationally endangered Hector’s dolphin, the main reason for the establishment within the “Wild Side” of Pohatu Marine Reserve, centred on Flea Bay.
Prior to human arrival, there would have been an abundance
of land birds, including moa, kiwi and several parrot species. All the
flightless birds have gone, along with many of the flighted ones. Bush remnants
still support reasonable populations of kereru, bellbird, pipipi (brown
creeper), rifleman, tomtit, riroriro (grey warbler), fantail, silvereye and
seasonal shining cuckoo. Tui, morepork and karearea (falcon) have diminished to
very low numbers. Plans are being made to re-introduce tui to the “Wild Side”,
and recent studies show that the habitat is favourable (Schmechel 2004, Wilson
2007). Buff weka, formerly common on Banks Peninsula and throughout Canterbury,
still exists in abundance on the Chatham Islands. Several attempts have been
made to re-introduce buff weka to the peninsula, without lasting success
(Schmechel 2004), but in the light of better knowledge a more favourable
outcome is likely with future attempts.
Coastal and sea birds
Two sea birds have breeding populations on the coast of the “Wild Side”, mere remnants of their former abundance but nevertheless still hanging on. Fairy prion breeds in burrows on several of the islets or rock stacks. Titi (sooty shearwater) has only one confirmed remaining breeding colony, a very small one at Stony Bay carefully nurtured by the landowners (Mark and Sonya Armstrong) with assistance from the Department of Conservation and Lincoln University (Schmechel 2004). A few titi may also breed on the larger islets. Other sea birds known to have had breeding colonies in Canterbury in the past are common diving petrel, Cook’s petrel, mottled petrel, white-faced storm petrel and Hutton’s and/or fluttering shearwater.
There are two penguin species that breed on the coast of the “Wild Side”. Both are listed as seriously threatened (‘nationally vulnerable’). White-flippered penguin (Eudyptula minor albosignata) is a distinctive subspecies of blue penguin centred on Banks Peninsula and Motunau Island. In size, coloration and behaviour it significantly differs from other blue penguins and arguably deserves species status. The “Wild Side” has strong colonies at Flea Bay, Stony Bay and Otanerito Bay, closely monitored and protected from predation. The work to date to protect the penguins in these colonies has been a collaborative effort involving landowners (in particular Francis and Shireen Helps and Mark and Sonya Armstrong) and agencies (the Department of Conservation and Environment Canterbury). It has resulted in a significant rise in penguin numbers and breeding success. Much smaller colonies of yellow-eyed penguin (Megadyptes antipodes) occur in Flea Bay, Otanerito Bay, Red Bay, Shell Bay, Gough Bay and Le Bons Bay. A trapline has recently been established in Le Bons Bay, funded by the Antarctic Centre, to help protect both penguin species.
Otherwise, notable coastal birds include spotted shag (for which Banks Peninsula is a key breeding area), pied shag, black shag, Caspian tern, white-fronted tern, South Island pied oystercatcher, variable oystercatcher, banded dotterel and reef heron.
Six species of lizards occur on Banks Peninsula, and all are present within the “Wild Side”. None are abundant, probably due to predation, and three are nationally threatened (Hitchmough et al 2005). Jewelled gecko (Naultinus gemmeus) and Canterbury gecko (Hoplodactylus aff. maculatus ‘Canterbury’) are both listed as threatened (‘gradual decline’). Forest gecko (Hoplodactylus granulatus), previously unknown on the peninsula, has recently been found in the upper Flea Bay catchment. Spotted skink (Oligosoma aff. lineoocellatum ‘Central Canterbury’), listed as highly threatened (‘nationally endangered’), is very uncommon, known from a few recent sightings at Hinewai and Stony Bay. McCann’s skink (Oligosoma maccanni) and common skink (Oligosoma nigriplantare polychroma) are more widely distributed. With assiduous predator control, all of these lizard species could recover in numbers.
Banks Peninsula and the “Wild Side” have considerable diversity of native freshwater fish species. Those that occur are: shortfin eel, longfin eel, lamprey, upland bully, common bully, giant bully, bluegill bully, redfin bully, koaro, banded kokopu, inanga, torrentfish and common smelt. Most of them need unimpeded access to the sea for parts of their life cycles. They also need favourable spawning habitat, as provided for inanga in the lower portion of Le Bons Bay Stream. Their continued existence depends on maintenance of the natural quality of their habitat (streams with pools, rills, cascades, falls, shaded stretches and conditions suitable for spawning) and minimisation of sedimentation, pollution, predation by exotic species (such as brown trout), disease and creation of artificial barriers. In the semi-estuarine mouths of the larger streams could also be yellow-eyed mullet, black flounder and estuarine triplefin.
Banks Peninsula is one of the key areas in Canterbury for native invertebrate conservation (Johns 1986, Evans 2006). Its invertebrate fauna differs from that elsewhere and is a reflection of its former island status, the localised microclimates and vegetation richness. Mature native forest is vital habitat for many invertebrates, whilst others are dependent on particular plants. There are quite a few endemic terrestrial species, including Banks Peninsula tree weta (Hemideina ricta) and six-eyed spider (Periegops suterii), both listed as nationally threatened, several ground beetles (Megadromus, Mecodema and Holcaspis species) and the native slug Pseudaneitia maculata. They have been reduced to quite low numbers by habitat loss and fragmentation, also by predation (by rats, mice, hedgehogs, cats, stoats, weasels and possums). Some of the endemic terrestrial invertebrates have recently been translocated to Quail Island, to give them a safe refuge. The freshwater invertebrates of the peninsula also show a high degree of endemism and show similarities to those in alpine streams. The “Wild Side” contains representative populations of most of these Banks Peninsula invertebrates and therefore holds promise for their long-term conservation.
The natural attributes of the “Wild Side”, and the peninsula as a whole, are subject to a variety of threats. The following is a brief overview of the main threats.
A suite of ecological weeds has become established since European arrival, and is continuing to invade natural ecosystems. Some are garden escapees; others are agricultural in origin or are from forestry or earthworking. Several threaten bush remnants and regenerating native vegetation; some threaten rock outcrop ecosystems. A “dirty dozen” have been identified as requiring the most effort in control and spread prevention. Four are already common on Banks Peninsula: old man’s beard, sycamore, banana passionfruit and grey willow. The other eight are much less common, but for that very reason require assiduous control to prevent big problems later. They are: Chilean flame creeper, Japanese honeysuckle, wandering Jew (wandering willie), smilax, yellow ginger, selaginella, Darwin’s barberry and khasia berry (Cotoneaster simonsii). Gorse, broom, and wilding pines are the main woody weeds that threaten montane rocky outcrops, whilst exotic grasses and herbs are also a problem there. Several weeds, including those that have escaped from gardens, are established on the Port Hills and have the potential to spread to the rest of the peninsula unless checked. They include boneseed, boxthorn, spur valerian, pig’s ear and male fern.
Maori settlers brought kiore (Pacific rat) and kuri (dog) and both did tremendous damage to the naïve native fauna prior to European establishment. There is now a new suite of animal pests, largely derived from Europe, having major impacts on the native vegetation and fauna. The herbivores established on Banks Peninsula include domestic stock (largely sheep and cattle) and feral pig, goat, deer (red and fallow), possum, hare and rabbit. Increasingly, stock are excluded from native vegetation by fencing. Feral pigs, goats and deer are localised in distribution and could be eradicated; a concerted programme has virtually eliminated feral goats from the peninsula. Possums are controlled to low levels in places and there is a newly begun programme to control them more widely on the peninsula for agricultural and biodiversity reasons; it will reach the “Wild Side” in 2009/10. Ship rat and mouse, common everywhere, are partly herbivorous but are also efficient predators of small animals (lizards, birds and invertebrates). Pigs and possums also eat animals as well as plant matter. Other predators are feral cat, ferret, stoat, weasel and hedgehog, collectively devastating to native birds, lizards and invertebrates.
Birds considered pests on the peninsula are magpie and sulphur-crested cockatoo, but they are probably more of a nuisance than ecologically harmful. In the freshwater ecosystems, brown trout, chinook salmon, perch and goldfish are introduced fish that are predatory on native fish and invertebrates.
Fire is a perennial threat to native terrestrial vegetation and fauna, especially during drought periods. It was much used as a tool for land clearance in the past, but is now rarely used as a land use practice. The main risk comes from accidental fire, particularly the ignition of rank dry grass or exotic conifer plantations.
Land use practices that pose threats to native ecosystems and biodiversity include the indiscriminate application of herbicides and pesticides, insensitive earthworks (including road works, building site preparation and drainage) and uncontrolled subdivision development. Subdivision and settlement usually bring with them a raft of exotic plants and animal pests (including domestic cats and dogs and smaller pests such as exotic ants and wasps) and altered runoff and drainage. Alternatively, provided ecological restoration and sustainability philosophies are adopted, subdivision and settlement can be positive for conservation.
Disease is often cited as a threat to native plants and animals, but has rarely been clearly demonstrated. It could be implicated in the loss of tui from Canterbury and the peninsula and is certainly responsible for sudden decline of cabbage trees in the North Island and northern South Island.
Natural threats include drought, severe frost, snowfall, storm damage, landslip and catastrophic events such as major earthquakes and tsunamis. Most natural ecosystems have the capacity to recover from these episodes, but they could tip something with a tenuous hold over the edge.