A New Zealand freshwater snail takes over the world
Give it a crack, try NZGeo for $1
Unlimited access to every NZGeo story ever written and hundreds of hours of natural history documentaries on all your devices.
Already a subscriber? Sign in
In 1869 a strange faceted stone, shaped a little like the segment of a small mandarin, was found near an old Maori kitchen-mound at Lyall Bay, Wellington. It was duly examined by a trio of renaissance men, Captain William Travers, Dr James Hector and Mr Walter Mantell, all of whom agreed it must have been fashioned by humans. They speculated it might once have been used as an arrowhead or perhaps a tool to cut and polish the grooves in hei tiki. Maori were consulted but claimed never to have seen an implement like it, and scoffed at the hei tiki hypothesis. With an eagerness to unravel the mystery, the men headed for the discovery site, whereupon it soon became clear that the alleged artefact was, on the contrary, a product of nature. The site was littered with many similar stones that together formed part of a boulder bank, separated from the sea by sand dunes. Sand was constantly being pushed over the boulder bank by the prevailing winds and surprisingly, it was the cutting-action of this mobile sand that had fashioned the stones into their remarkable shapes. Stones that have been sculpted and polished by long-term exposure to abrasive wind-driven sands are called ventifacts—from the Latin “make by wind”. Even these days, ventifacts are commonly mistaken for the artefacts of stone-age people, such as those recently misidentified as tools of Indian origin at Cape Cod, Massachusetts. Extraterrestrial origins have also been suggested ahead of the wind. The semi-circular Mason Bay, on the west coast of Stewart Island was, in the 1980s, seriously suspected of being an asteroid impact crater, some 20 km in diameter. Evidence for this theory included some unusual fan-shaped grooves that had been carved into granite outcrops. The grooves seemed aligned to the centre of the bay and were suspected of being shatter cones, a phenomenon associated with massive impacts. However, in 1991 geologists Graham Bishop and Tony Reay dismissed the cosmic link, saying that the grooves had instead originated from sandblasting by the exceptionally strong westerly winds that slam into Stewart Island. Mason Bay is classic ventifact country. The main requirements for ventifaction to proceed are strong winds that blow persistently in the same direction and a plentiful supply of sand that can be mobilised by those winds. In such environments, ordinary pebbles and boulders suffer severe abrasion and slowly begin to take on seemingly unnatural shapes. Their surfaces become flattened and smoothed on the windward side and given time, a variety of alluring shapes can result. The classic forms are those with multiple facets that intersect along distinct ridgelines and terminate in pyramidal peaks. Highly prized among collectors are the so-called dreikanter or ‘three-ridged’ types that look somewhat like minimalist sculptures of Mt Aspiring. How such ventifacts form has been the subject of some confusion. Some two- or three-sided forms might indicate that strong winds have blown from more than one direction, as is true at Lyall Bay. New facets can also be added if the ventifact is moved during its period of sandblasting, which probably explains those rare ventifacts with up to twenty facets. One way that they can move is when the ground upon which they rest is scoured out on the lee side by wind eddies. Unsupported, the ventifacts then roll over, thus exposing their underbellies to the blast. The erosive power of the wind is relatively insignificant when compared to that of moving water and ice. However, in deserts and those regions frequented by tumultuous gales, the wind becomes an important destructive agent. Wind abrasion occurs in two ways. Very fine particles can be held aloft by strong winds before striking and abrading obstacles in their path. Most ventifaction, though, results from the impact of sand grains that are too large to be held in suspension. Instead these grains roll along, generate some uplift and then jump a short distance before settling again. When the grains encounter a rock in their path they strike its surface with enough force to produce a minute star-shaped fracture, much like those seen on windscreens. Microscopic shards of rock are spalled off and after myriad impacts a polished or etched appearance results. Surprisingly, winds armed only with ice particles can also abrade rock, as shown by the smoothly worn, west-facing rock surfaces at Browning Pass, in the Southern Alps. When ice is near its melting point it is softer than a fingernail, but its hardness increases progressively with cooling until, at minus 40° C, it is as hard as quartz. The rate at which a ventifact forms depends on many factors, such as wind strength and duration, sand availability and the hardness of the original rock. In the tempests of Nova Scotia, ventifacts are known to have formed in only ten years, although in most climes millennia are probably required. The surfaces of ventifacts can be decorated with deep pits, elongated grooves and scallop-shaped flutes. Pitting tends to occur in soft sedimentary rocks where sand grains can become trapped in depressions by the wind. The grains then oscillate within the holes, wearing and deepening them, until the rock looks like Swiss cheese. Ventifacts are not particularly useful, although these surface decorations can record the wind direction at the time of formation, which is of interest to scientists who decipher past climates. Most ventifacts, though, are merely of use as trinkets. I know of ventifacts employed as paperweights, worry stones and mantelpiece curios to break the ice at parties. It seems that many people harbour a feverish desire to own ventifacts, an affliction that got out of hand near the mouth of the Waitotara River in the 1970s. Ventifacts were being plundered there by the trailer-load and one county official even saw a truckload taken. When it comes to conservation, native birds and plants are now thankfully in steady receipt of our preservation efforts, yet rocks are rarely, if ever, considered. Many outstanding geological features have been destroyed by development and plundering. Some Auckland beaches, long seen as free-for-all landscape supply centres, are now almost devoid of sediment. At Waitotara River, many ventifacts had been senselessly smashed to pieces with hammers. Another threat to these ventifacts were plans by local authorities to stabilise drifting sands with lupin and marram grass, a move that would have obscured them for good. Upset by this, the Geological Society of New Zealand applied to have some ventifacts formally protected with the result that several scientific reserves now exist along the Taranaki-Wanganui coastline. Trailers are most unwelcome in these areas now and thieves risk hefty fines. In Antarctica also, we have progressed from plunder to preservation. Unquestionably, the oldest landscapes on earth are to be found in the severe polar deserts known as the Dry Valleys, within the New Zealand-administered Ross Dependency. The artefacts here include ventifacts of incomparable beauty and many were taken by early visitors, although such acquisitive tendencies are now strictly forbidden. It is impractical to return the gathered ventifacts to Antarctica, so a collection has been assembled for the public to appreciate in the foyer of the Dunedin office of the Institute of Geological and Nuclear Sciences. One resembles a Bishop’s mitre both in size and shape. Others are perfectly pyramidal and one is faceted like a well-cut gemstone. It took a couple of decades of research to glean the true significance of the Dry Valleys and it is now known that their rocks have lain undisturbed for many millions of years. Rain never falls but dust-laden winds blow every day. The valley sides control the winds and therefore only two directions are possible: the katabatic westerly that flows down the valleys from the massive Antarctic ice cap, and a less severe summer sea breeze that blows in from the Ross Sea. Salt also corrodes the exposed rocks of the Dry Valleys. The winds trim their tops, while salt crystals attack from beneath, prising them apart crystal by crystal. Bizarre arch-like forms result and ultimately this destructive collaboration reduces the rocks to mere shells of their former selves. In places the thinned rocks emit haunting edge tones during strong winds, and have thus been dubbed the “singing rocks”. The shapes are best described as “out of this world”, and indeed NASA used the Dry Valleys as a Martian analogue when planning and testing for the Viking missions of the early 1970s. It is no surprise then that Mars too has ventifacts. NASA’s Spirit Rover, which landed on the red planet in January of this year, has sent back spectacular photographs of orange-hued ventifacts, all of which now bear Christian names such as Adirondack, Cake and Blanco. It is thought that these Martian ventifacts are relics from a time when great floods deposited sands that were then blown about on the planet’s surface. Photographs of sand tails on the leeside of pebbles indicate that the direction of the Martian wind is from the NE. Interestingly, two ventifacts named Soufflé and Stimpy reveal this has not always been so because grooves on their facets attest to a dominant SE wind that once blew on Mars. Life is hard where ventifacts are formed. Recently, while walking on the mercilessly exposed south coast of the South Island, I saw a pine tree cowering like a reprimanded dog. Despite its 10 m long trunk, the tree never extended more than two metres above the ground – a botanical ventifact. Lichen grew on nearby rocks but never on their windward sides. The Waitotara ventifacts are perhaps the finest examples in New Zealand. They have been said to resemble Brazil nuts or Chinese hats and are between one and twenty centimetres in length. They are sculpted from a variety of rock types but one Waitotara ventifact holds a special intrigue for geologist Vince Neall because it is formed from a rock type not known from the North Island. This “exotic” specimen is sculpted from garnet-mica schist and was found by a Mr T. Smith of Aramoho, however, it is now missing. To Vince Neall the specimen suggests that rocks from the South Island might have been transported to the North Island during past glacial periods, the last of which was 20,000 years ago. During these times of lower sea level, the North and South Islands were joined between Nelson and Taranaki by a land bridge and gravel from the South Island is thought to have drifted northward up that now severed coastline. Sea lions provide another way in which “exotics” can be transported. The animals are known to swallow stones to aid their digestion and witnesses have reported seeing sea lions at rest on land regurgitating piles of stones weighing several pounds. Such stones are known as gastroliths and sea lions, in their role as geological agents, can transport pieces of rock hundreds of kilometres from their original source. At the mouth of the Waikato River, accumulations of once rounded pumice boulders have been planed down by the prevailing sou’wester to the extent that their upper portions are entirely removed. They look like a neat artificial pavement made of inlaid cobblestones. Although for the most part ventifacts in New Zealand are a coastal phenomenon, they can be found in Central Otago. These are sculpted from hard silica boulders that lie strewn upon much of Central’s schist surface. In places these have been ventifacted by the nor’west föhn winds. Strange looking ventifacts also occur around the Clarence River in Marlborough. Here the medium is white limestone and the upper surfaces of the ventifacts have taken on a texture comparable to the hide of an elephant. Tall security fences now encircle the site of the Lyall Bay ventifact discovery of 1869 but not for reasons of conservation. Wellington Airport occupies the area today. Whiteknuckled passengers aboard gyrating aircraft will readily confirm that the intensity of these winds has not abated.
There is a common, but misguided, view of New Zealand Geographic: that it is politically partial and conservation focused, a green-spun publication. Hence, when the editor has the temerity to commission a viewpoint article from an environmentally challenged author—perhaps a nay-sayer’s piece on global warming, or an apologist’s view of GE, we get our fullest mailbags. We are accused of betrayal, of becoming a mouthpiece for Big Business we get it all! That’s not to say that we scoff at environmental values here in the Geographic sweatshop. Far from it! Our natural history stories celebrate New Zealand’s unique organisms, and sadly, too often, the stories have titles like Kakapo—Bird on the Brink, Hoiho—Still on the Brink, Silence of the Fantails, or Disappearing Mistletoe, salient warnings that many of our treasured plants and animals face uncertain futures. With such stories, we think there is little need to mount the soapbox and harangue the reader. Conservation values are self-evident in any comprehensive, impartial and honest accounting—which is what we aim for. We assume readers are adequately equipped to reach their own conclusions without the need for “spin” if the reported trend is one of declining numbers/habitat or voracious predation. Normally our writers quote people working in the field who express such views anyway, so there is little chance that a story on kakapo will omit a sense of their struggle for survival. But, if the story involves logging on the West Coast, we will talk to logging interests as well as those who have chained themselves to the threatened vegetables. Balance is critical to informed understanding. Aside from serving as a documentary of New Zealand geography, biodiversity, history and culture, we think there is another duty we can perform. Where one view of a situation already receives disproportionate representation, we are happy to present alternative ideas if they are considered, thoughtful and plausible. We run a regular viewpoint column and contributors are chosen for their thought-provoking perspectives. The most vehement response we ever received to one of these columns followed issue 52 (Jul-Aug 2001) in which deputy editor (now editor) Warren Judd—who holds a PhD in zoology/cell biology—wrote a piece about crop-based genetic modification. His aim was to provide scientific background on this topic at the time that the Royal Commission on Genetic Modification was publishing its report. In that column he pointed out, for example, that all the organisms we eat are in some sense transgenic anyway! Nature is nothing if not economical and the bulk of our genes, along with those of our food animals, are derived from bacteria, fungi and invertebrates. We are, so it seems, pretty much what we eat! GM is a subject about which many people are intensely passionate. Some readers even cancelled their subscriptions to protest the article’s stance. While that response seems to me a trifle melodramatic, it at least indicates that Warren was correct in his belief that we could explore the issue in ways that other media had not. In this issue we feature a story about Tuvalu, which due to its low-lying topography has become the cause célèbre of the global warming debate. Will Tuvalu and a host of other sea-level nations disappear under rising sea levels? Sadly the answer is almost certainly yes, although we lack sufficient knowledge to say just when these islands, atolls and similarly threatened landscapes will lose their fight to stay above the tides. The process by which this is happening is both inevitable and unstoppable. For thousands of years the earth has warmed and sea levels have risen. This warming has not yet reached its peak but its mechanism has been set at least since we began climbing out of the last ice age, and, in an overview, long before that. Glaciation/interglacial epochs are a fundamental rhythm of our planet, happening on average every 50,000 years, and each epoch is variable in severity and duration, determined by a raft of factors which are poorly understood. Land masses that fall into the zone between upper and lower sea levels are periodically submerged or revealed by these occillations. To what extent, then, is human agency involved in the present warming? There is little doubt that industrial production of greenhouse gases has added a possible accelerant to this natural cycle, but the sum of that addition is hotly debated. Is it marginal, almost lost in the noise of other variables, or will it produce profound changes? Will our input accelerate warming toward its peak which is then sustained a little longer or will it push the peak higher—even catalyse a dramatic or unique climate shift? We don’t know. Would we have done things differently at the start of the the industrial revolution (to which we owe our present standards of living, longevity and health) had we foreseen these developments? No, we are the future eaters. Our civilisation is built on consuming limited natural resources following a model that assumes they are unlimited and that their processed byproducts are not our concern. In much the same way that we trawl our seas ever more efficiently for dwindling marine resources, or wipe out forests that harbour diversity to create arable land for monocultures, interest in short term enhancements overrides any pangs of concern arising from portents of whatever mess we might bequeath future generations. Past civilizations have reached a zenith, then fallen. Many species came before us that are now extinct. While our habit is to see ourselves as a permanent fixture on this blue planet, our short history does not in any way support this view.
Almost two centuries after their ancestors were nearly exterminated, a small flock of flightless Campbell Island teal have been returned to re-colonise their home island deep in the Southern Ocean. This teal, at a tiny 300–370 g, are the smallest, as well as the rarest, duck in the world and by a combination of lucky breaks and innovative rescue operations, has only narrowly escaped extinction. Until the arrival of sealing gangs in the early 1800s Campbell Island was the undisturbed domain of millions of seabirds, hundreds of thousands of seals and sealions, and myriad small birds and insects. This unique living community was also home to a local species of teal, the smallest duck in the world. Its only natural predators were probably the opportunistic southern skuas, which will snatch unguarded seabird chicks, eggs and little ducks if they get the chance. Over the next century the ecological balance of the remote island was disrupted by the introduction of sheep, goats and pigs which were deliberately liberated at various times to provide a food source for shipwreck survivors—a common practice among most seafaring nations of the time. In 1895 sheep were introduced again, this time for farming, and the island remained a leasehold sheep and cattle run for many years. When farming was finally abandoned in 1931, the livestock were left to run wild. The cattle and sheep were eventually removed over several years with the last animals destroyed by the Department of Conservation in 1991. Cats, descendants of farm pets and probably at the extreme limit of their ability to survive in the harsh wet climate, appear to have died out at about the time the last of the sheep were removed. That left the accidentally introduced Norway rats, the toughest and most adaptable of the newcomers, still thriving on the island. They had found a paradise of small birds, large insects and an endless supply of seeds. The flightless teal had no defence against these tough new predators. Eggs, ducklings and even adult birds were all easy prey. By the early 1930s Campbell Island had a higher density of rats than any other measured landmass on earth at up to nine rats per hectare. By the `30s, modification of the island ecology was widespread and the little teal had been almost wiped out on the main island. However, a small colony remained on Dent Island, a 26 hectare spike off the coast of Campbell Island. This population of between 30 and 50 birds was rediscovered in 1975 by a Wildlife Service expedition which found clear evidence of the grim situation faced by Campbell Island teal, and a plan was set up to rescue as many of the surviving birds as they could catch. Wildlife officers Chris Robertson, Rodney Russ and Gerry van Tets spent two hours on windswept Dent Island and managed to capture and study a single female before releasing it again. In February 1984 waterfowl biologist Dr Murray Williams and Andrew Garrick were part of a Campbell Island expedition which revisited Dent Island to search for the tiny teal. They camped for two nights and of the very few birds seen they managed to capture a male teal and took it back to New Zealand. Over the next six years other teal were captured from the island to form the basis of a captive rearing programme and by 1999 the teal population had been increased to 60 birds. All were held in captivity as there was no place safe enough to release them. A year earlier, the Department of Conservation had undertaken a rat eradication project on Whenua Hou, a 1400 ha island five kilometres north-west of Stewart Island. The eradication technique was developed in New Zealand by innovative conservation officers using GPS-guided helicopters to drop poisoned cereal pellet baits designed specifically for rats. Many pundits suggested that Whenua Hou was too big for the system to be successful, but by 2000 the island was officially declared rat free and 24 teal were released there as an interim measure until their subantarctic home island could be cleared of predators. By May 2001 Campbell Island had also been cleared of rats using the same system. At 11,300 ha, it is the largest island to be cleared of rats anywhere in the world. In April this year a geological team on Campbell Island found a lone male teal, which had apparently swum the three km of open sea from Dent to the main island, and then another 20 km around the coast. Prior to the removal of the rats, this little voyager would have been snapped up as soon as he set foot on the island. The Campbell Island pipit, which was also isolated on small rat-free islets, has self-reintroduced to the main island and is now rapidly re-colonising its former home range. Conservation officers hold hopes that the Campbell Island snipe, which was only discovered in 1997 on a single 19 ha islet by specialist bird recovery dog handler Dave Barker and his German short haired pointer Bob, will also make its own way to the main island. In the meantime, the teal on Whenua Hou had held their own in the predator-free environment and, in early September this year, they were joined by a similar number of birds from a captive breeding population held at Mount Bruce in the Wairarapa. All 50 birds were returned to Campbell Island aboard HMNZS Canterbury—the same vessel which brought the first teal back to New Zealand in 1984—in September. Unlike other endangered native birds on the New Zealand mainland, Campbell Island teal now no longer need human intervention on their home range, but a small population has been kept on mainland New Zealand at least until the fate of the birds on Campbell is known. They are now once more on their own and free to re-colonise the home range of their ancestors almost 200 years after the invasion which almost sent them into oblivion.
Travel down State Highway 5 and it’s hard to miss Tirau. The township’s big sheep and matching dog cause many a visitor to do a double take. Those tourists alighting for photo opportunities find a town bedecked with corrugated critters. For this Tirau cheerfully blames Nancy and John Drake. They started it all a decade ago. The Drakes were school teachers. During a spell in the Wairarapa, Nancy learned the art of spinning and became passionate about wool. Her knitwear clothed her family and she hankered after a shop in which to sell her excess product. When John abandoned teaching some years later, they packed a campervan and went in search of a shop site on the main North Island tourist routes. Towards the end of their protracted and somewhat frustrating quest they purchased an empty section in the middle of Tirau. Nancy was prepared to bring on a Skyline garage and start selling immediately. John, however, comes from the slow-but-steady school. He counselled building a full-sized shop in which she might sell a range of woollies and sallied forth to find the cheapest building they could afford that would be big enough. A barn was the answer. For the price of an ordinary house, they could get a kit-set barn complete with its own flat. However, they realised that few travellers would stop for a barn alone. They needed something that would cause potential customers to back up. Much brainstorming led to the idea of “a very big, eye-catching sheep—in white”. But how to make a barn look sheepish? John tried and rejected both sprayed concrete and polystyrene. Both produced results that more closely resembled a corrugated caterpillar than a sheep. Then one serendipitous day, a young architect suggested trying corrugated iron. He even steered John in the direction of a redundant manual iron roller. John was now set on a whole new tack. He built models from balsa and paper and finally figured how it might be done. However, when he sought council approval he found himself hamstrung by the lack of plans and specs. Fortunately the South Waikato District Council was keen to capture new businesses and their building inspector went out of his way to help. Among other things, he ruled that the head was merely a façade and there were no regulations covering façades—just so long as they didn’t fall down. And so in January 1994 the Drakes began construction, their trusty campervan doubling as builder’s wagon and sleeping quarters. The Big Sheep is essentially a kitset barn with a head grafted on to the front. No local builder would touch the project. Builders in Tirau are a prudent bunch, allergic to projects that lack plans or specs. Fortunately, local chippy Keith Carver was between jobs. Despite reservations, he offered to help out. And so it came to pass that Keith climbed ladders and hammered while John sawed and schemed. Building the head was somewhat hit-and-miss. Seven prefabricated barn quarter-arcs, arranged in a semicircle, provided the basic structure of the head. On them a 100 x 50 mm wooden framework was hung. John worried that the nails needed to restrain the sections of iron needed for the head could result in unsightly streaks of rust. Serendipity again kicked in. He discovered that roofs in Rotorua use corrugated aluminium and was able to scavenge what he needed from a local scrap merchant. Suddenly John’s dream was a reality, although for a short time Keith argued that the structure more closely resembled a baboon than a sheep. However, the day the nose was clipped in place Tirau suddenly took on a decidedly sheepish look. The total cost had been a little over $100,000. The sheep proved an instant attraction. People stopped. They looked. They came. They spent money. Nancy had insisted on opening her shop before the head was added. For a while she seldom made $300 a month. On one occasion she sold nothing for five days in succession. But the day the head was finished it all turned around. She found herself with a $1000-a-day business on her hands. The Drakes never looked back and nor has Tirau. With the sheep finished and a proven success, John advocated building more corrugated iron structures about town. The city fathers—and a few mothers—were reluctant. They had hoped to revitalise their township with gentile, olde-worlde antique shoppes. But one day Tirau needed new public toilets. The township asked to use a piece of John and Nancy’s property. The Drakes agreed and offered a peppercorn lease, provided the toilets were built in a style that would complement the sheep and incorporated an information centre. The upshot was Tirau’s dog, the construction of which became a voluntary community project. The dog was driven by Henry Clothier, one of the olde-worlde antique shop owners. He twisted the arm of his son, engineer Stephen, to co-ordinate the building. John produced plans for a dog of similar parentage to the sheep but engineer Stephen wanted something more refined. He enlisted his bull terrier as a model but regrettably this failed to provide the required sheep-doggy appearance. Modifications were called for, such as the droopy ear tips. It was duly completed in July 1998. The dog led to Stephen being asked to undertake other corrugated commissions. Gradually Tirau has been transformed to Corrugated City. Even the street lamps now bear the town’s logo of a cabbage tree, the ti, punched in corrugated metal. The effectiveness of John’s design is shown by Nancy’s wool shop never having to advertise. From day one journalists flocked to Tirau. The sheep and the dog, and now the mantis, moo-loo mouse and a bevy of other corrugated critters have become regular features of travel mags and TV programmes. Today the Drakes have retired to Milford, leaving the shop in the capable hands of daughter Sally. John retains one not-so-secret ambition. He would like to build a giant corrugated pink pig. He is looking for a sponsor and a community wanting a sure-fire tourist attraction.
In a windy land, the most notorious gale is the Canterbury nor’wester. Born in the heart of the mountains, it accelerates down the great valleys east of the Main Divide and roars out across the plains. Distinctive lenticular clouds, as seen here above the Ben Ohau Range, are regular companions of the wind.
Everyone knows that trees are good for the environment. They hold land together, produce oxygen and turn that pesky carbon dioxide into carbon credits—formerly known as wood. But now comes a smut that mars this benevolent image a little. In the US, there has been some puzzlement over why atmospheric levels of a class of pollutants known as volatile organic compounds (VOCs) have not been falling as quickly as anticipated. Unburned fuel emitted from vehicle exhausts contains these chemicals, as do some industrial emissions. However, rules about such emissions have been tight in the US for decades and contributions from both sources have diminished steadily. But trees also release VOCs naturally and they have not proved so responsive to the clean-air laws. As agriculture intensifies in favourable areas—such as in California’s Central Valley—more marginal land in the south-eastern states and elsewhere has reverted to woodland. Plantations of fast-growing trees have also been established. Trees are on the increase in the US! In a new study of 2.7 million trees on 250,000 plots of land across the US by scientists from Princeton, Harvard, Toronto and New Hampshire, production of natural VOCs has been found to be much higher than thought, and it outweighs the reductions that have been brought about by reducing emissions. The main culprits are fast-growing trees—indeed, virtually every tree that grows fast is a heavy producer of VOCs. Old-growth forests generate much smaller amounts. Why are VOCs considered undesirable? Under warm, sunlit conditions, they react with nitrogen oxide compounds (NOX) to form ozone (O3). High up in the atmosphere, ozone performs the invaluable task of absorbing incoming ultraviolet radiation, but in the lower atmosphere it is a major and pernicious component of smog. As a molecule, ozone is particularly reactive and causes damage to respiratory systems and plants alike at concentrations as low as 50 parts per billion. NOX is another pollutant with both an anthropogenic origin (the internal combustion engine) and a natural origin (lightning bolts). While the recent study drawing attention to the problem was based entirely on US research, fast-growing American trees are not unknown in New Zealand. Will we now see them felled as an anti-pollution measure? Most unlikely. Trees are still essential for sequestering carbon dioxide and we still need wood with which to build houses. More likely, attempts will be made to curtail the production of NOX. In 1980, US President Ronald Reagan said, “Approximately 80 percent of our air pollution stems from hydrocarbons released by vegetation”, a comment that was widely derided at the time. It seems as if he wasn’t quite as wrong as has been generally believed.
Contrails, the condensation clouds that form from jet aircraft exhaust or wingtip vortices are the latest culprit in the global warming saga. Research by scientists at NASA’s Langley Research Center has shown that contrails may be signiÞcantly increasing the cloudiness of Earth. Contrails can expand into extensive cirrus clouds, which allow most of the Sun’s visible light to pass through but then trap some of the resulting heat emitted by the Earth’s surface and lower atmosphere. Satellite photographs on one occasion recorded a cloud covering 34,000 sq km over New Mexico that was produced by commercial aircraft. It is estimated that during the past several decades there has been a one per cent, per decade increase in cirrus cloud cover over the US, enough to increase surface temperatures by 0.2–0.3° C. The measured increase in temperature over that time is 0.27° C. An increase in cloud coverage directly related to contrails is therefore enough to account for all the warming which has occurred in the US between 1975 and 1994. Cirrus coverage also rose in North Pacific and North Atlantic flight corridors and in Western Europe, as air traffic has steadily increased there. When air traffic was suspended for three days following September 11, 2001, a 1° C greater temperature difference between day and night was recorded in the US. With air travel increasing worldwide, contrails could be a significant factor in climate change.
Every year, on a marae in Northland, a group of college students from Auckland step into Maori shoes. In this year’s party was Jodine Gribble, here making the acquaintance of course leader Howard Reti. ANKE RICHTER, recently arrived from Germany, watched this cultural encounter.
Although it was Plato’s opinion that a dog has the soul of a philosopher, a view that might possibly find favour in some of our umbrageous suburbs, there is not a lot of evidence to suggest that it was widely held in early rural New Zealand. A New Zealand sheepdog was something to be worked. But dogs have not just left their mark on farming: a considerable number of words have been generated around them in our language. The first rural dogs were actually an impediment to pastoralism, killing and maiming sheep. Originating from Polynesian exploration vessels and, later, whaling ships, the kuri, also known as the bush dog, Maori dog, native dog or pa dog, roamed widely once mutton was available to the Maori, and kuri ceased to be the delicacy it had been. Newspapers reports from the 1850s and 1860s record the nuisance status of the kuri to early pastoralists, and to distinguish their dogs from kuri, the early sheep kings referred to sheepdogs as colonial dogs. Dog tax has been controversial since its inception. In 1898 a potential major conflict known as the Dog Tax Rebellion occurred in Northland, when local Maori refused to pay a dog registration fee and declared an attack on the settlement at Rawene, resulting in Government forces being sent to enforce the law. Fortunately, the confrontation was settled as troops drew their weapons, just one shot being fired by Maori. Nonetheless, fourteen Maori were found guilty of treason in the bloodless last clash between Maori and Government troops. For some years, Kiwi sheepdogs were awarded little privacy for the most basic of their bodily functions. In the 1950s, 60s and 70s, most rural localities had dosing-strips along roadside fencelines where dogs were purged and a sample of faeces for hydatids testing collected. The ‘dog-dosing strip at Dunsandel’ was incorporated into a national song. Dog-dosing, like other rules and regulations relating to dogs, was controversial. The dog-doser or hydatids man was regarded as a nuisance in a busy farming schedule, and was widely known as the hydatids hinderer. The first heroes in the New Zealand canine scene were were boundary dogs or dog shepherds that patrolled station boundaries, living frustrated lives of isolation tethered to a pole and being fed once a week by an itinerant shepherd. Once stations and farms were fenced, in lieu of gates, gate dogs were tethered at fence openings traversed by roads, to prevent sheep crossing boundaries, but allowing traffic to pass. Here again, the unfortunate lone dog was fed only infrequently by passing station staff. The rural sheepdog hierarchy reflects topography, a high-altitude shingle dog, high country dog, hill dog or mountain dog earning more respect than a paddock dog, used for mustering or shepherding on easier country. A cocky’s dog or a carpet grass with even more tender paws earns contempt amongst the high country fraternity, and the powder puff or townie dog is almost beyond contempt, being soft and not a real man’s dog. Work performance is the genesis of many colloquial terms. From as early as 1917 we find terms for sheepdogs that did not meet expectations—the half-day dog and the show dog. The half-day dog lacked stamina, its more modern equivalent being the ten o’clock dog that refuses to work after the cooler part of the morning is over. The show dog, like the powder puff or poser, is full of attitude and pose, but its performance leaves a lot to be desired. The Sunday dog is the ultimate in laziness, regarding each day as the Sabbath, and refusing to work. The gravel-scraper or shingle-scratcher, another poser, makes a great fuss and barks wildly, but makes little impact on the sheep s/he is supposed to be moving. The bludger, flea taxi, fly-flicker, freeboarder, freeloader, passenger, and sundowner are each part of the lazy dog contingent, along with the sooner, who would sooner be lying in the shade than confronting the sheep, and would sooner the master or other dogs got on with shifting the mob. A meat-converter or turner is the lazy dog with a prodigious appetite that turns good food into something less desirable. Looked upon more favourably, however, is the backdoor pensioner, the old dog that, in retirement, is retained and permitted to hang about the station compound or homestead back door, or, if s/he can be trusted, the dog-tucker tree, where the carcase for the next canine meal swings. Dogs that ‘worry’, injure or kill sheep are shown little lexical mercy, being known as chisellers, hotchoppers, meat graders, meatmanglers, meatmunchers, wool-classers, wool-sorters, or euphemistically, worriers. Those that ‘nudge’ sheep in the correct direction from the rear are known as hock-hunters, rump-munchers or sparrowhawks; nosers being those that ‘encourage’ from the head of a sheep (or cattle beast). The hooler creates a noisy fuss in order to successfully coax reluctant animals. Other recalcitrant dogs are the dividers, slewers or splitters that, in a surplus of enthusiasm, scatter a mob of stock being gathered together. Specificity is a notable characteristic of the canine lexicon, with sheepdogs having a range of distinct roles and responsibilities. In droving and mustering, the wing dog or wing leader works at the side of the mob as it moves forward, with the lead dog, leader or leading dog working at the front. The tail-ender or tail shepherd follows a mob of sheep as it is driven. In the paddock or on the run, the artful shedding dog separates sheep into two or three separate mobs. The huntaway, New Zealand’s own breed, uses its bark to gather, hunt and drive sheep towards gateways or yards. (Also known as a hunter, an example of the breed is sculpted in bronze at Hunterville, the service town of a rugged farming area in the North Island.) The near-at-hand huntaway is a specialist that works in close proximity to its master and quarry. The heading dog, header, driving dog or eye dog specialises in surrounding or heading off sheep and bringing them towards a shepherd or handler. The specialist eye dog that will control a sheep with hypnotising eye contact is often known as a thistle-peeper, while a blocker, gathering dog, stopper or stopping dog is a heading dog that specifically gathers in single potential ‘escapees’ from mobs of sheep, and is often seen circling a mob. A shandygaff or handy dog, also known as a head-and-hunt, is one that heads, hunts and often backs as well. A New Zealand Journal of Agriculture columnist, in lighter spirit, offers an alternative view of the head and hunt term: a low-class dog that heads for home and hunts for tucker. The holding dog or minding dog has a specific task of holding a mob of stock together on a roadside, or in a mustering situation where waiting is required. (Holding dog is a term also applied to a pig-dog that contains a pig once it is bailed.) Those that specialise at sheepyards and saleyards are known as yard dogs, with a different function from the yard dog in other nations, which usually guards a section. A type of huntaway, the forcer or forcing dog doubles as a yard dog, and will persevere in moving individual sheep. The backer or backing dog, also known as a wool-walker, is trained to run along the backs of sheep to clear congestion or lead sheep reluctant to enter loading banks, pens, races, ramps, stock crates or trucks. The penning up dog is also used in yarding, penning and drafting work at sheepyards or saleyards, often being known as a trucking dog, if he is used to load and unload sheep from crates or trucks. A shaker or shaking dog, indispensable in a large mustering or shepherding team, is the disciplinarian, keeping order amongst the individual dogs. The world’s first sheepdog trials were held in Central Otago in 1867, and a host of New Zealandisms evolved from this activity, which quickly became a national pastime. On dog-trial circuits, a beautiful dog is not an aesthetically pleasing or wellbred animal, but a sheepdog that does its job well. It may be a sooler, a bread-and-butter dog, or an all-rounder—all canine Jacks of all trades. The trial dog that is heavy is one that is slowly and steadily in command of his sheep, while the light dog succeeds with speed, luck and a softer touch. And dogs’ masters and mistresses? Drovers, musterers and shepherds are variously referred to as dogbludgers, dog-drivers, dog-floggers and dog-wallopers. New Zealand shepherds and musterers with a reliable team of dogs are said to be well-dogged. Although musterers and shepherds are known as horse and dog men, dog men is usually applied to dog-trialists. A cultural message is enshrined in a real dog man, who is probably known nationally for working sheepdogs at an exceptionally high and exemplary standard. Sheepdogs can be full-tongued (a useful attribute in a blind gully, rather than in the suburbs), or well-noised; they can be strong-eyed, or even over-eyed. They can be chain-crazed, when given insufÞcient exercise, and whip-shy (an utter disgrace). Although there does not appear to be much neurosis in the modern sheepdog, particularly since the 1960s when s/he has been housed in dog-motels, the Kiwi woof will often become highly frenzied or bike-happy when the farmbike starts up. A little instability can also creep in when s/he has become used to competing in dog trials, becoming trial-happy, to the profound distress of its owner. Roles are also specific for dogs in the pig-hunting game, with finders, bailers and holders all taking part in the chase and capture. One of the quaintest of monikers in this team is that of the bonnet Þnder that sits on the bonnet of a hunting vehicle in order to sniff the trail of pigs. Lowly or useless objects and worn, bankrupt citizens are known as dog-tucker in the Antipodes. Boiled dog, in early twentieth century New Zealand, was the term used for affectation. US English introduced ‘in the dog-house’ for those in trouble, while errant New Zealanders are in the dog-box. Any machine, activity or person that operates slowly is dog-slow. New Zealand journalists have been moved to use lapdoggery to describe the nation’s foreign policy and as recently as April this year, one of Auckland’s oldest pubs was referred to as an old dog. A business journalist in a recent daily could not resist citing business leader, ex-Fonterra CEO, Craig Norgate, who commented “Wrightson’s rural services division was ‘an absolute dog’ but its seeds business could be described as ‘a jewel’.” A recent editorial page in a farming newspaper sported two dog-related references in ‘it’s a dog-eat-dog business making a living out of the meat industry’ (!) and ‘Landcorp’s a dog – get private farmers into it’. The rural dog has left its mark on the tourist industry with organisations such as Kiwi Experience offering nationwide tours with the names of Stray Dog, Sheep Dog, and Dog Leg. (The shape of a dog’s back leg was applied to dog-leg fences, early rural New Zealand and Australian fences made of bent scrub and tree branches.) In the twenty-first century, the national sheep population has dropped from its twentieth century high of seventy million to fewer than 40 million. The lexis that has developed around the New Zealand sheepdog has nevertheless made a worthy contribution to our cultural storehouse, and many of these terms will certainly be part of the linguistic landscape for years to come.
Albertland was to be a city to rival Auckland, a third religiously based settlement following the successful examples of Anglican Christchurch and Presbyterian Dunedin. Despite great fanfare surrounding the departure of the settlers from London in 1862, little came of the grand scheme, which was based in a quiet arm of Kaipara harbour 15 kilometres west of present-day Wellsford.
The last 50 years has seen a focus on cleaning up environmental messes—in policy jargon, mitigating the effects of human activities. This approach has led to the creation worldwide of institutions such as environmental protection agencies and, in New Zealand, to legislation such as the Resource Management Act. While this ‘clean up’ is important, the concept of sustainability is much broader and more positive. Essentially, it means developing systems that deliver qualities of life without making a mess in the first place. In physical terms there are many ‘visions’ of a more sustainable future. Many include more public transport and hopefully fewer cars; more solar water heaters on our houses and fewer heated towel rails in our bathrooms; more wind turbines and fewer thermal powered stations; more children walking to school and fewer SUVs at the school gate; more trees in our cities and fewer acres of concrete; cleaner lowland streams and rivers; and our seas still rich in species of all types, fished or unfished, and our dawn choruses at full volume. That is our common physical utopia. However, it is a rather one-dimensional view. The end game may be physical, but to redesign the mechanisms by which we arrive there is a quite different exercise. Sustain, in its simplest terms, means to endure and to remain healthy—how we continue to exist, provide shelter, and clean water or food into a very distant future. When most of us think about sustainability, we think about our biophysical world, our waters, forests, pastures, orchards, rivers and oceans. But I would also look at what we value; what we celebrate and honour; and what and how we learn for life. We need a broader picture of how to craft our learning, economic institutions, and tax systems for a more sustainable physical world. Above all, we need new values and beliefs to underpin that picture. There is a difference between conserving and sustaining. Conserving our indigenous flora and fauna is just one component—a far greater challenge is to sustain, in good health, the natural capital in that 70% of New Zealand from which we extract a living. Sustaining is about using while keeping our natural capital healthy. It is a matter of going back up the pipe and crafting industrial, agricultural, legal and business models that use materials and resources more efficiently, create much less waste, and remove the pressure of ever increasing demand. That is why I maintain that sustainability is a positive construct—it offers enormous opportunities for developing totally new ways of providing for our societies. However, seizing these opportunities is where the going gets tough. Many commentators over the last decade have noted little change in unsustainable patterns of consumption and production. Our economic and taxation systems continue to offer incentives for unsustainable behaviours. In terms of the continual increase in demand for physical resources of fuel, minerals, water, and land for housing, plenty of data suggests that four million Kiwis are living in unsustainable ways. This constant expansion of physical demands and the associated pressures on our receiving environments—our rivers, ground waters and atmosphere—cannot be sustained. As the noted economist Herman Daily said in 1989, we need to distinguish between growth and development, quantity and quality: “Growth of the economic organism means larger jaws and a bigger digestive tract. Development means more complete digestion and wiser purposes.” Here lies the biggest single challenge, to sustain and advance quality of life without constantly expanding the physical economy. It requires major changes in how we view the world—our values and beliefs—and in the way we arrange our social and economic systems. It is beyond the scope of this viewpoint to argue the ‘hows’ of this transformation. Rather, I would like to concentrate on what things are happening in a more sustainable New Zealand that are good indicators that we are making the needed changes in our thinking and behaviours. Already there are signs that in the key area of what we teach and learn about sustainability, change is occurring. My January 2004 publication, See Change: Learning and Education for Sustainability, gave an example of the Enviroschools programme that emerged from Hamilton City Council efforts to promote sustainable learning in school activity and thinking. Ideas around sustainability are embedded into all teaching, whether language, maths, science or geography. However, it’s not just what is taught in the classroom, but the very way running the school is thought about, whether building a new classroom, buying a mini bus for taking children to sports, or a project in the school grounds. The sustainability ruler is run over every decision. This is a whole-oflife approach in that the kids take ideas from school to home and create an interaction between the school and the wider community. I would also look for major reshaping of our formal teaching curricula at secondary and tertiary levels. In tertiary, while the government’s 2002 Tertiary Education Strategy recognises sustainability as important, there is very little focus on action. The concept needs to be embedded so that institutions are teaching what amounts to a core subject, as important in the 21st century as teaching our arithmetic in earlier days of education. One Australian institution, the University of Queensland, is responding to the challenge to create talent that can work across the spectrum of social, environmental and economic worlds. Its School of Natural and Rural Systems Management (NRSM) was developed in response to the growing demand for graduates with research capabilities that were truly interdisciplinary. Farmers, agri-industries and governments find they struggle with the complexity of developing profitable, environmentally friendly and socially acceptable management practices. Many NRSM students have returned to university after working in some part of the rural and agribusiness sector. They typically had completed a degree in science, economics, resource management or social science, but found it did not adequately equip them to deal with the sheer complexity of issues, often to do with environmental sustainability, they were facing in their work. The school meshes three areas of activity: a focus on social, biophysical and quality of life issues; clean and green production of food, fibre and ecosystem services; and enterprise development. Such developments are also needed in New Zealand. Beyond formal education, a more sustainable New Zealand would be characterised by major reshaping of our taxation system so that it offers incentives to efficient resource use and recovery. Increasingly we would be shifting taxation from labour and capital to resource uses in ways that did not, of necessity, increase the total tax take. On the wider economic front, we would see more extensive valuation of ‘environmental externalities’—all environmental costs associated with whatever it is we are doing. These would appear on balance sheets so we can clearly see the full cost of producing a megawatt of electricity, a tray of kiwifruit or a litre of milk. This is not entirely radical, given we have signed the Kyoto Protocol which seeks to bring carbon onto our economic balance sheets. Today we measure our progress almost totally by economic indicators, with the occasional Olympic or World Cup sporting index thrown in. In the future I hope we will consider measures of our natural, social and cultural capital. An annual sustainability scorecard listing 20 key social, economic, environmental and cultural measures, devised after consultations with communities the length and breadth of New Zealand, should attract more attention from politicians and stock-markets than the Reserve Bank’s interest rate pronouncements. The New Year and Queen’s Birthday Honours lists will feature prestigious and much sought-after awards for New Zealanders’ contributions to sustainability. We will have got to grips with seeing quality of life, not in largely material terms, but in terms of experiential wealth. Yes, incomes will have increased, but what will matter to New Zealanders is clean water at the beach, well maintained sports grounds accessible to all, family friendly waterfronts, safe, well-lit city streets, and quality schools and medical facilities. These indicators, on which we already place a high premium, will be public, widely understood, and the benchmark of our national wellbeing. They will flow through to the nature of our businesses, to where we live and our patterns of settlement and movement. Present trends are towards ever larger retail units, often in mall complexes dominated by a handful of conglomerates. Two companies now provide over 90 per cent of New Zealand’s food and household good supplies. In a more sustainable New Zealand, retail will again be more dispersed. Smaller business units, which may be part of collectives, will be back to the high streets of our villages or to suburban centres within our cities and smaller towns. Neighbourhood retail rather than mega stores will be the focus. Internationally, we will have moved on from our somewhat fragile ‘clean green’ or ‘100% New Zealand pure’ image. We will be celebrated as a sustainable nation, the lynchpin of a thriving tourism industry. Such is the demand to come and share our land and spaces that, for some time, we will have had to limit visitor numbers, in the same way the French have limited visitors to the Lascaux Caves because of the effect of CO2 on the unique ice age paintings. Our authors, playwrights and film directors will be world renowned for their portrayals of a more sustainable New Zealand. A telling sign that we are well down the path will come when the annual Fonterra Award, given for a book, play or film that contributes most to our understanding, is presented to Roger Hall for his blockbuster play about our transition to a more sustainable nation.
It is estimated that 100 lightning flashes occur on Earth every second, which adds up to a respectable total of more than 8 million a day. New equipment developed in the last decade or so is now able to detect lightning strikes and pinpoint their position to within several hundred metres. This shows that only about one lightning flash in five reaches the ground. The majority stay within the clouds, travel from one cloud to another, or occasionally shoot out from a cloud and stop in midair. In the United States, an average of about 30 million lighting bolts strike the ground each year. That works out at about one per second though in fact three quarters of the strikes occur in the three months of summer. Florida is a prime target because of an abundance of heat and moisture and also the fact that it is a peninsular, so that sea breezes moving inland from opposite coasts collide in a convergence zone kicking off the towering cumulonimbus clouds that give birth to thunderstorms. Parts of Florida have a lightning density of over seven strokes per square kilometre per year. The frequency of lightning generally decreases as you move north and west away from Florida, although a large part of the central and eastern States has above three hits per square kilometre per year. However, the west coast and the far north are less dangerous, having less than one hit per sq km every two years. One interesting discovery solves the mystery of lightning striking from a blue sky. An investigation of a strike that hit an airport worker on a fine day found that the lightning had travelled more than 50 kilometres away from its parent cloud before finally striking the ground. A network of detection equipment was installed in New Zealand just over four years ago. Owned by Transpower NZ, the network is maintained by MetService. Accurately detecting the location of a lightning strike on power lines is extremely useful for a power transmission company so it knows exactly where to send its repair crews. For MetService, accurate lightning detection provides the opportunity to verify, and thereby fine-tune, forecasts of thunderstorms, as well as to develop a clearer picture of when and where our lighting strikes. In the four years up to September 2004 there were 214,043 lightning strikes to ground in New Zealand, an average of 53,511 per year. Most strikes occurred in the 12 months ending September 2002, with 70,071, and the least, 41,591, in the following 12 months. From a glance at the diagram (next page) it is clear that lightning strikes occur most frequently to the west of the main mountain chains of New Zealand, especially on the West Coast of the South Island. One reason for this is that airstreams from the westerly quarter are the most frequent in our latitudes. Storm clouds approaching from that direction usually drop all their rain as they rise up over the mountains and are changed beyond recognition when they reach the lee side of the hills. This is especially true in the South Island where the main divide is roughly twice as high as in the north. Some thunderstorms occur just ahead of cold fronts and others are in the deep pools of cold air that usually follow several hundred kilometres behind the fronts. Often, these fronts weaken as they approach the North Island, and the cold pools more often track across the South Island than the North. Among the places with the least lightning are Wairarapa, eastern Gisborne and some inland parts of Southland. There is also a small gap over Lake Taupo where the absence of surface heating makes the formation of thunderstorms less likely. Lightning strikes are more common in summer than in winter, but the winter strikes usually have a stronger current, averaging about 50 per cent more amps than the summertime strikes. In spring and summer thunderstorms are more likely in the afternoon and evening, whereas in autumn and winter they are fairly evenly distributed between night and day. In summer, the proportion of strikes over land, rather than the sea, is greater than in winter. Also, summertime strikes tend to occur along the ranges, where sea breezes converge, such as the Kaimai Ranges, or the Raukumara Range between Gisborne and Bay of Plenty. The reason for these differences lies in the role surface heating plays in spring and summer. Then sunlight is intense enough to significantly heat the land and consequently the air just above it, making a major contribution to the atmospheric instability that causes the thunderstorms. In winter the instability comes primarily because of extreme cold temperatures through a great depth of the atmosphere during an influx of polar air. This cold air often causes greater instability in a winter thunderstorm than occurs in a summertime storm and therefore stronger upward motion inside the cloud and consequently greater charge separation, ultimately producing a stronger discharge. The drop-off in lightning strikes in autumn comes despite the fact that temperatures over the land may still be high. The difference is that the air aloft tends to be much warmer in autumn than in spring or early summer, thereby making the atmosphere more stable. Also, the sea temperatures are at their warmest in early autumn, therefore the temperature difference between land and sea, on a sunny afternoon, is not as great as in spring or early summer. This makes the sea breezes weaker in autumn and therefore weakens the convergence of sea breezes from opposite coasts. Another use for the lightning data is verifying damage claims. One farmer filed an insurance claim for crops consumed by cattle that crossed an electric fence possibly knocked out by lightning. When it turned out that no lightning had occurred, the farmer remembered that he had forgotten to switch the fence on and withdrew the claim! On another occasion a pet cow was found dead under a tree and the owners wanted to know if an overnight thunderstorm was responsible. In fact a strike had been recorded in the vicinity of the tree during the night. Although it is some years since lightning caused a human fatality in New Zealand, around a hundred people are killed by lightning each year in the United States. This has lead to wide publicity there of the “30/30” safety rule. If you hear thunder within 30 seconds of seeing a flash, you should take cover in a well-constructed building and not leave until 30 minutes after the last thunder is heard. Many people hit by lightning can be revived with mouth-to-mouth resuscitation. During one of Benjamin Franklin’s experiments, lightning stunned a turkey but it revived when Franklin repeatedly blew into its lungs only to then run straight into a wall. Franklin’s invention of the lightning rod in 1766 was a great success and news reached Captain Cook in time for him to take one on the Endeavour three years later. But the news had not travelled to Italy where in 1769 the church of St Nazaire in the town of Brescia was struck at a time when 100 tons of gunpowder was being stored in the vault. The resulting explosion killed 3000 people and destroyed one sixth of the city. However, not all lightning is bad news. In Queensland there is a crocodile farmer who is convinced that thunder and lightning are an aphrodisiac for crocodiles. During droughts he fakes the thunder by hiring helicopters to fly over the farm, although apparently not all the crocodiles are susceptible to this deceit. And our very existence may be attributable to lightning.One school of thought in the origin of life debate considers that lightning may have played a pivotal role in combining the right molecules to begin the first stirrings of life.
In the average garden, life-and-death struggles are a daily fact of life as tiny creatures battle to survive in an ever-changing environment. Keen gardeners, intent on keeping up with the latest fashions in plant selection and garden design, are forever digging, pruning, spraying, mulching, watering, planting, weeding and fertilising to keep their little patch of paradise looking at least as good as that of their neighbours. Many take great satisfaction from growing their own fruit and vegetables. Waiting to spoil their efforts is an army of insects, seemingly poised to suck and chew every plant that the gardener lays out. Almost overnight, a perfect specimen can be reduced to little more than compost by almost invisible critters. But nature is not entirely opposed to gardeners. A rival insectile army holds the voracious vegetarians in its sights, regarding them as entrées and mains on its own menu. Man has long used the parasites and carnivores of this second legion to control pests; indeed, many species have been deliberately introduced into New Zealand in an effort to reduce pests on food crops. Their effect is rarely total annihilation, for a predator that killed every last one of its prey would wipe itself out too. However, they can be effective in reducing damage to plants. One pest that has been almost eliminated is the cottony-cushion scale insect. This Australian native can be very destructive in citrus orchards but was brought under control in New Zealand within two years of the introduction of the cardinal ladybird. From New Zealand, the ladybird was taken to California where it also saved their citrus industry. There are now many ladybird species in New Zealand, most of which do a great job of demolishing aphids. [caption id="attachment_19226" align="alignnone" width="600"] To avoid the all-too-common fate of becoming someone's meal or birthing chamber, many a denizen of the insect world resorts to camouflage. The common grass moth (Orocrambus flexuosellus) tightly folds its wings when resting, allowing it to blend with stems and dead twigs, whereas a row of planthoppers (bottom) appears like thorns or budding leaves.[/caption] For the last 10 years I have been photographing the deadly tussles among the smaller denizens of our garden in Katikati. Over this period, I have been surprised at how the insect population has changed. New species have arrived and thrived, while others that were common a decade ago are now rarely, if ever, seen. Natives seem to be the most vulnerable to aggressive newcomers. The native praying mantis (possibly an accidental import from Australia in the early days of European settlement) was abundant in our garden in 1993, half a dozen or more commonly being found on a single shrub. Next summer I spotted the first springbok mantis, a larger and more aggressive species from South Africa. This species has since multiplied rapidly and now seems to have largely replaced its native counterpart. Stick insects, also once abundant, are now another rarity. I suspect sparrows feast on the juveniles. One of the few native insects to thrive in our garden in the face of foreign invasions was the tree weta. I encouraged them by drilling 20 mm holes in lumps of wood that I fixed to the fence under the dense foliage of some trees overhanging from neighbouring properties. At the colony’s most populous, there were upwards of 20 weta, but numbers fell to 3 or 4 after new neighbours reduced the trees to firewood. These insects are not exactly a gardener’s best friend as they have an appetite for numerous garden plants, particularly bromeliads. Some predators, like wasps and mantids, are outright carnivores, grabbing and devouring a wide range of insects and their larvae. Others, like the brown soldier bug and the robber fly, seize their prey then suck it dry, siphoning off its body fluids with a long proboscis, which they wield like a syringe. Another group of parasitic insects inject an egg or eggs into their prey, the resulting larvae gradually gnawing away its insides as they grow. Somehow, most of the larvae eat round the critical organs required for survival, allowing the parasitised host to survive for a period of weeks before it finally collapses. The Asian paper wasp first appeared in our garden in numbers in 1993 also. The Australian paper wasp had been resident in the district as far back as I could remember, but it never became as common as the Asian species now is. We find Asian paper wasp nests by the dozen every spring and summer, and though they prey helpfully on the numerous varieties of caterpillar that damage so many of our plants, they make it virtually impossible to maintain a population of monarch butterflies. They discover and tuck into every last caterpillar, even though other predators, birds included, appear to be warned off by the wrigglers’ black and yellow colouring. The cabbage white is one of the few butterflies that seems able to survive in any numbers despite a plethora of predators. Several parasitic wasps have been introduced to defeat this foreign pest, but from earliest spring to the first frosts of winter we continue to suffer an endless stream of these pesky lepidopterans in our garden. The Asian paper wasps take a considerable toll of the plump green caterpillars, and it is not uncommon to find clusters of tiny, golden silk cocoons of the parasite Apanteles beside a dying caterpillar from which the black wasp-like creatures, just 3 mm long, have recently exited. Unfortunately, Apanteles—rarely noticed in the garden on account of its diminutive size—is itself prey to an even smaller wasp, Baryscapus galactopus, which lays its eggs in pupating Apanteles larvae, thereby killing them. Such predating of predators is not uncommon. A minute Aphidiinae that parasitises other aphids is in turn killed by another parasite. You need a lens to see these tiny insects clearly, and some I have come to recognise only since sending slides to John Early, entomologist at the Auckland War Memorial Museum, for identification. [Chapter-Break] Among the parasitic insects are many black-and-yellow or black-and-orange wasp-like creatures, the females of which have long ovipositors at the end of their abdomens. They look quite intimidating but most are entirely harmless and make welcome residents in the garden. Especially colourful is the introduced yellow-banded leaf roller, 8 mm long and patterned in brilliant yellow with black spots and stripes. This has become very common in our part of the North Island in recent years, and is extremely useful as it parasitises a wide range of other, more destructive leaf rollers, which it has significantly reduced in numbers. Another highly colourful species is the lemon-tree borer parasite, a native about the same size as a paper wasp but much brighter, with cream and black bands on its body and with bright-orange legs. It has a long ovipositor with which it drills through the tough exterior of a tree to lay its egg in the grub of beetles deep inside the wood. Ctenochares bicoloris is a colourful, self-introduced insect from Africa, 25 mm long and bright orange with black tips to its wings and abdomen. It is one of several useful parasites of the green looper. Insects adopt a range of strategies to avoid becoming prey. Some harmless species are coloured so as to appear dangerous or unpalatable. Others resemble entirely different species, thereby going unrecognised by many a predator (not to mention the average human observer) despite being quite common. The drone fly looks like a bee, and even acts and sounds like one as it buzzes around the flowers feeding on pollen. Even more apian in appearance is the large, fat narcissus-bulb fly, a perfect replica of the common bumblebee. This little-noticed insect is a major pest to many bulb species, its maggots eating the insides of some of our loveliest flowering bulbs. They don’t necessarily kill their plant hosts but force them to multiply, the resultant bulbs being too small to support flower production. The caterpillars of native moths can be every bit as damaging as those of the cabbage white butterfly and loopers. An infestation of cabbage-tree moth caterpillars can turn a large cabbage tree into an eyesore, every leaf scalloped with dozens of deep notches. Predators do not seem to find the culprits particularly palatable compared with many introduced species. [caption id="attachment_149151" align="alignnone" width="981"] As its name suggests, the manuka chafer (Pyroonata festiva) dines on the aromatic leaves of New Zealand tea tree. Usually emerald green, this member of the scarab, or dung-beetle, family may also appear in blue, orange, red or purple livery. It is especially common beside streams.[/caption] The kowhai moth is another native that can almost completely defoliate a shrub, especially the dwarf varieties of kowhai. The caterpillars are thin and greenish with a few bristles and dark spots and are very difficult to spot. At the slightest shaking of a twig they will drop to the ground. Our miniature kowhai is regularly almost stripped of foliage by these hungry leaf-eaters, though our larger specimen seems to suffer little—chiefly, it appears, thanks to the efforts of the local sparrows, which visit the tree daily in considerable numbers. In recent years, silvereyes have also become regular visitors, and between them the birds keep the caterpillars in check. Curiously, they rarely visit the dwarf kowhai nearby. The cabbage-tree moth is an extraordinary insect, rarely seen on account of its highly effective camouflage markings. It seems to know that the brown stripes across its wings can be aligned perfectly with the striations on a dead cabbage-tree leaf, and is almost invariably found facing across a leaf, thus achieving this effect. Caterpillars of this species regularly deface the leaves of cabbage trees, gnawing large embayments along their otherwise straight margins. Most of the damage seems to occur when the leaves are tightly curled in the early stages of growth. Common katydids can, to a degree, vary their colour according to what they feed upon. Those we spot in our garden are occasionally of a purplish hue rather than the more typical leaf green. I recovered one such individual from a variegated brush-box tree on which it was feeding, its red-blue legs blending with the reddish stems of the leaves. Green katydids can be very difficult to find on large shrubs and are much more common than they appear to be. On summer evenings their soft chirping calls flutter round the garden, but being ventriloquial these are extremely difficult to trace. Though katydids feed on foliage, they do not seem to accumulate to the extent that they cause overt damage. One insect that seems to have few enemies is the bronze beetle. This extremely destructive native is only 4 mm long but has a voracious appetite for leaves and apples and appears almost immediately after fruit set in spring. Large numbers chomp into newly formed apples, on which they inflict huge scars. They also have a taste for rose flowers, especially our Rosa rugosa, the petals of which they shred. We are reluctant to use poisonous sprays on our edible crops, but trying to pick off these tiny villains by hand is virtually impossible as at the slightest disturbance of the foliage they drop to the ground. If your trees are small and you have lots of time, they can be shaken into a container. This all just goes to show that, despite our size and intelligence, without pesticides or organisms that inadvertently take up cudgels on our behalf we are no match for insects. [caption id="attachment_19236" align="alignnone" width="1600"] This attempt by a male springbok mantis (Miomantis caffra) to mate with a female New Zealand praying mantis (Othodera novaezealandiae, identifiable by the yellow mark on her upper front leg) is doomed to be fruitless. The South African intruder, which arrived in the late 1970s, is now common across the north of the country and still spreading.[/caption] [caption id="attachment_19238" align="alignnone" width="1600"] The tiny bronze beetle (Eucolaspis brunneus), only 3-4 mm long, is a severe peset. Shredded rose petals, scarred new fruit and leaves perforated with "shotholes" are all signs of its nocturnal feasting—just one of countless challenges to our ability to manipulate or accommodate the insect hordes that fly, crawl, wriggle, chomp and swarm through our gardens, orchards and field crops.[/caption]
Tuvalu’s children face an uncertain future as the seas surrounding their tiny Pacific homeland slowly rise. The country’s leaders believe it is only a matter of time before Tuvalu’s 130 odd islands and islets none of which rises higher than five metres above sea level—slip beneath the waves, forcing the 9500 inhabitants to evacuate. But is Tuvalu really facing national extinction, or has the islands’ dilemma become, as one conservative think-tank claims, “an icon of environmental and political deceit?”
Thanks, you're good to go!
Thanks, you're good to go!
Ask your librarian to subscribe to this service next year. Alternatively, use a home network and buy a digital subscription—just $1/week...
Subscribe to our free newsletter for news and prizes