Amphibian Armageddon and killed-off kauri: the worldwide battle against fighting fungi

I recently wanted to visit the Ark in the Park, an open sanctuary in the Waitakere Ranges west of Auckland that uses constant predator control to protect native plants and animals. However, I was stopped by a sign stating that Te Kawerau a Maki, the Maori of the district, have placed a rāhiu or prohibition on entering the forest. Although not legally binding, the rāhui is intended to stop people walking through the area and spreading infection, serving in place of any notice by the New Zealand Government or Auckland City Council, since the latter two bodies have failed to take action. Perhaps this inactivity is because the infection does not directly affect humans or farming. Instead a fungus-like pathogen is killing the native kauri Agathis australis, one the largest tree species on Earth.

Known to live for over a thousand years and grow to over fifty metres tall, the largest kauri are seen by Maori as the lords of New Zealand's northern forests. Yet since 2009 the microscopic water mould Phytophthora agathidicida has been causing kauri dieback at an ever-increasing rate. Surveys in the Waitakeres show that most of the infected areas are within ten metres of walking paths and therefore the mould is being spread by visitors to the lowland forests who fail to thoroughly clean their shoes with the supplied disinfectant spray. In a truly David versus Goliath battle between the miniscule mould and giant trees, introduced species such as possums and pigs are aiding the former by accidentally spreading the minute spores.

Auckland Council reported last winter that the amount of affected kauri has reached 19 percent, meaning a doubling in scale in only five years. Since there is no cure for infected kauri, some scientists are now predicting the extinction of this magnificent tree in the near future. The combination of the pathogen's microscopic size with its rain-based activation after dormancy means there are currently no methods that can prevent the infection from spreading. In a way, the rāhui may just slow down the inevitable. Considering the immense kauri are home to a unique ecosystem of epiphytes, orchids and associated symbiotic organisms, the future flora and fauna of kauri-free forests may well be markedly different from the Waitakeres as they are today.

I've previously discussed the ubiquity of the unsung fungi and how prominent they are even within totally man-made environments. It seems surprising that New Zealand's authorities, so keen to preserve native birds and reptiles, are failing to take any action to at least buy time for the kauri; perhaps they have already deemed extinction as unavoidable and not worth spending public funds on.

The kauri are far from being the only organisms currently threatened by fungi or their kin. Over the past decade more than thirty snake species in the eastern and mid-western United States have started succumbing to what has been termed Snake Fungal Disease. The culprit is thought to be a soil-based fungus called Ophidiomyces ophiodiicola, with a similar organism now also thought to be affecting snakes in the United Kingdom and mainland Europe. Research suggests that up to ninety percent of infected snakes die from the condition, so clearly if humans and their vehicles play unwitting hosts to the microscopic fungal spores, the future for the world's snake population looks depressing. Although many people might not like snakes, ecosystems without them may see an explosion in the numbers of their prey animals, including rodents; to say the least, this would not bode well for crop farmers!

Perhaps the best-known of the global fungal-caused epidemics is the amphibian-decimating Chytridiomycosis, whose affects were initially recognised twenty years ago but may have started much earlier. As its spores can live in water, the responsible Batrachochytrium fungi are ideally situated to infect about one-third of all frog, toad, newt and salamander species. Again, it is thought that man has inadvertently caused the problem, as the African clawed frog Xenopus laevis is an immune carrier of the fungus and has been exported worldwide since the 1930's.

Another contributor may be climate change, as amphibian-rich forests experience temperature variations that are ideal for the chytrid fungi to proliferate in. As a final nail in the coffin - and as with bees and Colony Collapse Disorder - pesticides may play a key role in the epidemic. Agrochemicals are shown to lower the amphibian immune response and so increase their susceptibility to infection. However, the situation isn't completely hopeless: here in New Zealand, researchers at the University of Otago have used chloramphenicol, an antibiotic eye ointment, to cure infected Archey's frogs (Leiopelma archeyi). This species is already critically endangered even without the chytrid epidemic; hopefully, the cure will prove to be the saviour of other amphibian species too. This would be just as well, considering the dangerous side effects found in other treatments such as antifungal drugs and heat therapy (the latter involving temperature-controlled environments that are lethal to the pathogen).

During the past decade, over five million North American bats have been killed by white-nose syndrome, which is caused by the fungus Pseudogymnoascus destructans. Again, humans have inadvertently spread the pathogen, in this case from Eurasia, where the bat species are immune to it, to North America, where they are most definitely susceptible. The bats are only affected during hibernation, which makes treating them difficult, although brief exposure to ultraviolet light has been shown to kill the fungus. This may prove to be a cure to infected colonies, although how the UV could be administered without disturbing the cave-roosting populations will take some figuring out.

It appears then that a combination of manmade causes (international travel, climate change and chemical pollution) is creating a field day for various tiny fungi or fungus-like organisms, at the expense of numerous species of fauna and flora. The culprits are so small and pervasive that there is a little hope of preventing their spread. Therefore if conventional cures cannot be found, the only hope for the likes of the kauri might be the use of genetic engineering to either give the victim resistance or to kill off the pathogen. This science fiction-sounding technology wouldn't be cheap and its knock-on effects unknown – and potentially disastrous. The former technique would presumably not be any use to the existing populations, only to the germ line cells of the next generation. Whatever happens, our short-sighted approach to the environment is certainly starting to have major repercussions. A world without the magnificent kauri, not to mention many amphibian, reptile and mammal species, would be a much poorer one.

Counting keruru: can public surveys and competitions aid New Zealand conservation?

Whilst some other countries - the UK, for example - have dozens of general and specialised wildlife surveys undertaken by members of the public, New Zealand has comparatively few. Whilst this might seem odd, considering the Kiwi penchant for the great outdoors (not to mention the little matter of the endangered status of so many native species) it should be remembered that the nation has a rather small (human) population. In addition, New Zealand is no different from other developed countries, wherein environmentalists often appear at loggerheads with rural landowners, especially farmers.

Since agriculture forms a fundamental component of the New Zealand economy, any anti-farming sentiment can quickly escalate into unpleasantness, as even a cursory look at agriculture versus environmentalists news stories will confirm. Farmers are often reported as resenting what they deem as unrealistic or uninformed opinions by wildlife campaigners. But lest farmers consider this particular post being yet another piece of anti-farming propaganda, it should be noted that campaigns are usually driven by a perceived need for action in the face of government inactivity: after all, New Zealand is second only to Hawaii in the number of introduced species, many of which are in direct competition with, or predate upon, native ones.

Talking of competitions, this year's Bird of the Year contest has just been won by the cheeky, intelligent kea, the world's only alpine parrot. Run by Forest and Bird* and now in its thirteenth year, it aims to raise publicity for the plight of New Zealand's native birds and the wider environment they rely upon. With over 50,000 votes cast, this means approximately 1% of New Zealand citizens and residents entered the competition (assuming of course that non-Kiwis didn't participate).

The international level of awareness about the competition seems to be on the increase too, with the kea's victory even being reported on the website of the UK's The Guardian newspaper, albeit in an article written by a New Zealand-based journalist. The competition doesn't appear to offer anything to science, except a potential – if not unobvious - theory that the public's fondness for particular wildlife species is based upon their aesthetic qualities, with drab birds for example getting less attention than colourful ones. Then again, perhaps Forest and Bird are more interested in spreading their message rather than the results; as the old adage goes, there's no such thing as bad publicity. Indeed, the story of a Christchurch-based who tried to rig the vote in favour of the white-faced heron was reported by the BBC.

Another prominent example of the New Zealand's public involvement in environmental matters is the Annual Garden Bird survey, which began in 2007 and is run by the Government-owned Landcare Research. This more obvious example of citizen science states that the results are used to analyse population trends for both native and introduced bird species and so aid pest control programmes. However, it would be difficult to ascertain the validity of the observations, since less than 0.3% of the nation's gardens (or rather their owners) participate.

Whilst 5000 entries might be considerably more than could be achieved by other means, there are probably all sorts of details that are missed with this level of coverage. I have participated for three years now and have found that my observations do not agree with the reported trends. For example, last year's results show that the silvereye, blackbird and song thrush have declined in my area, whereas I have not noticed any such a drop-off for these birds -  and it's not as if I particularly encourage the latter two (non-native) species.

A more specific example of bio-recording was last month's Great Kereru Count, which claims to be New Zealand's biggest citizen science project. Clearly, they don't consider the Bird of the Year competition as science! Various organisations run this survey, which gained around 7000 reports this year. There are also continuous monitoring schemes, such as for monarch butterflies (which is interesting, as this is a far-from-endangered, recently self-introduced creature) whilst NatureWatch NZ allows anyone to supply a record of a plant or animal species, or indeed to request identification of one. The latter might not sound particularly necessary, but judging by how little some New Zealanders seem to know about their own environment (for example I've met Kiwis who cannot identify such common organisms as a tree weta or cabbage trees) this resource is probably essential in understanding the spread of non-native species.

With native species protection in mind, there are other, more direct, citizen science projects in the country, with everything from the Great Kiwi Morning Tea fundraiser this month to allocation of funding for predator control tools and traps – including in urban gardens - via the independent trust Predator Free New Zealand.

For an even greater level of public involvement in science and technological research, in 2015 the New Zealand Government initiated the Participatory Science Platform to aid partnerships between professionals and community groups. Three pilot projects are currently under way, with Dr Victoria Metcalf as the National Coordinator (or Queen of Curiosity as she has been nicknamed.) These projects are exciting because they involve the public from project development through to conclusion, rather than just using non-scientists as data gatherers. In addition, the ability to gain first-hand experience on real-world undertakings may even encourage children from lower decile areas to consider STEM careers. That's no bad thing.

Back to surveys. Although science communication (sci-comm) is in vogue, my own feeling is that participation is key to promoting science – the methods as well as the facts – to the wider public. Yes, some science is very difficult to understand, but there's plenty that is also easy to grasp. This includes the dangers facing species pushed to the brink of extinction by habitat loss, pollution, and introduced organisms. By actively involving entire communities, surveys and competitions can also play a part in preserving species whilst allowing a sustainable level of development.

Of course this requires a government with vision, but with New Zealand's Green Party gaining positions in the Jacinda Ardern-led coalition, perhaps the newly-formed New Zealand Government will pick up the slack after years of prevarication and inactivity. That way our grandchildren will be able to experience the cheeky kea and company for real, rather than just via old recordings. How can that fail to make sense? After all, at the lower end of the bio-recording spectrum, all it requires is for someone to make a few taps on their keyboard or smartphone. It's certainly not rocket science!

*Forest and Bird have actively lobbied the New Zealand Government in numerous cases to prevent environmental degradation via land swaps, mining and hydro-electric schemes. They have produced a volume on environmental law and a mobile app called the Best Fish Guide. All in all, they perform an immensely valuable contribution to ensure that development in New Zealand is sustainable and that the public are made aware of schemes that might impact the wider environment.

The zeal in Zealandia: revealing a lost continent

From an outsider's standpoint, geology appears to be a highly conservative science. As I have mentioned on numerous occasions, it seems astonishing that it took over four decades for Alfred Wegener's continental drift hypothesis to be formalised - via the paradigm-shifting discovery of sea floor spreading - into the theory of plate tectonics. I suppose that like evolution by natural selection, the mechanism, once stated, seems blindingly obvious in hindsight.

Regardless, the geological establishment appears to have been stubbornly opposed to the ideas of an outsider (Wegener was a meteorologist) who was unable to provide proof of an exact mechanism. This was despite the fact that the primary alternative, hypothetical submerged (but extremely convenient) land bridges, appear even more far-fetched.

Over the past few decades geophysical data has been accumulating that should generate rewrites of texts from the most basic level upwards. Namely, that the islands making up New Zealand are merely the tip of the iceberg, accounting for just six per cent of a mostly submerged 'lost' continent. Once part of the Southern Hemisphere's Gondwana, in 1995 the newly discovered continent was given the name Zealandia. Approximately five million square kilometres in size, it broke away from the Australasian region of Gondwana around 70-80 million years ago.

After a decade or two of fairly lacklustre reporting, 2017 seems to be the year in which Zealandia is taking-off in the public domain. First, the Geological Society of America published a paper in February. stating that Zealandia should be officially declared as a continent. Then in July the drill ship Joides Resolution began the two month long Expedition 371, a research trip under the International Ocean Discovery Programme (IODP). Scientists from twelve countries undertook deep sea drilling, gaining data on plate tectonics, palaeontology and climate history as well as research directly relevant to understanding the geology of the newest continent.

It is surprising then to learn that geologists first mooted the idea as early as the 1960s but that apart from some marine core samples collected in 1971, no-one undertook the necessary ocean-based research until very recently. Earth resources satellites have helped somewhat, but nothing could replace the evidence that emerged with deep drilling of the seabed. Therefore I wonder what has sparked the sudden interest in an idea that has been around for so long?

One possibility is the large amount of data that the international geological community required to prove the theory beyond doubt, coupled with the fact that this sort of research has little in the way of an obvious immediate practical benefit. It is extremely expensive to undertake deep sea drilling and few vessels are equipped for the purpose. Joides Resolution itself will be forty years old next year, having undergone several years' of refit to keep it going. Those areas of sea bed with potential oil or gas deposits may gain high-fidelity surveying, but compared to fossil fuels, fossil biota and sea bed strata research are very much at the whim of international project funding. In the case of the IODP, governments are cutting budgets on what are deemed non-essential projects, so it remains to be seen whether the intended follow-up trips will occur.

It would be disappointing if there was no further research as despite the acceptance of Zealandia, there is still a great deal of disagreement about what is known as the Oligocene Drowning. I first came across the notion of an eighth continent in the excellent 2007 book In Search of Ancient New Zealand, written by geologist / palaeontologist Hamish Campbell and natural history writer Gerard Hutching. The reason that over ninety per cent of Zealandia is underwater is due to the lack of thickness of its continental land mass - only 20-30km - making it far less buoyant than other continents.

But has this submerged percentage varied during the past eighty million years? There are some very divided opinions about this, with palaeontologists, geneticists and other disciplines taking sides with different camps of geologists. These can be roughly summarised as Moa's Ark versus the Oligocene Drowning, or to be more precise, what percentage, if any, of New Zealand's unique plants and animals are locally-derived Gondwanan survivors and how many have arrived by sea or air within the past twenty or so million years?

The arguments are many and varied, with each side claiming that the other has misinterpreted limited or inaccurate data. If Zealandia has at any time been entirely submerged, then presumably next to none of the current fauna and flora can have remained in situ since the continent broke away from Gondwana. The evidence for and against includes geology, macro- and micro-fossils, and genetic comparisons, but nothing as yet provides enough certainty for a water-tight case in either direction. In Search of Ancient New Zealand examines evidence that all Zealandia was under water around twenty-three million years ago, during the event known as the Oligocene Drowning. However, Hamish Campbell's subsequent 2014 book (co-written with Nick Mortimer) Zealandia: Our continent revealed discusses the finding of land-eroded sediments during this epoch, implying not all the continent was submerged.

It's easy to see why experts might be reticent to alter their initial stance, since in addition to the conservative nature of geology there are other non-science factors such as patriotism at stake. New Zealand's unusual biota is a key element of its national identity, so for New Zealand scientists it's pretty much a case of damage it at your own peril! In 2003 I visited the predator-free Karori Wildlife Reserve in Wellington. Six years later it was rebranded as Zealandia, deliberately referencing the eighth continent and with more than a hint of support for Moa's Ark, i.e. an unbroken chain of home-grown oddities such as the reptile tuatara and insect weta. With the nation's reliance on tourism and the use of the '100% Pure New Zealand' slogan, a lot rests on the idea of unique and long-isolated wildlife. If the flightless kakapo parrot for example turns out not to be very Kiwi after all, then who knows how the country's reputation might suffer.

What isn't well known, even within New Zealand, is that some of the best known animals and plants are very recent arrivals. In addition to the numerous species deliberately or accidentally introduced by settlers in the past two hundred years, birds such as the silvereye / waxeye (Zosterops lateralis) and Welcome swallow (Hirundo neoxena) are self-introduced, as is the monarch butterfly.

The volcanic island of Rangitoto in Auckland's Hauraki Gulf is only about six centuries old and yet - without any human intervention - has gained the largest pohutukawa forest in the world, presumably all thanks to seeds spread on the wind and by birds. Therefore it cannot be confirmed with any certainty just how long the ancestors of the current flora and fauna have survived in the locality. A number of New Zealand scientists are probably worried that some of the nation's best-loved species may have arrived relatively recently from across the Tasman; a fossil discovered in 2013 suggests that the flightless kiwi is a fairly close cousin of the Australian emu and so is descended from a bird that flew to New Zealand before settling into an ecological niche that didn't require flight.

Other paleontological evidence supports the Moa's Ark hypothesis: since 2001 work on a lake bed at St Bathans, Central Otago has produced a wide range of 16 million year-old fossils, including three bones from a mouse-sized land mammal. The diversity of the assemblage indicates that unless there was some uniquely rapid colonisation and subsequent speciation, there must have been above-water regions throughout the Oligocene. In addition, whereas the pro-underwater faction have concentrated on vertebrates, research into smaller critters such as giant land snails (which are unable to survive in salt water conditions) supports the opposite proposition.

So all in all, there is as yet no definitive proof one way or the other. What's interesting about this particular set of hypotheses is the way in which an array of disciplines are coming together to provide a more accurate picture of New Zealand's past. By working together, they also seem to be reducing the inertia that has led geology to overlook new ideas for far too long; Zealandia, your time has come!

Cow farts and climate fiddling: has agriculture prevented a new glaciation?

Call me an old grouch, but I have to say that one of my bugbears is the use of the term 'ice age' when what is usually meant is a glacial period. We currently live in an interglacial (i.e. warmer) era, the last glaciation having ended about 11,700 years ago. These periods are part of the Quaternary glaciation that has existed for almost 2.6 million years and deserving of the name 'Ice Age', with alternating but irregular cycles of warm and cold. There, that wasn't too difficult now, was it?

What is rather more interesting is that certain geology textbooks published from the 1940s to 1970s hypothesised that the Earth is overdue for the next glaciation. Since the evidence suggests the last glacial era ended in a matter of decades, the proposed future growth of the ice sheets could be equally rapid. Subsequent research has shown this notion to be flawed, with reliance on extremely limited data leading to over-confident conclusions. In fact, current estimates put interglacial periods as lasting anywhere from ten thousand to fifty thousand years, so even without human intervention in global climate, there would presumably be little to panic about just yet.

Over the past three decades or so this cooling hypothesis has given way to the opposing notion of a rapid increase in global temperatures. You only have to read such recent news items as the breakaway of a six thousand square kilometre piece of the Antarctic ice shelf to realise something is going on, regardless of whether you believe it is manmade, natural or a combination of both. But there is a minority of scientists who claim there is evidence for global warming - and an associated postponement of the next glaciation - having begun thousands of years prior to the Industrial Revolution. This then generates two key questions:

1. Has there been a genuine steady increase in global temperature or is the data flawed?
2. Assuming the increase to be accurate, is it due to natural changes (e.g. orbital variations or fluctuations in solar output) or is it anthropogenic, that is caused by human activity?

As anyone with even a vague interest in or knowledge of climate understands, the study of temperature variation over long timescales is fraught with issues, with computer modelling often seen as the only way to fill in the gaps. Therefore, like weather forecasting, it is far from being an exact science (insert as many smileys here as deemed appropriate). Although there are climate-recording techniques involving dendrochronology (tree rings) and coral growth that cover the past few thousand years, and ice cores that go back hundreds of thousands, there are still gaps and assumptions that mean the reconstructions involve variable margins of error. One cross-discipline assumption is that species found in the fossil record thrived in environments - and crucially at temperatures - similar to their descendants today. All in all this indicates that none of the numerous charts and diagrams displaying global temperatures over the past twelve thousand years are completely accurate, being more along the lines of a reconstruction via extrapolation.

Having looked at some of these charts I have to say that to my untrained eye there is extremely limited correlation for the majority of the post-glacial epoch. There have been several short-term fluctuations in both directions in the past two thousand years alone, from the so-called Mediaeval Warm Period to the Little Ice Age of the Thirteenth to Nineteenth centuries. One issue of great importance is just how wide a region did these two anomalous periods cover outside of Europe and western Asia? Assuming however that the gradual warming hypothesis is correct, what are the pertinent details?

Developed in the 1920s, the Milankovitch cycles provide a reasonable fit for the evidence of regular, long-term variations in the global climate. The theory states that changes in the Earth's orbit and axial tilt are the primary causes of these variations, although the timelines do not provide indisputable correlation. This margin of error has helped to lead other researchers towards an anthropogenic cause for a gradual increase in planet-wide warming since the last glaciation.

The first I heard of this was via Professor Iain Stewart's 2010 BBC series How Earth Made Us, in which he summarised the ideas of American palaeoclimatologist Professor William Ruddiman, author of Plows, Plagues and Petroleum: How Humans Took Control of Climate. Although many authors, Jared Diamond amongst them, have noted the effects of regional climate on local agriculture and indeed the society engaged in farming, Professor Ruddiman is a key exponent of the reverse: that pre-industrial global warming has resulted from human activities. Specifically, he argues that the development of agriculture has led to increases in atmospheric methane and carbon dioxide, creating an artificial greenhouse effect long before burning fossil fuels became ubiquitous. It is this form of climate change that has been cited as postponing the next glaciation, assuming that the current interglacial is at the shorter end of such timescales. Ruddiman's research defines two major causes for an increase in these greenhouse gases:

1. Increased carbon dioxide emissions from burning vegetation, especially trees, as a form of land clearance, i.e. slash and burn agriculture.
2. Increased methane from certain crops, especially rice, and from ruminant species, mostly cattle and sheep/goat.

There are of course issues surrounding many of the details, even down to accurately pinpointing the start dates of human agriculture around the world. The earliest evidence of farming in the Near East is usually dated to a few millennia after the end of the last glaciation, with animal husbandry preceding the cultivation of crops. One key issue concerns the lack of sophistication in estimating the area of cultivated land and ruminant population size until comparatively recent times, especially outside of Western Europe. Therefore generally unsatisfactory data concerning global climate is accompanied by even less knowledge concerning the scale of agriculture across the planet for most of its existence.

The archaeological evidence in New Zealand proves without a doubt that the ancestors of today's Maori, who probably first settled the islands in the Thirteenth Century, undertook enormous land clearance schemes. Therefore even cultures remote from the primary agricultural civilisations have used similar techniques on a wide scale. The magnitude of these works challenges the assumption that until chemical fertilisers and pesticides were developed in the Twentieth Century, the area of land required per person had altered little since the first farmers. In a 2013 report Professor Ruddiman claims that the level of agriculture practiced by New Zealand Maori is just one example of wider-scale agricultural land use in pre-industrial societies.

As for the role played by domesticated livestock, Ruddiman goes on to argue that ice core data shows an anomalous increase in atmospheric methane from circa 3000BCE onwards. He hypothesises that a rising human population led to a corresponding increase in the scale of agriculture, with rice paddies and ruminants the prime suspects. As mentioned above, the number of animals and size of cultivated areas remain largely conjectural for much of the period in question.  Estimates suggest that contemporary livestock are responsible for 37% of anthropogenic methane and 9% of anthropogenic carbon dioxide whilst cultivated rice may be generating up to 20% of anthropogenic methane. Extrapolating back in time allows the hypothesis to gain credence, despite lack of access to exact data.

In addition, researchers both in support and opposition to pre-industrial anthropogenic global warming admit that the complexity of feedback loops, particularly with respect to the role of temperature variation in the oceans, further complicates matters. Indeed, such intricacy, including the potential latency between cause and effect, means that proponents of Professor Ruddiman's ideas could be using selective data for support whilst suppressing its antithesis. Needless to say, cherry-picking results is hardly model science.

There are certainly some intriguing aspects to this idea of pre-industrial anthropogenic climate change, but personally I think the jury is still out (as I believe it is for the majority of professionals in this area).  There just isn't the level of data to guarantee its validity and what data is available doesn't provide enough correlation to rule out other causes. I still think such research is useful, since it could well prove essential in the fight to mitigate industrial-era global warming. The more we know about longer term variations in climate change, the better the chance we have of understanding the causes - and potentially the solutions - to our current predicament. And who knows, the research might even persuade a few of the naysayers to move in the right direction. That can't be bad!

Valuing the velvet worm: noticing the most inconspicuous of species

Most of the recent television documentaries or books I've encountered that discuss extra-terrestrial life include some description of the weirder species we share our own planet with. Lumped together under the term 'extremophiles' these organisms appear to thrive in environments hostile to most other life forms, from the coolant ponds of nuclear reactors to the boiling volcanic vents of the deep ocean floor.

Although this has rightly gained attention for these often wonderfully-named species (from snottites to tardigrades) there are numerous other lifeforms scarcely noticed by anyone other than a few specialists, quietly going about their unassuming business. However, they may provide a few useful lessons for all of us, including that we should acknowledge there may be unrecognised problems generated when we make rapid yet radical modifications to local environments.

There is a small, unassuming type of creature alive today that differs little from a marine animal present in the Middle Cambrian period around five hundred million years ago. I first read about onychophorans in Stephen Jay Gould's 1989 exposition on the Burgess Shale, Wonderful Life, and although those fossil marine lobopodians are not definitively onychophorans they are presumed to be ancestral. More commonly known by one genus, peripatus, or even more colloquially as velvet worms, there are at least several hundred species around today, possibly many more. The velvet component of their name is due to their texture, but they bear more resemblance to caterpillars than to worms. They are often described as the ‘missing link' between arthropods and worms but as is usually the case this is a wildly inappropriate term in this context of biological classification. The key difference to the Burgess Shale specimens is that today's velvet worms are fully terrestrial: there are no known marine or freshwater species.

Primarily resident in the southern hemisphere, the largely nocturnal peripatus shun bright light and requiring humid conditions to survive. Although there are about thirty species here in New Zealand, a combination of their small size (under 60mm long) and loss of habitat means they are rarely seen. The introduction of predators such as hedgehogs - who of course never meet peripatus in their northern hemisphere home territory - means that New Zealand's species have even more to contend with. Although I frequently (very carefully) look under leaf litter and inside damp logs on bush walks in regions known to contain the genus Peripatoides - and indeed where others have told me they have seen them - I have yet to encounter a single specimen.

There appears to be quite limited research, with less than a third of New Zealand species fully described. However, enough is known about two species to identify their population status as 'vulnerable'. One forest in the South Island has been labelled an 'Area of Significant Conservation Value' thanks to its population of peripatus, with the Department of Conservation relocating specimens prior to road development. Clearly, they had better luck locating velvet worms than I have had! It isn't just the New Zealand that lacks knowledge of home-grown onychophorans either: in the past two decades Australian researchers have increased the number of their known species from just seven to about sixty.

Their uncanny resemblance to the Burgess Shale specimens, despite their transition from marine to terrestrial environments, has led velvet worms to be described by another well-worn phrase, 'living fossils'. However, is this short-hand in any way useful, or is it a lazy and largely inaccurate term? The recent growth in sophisticated DNA analysis suggests that even when outward anatomy may be change little, the genome itself may vary widely. Obviously DNA doesn't preserve in fossils and so any such changes cannot be tracked from the Cambrian specimens, but the genetic variation found in other types of organisms sharing a similar appearance shows that reliance on just external anatomy can be deceptive.

Due to lack of funding, basic taxonomic research, the bedrock for cladistics, is sadly lacking. In the case of New Zealand, some of the shortfall has been made up for by dedicated amateurs, but there are few new taxonomists learning the skills to continue this work - which is often seen as dull and plodding compared to the excitement of, for example, genetics. Most people might say so what interest could there be in such tiny, insignificant creatures as peripatus? After all, how likely would you be to move an ant's nest in your garden before undertaking some re-landscaping? But as shown by the changing terminology from 'food chains' to 'food webs', in most cases we still don't understand how the removal of one species might generate a domino effect on a local ecosystem.

I've previously discussed the over-reliance on 'poster' species such as giant pandas for environmental campaigns, but mere aesthetics don't equate to importance, either for us or ecology as a whole. It is becoming increasingly clear that by weight the majority of our planet's biomass is microbial. Then come the insects, with the beetles prominent both by number of species and individuals. Us large mammals are really just the icing on the cake and certainly when it comes to Homo sapiens, the rest of the biosphere would probably be far better off without us, domesticated species aside.

It would be nice to value organisms for themselves, but unfortunately our market economies require the smell of profit before they will lift a finger. Therefore if their usefulness could be ascertained, it might help generate greater financial incentive to support the wider environment. Onychophorans may seem dull, but there are several aspects to them that is both interesting in itself and might also provide something fruitful for us humans.

Firstly, they have an unusual weapon in the form of a mechanism that shoots adhesive slime at prey. Like spider silk, is it possible that this might prove an interesting line of research in the materials or pharmaceutical industries? After all, it was the prickly burrs of certain plants that inspired the development of Velcro, whilst current studies of tardigrades (the tiny 'water bears' living amongst the mosses) are investigating their near indestructability. If even a single, tiny species becomes extinct, that genome is generally lost forever: who knows what insights it might have led to? Although museum collections can be useful, DNA does decay and contamination leads to immense complexities in unravelling the original organism's genome. All in all, it's much better to have a living population to work on than rely on what can be pieced together post-extinction.

In addition, for such tiny creatures, velvet worms have developed complex social structures; is it possible that analysis of their brains might be useful in computing or artificial intelligence? Of course it is unlikely - and extinction is nothing if not natural - but the current rate is far greater than it has been outside of mass extinctions. Losing a large and obvious species such as the Yangtze River dolphin (and that was despite it being labelled a ‘national treasure') is one thing, but how many small, barely-known plants and animals are going the same way without anyone noticing? Could it be that right now some minute, unassuming critter is dying out and that we will only find out too late that it was a vital predator of crop-eating pests like snails or disease vectors such as cockroaches?

It has been said that ignorance is bliss, but with so many humans needing to be fed, watered and treated for illness, now more than ever we need as much help as we can get. Having access to the complex ready-made biochemistry of a unique genome is surely easier than attempting to synthesise one from scratch or recover it from a long-dead preserved specimen? By paying minimal attention to the smallest organisms that lie all around us, we could be losing so much more than just an unobtrusive plant, animal or fungus.

We can't save every species on the current endangered list but more attention could be given to the myriad of life forms that get side-lined by the cute and cuddly flagship species, usually large animals. Most of us would be upset by the disappearance of the eighteen hundred or so giant pandas still left in the wild, but somehow I doubt their loss would have as great an impact on the surrounding ecosystem than that of some far less well known flora or fauna. If you think that's nonsense, then consider the vital roles that bees and dung beetles play in helping human agriculture.

Although the decimation of native New Zealand wildlife has led to protective legislation for all our vertebrates and a few famous invertebrates such as giant weta, the vast majority of other species are still left to their own devices. That's not to say that the ecosystems in most other countries are given far less support, of course. But without funding for basic description and taxonomy, who knows what is even out there, never mind whether it might be important to humanity? Could it be that here is a new field for citizen scientists to move into?

Needless to say, the drier climes brought on by rising temperatures will not do peripatus any favours, thanks to its need to remain in damp conditions. Whether by widespread use of the poison 1080 (in the bid to create a pest-free New Zealand by 2050) or the accidental importation of a non-native fungus such as those decimating amphibians worldwide and causing kauri dieback in New Zealand, there are plenty of ways that humans could unwittingly wipe out velvet worms, etal. So next time you watch a documentary on the demise of large, familiar mammals, why not spare a thought for all those wee critters hiding in the bush, going about their business and trying to avoid all the pitfalls us humans have unthinkingly laid for them?

Owning the aliens: who should support endangered species thriving outside their home territories?

On holiday in Fiji last year I was surprised to learn that the most commonly-seen animals - with the exception of flying foxes - were recent introductions from other countries, primarily India. Examples include the red-vented bulbul, mynah bird, house gecko, and mongoose, all of which have brought their own problems to either native wildlife or Fijian agriculture.

From Hawaii to New Zealand, the deliberate or accidental introduction of non-native animals, plants and fungi has had profoundly negative effects on these previously isolated ecosystems. So what happens if an introduced organism, especially one that has a deleterious effect on wildlife, thrives in its transplanted habitat whilst becoming endangered across its original range? Two questions spring to mind: should the adopted homeland be able to exterminate the alien invader with impunity; and/or should the country of origin fund work in the invaded nation during a 'lifeboat' phase, until the home turf is suitable for restocking?

Almost inevitably, the countries with the highest number of at-risk species tend to be the poorer ones, Australia and the United States excepted. Reports over the past four years list a variety of nations with this sorry state of affairs, but amongst different conservation groups those within the top ten for endangered animal species include Indonesia, Malaysia, Ecuador, Mexico, India and Brazil. In some of these there is little political willpower - or indeed funding - to support anything deemed non-critical, with biodiversity seen as a nice-to-have.

For small nations such as Fiji there is little in the way of an environmental lobby. NatureFiji-MareqetiViti is an organisation that attempts to safeguard such threatened animals as the Fijian Crested Iguana whilst enhancing regional biosecurity, but with grants - including from the European Union - rarely exceeding a few tens or hundreds of thousands Fijian dollars they are woefully underfunded.

Which brings us to New Zealand, with its collection of endangered birds, lizards, freshwater fish and the Maui dolphin. In addition to Department of Conservation (Doc) budget cuts over the past decade - claimed by some organisations to total a 21% decline in real terms - the nation is home to several Australian animals that are nationally vulnerable in their native homeland across the Tasman Sea.

The green and golden bell frog (Litoria aurea) is a prime example of this, with a rapidly reducing Australian range having generated a status of 'globally vulnerable' yet being common enough in the northern part of New Zealand's North Island. I found this specimen at Auckland's Botanic Gardens earlier this year.

Therefore should the Australian Government fund a captive breeding programme - or simply a round-up - of individuals in New Zealand? After all, the latter has its own four native frog species, all rare and/or endangered, for its herpetologists to concentrate on.

There is a precedent for this. In 2003, three Australian trappers captured rare brush-tailed rock-wallabies on New Zealand's Kawau Island, where the marsupial's 'noxious' pest status meant
they were about to be targeted for eradication. The project included support from DoC but presumably - it's difficult to ascertain - the funding came from Australia.

Of course Australia may be able to afford to engage in restocking programmes abroad, but few other nations are in the same position. Although the largest conservation organisation in the world, the World Wide Fund for Nature (World Wildlife Fund in North America) has a comparatively large budget, even it cannot afford to support every repatriation or gene pool nursery scheme. Meanwhile, local charities such as NatureFiji-MareqetiViti tend to rely on volunteers rather than trained professionals and don't have the scope or capability for logistically-complex international undertakings.

With the USA becoming increasingly insular and Europe consumed with its own woes, the potential funding sources for these interim lifeboats is rapidly drying up. There are a few eco-angels, such as Norway's US$1 billion donation to Brazil - intended to curtail Amazonian rainforest destruction - but they are few and far between. It's one thing to support in-situ environmental issues, but another to raise funds to save selected endangered species thriving away from their native ecosystem.

It appears that there is no single solution to this, meaning that except for a few lucky 'poster' cases, many at-risk species may well fail to gain attention and be allowed to die out (or even be exterminated as foreign pests). The original home territory might no longer contain a suitable environment for them to thrive in whilst the foster nation lacks the impetus or funding to look after those pesky alien invaders. It seems that there are difficult times ahead!

Water, water, everywhere: the hidden holism of H2O

Like other northern regions of New Zealand, the summer of 2017 saw Auckland residents facing City Council requests to conserve water, as well as a hosepipe ban in effect during March and April. It therefore seems ironic that the water shortage occurred at the same time as flooding in the west of the city; thanks to a tropical downpour - one of several so far this year - the equivalent of an entire month's rain fell over a day or two. Clearly, water shortages are going to become an ever-increasing issue, even in nations with well-developed infrastructure.

The British historian of science James Burke, writer-presenter of The Day the Universe Changed, also made three television series called Connections 1, 2 and 3 (in 1978, 1994 and 1997 respectively) which examined the historical threads linking scientific and technological advances with changes in other areas of society. Therefore I'd like to take a similarly holistic approach to the wonderful world of water consumption and see how it ties into the world in general.

Although the statistics vary - it's difficult to assess with any great precision - there are published figures suggesting that the populace of richer nations use up to 5000 litres of water each per day, mostly hidden in food production. Many websites now supply details of the amount of water used to grown certain crops and foodstuffs, so you can easily raise your guilt level simply by comparing your diet to the water involved in its generation; and that's without considering the carbon mileage or packaging waste, either!

I've previously discussed the high environmental cost of cattle farming, with both dairy and beef herds being prominent culprits in water pollution as well as consumption. However, there are plenty of less-obvious foodstuffs proven to be notorious water consumers, for example avocado and almonds. Although the latter might be deemed a luxury food, much of the global supply is now used to make almond milk; with consumption increasing up to 40% year-on-year, this is one foodstuff much in demand.

Even though it is claimed to require much less water than the equivalent volume of dairy produce, almond farming is still relevant due to the massive increase in bulk production, especially in California (home to 80% of the global almond harvest). The reasons for the popularity of almond milk are probably two-fold: firstly, the public is getting more health-conscious; and secondly, a reduction or abstention in dairy produce is presumed to lessen food allergies/intolerance. These obviously link to prominent concerns in the West, in the form of high-calorie/low-exercise diets leading to mass obesity and over-use of cleaning chemicals in the home, preventing children from developing good anti-microbial resistance. Clearly, there is a complex web when it comes to water and the human race.

Even for regions chronically short of water such as California, more than three-quarters of fresh water usage is by agriculture. In order to conserve resources, is it likely that we may soon face greater taxes on commercially-grown water-hogging produce and bans on the home-growth of crops that have a low nutrition to water consumption ratio? I've recently read several books discussing probable issues over the next half century with the humble lettuce appearing as a good example of the latter.

Talking of which, the wet and windy conditions in New Zealand of the past year - blamed at least partially on La Niña - have led to record prices for common vegetables: NZ$9 for a lettuce and NZ$10 for a cauliflower, even in major supermarket chains. British supermarkets were forced to ration some fruit and vegetables back in February, due to their Mediterranean growers suffering from storms and floods. This suggests that even for regions with sophisticated agricultural practices there is a fine line between too much and too little fresh water. Isn't it about time that the main food producers developed a more robust not to mention future-proof infrastructure, considering the increased impact that climate change is likely to have?

The world is also paying a heavy price for bottled water, a commercial enterprise that largely breaks all boundaries of common sense. In the USA alone it costs several thousand times the equivalent volume of tap water and there are some reports that there may be chemical leaching from reusing plastic bottles. As you might expect, there is also an extremely high environmental cost. This includes the fossil fuels used by bottling plants and transportation, the lowering of the water table (whose level is so critical in areas utilising less sophisticated farming technologies) and the impact of plastic waste: the USA only recycles about 23% of its plastic water bottles, resulting in 38 billion bottles dumped each year at a cost of around US$1 billion. All in all, bottled water for nations with highly developed infrastructure seems like an insane use of critical resources.

Although accelerated population growth has become a widespread fear, there are indicators that later this century the global figure may peak at around nine billion and then level off. Increasing urbanisation is seen a primary cause for this and not just in developing nations; Auckland for example (New Zealand's largest city by far) experienced 8% population growth in the seven years from 2006. A larger population obviously requires more food, but a more urban and therefore generally better educated, higher income populace tends to demand access to processed, non-local and above all water-intensive foods. China is the touchstone here, having seen a massive increase in fish and meat consumption over the past half century; the latter has risen from 8 million tons per year in 1978 to over 70 million tons in recent years.

It has been claimed that 70% of industrial waste generated in developing nations is dumped into water courses, meaning that there will be a massive cost for environmental clean-up before local sources can be fully utilised. The mass outbreak of E-coli in Hawke's Bay, New Zealand, in February this year shows that even developed nations are having difficulty maintaining water quality, whilst there has been a shocking admittance of lead contamination above safe levels in 41 American states over the past three years. Does this mean bottled water - heretofore the lifeline of Western tourists abroad - is becoming a necessity in the West after all?

Some might argue that thanks to global warming there will be more water available due to the melting of polar caps and glaciers, which after all contain almost two-thirds of the world's fresh water resources. However, these sources are mostly located far from high-density populations and upon marine contamination they require energy-demanding desalination technology. It's small comfort that current estimates suggest that by 2025 about 14% of the global population will rely on desalination plants for their fresh water needs.

In the West we tend to take clean, safe water completely for granted but thanks to the demands of living in a society run on rampant consumerism - coupled with poor science education - everyday decisions are being made that affect the environment, waste critical resources and damage our own health. Pundits are predicting that water will be the new oil: liquid gold, a precious commodity to be fought over, if necessary. Surely this is one resource that all of us can do something to support, whether it is cutting down on water-intensive foodstuffs, using tap rather than bottled water, or simply turning off a tap sooner than usual!

Weather with you: meteorology and the public perception of climate change

If there's one thing that appears to unite New Zealanders with the British it is the love of discussing the weather. This year has been no exception, with New Zealand's pre-summer forecasts - predicting average temperatures and rainfall - proving wildly inaccurate. La Niña has been blamed for what Wellingtonians have deemed a 'bummer summer', January having provided the capital with its fewest 'beach days' of any summer in the last thirty years. Sunshine hours, temperature, rainfall and wind speed data from the MetService support this as a nationwide trend; even New Zealand flora and fauna have been affected with late blossoming and reduced breeding respectively.

However, people tend to have short memories and often recall childhood weather as somehow superior to that of later life. Our rose-tinted spectacles make us remember long, hot summer school holidays and epic snowball fights in winter, but is this a case of remembering the hits and forgetting the misses (meteorologically speaking)? After all, there are few things more boring than a comment that the weather is the same as the previous ten comments and surely our memories of exciting outdoor ventures are more prominent than being forced to stay indoors due to inclement conditions?

Therefore could our fascination with weather but dubious understanding - or even denial - of climate change be due to us requiring personal or even emotional involvement in a meteorological event? Most of us have had the luck not to experience extreme weather (or 'weather bombs' as the media now term them), so unless you have been at the receiving end of hurricanes or flash floods the weather is simply another aspect of our lives, discussed in everyday terms and rarely examined in detail.

Since we feel affected by weather events that directly impact us (down to the level of 'it rained nearly every day on holiday but the locals said it had been dry for two months prior') we have a far greater emotional response to weather than we do to climate. The latter appears amorphous and almost mythical by comparison. Is this one of the reasons that climate change sceptics achieve such success when their arguments are so unsupported?

Now that we are bombarded with countless pieces of trivia, distracting us from serious analysis in favour of short snippets of multimedia edutainment, how can we understand climate change and its relationship to weather? The standard explanation is that weather is short term (covering hours, days or at most weeks) whilst climate compares annual or seasonal variations over far longer timeframes. Neil deGrasse Tyson in Cosmos:A Spacetime Odyssey made the great analogy that weather is like the zigzag path of a dog on a leash whereas its owner walks in a straight line from A to B. So far so good, but there's not even a widespread designation for the duration that counts as valid for assessing climate variability.

As such this leads us to statistics. Everyone thinks they understand the word 'average' but averages can represent the mean, median or mode. Since the period start and end date can be varied, as can the scaling on infographics (a logarithmic axis, for example), these methods allow a single set of statistics to be presented in a wide variety of ways.

The laws of probability rear their much-misinterpreted head too. The likelihood of variation may change wildly, depending on the length of the timeframe: compare a five-year block to that of a century and you can see that climate statistics is a tricky business; what is highly improbable in the former period may be inevitable over the latter. As long as you are allowed to choose the timeframe, you can skew the data to support a favoured hypothesis. So much then for objective data!

By comparison, if someone is the recipient of a worse than expected summer, as per New Zealand in 2017, then that personal experience may well be taken as more important than all the charts of long-term climate trends. It might just be the blink of an eye in geological terms, but being there takes precedence over far less emotive science and mathematics.

Perhaps then we subconsciously define weather as something that we feel we experience whilst climate is a more abstract notion, perhaps a series of weather events codified in some sort of order? How else can climate change deniers, when faced with photographs proving glacial or polar cap shrinkage, offer alternative explanations to global warming?

This is where politics comes into the mix. Whereas weather has little obvious involvement with politics, climate has become heavily politicised in the past thirty years, with party lines in some nations (mentioning no names) clearly divided. Although some of the naysayers have begun to admit global warming appears to be happening - or at least that the polar caps and glaciers are melting - they stick to such notions that (a) it will be too slow to affect humans - after all, there have been far greater swings in temperature in both directions in previous epochs - and (b) it has natural causes. The latter implies there is little we can do to mitigate it (solar output may be involved, not just Earth-related causes) and so let's stick our head in the sand and do some ostrich impressions.

As an aside, I've just finished reading a 1988 book called Prehistoric New Zealand. Its three authors are a palaeontologist (Graeme Stevens), an archaeologist (Beverley McCulloch)  and an environmental researcher (Matt McGlone) so the content covers a wide range of topics, including the nation's geology, climate, wildlife and human impact. Interestingly, the book states if anything the climate appears to be cooling and the Earth is probably heading for the next glaciation!

Unfortunately no data is supplied to support this, but Matt McGlone has since confirmed that there is a wealth of data supporting the opposite conclusion. In 2008 the conservative American Heartland Institute published a list of 500 scientists it claimed supported the notion that current climate change has solely natural causes. McGlone was one of many scientists who asked for his name to be removed from this list, stating both his work and opinions were not in agreement with this idea.

So are there any solutions or is it simply the case that we believe what we personally experience but have a hard time coming to terms with less direct, wider-scale events? Surely there are enough talented science communicators and teachers to convince the public of the basic facts, or are people so embedded in the now that even one unseasonal rain day can convince them - as it did some random man I met on the street - that climate change is a myth?

Which way's up? Mental mapping and conditioning by familarity

I recently watched a television documentary on Irish prehistory that noted if you cunningly turned a conventional map of the British Isles ninety degrees anti-clockwise, then Ireland would appear to be an integral part of Europe's maritime trade routes and not stuck out on the edge of the known world. Be that as it may, it's interesting how easily we accept conventions without analysis. As you might expect, just because something is a convention doesn't necessarily mean it is superior, only that it has achieved such a commonplace status that it will usually be taken for granted. It's not the logical approach, but then we're not Vulcans!

Take maps of the world. Map projections have usually arisen in reponse to practical needs or due to the contingency of history. Most global maps today use the Mercator projection, which whilst being useful for maritime navigation in a time before GPS, increasingly distorts areas as they approach the poles. This shouldn't seem surprising, since after all we're taken a near-spherical object, transposing it onto the surface of a cylinder, and then unrolling that onto a two-dimensional plane.

In fact there are dozens of different map projections but none are good for all regions and purposes. This doesn't mean that the Mercator projection is ideal; far from it, since heavily-populated regions such as Africa appear too small whilst barely-populated areas such as Greenland and Antarctica are far too large. However, it is popular because it is familiar because it is popular...and so on. Like QWERTY keyboards, it may no longer be required for the purpose it originally served but is now far too common to be replaced without a great deal of hassle.

Aside from projection, there's also the little matter of direction. There are novelty maps with the south pole at the top, most commonly created by Australians, but since 88% of the human race currently live in the Northern hemisphere (which has 68% on the total landmass) it's hardly surprising that the North Pole is conventionally top-most.

However, this hasn't always been the case: before there was worldwide communication, the ancient Egyptians deemed 'upper' as towards the equator and 'lower' away from it. Early medieval Arab scholars followed suit whilst the mappa mundi of medieval Christian Europe placed East at the top of a topography centred on Jerusalem.

Photographs of the Earth that show a recognisable landmass usually present north uppermost too; there is no such thing as 'right' way up for our solar system, but the origin of the first great civilisations has set the geographic orientation for our global society.

None of this might seem particularly important, but ready acceptance of familiar conventions can easily lead to lack of critical thinking. For example, in the Nineteenth and early Twentieth Centuries, Great Britain exported pre-fabricated buildings to Australia and New Zealand, but as some architects failed to recognise that the Southern hemisphere sun is due north at midday there are examples with the main windows on the south-facing wall. Even the fact that most humans live in the Northern hemisphere has lead to the incorrect assumption that - thanks to their summer - the earth is closer to the sun in June than it is in December. There is such a thing as hemisphere parochialism after all!

If we can learn anything from this it is that by accepting popular conventions without considering their history or relevance, we are switching off critical faculties that might otherwise generate replacement ideas more suitable for the present. Unfortunately, we frequently prefer familiarity over efficiency, so even though tried and trusted conventions may no longer be suitable for changed circumstances we solidly cling to them. Thus we stifle improvements as a trade-off for our comfort. I guess that's what they call human nature...

Wondering about the wanderer: the life and times of the monarch butterfly in New Zealand

This summer has seen a proliferation of monarch butterflies in my garden. Over the past five years there's been little change in planting - except for a few additional self-seeded swan plants (a.k.a. milk weed Gomphocarpus fruticosus and similar species) - so why am I now seeing so many more Kahuku/Wanderer than previous years? This summer has seen a mixture of wet and dry weeks but not an extreme in either direction, when compared to the previous four summers in house. Is that the secret: just a balance of weather conditions; or is there more to it than that? As I pointed out in a recent post, a cluster of swan plants several street's away has seen very few monarch butterflies. Let's have a look at the details.

My experience:

Although common enough in all except the coldest regions of New Zealand, Danaus plexippus is not a native species but seemingly self-introduced at some point within the last 150 years. It's large size and colourful wing markings have led to its popularity in art and science. I've seen paintings, collages, sculptures and jewellery utilising its patterns, which contrast vividly with New Zealand's predominantly green appearance.

Swan plants, the almost sole food source, are readily available from garden centres and buying one can lead to large numbers of self-seeded plants, aiding the spread of the monarch. I've found this year that even young plants under 50cm tall have had eggs laid on them. I've also noticed that the swan plants in my back garden contain more than double the number of caterpillars than those in the front garden, despite the latter garden being much larger and having a lot more vegetation. I've even noticed that some caterpillars in the front garden disappear shortly after starting to pupate; perhaps the denser planting attracts or hides more predators?

Lifecycle:

The eggs are usually found on the underside of leaves and tend to be more conspicuous than the first instar (freshly-hatched) caterpillars. Apparently, larger caterpillars will munch through both eggs and smaller caterpillars without noticing, so it's a monarch-eat-monarch world out there! I've had to move some caterpillars when they get to a decent size in order to prevent them eating their entire plant and starving to death. Females can lay hundreds of eggs in their lifetime at a rate of up to 40 per day, so monarch care sites recommend destroying later eggs to allow the earlier individuals to survive. In general, the warmer the weather the quicker the caterpillars grown to full size before pupating. However, it has been noted that butterflies that hatch in the autumn can survive over winter, often in colonies, their lifespan extended from two months for same-summer breeders up to nine months. Unlike in their North American homeland, New Zealand monarchs do not migrate enormous distances.

Predation:

Despite absorbing toxins from milkweed, both caterpillars and butterflies are predated by a range of other animals. I've occasionally found a pair of wings on the ground, which is a good indication of predation by a South African praying mantis, Miomantis caffra. Other introduced invertebrates such as wasps will also attack monarchs. It's interesting that these predators tend to have originated in Europe, Africa and Asia yet the monarch evolved in North America; clearly, the former aren't too specialised to be able to handle alien prey. Which of course is what has happened in general to New Zealand's native birds and reptiles, with European mustelids and rodents and Australian possums finding a veritable feast amongst the kiwi and company.

Caring for monarchs:

Apart from removing caterpillars from overcrowded plants, my only other assistance is to rehang any fallen chrysalis and move the occasional pre-pupating wanderer into a wood and wire cage until they metamorphose. Although I have found one chrysalis about eight metres from the closest swan plant, a fully-grown wandering caterpillar might just prove too tempting a morsel. Otherwise I tend to leave nature to do its thing; after all, it's hardly an endangered species. Many caterpillars disappear before reaching pupation due to a combination of disease and predation and any swan plant that gets completely eaten may lead the incumbent caterpillars to starvation. Darwin was famously inspired by Thomas Malthus' An Essay on the Principle of Population, so it's great to be able to see such a theory in action in your own garden!

Public interest:

Despite being neither native nor endangered, there are various New Zealand-based citizen science projects studying them, such as by fitting wing tags for tracking purposes. Much as I am in favour of direct public engagement in science, I wonder if the effort wouldn't be better redirected towards endangered native species. As I've previously discussed, if visually attractive poster species get much of the attention, where does that leave the smaller, more drab, less conspicuous critters that may be more important?

I'm still at a loss to what has caused this summer's proliferation of monarch butterflies in my garden. There are just as many other summer species as usual, such as adult cicada and black crickets, and seemingly as many monarch predators such as praying mantises. But as I've mentioned before, perhaps what to human eyes appear similar conditions are not so to these colourful creatures. Although how much effort would be required to detail those conditions is somewhat beyond the capability of this amateur entomologist!

Backyard bonanza: collating stats for a predator-free future

I've previously discussed how a lack of understanding of statistics can cause consumers to make poor choices, so it would seem that increasing the public's understanding of them can only be a good thing. Therefore, along the lines of New Zealand's annual garden bird survey, I decided to do a bit of citizen science. My aim was to record the highest number of each fauna species seen at one time, either actually in my garden or seen from my garden. The time frame was a calendar year, so as to take into account seasonal migrations and food availability. As an aside, it might have been easier to count flora (after all, it doesn't move very fast) but with Auckland being the weediest city in the world and my floral knowledge much weaker than my recognition of fauna, I opted for the easier option of any animal that I could see without using a microscope.

A meta-analysis released this month states that almost twenty-five percent of birds on the IUCN Red List of Threatened Species are being affected by climate change. In addition, with last years' announcement to make New Zealand predator-free by 2050, such surveys might be useful for locating concentrations of introduced pest species. In a way, I'm providing a guide that anyone can follow with the minimum of effort (hint, hint). So here are my results, followed by some more information:

Class/species	Native/self-introduced	Number seen
Insecta
Ant (unknown species)	Yes	Numerous
Asian paper wasp	No	3
Black field cricket	Yes	4
Bumble bee	No	1
Bush cockroach	Yes	14
Cabbage tree moth	Yes	7
Cabbage white butterfly	No	2
Cicada	Yes	2
Click beetle	Yes	2
Common bag moth	Yes	1
Crane fly	Yes	1
European earwig	No	1
Ground beetle	Yes	2
Honey bee	No	1
Housefly	No	7
Ladybird	Yes	2
Monarch butterfly	Yes	17
Shield bug	Yes	3
South African praying mantis	No	22
Tree weta	Yes	18
Arachnida
Bird dropping spider	Yes	1
Black cobweb spider	Yes	1
Black house spider	Yes	1
Daddy long-legs	Yes	3
Jumping spider	Yes	1
Nurseryweb spider	Yes	1
Slater spider	Yes	1
White tail spider	No	1
Annelida
Earthworm	No	5
Tiger worm	No	Numerous
Hexapoda
Springtail	No	Numerous
Chilopoda
Centipede	Yes	3
Mollusca
Common garden snail	No	9
Reptilia
Rainbow skink	No	2
Aves
Australasian hawk	Yes	1
Blackbird	No	2
Black headed gull	Yes	3
Eastern rosella	No	4
Fantail	Yes	2
Goldfinch	No	3
Greenfinch	No	2
House sparrow	No	14
Myna bird	No	4
Rock pigeon	No	5
Silvereye	Yes	7
Song thrush	No	1
Spotted dove	No	1
Starling	No	4
Tui	Yes	1
Mammalia
Cat	No	2
Chicken	No	1
Dog	No	1
Hedgehog	No	1
Mouse	No	1
Rabbit	No	1

The first thing that seems obvious is just how many non-native species I observed, some deliberate introductions whilst others accidentally brought to New Zealand, but all within the past two centuries.

Now for some interesting comments about how statistics can be (mis)interpreted:

1) The method I chose to order the table by could affect how easy it is to find key points of interest. Alphabetical order is familiar but is simply a well-known form of cataloging. Therefore it can be seen as a neutral form of presentation, not emphasising any particular pattern of the results. Had I ordered by native/non-native, it might have become more apparent how many of the latter bird species there are. If I had ordered all species in one list by this method, rather than in separate classes, the pattern would have been obscured again. So simply by selecting a certain order, results can appear to support a certain notion.

2) How useful is this data if it lacks supporting information? By this, I mean factors that might affect the count: Is it a common or garden (yes, that's a pun) location or an highly unusual one? Is the locale urban or rural? What are the surroundings? How big is the garden and how much vegetation is there? Is the vegetation primarily native or non-native? I could go on like for this ages, but clearly to get a more sophisticated understanding of the causes behind the figures, this information is necessary. Even then, two locations that are almost identical to a casual observer might appear profoundly different from the vantage point of say, earthworms. I will admit to (a) having built 2 weta motels and a bug motel; and (b) feeding silvereyes in winter; and (c) having made a tui sugar water feeder that has been totally ignored. Go figure!

3) Are there any other obvious factors that could affect wildlife? How managed is the location? Are chemicals such as weedkiller used or is the garden solely organic? Again, this can have a massive effect on wildlife, such as pesticides that remove insects at the base of food webs. On the one hand, if mine is an organic garden surrounding by neighbours who spray their foliage, then it could be an island of suitability in a comparatively barren terrain. But alternatively, if most of the neighbourhood isn't fauna-friendly, how likely would my garden get visited even on the off-chance by animals that can't live in the wider area?

4) Of course there's also contingency within natural selection. For example, quite by chance some species can survive on foods not native to their ecosystem. Although stick insect numbers in New Zealand were drastically reduced thanks to DDT, gardens don't need to contain their native food plants in order to support them. In the south-west of England, three species of accidentally-introduced New Zealand stick insect have flourished for decades on the likes of roses! Also, unusual events can affect populations: in this case, the two rainbow skinks appeared several months' after laying some ready lawn so I can only assume their eggs arrived with the turf, the previous five years having seen no skinks whatsoever.

5) When it comes to surveys, timing is also important. As you might expect, most of my observations took place during the day, with the only nocturnal ventures being on clear nights when using my telescope. The moths and hedgehogs were mostly seen at night, whilst had I included birds I could hear as well as see, then a morepork would have been added to the list. Again a simple prejudice, in this case sight over sound, has skewed the statistics. The large number of mantises were not adults but nymphs all hatching from a single ootheca. As for the monarch butterflies, they were a combination of caterpillars, chrysalis and adults, having appeared in much greater numbers this year than previous, despite no additional swan plants (their only food). Interesting, a clump of twenty or so mature swan plants a few streets away hasn't yielded any monarchs in any of the three stages. Presumably, predators such as wasps are responsible.

The sheer randomness of nature is exciting, but doesn't exactly help to uncover why populations are such as they are found via small-scale studies. Oh, and further to the damage invasive species have wrought on native wildlife, you may be interested to learn that none of the mammals belonged to me, the cats and dog being owned by friends and neighbours whilst the rabbit was an escapee from a dozen houses away!

6) Finally, there's the scale prejudice. Although I have a basic microscope, I didn't include such tiny wonders as tardigrades and bdelloid rotifers, even though garden moss and leaf litter respectively has revealed these wee critters. My page of nature photographs shows this prejudice, with microscopic fauna getting their own page.

So, what can we learn from this, apart from the large number of non-native species commonly found in Auckland? Perhaps that raw data can be presented in ways to obscure patterns or suggest others, should the publisher have an agenda. Furthermore, without access to highly detailed meta data, the statistics by themselves tell only a small part of the story and as such are open to wide-ranging interpretation by the reader. Therefore the next time you read about some percentage or other, remember that even without manipulation or omission, survey data is not necessarily pure, unsullied and free of bias.

Unwanted aliens: is a predator-free New Zealand realistic by 2050?

In a moment of half-baked madness worthy of Donald Trump, the New Zealand Government has announced a plan to make the nation predator-free by 2050. As can be imagined this statement has attracted a wide range of opinions, even from across various conservation groups. These vary from the extremely optimistic viewpoint of Forest and Bird advocacy manager Kevin Hackwell, who claims it is achievable even earlier, to the Green Party's conservation spokesman Kevin Hague, who publicised a University of Auckland study estimating the project's budget at an astonishing if not untenable NZ$9 billion.

With the government prepared to provide just one-third of the plan's funding, it's difficult to imagine which private sector companies would be willing to supply the lion's share over the next three decades. As expected, the response of New Zealand's political opposition has been to pour very cold water on the plan, including the claim that no nation has ever managed to wipe out its population of rats (Hamelin and its Pied Piper notwithstanding).

One of the most essential questions is what is defined as a pest in the context of this proposal?  The relevant Department of Conservation (DoC) page names three principle animal pests: possums, rats and stoats, with a further page expanding the list to other introduced animals and freshwater fish, including cats and dogs (both domestic and feral). Some of the species listed were deliberate introductions, mainly in the Nineteenth Century, whilst others came in accidentally under the radar - New Zealand's biosecurity protocols not always being as draconian as they are now.

A few statistics offer a frightening idea of the scale required: as of 2001 it was estimated that there were seventy million possums in New Zealand, eating 21,000 tonnes of vegetation every night. Needless to say, much of this material consists of endemic species such as pohutukawa and southern rata trees. This then has a knock-on effect for the native fauna that feeds or nests on these species, which of course is in addition to being direct prey for the possum.

Although cats and dogs might be thought of more as pets than pests, even in low numbers they can be devastating to native wildlife. A classic example is the extinction of the Stephens Island wren thanks to a number of feral cats, whilst it is thought that one stray dog managed to kill more than five hundred large brown kiwi in the Waitangi State Forest in less than a year.

DoC's Battle for our Birds scheme relies on aerial drops of poison and ground baits/traps to eradicate the key non-native pests. This year their target area was almost 900,000 hectares; to give an indication of the increase in scale necessary for a nationwide eradication, New Zealand is close to 27 million hectares in total. Perhaps the much-misused term 'paradigm shift' could be safely applied in this circumstance?

At this point it should be mentioned that there are varied opinions as to what the government's planned outcome is. After all, there have been humans living in New Zealand for over seven centuries, so there is little chance of any except the most remote locales returning to a pristine ‘natural' wilderness, even if we knew exactly what that meant. Having said that, the Pleistocene Park project in Russia is attempting something along similar lines. A small region of north Siberian tundra is being converted into glacial period steppe, using musk ox and other large animals as surrogates for extinct mega fauna such as mammoth and woolly rhinoceros. The resulting flora appears to be much more diverse and interesting than the unmanaged wilderness surrounding it, which is ironically the antithesis of what one would expect or hope for with untouched versus deliberately altered landscapes!

Then there's the scale issue: whilst possums, rats and mustelids are relatively easy to track and observe, small species such as wasps and argentine ants are far more difficult to locate, never mind eradicate. Although they don't inflict as much obvious damage to the native flora and fauna, they can nonetheless cause fundamental changes to the ecosystem. Wasps for example eat honeydew, which is an important food source for lizards and native birds such as kaka.

It isn't just insects that would be tricky to wipe out. The rainbow or ‘plague' skink was accidentally introduced from Australia about half a century ago and now seems ubiquitous in Auckland; I've seen it everywhere from volcanos to paddocks, gardens to garages, even inside a bookshop. Thanks to much faster reproduction and maturation rates than native equivalents, it appears to be rapidly out-competing them.

One issue that prevents a complete turning back of the clock is the extinction of dozens of species since the arrival of humans in the country. How can the ecosystem, especially food webs, maintain a long-term balance with key species missing? No-one is suggesting we bring in cassowaries to replace the nine species of moa. Of course, being large creatures they were probably none too numerous, yet there is an hypothesis that they may have been involved in an evolutionary arms race with lancewood, the juvenile trees being well-protected against moa browsing them.

Therefore any attempt to preserve a largely native ecosystem will need to ensure the food webs are fully-functional, with plenty of indigenous pollinators such as short-tailed bats and kereru (native pigeon). Key native species need to identified and preserved just as much as introduced ones removed. This in turn begs the obvious point that since evolution is an ongoing process, are we attempting to freeze the environment at a particular snapshot in time rather than allowing nature to take its course? Even accounting for punctuated equilibrium, natural selection hasn't suddenly stopped in New Zealand any more than it has elsewhere.

The pest-free project will presumably need to tackle species in a certain order, since if mustelids and feral cats are eliminated then rats will proliferate, whilst without rats as prey, the former species will be forced to look for alternative food sources instead; doubtless native birds would form the mainstay of this.

As I have discussed elsewhere, it shouldn't just be the enemies of the native poster species that are targeted. There are plenty of critters less famous than parrot kakapo and ancient reptile tuatara that deserve some attention too, with the endemic weta an obvious example (over twenty percent of its species are currently under threat). Invertebrates play an almost unknown role in nutrient recycling and waste disposal, as well as appearing on the menu of more conspicuous animals. Considering that the takahe, the largest species of swamp hen, was thought extinct for half a century, perhaps we shouldn't be surprised about how little is known concerning the size and condition of native creepy crawly populations. However small and insignificant we might judge them, we ignore their loss at our peril.

Also often overlooked are the native freshwater creatures. Competition comes in the form of the high number of invasive species that compete or predate on them. A key example is the aggressive gambusia, a Mexican fish introduced to eat all the mosquito larvae - which of course it fails to do. Interestingly enough, the DoC website excludes some introduced species from its list of pests: salmon and trout for example are categorised as 'sports fish'. Therefore is economics the government's primary motive for the pest eradication plan, rather than good old-fashioned conservation for the sake of it? After all, the extremely rare takahe was once given second place to herds of elk that had been introduced to serve as a big game animal.

There may be something in this. Mainstream politicians are renowned for their lip service commitment to environmental issues. Could it be that in the wake of the highly negative stories earlier this year concerning exceeded fishing quotas and river pollution, the government is fighting to redeem New Zealand's '100% Pure' brand image?  In addition, agriculture might benefit from an increase in native species' populations. An outstanding example of the latter is shown by a Federated Farmers of NZ estimate that native bees provide pollination services to the tune of NZ$4.5 billion per year!

Finally, we get to flora. As Bec Stanley, a curator at Auckland's Botanic Gardens, is keen to point out, the majority of people have plant blindness compared to their interest in animals. There are thought to around three invasive plant species for every four natives, with old man's beard, gorse, ragwort and nightshade being amongst the best-known culprits. These can smother and kill native plants, thus depriving indigenous animals of food. Despite being vital to the ecosystem, the war on introduced vegetation really seems to be underdeveloped compared to that against non-native animals.

It doesn't take much to upset the balance of at least a local-scale environment. The surviving remnants of mighty kauri forest are currently facing a disease thought to be caused by an introduced water-mould pathogen, a clear case of David conquering Goliath. Without careful consideration, the project to rid New Zealand of introduced pest species could end up doing more harm than good. The motives are potentially dubious and the research chronically under-funded. It remains to be seen whether there is the willpower to see it through or if it is just one more piece of political rhetoric that evaporates by the next election. Personally, I'm in favour of the idea, but uncertain of how realistic it is. Regardless, the citizens of New Zealand need to do their best, lest many more species join the ranks of moa, huia, adzebill and many, many others. After all, who wants their children living in an environment dominated by feral pigeons, rats and possum?