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...

The moons of Saturn and echoes of a synthetic universe

As fans of Star Wars might be aware, George Lucas is nothing if not visually astute. His thumbnail sketches for the X-wing, TIE fighter and Death Star created the essence behind these innovative designs. So isn't it strange that there is a real moon in our solar system that bears an astonishing resemblance to one of Lucas's creations?

At the last count Saturn had 53 confirmed moons, with another 9 provisionally verified - and as such assigned numbers rather than names. One of the ringed planet's natural satellites is Mimas, discovered in 1789 and at 396 kilometres in diameter about as small as an object can be yet conform to an approximate sphere. The distinguishing characteristic of Mimas is a giant impact crater about 130 kilometres in diameter, which is named Herschel after the moon's discoverer, William Herschel. For anyone who has seen Star Wars (surely most of the planet by now), the crater gives Mimas an uncanny resemblance to the Death Star. Yet Lucas's original sketch for the battle station was drawn in 1975, five years before Voyager 1 took the first photograph with a high enough resolution to show the crater.

Okay, so one close resemblance between art and nature could be mere coincidence. But amongst Saturn's retinue of moons is another with an even more bizarre feature. At 1469 kilometres in diameter Iapetus is the eleventh largest moon in the solar system. Discovered by Giovanni Cassini in 1671, it quickly became apparent that there was something extremely odd about it, with one hemisphere much brighter than the other.

As such, it attracted the attention of Arthur C. Clarke, whose novel 2001: A Space Odyssey described Japetus (as he called it) as the home of the Star Gate, an artificial worm hole across intergalactic space. He explained the brightness differentiation as being due to an eye-shaped landscape created by the alien engineers of the Star Gate: an enormous pale oval with a black dot at its centre. Again, Voyager 1 was the first spacecraft to photograph Iapetus close up…revealing just such a feature! Bear in mind that this was 1980, whereas the novel was written between 1965 and 1968. Carl Sagan, who worked on the Voyager project, actually sent Clarke a photograph of Iapetus with a comment "Thinking of you..." Clearly, he had made the connection between reality and fiction.

As Sagan himself was apt to say, extraordinary claims require extraordinary evidence. Whilst a sample of two wouldn't make for a scientifically convincing result in most disciplines, there is definitely something strange about two Saturnian moons that are found to closely resemble elements in famous science fiction stories written prior to the diagnostic observations being made. Could there be something more fundamental going on here?

One hypothesis that has risen in popularity despite lacking any hard physical evidence is that of the simulated universe. Nick Bostrum, the director of the University of Oxford's Future of Humanity Institute has spent over a decade promoting the idea. Instead of experimental proof Bostrum uses probability theory to support his suppositions. At its simplest level, he notes that the astonishing increase in computing power over the past half century implies an ability in the near future to create detailed recreations of reality within a digital environment; basically, it's The Matrix for real (or should that be, for virtual?)

It might sound like the silliest science fiction, as no-one is likely to be fooled by current computer game graphics or VR environments, but with quantum computing on the horizon we may soon have processing capabilities far beyond those of the most powerful current mainframes. Since the ability to create just one simulated universe implies the ability to create limitless - even nested - versions of a base reality, each with potentially tweaked physical or biological laws for experimental reasons, the number of virtual realities must far outweigh the original model.

As for the probability of it being true in our universe, this key percentage varies widely from pundit to pundit. Astronomer and presenter Neil deGrasse Tyson has publicly admitted he considers it an even chance likelihood, whilst Space-X and Tesla entrepreneur Elon Musk is prepared to go much further, having stated that there is only a one in a billion chance that our universe is the genuine physical one!

Of course anyone can state a probability for a hypothesis as being fact without providing supporting evidence, but then what is to differentiate such an unsubstantiated claim from a religious belief? To this end, a team of researchers at the University of Bonn published a paper in 2012 called 'Constraints on the Universe as a Numerical Simulation', defining possible methods to verify whether our universe is real or virtual. Using technical terms such as 'unimproved Wilson fermion discretization' makes it somewhat difficult for anyone who isn't a subatomic physicist to get to grips with their argument (you can insert a smiley here) but the essence of their work involves cosmic rays. The paper states that in a virtual universe these are more likely to travel along the axes of a multi-dimensional, fundamental grid, rather than appear in equal numbers in all directions. In addition, they will exhibit energy restrictions at something called the Greisen-Zatsepin-Kuzmin cut-off (probably time for another smiley). Anyhow, the technology apparently exists for the relevant tests to be undertaken, assuming the funding could be obtained.

So could our entire lives simply be part of a Twenty-Second Century schoolchild's experiment or museum exhibit, where visitors can plug-in, Matrix-style, to observe the stupidities of their ancestors? Perhaps historians of the future will be able to run such simulations as an aide to their papers on why the hell, for example, the United Kingdom opted out of the European Union and the USA elected Donald Trump?

Now there's food for thought.

Tsunamis and sunsets: how natural disasters can inspire creativity

Just as war is seen as a boost to developments in military technology, so major disasters can lead to fruitful outbursts in creativity. The word disaster, literally meaning 'bad star' in Ancient Greek, might seem more appropriate to meterorite impacts or portents associated with comets, but there are plenty of terrestrial events worthy of the name. One interesting geophysical example appears to have had an obvious effect on Western art and literature: the eruption of Mount Tambora in April 1815.

This Indonesian volcano exploded with such force that ash fell in a cloud over 2,500 km in diameter, with the initial flows and tsunami causing over 10,000 deaths. The subsequent death toll may have been ten times that number, primarily due to starvation and disease. The short-term changes in climate are thought to have accelerated the spread of a cholera strain, leading eventually to millions of deaths during the next few decades.

Although volcanic aerosols lasted for some months after the eruption, the effects were still being felt the following year. Indeed, 1816 earned such delightful nicknames as 'The Year Without a Summer' and 'Eighteen Hundred and Froze to Death', with global temperatures dropping just over half a degree Celsius. This might not sound like much, but as an example of the freak conditions the northern USA received snow in June. Thanks to the recording of weather data at the time, it seems that the climate didn't return to normal for that period until 1819.

The terrible weather and its resulting famines and spread of disease led to riots in many nations, with the short-term appearance of vivid sunsets - due to the fine volcanic dust - failing to make up for the deprivations of food shortages and very cold conditions. One artist who was probably inspired by the former effect was J.M.W. Turner, whose paintings of evening skies appear extremely garish. As a child, I thought this seemingly unnatural colouration was due to artifice, not realising that Turner was depicting reality.

The post-Tambora aerosols contributed to Turner's stylistic change towards depicting the atmospheric effects of light at the expense of form. His radiant skies and translucent ambience inspired the Impressionist school of painting, so perhaps modern art can be said to have its roots in this two hundred year-old disaster.

Literature also owes a debt to Tambora's aftermath: during their famous Swiss holiday in June 1816, Lord Byron produced the outline of the first modern vampire story whilst Mary Shelley started writing Frankenstein. It's easy to suggest that the food riots and wintry weather then current in Switzerland could have contributed towards her tale, in which mankind's best efforts to control nature are doomed to failure.

However, it isn't just the arts that were affected by the aftermath of the volcanic eruption: several key technologies had their roots in the widespread food shortages generated by Tambora. In 1817 the German inventor Karl Drais, aware of the lack of fodder then available to feed horses, developed the earliest steerable - if pedal-less - bicycle. Although its use was short-lived, the velocipede or hobby horse was the first link in the chain (go on, spot the pun) that led to the modern bicycle.

If that doesn't appear too convincing, then the work of another German, the chemist Justus von Liebig, might do. Having as a child been a victim of the post-Tambora famine, von Liebig is known as the 'father of the fertiliser industry' for his work in the 1840s to increase crop yields via nitrogen-based fertilisers.

There is still a widespread perception that scientists' thought processes differ from the rest of humanity's, utilising thought methods that lack any emotion. However, the after effects of Tambora imply that creativity in response to surroundings can be just as important for scientific advance, in the same way that artists respond to their immediate environment. Hopefully, recognition of this will be another nail in the coffin for the harmful idea of C.P. Snow's 'Two Cultures' and lead more people to respect the values of science, upon which our civilisation so heavily relies. Perhaps that way we'll be rather better prepared for the next great natural disaster; after all, it's only a question of time...

Wrangling robots: encouraging engineers of the next generation

On hearing my daughters' regaling some of their activities and technology at school, I frequently lament 'I wish we had that when I was their age'. I was lucky enough as it was for the early 1980s; for example, my school year was the first to actually get computers in the computer science classroom!

But enough of the trip down memory lane. The British Government has recently announced that it is pledging over £17 million towards robotics and artificial intelligence (AI) research in universities. Of course the drive behind this is as much economic as a love of STEM: Accenture's 2016 report Why Artificial Intelligence is the Future of Growth states that AI could contribute up to £654 billion to the UK economy by 2035, if comprehensively integrated into industry and society. Sectors utilising cutting-edge technology such as pharmaceuticals and aerospace will be able to grow markedly thanks to AI and robotics, so now is indeed a great time for children to learn the necessary core skills.

New Zealand too is determined not to be left behind in the development of such technology, which it is hoped will create new jobs whilst stimulating economic growth. One such programme aimed in this direction is Kiwibots, home to New Zealand's contenders for the annual Vex Robotics World Championship. The largest international robotics competition, over thirty nations are taking part this year. New Zealand's national finals recently took place at Massey University in Albany, north of Auckland. The winning teams have been announced and among those qualifying for the World Championship in Kentucky next month is one from an all-girls school, which is great news.

My daughters attend another all-girls school that competed in the national championships, giving me the opportunity to examine one of their robots in person. Vex EDR primarily consists of metal components including perforated strips reminiscent of the Meccano toy building system I had as a child - and indeed their construction techniques are not dissimilar - although EDR incorporates battery-driven motors and elastic band 'muscles'. EDR is aimed at senior/high school students, but primary/elementary and intermediate schools are not left out, thanks to the mostly plastic-built Vex IQ system which is closer to the Lego Mindstorms/Technic ranges.

Vex EDR robots can either be wheeled or tracked and include towers and arms with manipulators. They can be remote controlled or programmed using ROBOTC, a C-based programming language: not only do the students get to be engineers but computer programmers too. Younger roboteers can use a drag-and-drop interface to assemble code whilst older ones may write and test code using an editor. In order to aid code writing, Robot Virtual Worlds is, as the name suggests, a simulated environment for testing virtual robots, even including an underwater scenario (which is obviously not achievable with the real thing)!

To encourage more girls to participate in the traditionally male world of engineering, the Robotics Education and Competition Foundation has created Girl Powered, a series of challenges for EDR and IQ systems.

In addition to learning specific technical skills, the experience can generate enthusiasm for STEM subjects - after all, it's rather more exciting than most school lessons - whilst providing useful experience in general skills such as collaboration and problem-solving. The creativity and teamwork involved in Vex robotics shows that some elements of science and engineering are not overtly difficult, abstractly mathematical or plain boring. When I was an onlooker at the national finals, the looks of tension and joy on the roboteers' faces said it all.

As Vex themselves state: Think. Create. Build. Amaze.

What better way could there be to encourage children towards STEM careers, especially when AI and robotics will undoubtedly play an ever more important role in the coming decades?

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.