Archive | May 14, 2017

Travels in the Meddle Earth

Tuatara (Sphenodon punctatus)

“Go!” is the last word I hear, and then it’s only the swish of air, panic in my heart, and the river getting closer with every nanosecond. Right at the moment I am ready to have my skull crushed, something pulls me up, and I am flying towards the top of the canyon again. Ah, bungee jumping, the sport of the brave and the insane. But this is New Zealand, home of crazy adrenaline addicts who first inflicted this exercise on the world, and I would have never forgiven myself if I did not make myself try it. “Yeah, it was all right,” I say nonchalantly when back on the bridge, hands deep in my pockets to hide the shakes (from the cold, I think.) Then I get into the car, and drive away without looking back.

Two things had always attracted me to New Zealand. One was bungee jumping, which I had always seen as a sort of a dry run for a suicide. The other was a burning desire to see a beast that I had first read about when still a young boy. Tuatara, a unique reptile whose pedigree goes back over 230 million years, is the only surviving member of the reptilian order Sphenodontia, now found only in New Zealand. In books and articles that I read about the tuatara it was portrayed as the closest thing to a living dinosaur the human race would ever have a chance to see. Even its very name sounded mesmerizing – tuatara, a Maori word for “spiny back” – and I envisioned a gargantuan monster, perhaps a real life dragon.

But it quickly becomes apparent to anybody interested in tuataras that the appeal of these remarkable reptiles lies not in their rather underwhelming physique (although I strongly disagree with the assessment presented by an Auckland newspaper in the late 1870’s, which called them “…the ugliest of all creeping things, with the exception of frogs.”) At first glance a tuatara can be confused with a large, thick-legged lizard. Not surprisingly, the first tuatara, in the form of a single skull sent from New Zealand to the College of Surgeons in London, was formally described in 1831 as such. Its descriptor, John Edward Grey, then an assistant in the British Museum’s reptile collection, coined the name Sphenodon, and placed it, incorrectly, as it later turned out, among the lizards of the family Agamidae. Eleven years later, not realizing that he was looking at the same, but far more complete animal, Grey described another New Zealand “lizard,” Hatteria punctata, based on a tuatara preserved in alcohol (the name he later changed to the now accepted, and “less barbarous,” Sphenodon punctatus). But it was the paleontologist Sir Richard Owen, the man who famously coined the term “dinosaur,” who first noticed a strong similarity of the New Zealand “lizard” to certain Mesozoic reptiles excavated in South Africa. His suspicion of the ancient origin of the tuatara, published by Albert Günther 150 years ago this month, was later confirmed by other zoologists, who placed the species and its fossil relatives in a separate order of reptiles. At the end of his life, after it became clear that tuatara was not a lizard, but rather a unique animal close to extinct Mesozoic reptiles Grey published a self exculpatory paper, explaining that he did notice its unusual features, but “[…] it would have required more than usual hardihood in 1831, when the genus was described, to venture to form for it even a family; while an order may now be suggested for the single genus, with every probability of it being adopted – a decided proof of the progress of science in a few years.” While Grey’s definition of the progress of science may sound antiquated, he was right predicting the fact that nobody now questions the singular status of the tuatara amongst modern reptiles.

A portrait of a tuatara.

Superficially, a modern tuatara’s 40-70 cm long body resembles a chunky iguana, with soft, grey or sometimes greenish skin covered with small, non-overlapping scales. A low crest runs along its back, eventually turning into stout, conical pegs on the thick, muscular tail. The head is also covered with small scales, but unlike lizards, tuataras do not have external ear openings, or even functional tympanic membranes. Nonetheless they can hear surprisingly well, albeit their sound perception is restricted to low frequencies, such as the low, grumbling noises these animals produce when distressed. Incidentally, their ability to hear only low frequencies makes them strangely intrigued by human voices, which also span the lower registers of the sound spectrum. The strongest indication of tuatara’s ancient provenance lies in the structure of their skull, which still bears two pairs of large openings connected by strong, bony arches, features that have long been lost in all modern reptiles. The upper jaw is fully fused with the rest of the skull, making it inflexible, and severely limiting the speed with which tuataras can open their mouth, and how wide they can do it. Rather than snatching things directly with their jaws tuataras must rely on their thick, sticky tongue to catch their prey, a lingual ingestion is the technical term for this behavior, and ingest they do. Tuataras are known to eat pretty much anything they can catch, and this includes beetles, crickets, earthworms, lizards, other tuataras, and even birds. Once in tuatara’s mouth, the prey is quickly cut into pieces by the shearing action of a single row of teeth on the lower jaw against two rows of teeth at the base of the upper one. And while tuataras’ disposition is rather docile, if sufficiently annoyed they will bite, and the sensation this produces has been repeatedly described as similar to being gripped by a powerful vise, which will only tighten its clasp if one attempts to dislodge it.

The strongest indication of tuatara’s ancient provenance lies in the structure of their skull, which still bears two pairs of large openings connected by strong, bony arches, features that have long been lost in all modern reptiles (with the exception of turtles, whose ancestors never had those openings to begin with.)

Like so many still surviving relict lineages of organisms, tuataras relish the cold. They are, like all reptiles, ectothermic. This means that their body temperature is dependent on the ambient temperature of the environment, and while they can regulate the amount of energy that reaches their body through basking or hiding in the shade, they cannot generate their own heat. Unlike most reptiles who prefer warm or truly hot weather, tuataras optimal body temperature is 16-21°C, the lowest of any reptile, and they remain active even when the temperature drops to decidedly nippy 7°C. Although this adaptation to the cool, temperate climate of the present day New Zealand is probably a relatively recent phenomenon, it allowed tuataras to outlive all their Mesozoic relatives from other parts of the globe, and withstand the competition from lizards they have been sharing New Zealand with since its separation from the old supercontinent Gondwana.

But the more I was learning about tuataras, the more obvious it was becoming that my chances of seeing one in its natural habitat were slim to none. Although recent conservation assessments of tuataras sounded optimistic, the overall picture was far from rosy. The numbers of surviving individuals were impressive, and between 30 and 50 thousand individuals are said to live in New Zealand. Unfortunately, most of them are concentrated on the small, offshore Stephens Island. Thirty-four additional tiny islands have tightly monitored populations that vary in size from a few to a few hundred individuals, but the mainland New Zealand has not seen free-living tuataras since the arrival of the Maori ancestors and their accompanying menagerie of dogs, rats, and pigs, which quickly did away with the slow, tasty reptiles and their eggs (not to mention the many now extinct native bird species.) By the time the English came in the late 1700’s, tuatara, or ngarara as it was also called, was considered on the mainland an almost mythical creature, remembered only by the oldest of the Maori, and even by them only as something that their grandfathers hunted (and, apparently, really feared.) Luckily, some of the animals survived on a few small islands in the Bay of Plenty and the Cook Strait where rats and other introduced species never managed to get to. Only within the last twenty years, following massive rat eradication efforts and great advances in captive rearing of tuataras, the downward trend has been reversed, and new populations have been reintroduced to several additional islands.  On the mainland, however, tuataras seem to be a lost cause. And yet, some people just refuse to give up.

On the outskirts of the capitol Wellington, on the southernmost tip of the North Island lies a valley called Karori. Until the mid-1800’s its entire area was covered with nearly pristine, primeval woods, but after the arrival of English settlers most of the forest was cut down or burned and, following the construction of two dams, a lake appeared at the bottom of the valley. But about twenty years ago, after both dams were finally decommissioned, and nobody really knew what to do next with the place, a group of conservationists came up with an audacious plan to turn Karori into a sanctuary, to recreate a piece of a piece of the old fragment of Gondwanaland known as Zealandia, and return to it its rightful, native inhabitants, including the tuatara. The problem was, that like nearly all of the country, Karori was overrun with invasive plants, and introduced mammals and birds thrived there in place of the indigenous fauna. At least 30 mammal, 34 birds, over 2,000 invertebrates, and 2,200 alien plant species are fully naturalized in New Zealand; in fact, the number of exotic, invasive seed plant species now exceeds that of the native ones. And although only a portion of the New Zealand’s aliens lived in Karori, their dominance over the natives was overwhelming.

The most serious predicament the Karori project faced was the alien mammals. By a strange bit of luck, the landmass that broke off the eastern part of Gondwana in the late Cretaceous about 80 million years ago to later become New Zealand just happened not to invite any land mammals for its oceanic voyage. The only furry, native inhabitants of New Zealand were a handful of bat and seal species. This left many potential ecological niches vacant, niches that were promptly filled by other, rather unexpected groups. Birds took upon themselves to become giant grazers (the now extinct moa), sprightly, flightless insectivores (the now mostly extinct wrens), or nocturnal, scent-guided predators of soft-bodied invertebrates (the now highly endangered kiwis.) In the absence of wily mammalian predators many lineages of birds forwent flight, as there no longer existed a pressure to quickly take up to the air to escape. The role of mice and other rodents was filled by seed-feeding, cricket-like wetas, and since few birds were interested in these insects, they grew huge and sluggish. And so, when the mammalian invasion began, probably as early as 2,000 years ago with the arrival of the first Polynesian sailors, this vulnerable, insular fauna did not stand a chance. The first to go were flightless moas, massive birds nearly twice the size of present-day ostriches – they fell victim to the worst mammalian offender, man. With the first human settlers came other mammals, most notably pigs, dogs, and the Pacific rat (Rattus exulans). The last one was of course brought in accidentally, but that did not diminish the bloodshed this species has caused. Rats are probably the main cause of the extinction of a number of birds, a severe decline in the populations of wetas, and wiping out tuataras on the mainland. Not to be outdone by the natives, the early English settlers rolled up their sleeves and went about turning this singular, exotic land into a South Pacific version of their northern homeland. Deer and foxes were introduced for their hunting pleasure, followed by hedgehogs, cats, and a number of other furry species. Rats and mice brought by both the Maori and Europeans flourished and wreaked havoc among planted crops in the lack of competition of any kind, which finally attracted the attention of the colonists. In one of the most disastrous decisions in New Zealand’s history, stoats, a kind of a weasel, were brought in from Europe to control the outbreaks. But why should stoats bother trying to catch fast and elusive rodents, which over millions of years of coevolution with mammalian predators had developed great skills at avoiding being eaten, when the islands were full of naïve, slow or flightless birds and their tasty eggs? Unsurprisingly, an avian carnage ensued.

It soon became obvious that the only way to keep invasive mammals out of Karori was to surround it with an impenetrable fence, and then eliminate all the invaders inside the fence with a combination of traps and poisons. At the cost of slightly over 2 million NZ$ (approx 1.5 mln US$) a tall, metal mesh fence was erected around an area of about 1 square mile, capped with a wide, slippery metal ledge, impassable to all mammals. Or at least that was the idea – accidental damage to the mesh, designed to be fine enough to prevent even baby mice to slip through, allowed some mice to re-enter the reserve, and establish a population that still seems to be thriving. There was not much that could be done about invasive bird species – even if all alien birds were exterminated in Karori, new ones would simply fly in from surrounding areas – and getting rid off invasive plants turned out to be easier said than done. But, in the end, a remarkable progress has been made in replacing some alien plants with native vegetation, and a number of indigenous bird species as well as 200 tuataras were released in Karori. I decided that if I were ever to see one of these animals living free in something akin to a natural habitat, this was the place.

A big, beautiful wall — and nobody builds walls better than NZ, believe me — but still some rodents were able to get through and are now present in Karori. Seems that walls rarely solve anything.

I took a walk to Karori from downtown Wellington on a cold and windy October morning, and was met by a friendly volunteer who gave me a quick introduction to the history and the layout of the sanctuary. The place was undeniably impressive, although my introduction was constantly being interrupted by mallard ducks begging us for food. As we strolled along a wall of tall, imposing pine trees, I tried to spot a plant, any plant, that was not an introduced alien (“No, not that bush,” “No, not this either,” “No, that’s European Plantain,” “But look, here is native flax!”) We flushed a group of California quails, and a few European blackbirds flew over our heads as we approached the tuataras’ inner sanctum, a smaller area surrounded by another fence, which keeps out wekas – native, flightless birds known to attack and eat the reptiles. Behind it, to my surprise, was yet another, shorter fence. Its purpose was to separate a part of the Karori tuatara population (60 individuals) from mice that roamed its terrain. The terms “free-living” and “natural” were quickly becoming more and more relative. Unfortunately, by the time I reached the enclosure freezing rain was pouring and, understandably, no sane tuatara would stick its head out of the burrow in such weather. In the days that followed I visited the sanctuary every day, but the capricious Wellington spring kept tuataras underground. Only after a week, when I stopped there for the last time on my way to the airport, was I greeted with beautiful sunshine, and several tuataras basking in front of their dens.

But for the time being I had no choice but to move to the plan B, and visit Victoria University in Wellington, which maintains a small colony of the ancient reptiles. One of New Zealand’s most knowledgeable tuatara specialists is Dr. Nicky Nelson who for many years has lead the efforts in their conservation, and made some remarkable discoveries about their reproduction and sex determination. We met at the university cafeteria, a place with a stunning view of the Wellington harbor and the Matiu Island, which has a small population of repatriated tuataras. I had originally planned to visit the island as well, but became too entangled in bureaucratic red tape to make it worthwhile. Nicky filled me in on some of the latest research, including a genetic study that unequivocally demonstrated that all tuataras are members of one species, rather than two, Sphenodon punctatus and S. guntheri, as dictated by the traditionally accepted taxonomy. The latter, thought to be restricted in its original distribution to the miniscule Brothers Island in the Cook Strait, appears to be nothing more than a somewhat stunted by limited food availability, and marginally differentiated by genetic drift form of the widely distributed species.

This young, captive-raised tuatara hatchling will soon be released to augment one of the tightly controlled wild populations. There, it will lead a mostly diurnal life, trying to avoid being devoured by the nocturnal adults. It will take thirteen to twenty years before this individual is ready to reproduce.

After a chat and a cup of coffee I was finally standing in front of a large, glass-walled pen that held the animals. Each pane of glass was connected to a sensitive security system, and the door to the enclosure had two massive locks. None of it surprised me, of course, considering the US$20-30,000 asking price for a single tuatara on the black market of exotic pets. Nicky climbed inside and quickly located Spike, a 22 year old male, a captive-raised youngster (tuataras easily live to be a hundred, although reports of a 300 year old individual could not be substantiated.) He was a gorgeous specimen, and I really wanted to spend more time photographing him, preferably in a setting other than an enclosure inside a building. We agreed for Spike to meet me (with a couple of handlers) the next day in the cemetery adjacent to the university, where some semi-natural vegetation could be found. I found the arrangement somewhat peculiar, but at the same time strangely symbolic. As I stood on the following day among the graves of early Wellington settlers, watching the native New Zealander basking himself in the specks of early spring sun among seedlings of American maples and clumps of African grasses, his two caretakers vigilant over his every move, I could not help but feel extremely pessimistic about the fate of this island’s biodiversity. Tuatara, this magnificent animal, a Mesozoic relic if there ever was one, survives only thanks to the complete devotion of people like Nicky Nelson, surrounded by one of the greatest biodiversity disasters in the history of the human conquest of Nature. If left to its own devices, the entire population of these reptiles would probably disappear within a few decades, devoured by rats or pigs, or simply driven to extinction by their vanishing natural habitats. To add insult to injury, since sex in tuataras is not determined genetically as in it is in mammals or birds, but by the temperature in which their eggs develop, climate change can potentially accelerate their decline (if the temperature of incubation exceeds 21°C all hatchlings will be male.) Recent climatic models developed for the North Brother Island tuatara population suggest that by 2085 no females will be able to develop, thus spelling the end to that group of animals.

To help keep track of the movement of individual tuataras, each animal of the first batch of 70 released in Karori is marked with a unique combination of small color beads. Depending on the size of the animal, they may carry between 2 and 6 beads attached to their crest at the base of the head. Although the presence of beads somehow spoils the illusion of the animal being “wild,” a traditional alternative would have been to clip a toe or a combination of toes—a far more painful and risky procedure.

Other than apocalyptic annihilation of all life on Earth following an international spat about whether God’s word should be read from left to right or the other way around, one of the most frightening possible future scenarios for our planet is the arrival of a period that some scientists chose to call the Homogenocene – the Age of Uniformity. What they envision is a time when, thanks to voluntary and involuntary transfer and exchange of organisms between nearly all possible points of the globe, a feat well nigh impossible a thousand years ago but now trifling, all continents and smaller geographic regions will lose their biological identity. Nearly indistinguishable, relatively small suites of species will be present across climatically and physically similar areas, whereas the original, local ecosystems and associated, endemic and native species of those environments will be gone, replaced by more resilient, unfairly advantaged alien invaders (or invitees.) Regrettably, as tragically exemplified by New Zealand, it seems that the dawn of this new age is already on the horizon. Global commerce, tourism, migration, biological control, and plain, human stupidity have already done a splendid job of mixing things up, shuffling organisms from one continent to the next, opening the gates for barbarians to slaughter the unsuspecting natives. Virtually any place on Earth where humans have ever set foot is left with the trail of our inseparable biological satellites – rats, houseflies, clover – the list is thousands of species long. Each of them is likely to displace some local equivalent or, if there is none, carve for itself a deep and permanent niche in the new environment, and never without harming the existing balance of things. None rivals our own species in its thirst for destruction, but there are a few impressively accomplished contenders. Mice and rats now feel at home anywhere from Polar research stations to equatorial villages, and the list of local species they have extinguished may be even longer than that of species that humans speared and clubbed to extinction (there exists poor record of plant species we have picked or trampled to death, but there are some known cases.) Japanese beetles, Argentine fire ants, European earwigs, German yellow jackets, American cockroaches, Canadian waterweed, their names tellingly prefaced with the (presumed) point of origin, are wrecking havoc in places they would have never gotten to if it wasn’t for the convenience of ships and planes. But while these stowaways arrived to where they are now without our expressed consent, most invasive species that now reign supreme were lovingly carried across the oceans, nurtured and cared for upon the arrival, and let loose with a blessing (or at least their cages had locks that needed some work.) Goats, foxes, cats, pigs, horses, sparrows, starlings, pigeons, oaks, pines, ivy, kudzu, prickly pear, eucalypts, aloes, carp, trout, honey bees, bullfrogs, cane toads, the list goes on and on, are all united in their status as legal, consciously invited immigrants in places where they should have never gone to. In many cases the decision to bring in the alien species was well intentioned, but in the end nearly always with devastating consequences to the local ecosystems. Alien species, if introduced into an area that matches the physical aspects of their home turf, instantly gain the upper hand over the natives by the simple fact that they left behind an army of predators, parasites, and diseases that over thousands or millions of years had evolved along their side, and kept their populations in check. In the new place all these restraints are suddenly gone. The locals, however, still need to deal with their nemeses, but now these limiting factors are combined with the competition from the new arrivals. Not surprisingly, it often takes only one or two generations before local species are completely overwhelmed by the aliens, and either undergo a dramatic decline, or disappear completely.

The New Zealand Department of Conservation is doing a truly splendid job working on the restoration of natural habitats around the country, and nearly a third of its surface is at least partially protected. But it may take a long time to reverse the effects of the horrible devastation caused by the original settlers’ idea to convert New Zealand into a South Pacific version of England. Thousands of square miles have been turned in “green deserts,” where no native plants or animals are able to survive.

New Zealand, because of its geological and biogeographic history, exhibits a notable absence of many taxonomic and functional groups that dominate other lands (snakes, woodpeckers, mammals, to name just a few.) Alien species fill those gaps, and in the process profoundly alter the natural ecosystems. For example, New Zealand had no animals that specialized in stealing bird eggs or chicks. Brushtail possums, introduced to New Zealand 150 years ago to establish fur trade, and now roaming in numbers in excess of 60 million of free living animals, have become major bird nest predators, although in their native Australia they feed mostly on flowers and other plant material. The saturation with non-native organisms is now so complete that, according to a recent, comprehensive review of New Zealand invasive species, even a small patch of seemingly unmodified, native forest in the most remote corner of the country has on average 6 alien mammal herbivores, 5 alien mammal predators, 2 alien fish, numerous alien plants, and an unknown number of alien invertebrates, fungi and bacteria species.

It is painfully obvious that our understanding of the complexities and multilayered organismal co-dependencies within even the simplest of ecosystems is not comprehensive enough to predict the outcome of the introduction of even a single, foreign species to the mix. One would think that New Zealanders have learnt their lesson, and no more alien species will ever be willingly introduced. I was therefore positively shocked to learn that at Karori sanctuary, the very place that epitomizes the most heartfelt attempt to reverse the effects of human meddling with nature, an Australian, non-native plant known as Banksia integrifolia is purposefully introduced to the reserve in an effort to increase the availability of nectar to local birds. To add to the mystery, this particular species is one of the few banksias that do not require fire to disperse and germinate their seeds, which makes it a more likely candidate to escape from Karori and establish itself elsewhere. “Mistakes have been made,” the keepers of Karori seem to be saying, “but now we know what we are doing,” and let’s hope that they are right. Returning Karori to its former, pre-human glory is going to be a long process, estimated to take at least 500 years if everything goes as planned. It is a daring experiment, not unlike trying to keep an iceberg frozen in the middle of a scorching desert, one that will require constant care, significant financial resources, and an army of devotees. And this is for an area of about 1 square mile, or less than 0.001% of New Zealand’s surface.

To protect the country from additional invasions, the New Zealand government has created MAF Biosecurity, one of the most sophisticated and effective biological quarantine systems in the world. It screens all goods and passengers arriving in New Zealand, and every day uncovers about 240 cases of high risk items (potential weed plants, contaminated food etc.) being brought by people into the country. Unfortunately, for much of the islands’ biodiversity this noble effort came too late – 42% of native New Zealand birds are now extinct, as are numerous amphibians, reptiles, fish, insects, and an unknown number of other invertebrates and many plant species. The survival of the remaining native organisms hinges on the effectiveness of the quarantine and conservation as well as the good will of people who devote their lives to saving the remains of the old Zealandia, and it was only thanks to them that I was finally able to meet the tuatara. But with Homogenocene already at the door of this otherwise beautiful island country, the world’s attention should probably focus on other places that may soon be met with a similar fate. Other Pacific islands, New Guinea, Fiji, Solomon Islands, should become the targets of the most stringent quarantine efforts; it is not too late for them to save most of their native fauna and flora from the impact of alien species. And yet, if history has taught us anything, it is that we don’t need no stinkin’ history to teach us anything, thank you very much, and New Zealand’s mistakes will be promptly repeated in all those places. I really hope that I am wrong.

In 2005 the Karori Sanctuary near Wellington became the first site on the mainland New Zealand to see free-living tuataras in over 300 years. Seventy individuals, translocated from the Stephens Island in the Cook Strait were released, 60 of which were placed behind an additional enclosure that protected them from mice that unfortunately still roam in Karori. But as it turned out, animals outside the fence actually did better than the ones inside, and gained significantly more weight. A subsequent batch of 130 individuals was released two years later outside the mice-proof fence (but still inside a very large enclosure that protects them from wekas, flightless, predatory birds that like to eat the reptiles.) After five years the survival rate of the released animals was 33%, which may seem low, but these cryptic animals are notoriously difficult to spot, and the actual survival rate is almost certainly much higher (within the smaller, mice-proof area the survival rate was 89%.) But the ultimate proof that the translocation was a success came from the discovery of clutches of viable eggs and, in March 2009, the first born-free hatching.