Posts Tagged Thylacine
By Bridie Smith, Science Editor, The Age
The noise is piercing and poignant. It starts as a determined drill reminiscent of the “tut-tut” of Skippy – but delivered with a bit more chirrup – then accelerates to a pitch and pace rivalling that of a lorikeet. Then it goes quiet. That’s it. The last call, made by the last Christmas Island pipistrelle bat. It lasts barely 40 seconds.
Before the Christmas Island pipistrelle left the world for good, he was recorded over three nights as he moved through the rainforest. Using ultrasonic pulses of sound to forage for food, this bat was feasting on the fly: expertly catching and consuming insects mid-air. If he was aware scientists were tracking him, he wasn’t obliging them. More than 250 kilograms of equipment had been lugged to the tiny island outpost in the Indian Ocean, 1500 kilometres north-west of the Australian mainland, as part of a desperate attempt to rescue his species.
But he was having none of it. He gave the harp nets and mist nets the slip, zipping over the top, night after night. And he ignored a purpose-built 15-metre-long tunnel trap, despite it being set up in one of his favourite foraging spots, a corridor lined with thick rainforest vegetation. His calls, picked up by detectors, indicated he was active. He flitted between feeding sites and reassured researchers with frequent banter. But on the fourth night, the synchronised detectors planted on his island home met silence. Without intending to, scientists had captured the last call of a species, made on its last night in existence: August 26, 2009.
For scientists, the experience was shattering. Years on, many who made the long trek to the island are still mourning the loss of the tiny 3.5-gram creature. Rupert Baker, life science general manager at Healesville Sanctuary – a Victorian zoo specialising in native Australian animals – was on the expedition and remembers returning to camp burdened with the knowledge that a species had vanished for good. ”Everything on Earth is part of one big complex carpet … and each strand that you take away makes us a little bit more impoverished,” he says.
But for others, the pipistrelle’s plight prompted an uncomfortable question: should the rescue mission have taken place at all? And now, given the limited dollars available for conservation, some respected scientists are calling for a tough new way to preserve the nation’s threatened species: triage.
The concept, first applied during the Napoleonic Wars, is a way of prioritising the treatment of patients. Generally speaking, patients fall into one of three categories: those who are likely to live, regardless of what care they receive; those who are likely to die, regardless of what care they receive; and those for whom immediate care might mean the difference between life and death.
It is a process familiar to viewers of the film and later TV series M*A*S*H, set in the chaos of a mobile military hospital during the Korean War, and that to a lesser degree plays out daily in hospital emergency rooms. In times of disaster and war, it amounts to a pragmatic hierarchy of care based on a patient’s chances of survival given the severity of their condition and the resources available to treat them. Applied to Australia’s native animals, it is a controversial plan that hangs on a reluctant recognition that not all creatures can be saved. Proponents argue that cash should be concentrated on the threatened species with the greatest chance of survival. This means someone is going to have to decide which species get on board the ark, which get left behind, and what criteria should separate the two.
The undulating hills around Healesville, north-east of Melbourne, are neatly stitched with vineyards and fields of dairy cattle. Signs along the road leading to the zoo’s bush sanctuary display phone numbers for motorists who find themselves helping injured wildlife; creatures caught in the path of urbanisation and industry.
Jenny Gray, CEO of Zoos Victoria, is standing in an outdoor enclosure with keeper Monika Zabinskas. The pen, carpeted with leaf litter, houses a one-year-old Tasmanian devil. The animal was born here and, as a result, lives free of the devastating facial-tumour disease that has destroyed 50 per cent of her species across two-thirds of Tasmania. The devil, effectively a teenager, is showing a particularly independent streak. She squirms and grunts as Zabinskas tries to secure her in a handling pouch. Gray looks on, amused. The creature’s snout and whiskers twitch as she arches her neck towards Gray.
This year, Healesville Sanctuary will spend $3.5 million caring for the most critically endangered species under its wing and managing captive-breeding programs. It is not nearly enough for what is needed, so Gray has had to make tough decisions. The first was to exclude Australia’s threatened native fish and native insect species from the program. ”We’re not guaranteeing we can save every fish and every insect,” she says matter-of-factly. ”The fish are not our expertise. And the insects; we just don’t know enough to know how dire the situation is.”
Instead, the zoo has promised that no Victorian land-based vertebrate species will go extinct on its watch. Within these parameters, the organisation will focus its conservation efforts on 20 species, each listed as threatened, each found only in Australia’s south-eastern states. It is a limited form of triage. ”Our promise is that no species will go extinct, so where do we work?” says Gray. “We work right at that tipping point. We work with the animals on the brink of extinction.”
But is it enough? Australia’s animal extinction rate is among the worst in the world; we are now losing one mammal every 20 to 30 years and one bird a decade. More than 1800 species and ecological communities are listed as threatened nationally. Against this decline is a patchwork of funding: some state, some federal, some from the private sector. None of it adds up to the estimated $100 million a year required to stop threatened Australian plants and animals from vanishing. Yet it has been estimated that up to three times as many threatened species could be preserved if funding was allocated using what some argue is a more rational approach.
Hugh Possingham remembers when the penny dropped for him. Then an academic with the University of Adelaide, he was in Canberra in 1999 in a meeting with the federal government’s threatened species unit when it dawned on him that funds were being allocated to species with no real hope of rehabilitation.
Possingham, now with the University of Queensland and a director of the Australian Research Council’s Centre of Excellence for Environmental Decisions, wondered if there was a better way. So he asked. ”People were very hostile,” he recalls. The main concern was that it meant conceding defeat – admitting that some species were beyond saving. “I said, ‘Well, you are giving up on species that are not threatened.’ It’s an argument that has gone back and forward ever since.”
A birdwatcher since the age of 12, he is a vocal advocate of species triage as a means of keeping Australia’s ecosystems diverse and robust. But he argues that tackling a list of already marginal species from the top down is futile. “We should pick winners rather than struggling away with the ones on their last legs,” he says. Rather than concentrating conservation efforts at the “tipping point”, Possingham advocates focusing on ensuring creatures don’t make the threatened list.
Possingham is one of many who believe the Christmas Island pipistrelle’s rescue mission arrived too late to have any realistic chance of success. Widespread when it was first described in 1900, the bats first showed signs of decline in 1994, thanks to a combination of disease and introduced species including the yellow crazy ant, common wolf snake and black rat. The yellow crazy ant invaded the roosting spots of the bats which, being creatures of habit, do not relocate; returning microbats were sprayed with formic acid by the ants and eaten alive. The snake and rat, meanwhile, preyed on the bat, which had evolved free of tree-climbing predators.
Scientists were on the case but powerless to act without the authority of government. The pipistrelle, one of Australia’s smallest bats and the only microbat on Christmas Island, was listed as endangered in 2001, then critically endangered in 2006. By the following year, the bat was effectively on life support. But a rescue mission was only given the nod in July 2009 – by which stage there were as few as 20 bats left. For many, the pipistrelle was already a lost cause.
One of the most haunting exhibits at Healesville Sanctuary is an empty enclosure – or it might as well be. Among the native vegetation is a rust-coloured silhouette of a thylacine. Standing sideways, with its trademark stripes fanning out from the shoulder blades to the base of the tail, the metal sculpture is a silent reminder of what has been lost. Hunted almost to extinction, the last thylacine died at Hobart Zoo on September 7, 1936.
In the quiet hours before dawn, Gray sometimes lies awake and thinks about the thylacine, and about its closest living relative, the Tasmanian devil. ”I worry that one day I’ll be holding a Tasmanian devil in my hands,” she confided during a 2012 Melbourne TED Talk. ”He’ll be old. His fur will be grey. Patches might be missing. His nose will be dull and cracked.” And he will not be just any devil. “He just might be the last Tasmanian devil on the planet,” she says to the now silent audience. “And after I have taken that decision [to euthanase], they won’t exist any more.”
That said, the devil has one big asset in its battle for life: people like devils. It is easier for people to relate to a fellow mammal than to an insect. When the sanctuary’s teenage devil lets out her revving growls and blood-curdling screeches, it’s near impossible not to attach a personality to her behaviour. Her name, Mulana, is a Wurundjeri word meaning spirit.
Research shows that so-called flagship species – namely large mammals with forward-looking eyes – have the greatest marketing appeal and are most commonly used by non-government organisations to raise money for conservation; think the World Wildlife Fund panda. In human triage it would be morally abhorrent to administer care on the basis of affection or appearance, but in animal triage, looks, or at least charm, count.
Consider the critically endangered Baw Baw frog. For unknown reasons, the drab-looking amphibian with mottled brown-black skin suffered a population decline of 98 per cent between 1993 and 2008 in its southern Victorian habitat. Their numbers have slid even further in the past two years, with fewer than 2500 individuals left in the wild. In 2012, the Victorian government pulled up to $20,000 in funding for wild population surveys. Zoos Victoria has stepped in to allow the annual surveys to continue. But it does nothing to arrest the decline.
Compare the Baw Baw’s plight with that of another amphibian, the striking southern corroboree frog. With its butter-yellow and raven-black markings, it often gets described as charismatic. Its appeal is only enhanced by the fact it doesn’t hop (frog-like) but clambers around its mossy habitat in NSW’s Snowy Mountains. Like the Tasmanian devil, it has a fatal disease to contend with: a highly infectious fungal condition called chytridiomycosis that, like the devil’s tumour, has baffled scientists. Listed as critically endangered, there are fewer than 100 remaining in the wild and its alpine home is shrinking as the planet warms. Despite the obstacles, the black and buttercup beauty receives a combined $350,000 a year in conservation funding from five groups, including the NSW government.
But should a frog (albeit a pretty one) with a vanishing alpine home and a tenuous grip on survival have such a slice of the limited cash allocated to saving threatened species? Should a Tasmanian devil with a population decimated by a so-far incurable cancer be allowed to suck up so much of the conservation dollar, beautiful eyes or not?
The devil, however, has another advantage: its contribution to its society. When you consider the role played by any given species in the broader ecosystem, some creatures really are more equal than others. For the devil, Australia’s largest carnivorous marsupial, its position as a top-order predator makes it a keystone in the finely tuned ecosystem. Sitting at the top of the food chain, such species keep every other one in check, stifling the impact of introduced species such as foxes and preventing herbivores such as wombats and wallabies from eating out the habitat faster than it can regenerate.
On this basis alone – its unique role in its environment – the pipistrelle might have had trouble getting aboard the ark. Bats have been around since the time of the dinosaurs, at least 65 million years. Australia has about 75 types of native bat and microbat. Losing the Christmas Island pipistrelle was not going to cripple the local ecosystem.
Not so the endangered southern cassowary. Despite bad press about its antisocial behaviour (the imposing flightless bird has been known to attack and, on at least one occasion, kill humans), it is a vital seed distributor for 238 plants and trees in its north Queensland rainforest home. It is also the only representative of its subspecies on the continent. While habitat loss, cyclones, cars and dogs have reduced its numbers to less than 1000 in the wild – largely concentrated around Mission Beach, Cooktown and on Cape York – a medley of local, state and national governments are working with community and indigenous groups to turn things around for the giant bird.
That said, the greatest contributors to the health of an ecosystem still frequently miss out on conservation attention. A federal government committee told a senate inquiry last year that mammals, birds and flowering plants were represented in greater numbers in conservation efforts than animals that literally have never grown a backbone. Non-flowering plants, which play a vital role in ecosystems and biodiversity, are simply overlooked.
The prehistoric-looking Lord Howe Island stick insect is an unusual invertebrate, in that it is listed nationally and internationally as critically endangered. It also has a dedicated captive breeding program. Not all threatened insects are so lucky. ”Invertebrate animals are 95 per cent of all animal biodiversity but very few invertebrate are listed as threatened species, even though it is likely that many species would qualify for listing if nominated,” the threatened-species committee told the inquiry.
Hugh Possingham believes that rather than assessing bats, frogs and Tasmanian devils according to the odds of them vanishing from the planet, governments should manage biodiversity by weighing up the cost and chances of success against the unique nature, or taxonomic distinctiveness, of the animal. Echidnas and platypus score highly on this taxonomic scale, while a medium-sized wallaby would get a low score given the variety of members in its family tree.
It sounds drastic. But for Possingham, this is how M*A*S*H medics make their life-and-death decisions. ”Biodiversity is being lost at roughly a hundred to a thousand times the natural rate,” he says, almost in exasperation. ”If we are losing species at up to a thousand times the natural extinction rate, then we are effectively in a war zone.”
Opponents say it is not that simple, and that triage amounts to assisted, unnatural selection. The Austral-asian Bat Society argues that no one has the right to play God. The independent, non-profit Australian Wildlife Conservancy maintains that if funds are invested correctly, we should be able to save everything. Threatened-species scientists Deborah Ashworth and Todd Soderquist argue that applying triage to animals and even plants risks placing the most feasible and affordable projects at the top of the list, while letting the more complicated, long-term or expensive slide to the bottom. ”The simplicity of this approach is very seductive,” they warned in their senate submission.
But governments are coming around to Possingham’s way of thinking. In 2005, Queensland was the first state to introduce a triage test, called Back on Track. The logic underpinning the plan was to recover the greatest number of threatened species. Similarly, Tasmania has focused on 171 threatened species it says can be saved over 50 years at a cost of $155 million. And across the Tasman, New Zealand has identified 700 species in decline and prioritised 300 of those most likely to benefit from intervention.
The Australian Fisheries Management Authority has made its own list; starting with 2000 species, its focus over the past five years has narrowed to less than 70. And in NSW, where almost a third of native mammals, 28 per cent of birds, 18 per cent of reptiles and 13 per cent of plants are threatened, the state government has signed up to prioritise 967 threatened species.
Australia’s first threatened-species commissioner, Gregory Andrews, took up his post in July. Among his tasks is to draw up a list of threatened species most likely to benefit from intervention. “I trained as an economist, so I think of the opportunity cost of everything,” he says. “And there are some species that we are spending a lot more on.”
What, then, to make of the Tasmanian devil? An army of scientists is dedicated to saving the species. Captive breeding programs are well established on the mainland, and small islands off Tasmania have been quarantined for healthy devils. But will science deliver a cure in time? Or, more to the point, should we keep investing in the hope that it might? Granted, the devil’s public appeal will keep the dollars dribbling in, even as its population dwindles. But are we taking finite
finances away from another animal that is will score higher on the triage test? Has the devil earned its place on the ark? For Jenny Gray, the answer is clear. ”We won’t walk away,” she says. “It may be a hopeless cause, but it’s our hopeless cause.”
At the sanctuary, I bring the young devil’s swaddled body closer to mine. I open my forearms a little and spread my fingers wide to support the folds of blanket so she can prop her chin on the edge and watch as keepers prepare her bottle. Her weight is satisfying. Not heavy enough to create strain, but not so light as to seem less than substantial. I know she is there. I can feel her move. Her head bobs like one of those toys on a car dashboard as she sniffs the air with the matt-brown nose at the end of her whiskered snout.
So what say we? Does she get a berth?
I was watching yet another presentation about the possibility of reviving extinct life forms (http://www.ted.com/talks/hendrik_poinar_bring_back_the_woolly_mammoth.html). Now that we appear to have the technology, at least in theory, to extract DNA from long dead animals and place it in currently extant species there seem to be more and more articles about how terrific it would be to bring them back from oblivion. This particular talk concerned reviving the woolly mammoth but I have seen similar ones suggesting restoring the thylacine, or Tasmanian tiger, to life.
Technology has been astonishingly uninspiring when it comes to saving the world’s current long list of endangered species. While there have been a few cases of successful artificial insemination or an embryo from an endangered species being reared to term by a surrogate (http://www.scientificamerican.com/article.cfm?id=cloning-endangered-animals), the majority of effective conservation programs have relied on natural breeding to create enough animals to sustain a population, along with addressing the causes why the species became endangered in the first place. There are too many unknowns when it comes to artificially breeding wild animals: how best to harvest the eggs and collect sperm, how to freeze gametes and embryos, synchronising reproductive cycles, carrying a foreign species to term, providing appropriate milk, etc, etc. All these difficulties, and more, apply to the resurrection of extinct species.
If we are able to successfully impregnate a surrogate that takes the pregnancy to term, then what? We have a single individual being reared by an individual of a different species. If this works what do we then do with our mammoth or thylacine? Apparently appropriate mammoth habitat exists in Siberia. But what would our solitary mammoth do in such a place? We would need to produce at least 50 mammoths (probably more like 500: http://www.eoearth.org/article/Minimum_viable_population_size?topic=58074), to create a self-sustaining population. Given the paucity of genetic material available to play with, these mammoths would be virtual clones with very little genetic diversity. All conservation programs seek to maximise genetic diversity to avoid the problems that now occur in inbred populations e.g. Tasmanian devils and their contagious cancer.
What would be the point of bringing back one species? The mammoth will be no more than a curio, devoid of any real value, unless you bring back its entire ecosystem. This ecosystem would need to include not just all the extinct animals but also all the plants it shared its former existence with.
There is more logic in restoring the thylacine as it only became extinct in the 1930s, not 4000 years ago, but even there the Tasmanian ecosystem has changed in the past 70 years. Would it not make more sense to invest all that time, money and expertise into preventing other species from heading down the same extinction path, instead of wasting it on frivolous projects whose only purpose seems to be to let scientists marvel at their own cleverness?
Dr. F. Bunny