by David Owen
Control of wild animals for economic reasons is hardly unique to Tasmania but it is the manner in which it is done that can prove contentious, especially if it threatens Tasmania’s remaining carnivorous marsupial icon. Rabbit calicivirus has been cited as a potential cause of or contributor to the disease. Calicivirus was introduced in 1996 in the latest effort to control rabbits. Devils, of course, eat dead rabbits . . .
Devils also eat dead wallabies, kangaroos, pademelons and possums, which are targeted by the forestry industry because they eat tree seedlings. Once an area has been selected for plantation forestry, whether through clear-felling or conversion of farmland, and seeds sewn aerially or manually, the area is then scattered with carrots laced with the chemical toxin sodium monofluoroacetate (1080 poison). The result is good for seedlings but devastating to the browsers. The kill estimate of Forestry Tasmania and private plantation owners for the year 2003 was just under 100 000 macropods. As well as devils, endangered quolls and wedge-tailed eagles eat these poisoned carcasses, and domestic dogs are known to have died this way. The continued use of 1080 has caused much public anger in Tasmania. At the least, mass kills of browsers impacts locally upon devil populations, where suddenly their main prey base disappears.
Nick Mooney, while not discounting 1080, considers agricultural pesticides and forestry plantation sprays to have more obviously lethal potential to trigger the disease, given that some have carcinogenic properties—as does diesel fuel, which is used in vast quantities in rural Tasmania, and there is no doubt devils come into contact with it.
If any of these primary industry products, or a combination of them, were found to be the trigger, the management consequences would be profound.
There is always more. Over decades in the twentieth century, Australia, the United States and other countries solved a rural problem of dusty roads by regularly spraying them with an oil- based, liquid industrial waste. This liquid was laced with manmade toxic chemicals, PCBs (polychlorinated biphenyls), used in the manufacture of products including coolants, hydraulic fluids, paints, newsprint and varnishes. Some of the toxins have a life of hundreds of years, and many roads in the United States have been dug up in detoxification programs. PCBs were used in Tasmania until 1987, a decade after being banned in the United States and Europe, because they ‘cause cancer and many other problems in animals’, and in humans they ‘may damage the immune system, hinder sexual development and impair intellectual ability’.18
Official recognition of the potential role of toxins as triggers for DFTD followed:
A pilot trial is proposed in which statistically valid numbers of tissue samples from affected and unaffected devils will be selected and tested for the presence of a range of toxins. It is proposed that the 10 most commonly isolated toxins are then exposed to normal devil cell cultures in amounts similar to those found in affected devils and any changes in the cells noted. If there are positive effects of the toxins on the cell cultures then there is an indication that a much larger project is warranted and should be undertaken.19
From a peak of an estimated 150 000 devils in the mid-1990s, the state’s numbers had dropped by at least a third. Menna Jones concluded that a reduction to 15 000 could make extinction in the wild irreversible. The call grew to isolate healthy devils on an offshore island. But that carried its own set of potential problems. Against this backdrop, the first major step in tackling the disease came with the arrangement of a specialists’ workshop, held in Launceston on 14 October 2003. It was not before time.
The workshop got off to a controversial start. Despite widespread interest, the public was admitted only to the opening address by Environment Minister Green. Some participating scientists expressed surprise, wondering if the ban was intended to minimise potential negative political fallout. On the other hand, experts in deep discussion on a dilemma they knew little about could probably do without public attention, although interested scientists were also kept out and others had to indulge in manipulation to be invited. A media brief had to suffice for the public. It noted the key role of the devil in the state’s ecology and that all sections of the community had a role to play. In a practical sense, this might mean notifying authorities of, say, a diseased roadkill devil; it was also surely a plea to those rural Tasmanians for whom devil-killing remained a sport or duty.
Some 55 invited specialists, local and interstate, attended the workshop. It was a high-powered and unique gathering. As an icon species the Tasmanian devil ranks with endangered wildlife such as the panda, Asian tiger and American bald eagle, yet the apparent suddenness of its extinction threat created an added urgency.
Introductory presentations were followed by a koala leukemia case study. A plenary session identified key issues, and afternoon sessions were devoted to pathology and epidemiology, population monitoring and mapping and management responses.
A paper on options for management included data on the potential for establishing populations on one or more of Tasmania’s offshore islands. Selection criteria included size, a preference for public land, diverse habitat and suitable prey species, accessibility for monitoring, and an absence of vulner- able ground-nesting birds and small mammals. In Menna Jones’ estimate, a minimum of 40 devils would be required to represent full genetic diversity, with a minimum of 3 square kilometres per animal, which ruled out many of the smaller islands. (Tasmania has 334 offshore islands.)
Quarantining healthy devils in this way may appear straightforward, but a range of complications arises in relocation, including lack of genetic diversity, potential failure of the animals to establish themselves, impacts on existing wildlife, management of the predator–prey ratio, and the fact that such a relocation could be irreversible and damage equally important conservation attributes of the islands.
A flowchart presented at the workshop indicated just how complicated the issue had become. This is reproduced on page 188.
Case by case disease studies were presented at the workshop in order to lead to a better understanding of devil cancers, as the first step in arriving at a clinical definition of DFTD, including this first ‘official’ case from 1995:
History—A female Tasmanian Devil of unknown age was found at Greens Beach. Gross—very poor skin condition—hairless over much of surface, scabby, morocco leather-like patches, especially in the groin and flank. Subcutaneous lymph nodes enlarged and also scattered dermal and subcutaneous swellings. Necrotic reactionary lesion in the masseter muscle. The internal visceral organs appeared normal. Masses of cestodes (tapeworms) in the jejunum and moderate numbers in the ileum, plus there were ascarid-like nematodes mainly in the duodenal area. Histology— multifocal dermal leukosis with lymphosarcomatous infiltration of lymph nodes and in the periportal tissues of the liver and interstitially in the adrenal and also through skeletal muscle tissue. The lesion in the masseter muscle was due to heavy lymphosarcomatous infiltration of that muscle mass. This animal was affected by widespread lymphosarcomatous neoplasia. Diagnosis—Lymphosarcoma. Comment—There were occasional, but consistent findings of azurophilic intracytoplasmic material in some cells. Artefact or viral inclusions?20
The first gathering of specialists to combat DFTD took place in Launceston in October 2003. This flowchart gives some idea of the complexities of the issue facing the 55 biologists, veterinary pathologists, marsupial carnivore experts and others who attended the workshop.
(Courtesy Department of Primary Industries, Water and Environment)
Among the more disturbing findings to come out of the workshop were that the disease might not be diagnosed for another ten years, and that feral cats may already be rapidly filling the emptied devil niche. The very next day Burnie police retrieved a freshly dead fox from the Bass Highway near the seaside town’s old hospital. It might have been placed there as part of the obnoxious game being played by those importing foxes into the state, but it was a reminder that not only cats might be a threat.
Another depressing outcome of the workshop,
revealed through release of internal Department of Primary Industries, Water and Environment (DPIWE) documents, under freedom of information legislation, appeared to confirm that government reaction had been too slow, too late and too modest, with the result that ‘a happy ending to this issue’ appeared ‘very unlikely’.21 The consequences of a lack of long-term systematic monitoring of such an important animal were obvious.
The comments were seized open by the two opposition political parties as damning evidence in the wake of the altered Mooney memo. In parliament the Leader of the Opposition, Rene Hidding, accused Premier Jim Bacon of being caught flatfooted on the issue. Bacon hotly denied the charge. Later in the day, Bryan Green, the Labor Party Environment Minister, and Nick McKim, the Greens’ Environment Spokesman, clashed:
Mr Green—. . . So it was I who generated the interest in the devils, it was I who generated all of the work that has been done since that time [the memo] on Tasmanian devils.
Everything else that had been done had never formally come to the Government in any way, and that is the point.
And this is the point that you ought to understand, and not smugly smile over there and kick back as if you are the great expert.
Mr McKim—I’m allowed to smile. Don’t put words into my mouth; I’ve never claimed to be an expert on this. In fact I’ve said quite frankly that none of us is . . .
Mr Green—Mr Deputy Speaker, what I can say is that the State Government is extremely serious about this issue. I do not think we could be any more definite about an issue that has confronted us, any more serious about making sure that we do everything we possibly can to protect the devil. It is true it is an icon, it is true we do not understand what the disease is, but it is also true that we are doing what we have to do to make sure that we are given the best opportunity to understand the disease. We have done that in a number of ways, but I think I should keep this in perspective.
When we received the first briefs on this, it was about lesions; it was not talking about a disease as such, it was just talking about lesions. It was not until later on that people started talking about this in the context of a disease— Mr Booth [Green]—Did you think they were marshmallows stuck on their face?
Mr Deputy Speaker—Order. If you want to speak, please speak from your own seat.
Mr Green—This is where these blokes really do stray outside the realm of decency when they talk about this— Mr McKim—What would a lesion be if it wasn’t a disease?22
The vexed question of funding stayed at the forefront of the issue. An earlier state government application for federal funding through the Wildlife and Exotic Diseases Preparedness Program—resulting in just $7000, which is all the program had left in its budget—obliged Green to again defend his position. A week later, Jim Bacon announced that the government would make $1.8 million available, over four years, to combat the disease, a 450-fold increase over the existing $40 000.
Warner Bros., with its long association with animal stars, had a record of backing causes to protect vulnerable wildlife in the United States. Thus in 1999 it had teamed with the US Fish and Wildlife Service and the City of New Orleans to create an Urban Treaty for Bird Conservation. This pilot program aimed to educate city dwellers in the importance of conserving migratory songbird populations, for many of which urban habitats are crucial. Tweety the canary was named Official Spokesbird.23 Warner Bros. had in fact been approached for help soon after the realisation that the disease was rampant, but its chief corporate communications officer, Barbara Brogliatti, had then firmly stated that, whatever else the company might contemplate, the use of the Taz image remained off limits. Now, however, came the newspaper scoop—with a feisty Taz superimposed over a pair of real devils, a rare legal commercial image—declaring:
Warner Bros. is in advanced talks with the State Government over a rescue package for Tasmania’s virus-riddled devil population. The US-based entertainment giant . . . is planning to join the effort to help save the Tasmanian Devil . . . It is understood negotiations have reached an advanced but delicate stage and an announcement with more detail is expected . . . spokeswoman Barbara Brogliatti told international news agency Reuters last week: ‘We are in discussions with the folks in Tasmania to see what we might be able to do to help . . . Firstly, as human beings [concerned about] any endangered species and, secondly, it is our beloved Taz’.24
These discussions with Tourism Tasmania moved forward to a point where, by the end of the year, Warner Bros. designers had come up with a pair of prototypes for Taz soft toys, wearing caps and t-shirts bearing save-the-devil slogans.
Funding issues aside, areas of progress became apparent. Scientists concluded the disease appeared to result in a single type of tumour, a possible step forward in the task of identifying its cause. And the Nature Conservation Branch put in place a long-term monitoring program for devil populations. In addition to regular trapping, monitoring techniques now included microchipping to replace ear tattooing, and the use in remote locations of automatically-triggered cameras set up at feeding sites. Early tests returned high-quality photographs of diseased animals.
Mooney’s team in the field used a portable surgery that allowed biopsies and the removal of small early cancers. The team liased regularly with veterinarians from the state’s Animal Health Laboratories, and also passed its results to the government-funded Devil Disease Task Force, which itself had linked with the CSIRO, Taronga Zoo in Sydney and Murdoch University in Western Australia. The task force included a range of specialist wildlife experts.
Working in the field had its own difficulties. To begin with, handling grossly disfigured animals required an ability to cope with repeated exposure to suffering, a reality made tougher by the decision not to euthanase except in the most extreme cases, where an animal was on the verge of death. Diseased animals released with radio tracking collars provided valuable monitoring information. Others were lactating, with young denned somewhere. Set against this, fieldworkers had also to attempt to operate within the bounds of the Animal Welfare Act; a difficult balance to achieve, not least because the wording of the Act is very generalised.
Many professionals and volunteers work in task forces combating the deadly disease.
(Courtesy Nick Mooney)
A January 2004 survey at Table Mountain near Bothwell in the central highlands, undertaken by David Pemberton, showed a population crash of between 30 and 50 per cent. Traps were set at three locations over two nights in consistently pouring rain, which flooded creeks and paddocks and made the task difficult.
Nonetheless seven devils were trapped. Two had DFTD, a third had cloacal ulcers. Pemberton’s field notes of a moderately diseased female, which had pouch young, read:
The presence of disease on this animal was not obvious at first.
I noticed slight red swelling on both lips, a slight swelling on the left muzzle and pus on one swollen follicle. Inspection of the mouth revealed two lesions, one on the upper palate measuring roughly 3 cm across and one on the lower measuring 2 cm across. Both lesions were maroon-red. The red swelling on the lips corresponded with swellings on the inside of the lips, which were pale yellow and red. The distinctive markings of this animal mean I could probably identify if we follow progression of the disease.26
Fieldwork hygiene took on a new significance. Gone were the days of clunky old metal box-traps and casual handling without gloves. Newly designed PVC tube-traps had to be disinfected after each use, as well as the sacks into which devils were placed so they could be measured and inspected. Unwittingly spreading the disease through efforts to combat it would be devastating, and for this reason it was decided to dispose of sacks after one use.
Chapter 3 sets out the many and varied relationships devils have with other creatures in the wild. And although Hobart Town surveyor G. P. Harris had them eating whale blubber in 1806, even he would surely have struggled to further the marine link by associating the devil with the humble oyster. But it came about. St Helens in nort
heast Tasmania is the largest town on the east coast, situated on Georges Bay, in which commercial oyster farming began in 1980. Between 1997 and 2003, incidents of high mortality and shell deformity seemed to follow heavy rain. Oyster farmers contracted Sydney-based marine ecologist Dr Marcus Scammell to investigate. He concluded that rainfall introduced a damaging causal agent into the bay, and subsequent wind-drift patterns in the intertidal zone, the area where the tides rise and fall within an estuary, floated that agent into the oyster farms.
Scammell’s tests revealed the agent to be tri-butyl tin, a chemical long used in marine anti-fouling paint to keep boat hulls free of growths. Although banned from use in the paint, the chemical itself was still commercially available. Scammell’s finding led to it being banned altogether. He concluded that other unknown agents might also be responsible.
In January 2004 following flood rains (the same rains affecting the Pemberton Table Mountain survey), Georges Bay experienced up to 90 per cent oyster mortality. Other filter feeders—mussels and barnacles—as well as prawns, crabs, sea urchins and even non-marine frogs and insects, died in large numbers. This time Scammell’s investigations led him to focus on extensive forestry aerial spraying by helicopters the previous month. One of the helicopters had crashed. Tests of biocide spills at the crash site identified alpha-cypermethrin, atrazine, simazine, chlorothalonil and terbacil. They’re as toxic as they sound, and Scammell noted:
The importance of this information is not that it tells us what is at a small contaminated site, rather it tells us what is being sprayed over the vast area that these plantations cover . . . The normal environmental protection methods do not appear to be in place and no policing of the State’s own Forestry Code of Practice appears to be occurring. More disturbingly, the problems associated with oysters also correlate with tumours and mortality in Tasmanian Devils. Further there appears to be a risk to human health as contamination of local drinking water supplies is also possible.27