This is a Tiger Quoll (Dasyurus maculatus)
Photo courtesy of Sean McClean.

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It is Australia’s largest carnivorous marsupial on the mainland and it has become endangered because of humans destroying its habitat, shooting it and poisoning it.

It is not a cat. Much information may be obtained online simply by typing ‘tiger quoll’ on Google.

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The following extract is from the website ‘Convict Creations‘  (15-Feb-2010):

‘Tiger Quoll…the next to die’

“Without disrespecting the Koala or Kangaroo, the Tiger Quoll is one of Australia’s most interesting animals. It sort of resembles a cat except it has a pouch, bright eyes, a moist pink nose and a powerful bite. It can grow to up to 75 cm in length and weigh up to 7kg. If trained, it will even use a kitty litter tray.

The Tiger Quoll is the type of animal that tourists would love to see on their Australian safari.

Unfortunately, they are quite rare so few have ever caught a glimpse of them.
European colonisation of Australia could have been great for the Tiger Quoll. With Europeans introducing rabbits, rats and mice, the Quoll saw a drastic increase in its food source. Had the colonists warmed to them, then a mutually beneficial relationship could have formed. Farmers could have encouraged Quolls to take up residency in order to keep rodent numbers down with little fear that their livestock would be in danger. As an added bonus, by eating carrion, the Quolls would have reduced the threat of blowfly strike.

Alternatively, they could have just made pets out of the Quoll. Apparently the Quoll has all the positive characteristics of a cat or dog. According to Professor Mike Archer, Former Director of the Australian Museum, who once kept a Quoll as a pet:

“I just can’t praise these animals highly enough as companions for human beings. They have all the good features in dogs and cats, and in my experience not a single downside”.

If colonial owners had taken care of their Quolls, then both Quoll and owner would have been happy. If not, the Quoll would have just escaped and done Australia a service by cleaning up decaying meat, rabbits and other introduced vermin.

Unfortunately, colonists never formed mutually beneficial relationships with the Quoll. Instead, they introduced the cat to serve the role of pest controller. For more than a century, farmers deliberately released cats onto their properties in order to control rabbit and mice populations. Once the cats went feral, they started to compete with the Quoll for food. Although the Quoll was better adapted to Australia’s cycle of droughts, the cat’s symbiotic relationship with humans proved to be an even better environmental adaptation. If feral cats were ever wiped out in a drought, or declined for whatever reason, they still had the family home as an oasis in the desert. From the family home, they were well placed to repopulate the bush once good conditions returned.

Even worse than competition from the cat were the environmentalists’ attempts to “help” them. The use of 1080 poison has been one of the main helping strategies. When it is used to kill rabbits, it indirectly deprives Quolls of food. So much so, by killing rabbits, human deprive Quolls of even more food than is lost due to competition by cats. To compound matters, when 1080 poison is used to kill the cats and foxes competiting with Quolls, it also ends up being eaten by Quolls. In fact, Quolls are more likely to eat the poisons because they have a keen nose for carrion while the feral predators prefer fresh kills.

A very odd example of the misguided environmental policy was recently seen in in Tasmania. 1080 was first used to reduce rabbit numbers. A rumour then developed that foxes had finally established a breeding community in the island state. Even though it was just a rumour, to be on the safe side, environmentalists decided a large scale baiting regime needed to be implemented to eradicate foxes as well. On the State Government’s own data, more than 140,000 poison baits were laid. So far, there has been no evidence that foxes were actually present. There was; however, plenty of evidence of Quoll dying!

The odd wilderness protection policy caught the attention of David Obendorf, a vet with a research focus in marsupial diseases. According to Obendorf:

“Three Tasmanians have each offered $1,000 fox rewards (Tasmanian Times: “$1,000 fox reward”). All remain unclaimed despite farmers, landowners and professional shooters all knowing about them. And yet the government “guessimate” claims there are up to 400 foxes living in Tasmania … somewhere. In my opinion Tasmania’s use of 1080 poison over the last five decades – to kill browsing and grazing native herbivores – has had a significant effect on the over-population followed by the facial tumour disease-crash in devil numbers and in the widespread establishment of feral cats across the island….Ironically the state government has now ceased the use of 1080-laced carrot/apple baits on public lands to kill grazing wildlife but now uses tens of thousands of meat baits in public forests where they claim they are targeting those cryptic foxes.” (1)

The use of 1080 poison could be legitimately referred to as Australia’s dumbest environmental policy since the construction of a 1,833 km fence to “keep” rabbits out of WA. It seems that Western Australians weren’t smart enough to realise that rabbits can dig under fences. All that was required was for a single pregnant female to dig a hole and then 1,833 km of fence line would be obsolete. Perhaps WA politicians did in fact realise the folly of it all, but decided it was more to important to show they were “doing something”.

As an added bonus, “doing something” kept people in regional Australia employed. Perhaps 1080 poison is used for similar reasons. Unfortunately, “doing something” to help Quolls is really not helping them at all. It forces them into wilderness reserves where scientists can erect huge fences to keep out ferals and then make a lucrative income maintaining them. (2)

Even though the Tiger Quoll is mainland Australia’s largest native predator, Australia doesn’t have any professional sporting team named after them. In fact, they don’t really exist in public consciousness in any significant shape or form. Perhaps this is because Quolls spend their time out in the bush where they are only ever seen by rangers.
Alternatively, perhaps the name Quoll just isn’t scary enough.

Zoos – The only real industry is as a research subjects by scientists, or to provide an endangered animal story that can be used by wilderness groups to write emotive appeals asking for funding to save them.

Pest controllers – Potentially, Quolls could make great pest controllers. They could compete with cats and foxes for food, and eliminate rabbits and rats in the process. Landowners could breed them and sell them as a substitute to 1080 poison.

Pets – Sometimes scientists have made great pets out of Quolls. At present, the general public is not allowed to do likewise. The general argument is that Quolls require special care that only a scientist can give. Consequently, Australians have to reserve their abusive ownership methods for dogs and cats that simply go bush if they are unhappy with their owners.”

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The Snowy River is a surviving stronghold of the Tiger Quoll

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“In East Gippsland, the areas on the Errinundra Plateau, Snowy River and Tingaringy are strongholds of the Spot-tailed Quoll”. (GECO)

“The Upper Snowy River and its tributaries was the Victorian stronghold of the Tiger Quoll before (the 2003) devastating Alpine bush fires. The Tiger Quoll is believed to have lost up to 75% of an estimated population of 1,000 in the area.

Following the devastating effects of recent bush fires The Tiger, or Spotted-tailed Quoll (Dasyurus maculatus) has been reclassified as nationally endangered. it is feared that the fires will have a lasting effect on the Quolls that remain.”

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References:

[1]   ABC, ^http://www.abc.net.au/rn/science/earth/stories/s145805.htm
[2]   David Obendorf – ^http://www.animal-lib.org.au/news/1080–the-real-killer.htm”
[3]   ^http://www.fame.org.au/current_projects.html

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~ article by Tigerquoll, first published on CanDoBetter.net 15-Feb-2011

Golden Bandicoot is under threat of extinction in The Kimberley.

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“Australia has the worst extinction record for mammals of all countries in the world (Johnson 2007), and has international obligations (Convention on Biological Diversity 2006) and national commitments (Commonwealth of Australia 1999) to avoid species extinctions.  Meeting these obligations will require effective and ongoing conservation management.”

[Source: Priority threat management to protect Kimberley wildlife, p47,CSIRO Ecosystem Sciences, Feb 2011, Australia]

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At 6am on 1st June 1990, I started my prepared and serviced HT Holden outside my father’s place in Melbourne and executed my planned drive mission across to Adelaide then up the Centre to Kununurra in the East Kimberley.  I was 26; I had saved up.  I was on a mission to get my commercial helicopter license and to work in cattle mustering in the Kimberley in the process to ‘get my hours up’.

The Kimberley was a very hot and steamy; a world away from temperate urban Melbourne.

Well, after some months and growing up in a remote landscape, I did achieve  my license with Golden West Helicopters, then did some mustering. I took risks, recalling pivot turns over isolated beaches and I learnt a lot…what city kids should.

Some memories that will remain with me (until my memory doesn’t) are the waking to East Kimberley bird calls from the pilot shack at the red dusty caravan park down the road from Kununurra Airport.  When building my cross-county and low-level endorsement hours up, I will never forget flying the R22 low over wild rivers full of long lizards (crocs), or slowly navigating the thick mist at 50 foot AGL at dawn, or flying free over the wide rugged red rock landscape, or finding the eagles nest on a remote hill miles off in some north westerly direction from Kununurra.  My memory of the Kimberley is of a wild special place, like Emma Gorge and the amazing remote drive to Wyndham – so isolated – so free.  But it is the unique bird calls that recur in my memory of the magic natural tropical home of The Kimberley.

So when I now later learn that the Kimberley and its scarce wildlife are under threat, I have no hesitation posting the following article to advocate the urgency of the Kimberley’s wildlife conservation.

The Kimberley is indeed like nowhere else!

~ Editor

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According to the findings of a current ecological study and report published in February 2011 by the CSIRO and The Wilderness Society:

“up to 45 native species in the Kimberley region will die out within 20 years if no action is taken”.

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The report found that the two most destructive threats to survival of native species are:

1. Feral cats

2. Frequent large scale fire regimes   (deliberate or neglected)

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It has called for an immediate cash injection of $95 million to save wildlife like the Golden Bandicoot, the Scaly-tailed Possum and the Monjon Rock Wallaby from extinction.  Even with the current $20 million per year spent on Kimberley conservation the region is still set to lose some 31 native animals, according to the report.

The report is a culmination of collaborative ecological research and workshops was undertaking across the Kimberley region by scientists with the CSIRO’s Ecosystem Sciences, along with The Wilderness Society,  Australian Wildlife Conservancy, Fenner School of Environment and Society (ANU), and The Ecology Centre at the University of Queensland.  Its authors from these organisations include Josie Carwardine, Trudy O’connor, Sarah Legge, Brendan Mackey, Hugh Possingham and Tara Martin.   Regrettably,  the only contributing organisations permanently based in the Kimberley appear to be the Kimberley Land Council and Environs Kimberley.  Perhaps this is half the problem; the other half being ye ol’ lack of political will, because surely Australia has plenty of taxpayer funds in circulation.

If ever the ecological precautionary approach principle was a vital precondition of human actions, the Kimberley is the place where it most applies.  The recurring theme throughout the report is the lack of comprehensive survey data from the region.  Ecologically, the Kimberley is grossly data deficient.  Consequently, humans know not what they do, nor what the impact of what they do is, nor how close the thirty odd threatened and endangered native animals are to regional extinction.

The Scaly-tailed Possum (Wyulda) , Monjon Rock Wallaby and the Cave-dwelling Frog are thought to be uniquely endemic to the region, so if they are wiped out from the Kimberley, as a species they will become globally extinct, like the Tasmanian Tiger (Thylacene) and the Dodo.

Wyulda, or Scaly-tailed Possum (Wyulda squamicaudata)

endemic to the Kimberley, and highly sensitive to bushfires

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Due to human encroachment and habitat destruction across northern Australia and the ferals and destructive practices they have brought with them, the still mainly wild Kimberley remains the last survival refuge for many of Australia native at-risk species.

Native vertebrate fauna of the Kimberley like the Northern Quoll, Golden-backed Tree-Rat, Golden Bandicoot, Gouldian Finch, Spotted Tree Monitor, Western Chestnut Mouse, and Stripe-faced Dunnart are at serious risk of extinction.

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Priority Threat Management Actions for The Kimberley

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Experts identified key broadscale threat management actions for improving wildlife persistence (p5):

1.    Combined management of fire and introduced herbivores! – feral donkeys, cattle, horses, pigs
2.    Eradication, control, quarantine of weeds! – rubber vine, gamba grass, mesquite, passionfruit
3.    Control of introduced predators! (particularly feral cats)

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“The single most cost-effective management action would be to reduce the impacts from feral cats (at $500,000 per bioregion per year) with a combination of education, research and the cessation of dingo Baiting.”        [p.6-7]

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While anticipated to have low feasibility of success, the feasibility has not been started nor tested.

“The next most cost-effective action is to manage fire and introduced herbivores (at $2–7 million per bioregion per year); this action is highly feasible and, if implemented effectively, would generate large improvements in probabilities of persistence for almost all wildlife species.” [p.6-7]

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Northern Quoll  (Dasyurus hallucatus)

Native to the Kimberley, but seriously  at risk from feral cats and bushfires

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Natural Integrity and (Human) Threats

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Threats to The Kimberley from ‘Bushfire Management’

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“Frequent, extensive and very hot fires in the Kimberley affect its ecosystems in several ways. They change the structure and composition of vegetation, endangering some species of plants and removing important wildlife habitat refugia. They also leave the ground unprotected from the heavy monsoonal rains, causing soil erosion and later stream sedimentation.”

Inappropriate fire regimes pose a threat to biodiversity in the Kimberley and across northern Australia (e.g. Bowman et al. 2001; Russell-Smith et al. 2003). Historically, Indigenous people managed fire throughout the region, which included fine scale prescribed burning across a variety of vegetation types and around important cultural and food resource sites, such as rainforest patches. This most likely resulted in a mosaic of burnt and unburnt vegetation and provided buffers against unplanned wildfires around critical biodiversity refuges (Environmental Protection Authority 2006).

Broadscale State-sanctioned Arson of the Kimberley

(Photo: Ed Hatherley, Western Australia Department of Environment and Conservation)

[Source: ^http://www.australiangeographic.com.au/journal/new-fire-plan-for-the-kimberley.htm]

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These fire patterns have been replaced in the past few decades with one that is increasingly dominated by extensive and intense mid to late dry season fires. As a consequence, the mean age (and variance) of the vegetation has declined (Legge et al. 2010).

Altered fire regimes interacting with other degrading processes, especially over-grazing, have led to structural and floristic change in vegetation, declines in vegetation cover and critical resources such as tree hollows. They are also associated with increased soil erosion after heavy rains (doubled erosion rates have been recorded in similar situations in the Top End of the Northern Territory (Townsend and Douglas 2000), leading to increased sedimentation in stream beds. These changes have severe negative impacts on native flora and fauna (Vigilante and Bowman 2004; Legge et al. 2008). Extensive flat savanna areas are more vulnerable to large intense fires, as there are fewer inflammable refugia such as rocky areas.

Without appropriate management, the impacts of fire are likely to increase as the region is predicted to become even more fire prone with ongoing climate change (Dunlop and Brown 2008)”. [pp.11-12]

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Floodplain wetland of the Hann River

as it leaves the Phillips Range,Marion Downs Wildlife Sanctuary, The Kimberley.

© Photo by Wayne Lawler, Australian Wildlife Conservancy

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Threats to The Kimberley from ‘Feral Cats’

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“Invasion by feral predators has contributed to range reductions and population declines of many native animals in Australia; small to medium sized mammals have been particularly affected. The primary feral predator in the Kimberley is the domestic cat. Cats have possibly been present in the region since the 1880s and were established by the 1920s (Abbott 2002).

The number of cats occurring in the Kimberley is unknown due to difficulties in survey, although a radio-tracking study at Mornington Wildlife Sanctuary suggests there is one individual per 3 km², each eating 5–12 native vertebrates daily. If this population density of cats occurred throughout the region there would be over 100,000 individuals present, consuming at least 500,000 native animals every day (Legge unpublished data).

There is some evidence that dingoes, as a top predator, can help control the negative effects of smaller predators like foxes and cats (Glen et al. 2007; Johnson and VanDerWal 2009; Letnic et al. 2010; Kennedy et al. 2011). The regular baiting of dingoes is therefore likely to exacerbate the problem of introduced feral predators (Wallach et al. 2010).” [pp.13-14]

Cat killing wildlife

[Source:  Australian Wildlife Carers Network, ^http://www.ozarkwild.org/cats.php,

Photo: Australian Government]

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“The Kimberley is a national priority in this effort to avoid further extinctions due to its intact suite of wildlife species, including many endemics, and its role as a refuge for an increasing list of species that are declining or have been lost in other areas of northern Australia.” [p.47]

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Further Reading on Kimberley Conservation:

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[1] Carwardine J, O’Connor T, Legge S, Mackey B, Possingham HP and Martin TG (2011), Priority threat management to protect Kimberley wildlife , CSIRO Ecosystem Sciences, CSIRO Australia, Brisbane, and The Wilderness Society, (76 pages), ISBN 978 0 643 10306 1,  http://www.csiro.au/resources/Kimberley-Wildlife-Threat-Management.html

[2] ‘Australia to lose 45 species in 20 years’, 20110323, AAP, http://www.smh.com.au/environment/australia-to-lose-45-species-in-20-years-20110322-1c5bx.html

[3] Marion Downs Sanctuary (Kimberley), Australian Wildlife Conservancy, http://www.australianwildlife.org/AWC-Sanctuaries/Marion-Downs-Sanctuary.aspx.

[4] Mornington Sanctuary (Kimberley), Australian Wildlife Conservancy, http://www.australianwildlife.org/AWC-Sanctuaries/Mornington-Sanctuary.aspx

[5] Kimberley Land Council, http://klc.org.au/

[6]  Environs Kimberley, http://www.environskimberley.org.au/

[7] Kimberley Australia, http://www.kimberleyaustralia.com/kimberley-environment.html

[8] Save the Kimberley,  http://savethekimberley.com/blog/?tag=kimberley-environment-development-conservation

[9] Save the Kimberley,  http://www.savethekimberley.com/wp/tag/kimberley-environment-development-conservation/

[10] The Wilderness Society,  http://www.wilderness.org.au/campaigns/kimberley/northern-australia-taskforce-recognises-kimberley-environment-must-be-protected

[11] The Kimberley – Like Nowhere Else, http://www.likenowhereelse.org.au/what_needs_to_be_done.php

[12] (Government site)  West Kimberley National Heritage assessment, Australian Heritage Council,
http://www.environment.gov.au/heritage/ahc/national-assessments/kimberley/index.html

[13] Kimberley Foundation Australia (KFA), http://www.kimberleyfoundation.com

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– end of article –

https://www.habitatadvocate.com.au/?page_id=13848

by Editor 20100810.

The following article appeared on ABC Television in Tasmania (Australia), Friday 16th July 2010.

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‘Scientists are concerned about a decline in eastern quoll numbers in Tasmania.

The eastern quoll is a carnivorous marsupial and is sometimes known as a native cat.

Scientists predicted quoll numbers would rise as the tasmanian devil population was decimated by the facial tumour disease.

But spotlighting survey work has shown numbers have fallen by half.

University of Tasmania honours student, Bronwyn Fancourt, is now doing more detailed survey work but says initial results are concerning.

“We really need to protect these guys because we don’t want to see them end up as another thylacine,” she said.

Blood samples and measurements will be taken for further research into why the species is in decline.’

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Further reading on the plight of Quolls in Tasmania:

[The following article was extracted from the Tasmanian Times of 15th May 2010, by Nick Mooney, Richmond (Tasmania), ^http://www.tasmaniantimes.com/index.php/article/cynical-dismissal-of-substantial-material-evidence ].

‘Cynical dismissal of substantial material evidence‘

[This article was extracted from the Hobart Mercury of 16-July 2010, by Charkes Waterhouse, http://www.themercury.com.au/article/2010/07/16/159131_tasmania-news.html ].

‘Another native Tasmanian species is under threat, with the population of eastern quolls falling around the state.

The decline has alarmed experts as the eastern quoll was expected to thrive to fill the void left by falling numbers of disease-ravaged Tasmanian devils.

The University of Tasmania and the Department of Primary Industries, Parks, Water and Environment will investigate the extent of the falling population.

DPIPWE threatened species zoologist Clare Hawkins said the study would provide scientific data on the status of the species.

She said annual spotlighting information suggested the population of the eastern quoll had declined.

“It does appear quite complicated as at the same time there are areas of the state, such as Bruny Island, where landowners are reporting they have never seen so many eastern quolls,” she said.

“It may be that in some areas of the state they remain in high numbers, whereas other parts of Tasmania have had declines, or it may be that in some areas they are coming into closer contact with the urban environment making them more observed, which could be masking an overall decline.”

University of Tasmania zoology honours student Bronwyn Fancourt said a systematic survey would provide scientific information on the wild population, building on information about population changes and showing whether there were areas where increases or decreases had occurred.

“Tasmania is the last stronghold for the eastern quoll as it is now presumed extinct on mainland Australia, which highlights the importance of having scientific data on what the population is doing,” Ms Fancourt said.

She said the survey was taking place through a trap-and-release program at various sites.

Information from this program and any other data collected could help an understanding of possible contributory factors if the quolls were in decline.

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‘Foxes, quolls, devils and 1080‘

[This article is extracted from the Tasmanian Times, 24-Nov-2006, by wildlife biologist Nick Mooney,^ http://tasmaniantimes.com/index.php?/article/nick2/].

Assessing the Risks

When assessing the risks of 1080 fox baiting to individuals or populations of any particular species a number of things should be taken into account, including:

• The physiological sensitivity of the species to 1080 poison (depends on many things principal amongst them the historic exposure of the species to 1080 as it occurs in Australian plants), something that can be experimentally measured.

• How many baits the species might find (depends on the sensory abilities of the animal, how, where and the number of baits placed in a given area — the landscape density).

• How many baits the species might eat within a certain period. To cause death, a lethal dose has to be ingested in a certain time — usually within 2 days because sub lethal doses of 1080 are metabolised. Dried meat baits are too hard for many species to do more than mouth and nibble but many species can eat other baits such as Foxoff (eg non toxic bait trials — Belcher 1998 and DPIW data). There is evidence some species can detect 1080 in baits and avoid eating them (eg the spotted-tailed quoll in Foxoff baits, Kortner et al 2003).

• How much 1080 is left in baits when they are eaten (if they are decomposing, 1080 will have also degraded to a comparable degree).

• The likelihood of the species digesting baits (many carnivores and omnivores regurgitate food containing significant amounts of 1080. There are past records of devils regurgitating 1080-laced food in captive trials).

• The age and health of the individual eating the bait or carcasses of poisoned animals (smaller individuals of a species likely have higher metabolisms and consequent usual higher sensitivity to 1080 and healthy individuals likely have more resistance to 1080)

• The size of individuals in the population at baiting (size effects metabolism and consequent susceptibility to 1080. Individuals of the same species might be different in size in different populations, eg devils on the east coast of Tasmania are much larger than west coast individuals, and there may be many small juveniles just after breeding).

• How the species’ range and abundance overlaps with 1080 baiting (the proportion of the species that might be exposed to baiting).

Physiological sensitivity

The level of physiological sensitivity of a species to 1080 is usually described as the species’ LD50 – that is the mg of 1080 ingested per kg of animal during a very short period that will kill 50% of the individuals exposed (LD = Lethal Dose). Most of the research on LD50s for Australian animals and the potential impacts of 1080 was done on captive animals decades ago by Dr John McIlroy, then at CSIRO, and published in various issues of Australian Wildlife Research (eg McIlroy, 1981a, 1981b and 1981c) and he still gives occasional advice on the matter to DPIW. It is doubtful if this work could ever be substantially expanded or repeated because it involves lethal testing.

LD50s for some Tasmanian animals of obvious interest as potential non-target consumers of fox baits (mainly dried kangaroo meat but also some Foxoff meat compound) are

We see that kg-for-kg, red foxes are over 13 times as sensitive to 1080 as are spotted-tailed quolls and 30 times as sensitive as devils. The LD50 for spotted-tailed quolls is lower than might be expected considering those for its relatives, the eastern quoll and Tasmanian devil. McIlroy has expressed the opinion the small sample size and temperatures the results were obtained under may have given a too low result. This is born up by most mainland research that shows little effect of fox and wild dog baiting on spotted-tailed quolls (eg Kortner et al 2003).

Persistence of 1080 in baits

In the field, 1080 breaks down by microbe and fungal activity. Meat baits as used in Tasmania are about 120g of fresh kangaroo meat, each dosed with 3mg of 1080 dried hard to about 40g for storage then use (eg Saunders et al 1995). By the time they are set (buried) some 1080 is already broken down and on average they then only contain 2.7mg – a 10% loss. Once buried, degradation of 1080 accelerates, the rate depending on soil conditions (particularly moisture and temperature) and consequent baits degradation. Such degradation of 1080 is well known (eg Saunders et al 2000).

Tasmanian 1080 fox dried meat baits have been tested after different times in the ground in field conditions and on average after 2 days in the ground only 43.3% of 1080 remained, after 5 days there was 28.2% left, after 10 days 19.7% and after 15 days 11.6%. However, there was considerable variation even between neighbouring baits; some in wet places have much less 1080 residue and some in dry places much more than the average.

Number of baits needed to put individuals at risk

Considering the sensitivity of spotted-tailed quolls, devils and foxes to 1080 and degradation of 1080 in buried baits we can calculate how many baits buried for various times need to be eaten by different sized spotted-tailed quolls, devils and foxes within 2 days to have a 50% chance of being killed.

We see below that a very small spotted-tailed quoll will consume an LD50 if it eats most of one freshly layed bait but that same animal would have to eat at least 5 baits within 2 days once they had been in the ground for two weeks to be at similar risk. Similarly a very large spotted-tailed quoll would have to eat more than 4 freshly layed baits to be at risk but more than 30 after two weeks in the ground.

We see below that even a very small devil (probably not even weaned) needs to eat more than 3 freshly layed baits within 2 days to reach an LD50 and large devils need to eat very many baits in a short period to reach an LD50.

We see that foxes are extremely susceptible to 1080 baiting and in many circumstances need less than 1 bait to reach an LD50.

The chances of individuals finding enough baits in a short enough period to be at risk

Extensive testing with foxes on mainland Australia clearly shows they can find baits immediately they are buried; initial take is often high and usually continues until baits and/or foxes are greatly reduced (eg Saunders et al 1995). Limited testing with Foxoff and fresh meat baits with captive and wild spotted-tailed quolls in NSW showed they could detect buried baits but trials only identified this species as taking 2 of 7 baits taken after 3-4 weeks buried adjacent to a spotted-tailed latrine in the wild (Belcher 1998); results consistent with Tasmanian observations considering time buried and that baits were replaced exactly where taken (see below).

Research on take of fox baits without 1080 was undertaken with an isolated, island population of devils (no quolls or foxes present). Initial take was very low (a few % per night) but escalated once baits began to rot, to the point where most baits were taken after 3 weeks. These results were mirrored in places with devils and spotted-tailed quolls, devils and eastern quolls and eastern quolls alone; there are no places exclusively with spotted-tailed quolls in Tasmania. If baits were replaced in a hole where a previous bait had rotted then re-take could be immediate but if placed in a new hole take was very low. Devils in particular would sometimes deeply excavate holes in which baits had rotted.

It seems devils and quolls are not well equipped to find buried baits until they rot or are otherwise smelly (or replaced); probably there has been no need in their evolution. On the other hand, foxes and dogs evolved under conditions of extremely harsh winters where caching and recovering food (or raiding others’ caches) was fundamental to survival. Therefore, these canids are ‘professionals’ at finding buried food (eg Saunders et al 1995, Twigg et al 2000). This does not mean that other species cannot find any buried baits or might even be exposed accidentally (eg during echidna excavations) but it is a clear trend.

There has been considerable questioning of what animals have taken the thousands of baits of the nearly 80,000 sofar set in Tasmania. Checking baits daily allows a reasonable judgment of what might have taken them and in the early days of baiting (2002/3) when daily checks were undertaken about 20 baits were recorded as taken in typical fox style (as seen else where in Australia). Once baiting expanded and baits were only checked at recovery such judgments of take could rarely be made; hence the experiments reported here. If baits were recovered 2-3 weeks after burial few were missing but if it was 3 weeks or more most might be – it seemed a simple fact of rotting and then being found.

In operational fox baiting in Tasmania, baits are buried at a landscape density of 5-10/km2. The number of baits in an animal’s home range can also be considered and how much competition there might be for baits. A large devil might have 100 baits in its home range but that home range would likely be shared by 10-30 other devils plus quolls (and possibly foxes). Thus, the baits available per individual are comparatively few.

The chances of individuals eating enough baits in a short enough period to be at risk

Although they can easily eat soft baits, test have shown that small or even medium sized spotted-tailed quolls and very small devils do not (probably can not) eat very dry and hard baits and it is not until they are independent that they are likely to be under enough nutritional pressure and are strong enough to eat such. Tests on captive mainland Australian spotted-tailed quolls support these results (Belcher 2000).

What actually happens in the field?

Considerable research has been done on effects of 1080 fox baiting on spotted-tailed quolls on mainland Australia (eg Kortner ET al 2003). In Tasmania, experimental 1080 baiting was not carried out but rather, research waited until an operational baiting occurred in an area with enough spotted-tailed quolls to usefully study (near Wynyard).

Although there were too few quolls in the study sites area (and a comparative control site with no baiting) to have statistically robust comparisons of numbers before and after baiting we found individual spotted-tailed quolls similarly persisted in both areas through and after baiting. Importantly, there were breeding females (with pouch young) and free ranging juveniles present in both sites after baiting; there was no identifiable difference between baited and non-baited sites. This work will be repeated as opportunity presents.

In the northern midlands where the effects of 1080 fox baiting on devils was being studied, there was also a ‘background’ population of spotted-tailed quolls. Trapping after a prolonged baiting period showed all elements of a normal devil population in place – breeders and juveniles with no apparent drop in density. Perhaps most interestingly, in the months after this research a substantial drop in numbers of devils due to Devil Facial Tumour Disease occurred and in another 6 months numbers of spotted-tailed quoll seemed to have measurably increased (probably due to decreased competition and predation from the fewer devils) and has stayed high with an apparently normal mix of breeders and juveniles. DFTD it seems has absolutely overwhelming effects (even if indirect) compared to fox baiting.

In an area in which Foxoff meat compound baits were operationally used extensive capture-mark-recapture studies were done of large local populations of Tasmanian bettongs Bettongia giamardi and brushtail possums Truchosaurus vulpecula, two species likely to eat these baits. Very few Foxoff baits were taken and there was no difference in population change between the baited site and a control site.

These Tasmanian ‘pilot’ studies suggest there is little if any damage to local populations of spotted-tailed quoll, Tasmanian devils, Tasmanian bettongs or brushtail possum from 1080 fox baiting in Tasmania as is known to have severe effects on fox populations on mainland Australia (eg Saunders et al 1995).

State-wide Effects

A final check can be made by looking at what proportion of Tasmania’s spotted-tailed quoll and devil population might be exposed to 1080 fox baiting. Sofar, 1080 fox baiting has only touched the fringe of Tasmania’s core spotted-tailed quoll habitat and perhaps less than 2-3% of Tasmania’s spotted-tailed quolls have been in baited areas. Similarly perhaps 5% of Tasmania’s devils have been in baited areas. These areas and percentages may increase by half with planned fox baiting but, even then the reality is little or no effect on a small proportion of the State’s populations of these important species.

References

1. Belcher, C. (1998). Susceptibility of the tiger quoll, Dasyurus maculatus, and the eastern quoll D. viverrinus, to 1080-poisoned baits in control programmes for vertebrate pests in eastern Australia. Wildlife Research 25, 33-40.
2. Belcher, C. (2000). The ecology of the Tiger Quoll Dasyurus maculatus, in south-eastern Australia. Unpublished PhD thesis, Deakin Uni.
3. Kortner, G., Gresser, S. and B. Harden (2003). Does fox baiting threaten the spotted-tailed quoll, Dasyurus maculatus? Wildlife Research 30, 111-118.
4. McIlroy, J. C. (1981a). The sensitivity of Australian mammals to 1080 poison. 1. Intraspecific variation and factors effecting acute toxicity. Australian Wildlife Research 8, 369-383.
5. McIlroy, J. C. (1981b). The sensitivity of Australian mammals to 1080 poison. 11. Marsupial and eutherian carnivores. Australian Wildlife Research 8, 385-399.
6. McIlroy, J.C. (1981). The sensitivity of Australian animals to 1080 poison.1X. Comparisons between the major groups of animals, and the potential danger non-target species face from 1080 poisoning campaigns. Australian wildlife Research 13, 39-48.
7. Saunders, G., McLeod, S. and B. Kay (2000). Degradation of sodium monoflouroacetate (1080) in buried fox baits. Wildlife Research 27, 129-135.
8. Twigg, L., Eldridge, S., Edwards, G., Shakeshaft, B., dePeru, N. and N. Adams (2000). The longevity and efficacy of 1080 meat baits used for dingo control in central Australia). Wildlife Research 27, 473-481.

Other Useful Reading

Kinnear, J.E. (2003). Eradicating the fox in Tasmania: A review of the Fox Free Tasmania Program. Unpublished report to DPIWE, Hobart.
Saunders, G., Coman, B., Kinnear, J. and M. Braysher (1995). Managing vertebrate pests: Foxes. Australian Government Printing Service, Canberra
Saunders, G., Lane, C., Harris, S. and C. Dickman (2006). Foxes in Tasmania: A Report on the Incursion of an Invasive Species. IACRC, Canberra.

Nick Mooney is a wildlife biologist with DPIW and has been working with Tasmanian wildlife for more than 30 years. Amongst other hats, he pioneered Tasmanian rehabilitation and conservation of raptors including eagles in forestry, has monitored reports of Thylacines and foxes, helped with responses to newly discovered diseases, whale strandings and oil spills and developed practical conservation of devils and innovative wildlife tourism. Most recently he kicked off the response to Devil facial Tumour Disease and has been giving advice for the response to recent evidence of foxes in Tasmania. Nick is assessing the potential ecological effects of DFTD, foxes and cats; he sees the biggest ecological threat as establishment of foxes because of DFTD, a process that could cause the ultimate long term threat to devils (his favourite animal).

Nick Mooney

There has been a recent spate of public concern over the effect that 1080 baiting targeting the red fox Vulpes vulpes in Tasmania might have on the spotted-tailed quoll Dasyurus maculatus and the Tasmanian devil Sarcophilus harrisii.

Considerable research has been done on that quoll species on mainland Australia, studies augmented by work in Tasmania on both it and devils.

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‘Foxes, quolls, devils and 1080 #2‘

[This article is extracted from the Tasmanian Times, 27-Nov-2006, by David Obendorf,^ http://tasmaniantimes.com/index.php?/article/obis1/].

AS NICK MOONEY states: ‘Most of the research on lethal dose to 50% (LD50) for Australian animals and the potential impacts of 1080 was done on captive animals decades ago by John McIlroy, then at CSIRO, and published in various issues of Australian Wildlife Research. It is doubtful if this work could ever be substantially expanded or repeated because it involves lethal testing.’  (Foxes, quolls, devils and 1080)

With DPIW poised to embark on a decade-long $56 million dollar fox eradication campaign using 1080 meat baits as the principle eradication tool, I believe there are several very good reasons why 1080 testing of non-target Tasmanian species exposed to these baits must now be repeated. For Tasmanian wildlife authorities to rely solely on this unrepeated toxicological data would be reckless.
John McIlroy commenced his work on the sensitivity of Australian animals to the poison 1080 (Sodium Fluoroacetate) a quarter of a century ago. John was a research scientist working at the CSIRO Division of Wildlife Research at Gunghalin near Canberra. During the period from 1980-86 he conducted a series of dose-response experiments to assess the sensitivity of 1080 on a representative range of Australian animals, covering species in all the main vertebrate taxa. He published 9 scientific papers in this series; 7 as the sole author and 2 in collaboration with others.

In documenting his research findings, John was careful to firstly prepare the theoretical and statistical ground work on which this series of experimentally-based toxicity would be based (McIlroy 1981a).

“In toxicological work the sensitivity of different [species of] animals to a poison is usually expressed as the LD50 or median lethal dose, a statistical estimate of the dose — in milligrams of poison per kilogram body weight, that will kill 50%  of a large population.

The LD50 of a poison and its 95% confidence limits are only an indication of the values that might be expected from repeated trials on the same strain of animals under the same experimental conditions.”

In applying the LD50 values to a test poison, McIlroy states:

“The necessity for such a standardised procedure has been questioned … [as] statistically significant differences in LD50 values (up to 3.2 fold) within and between laboratories, related to differences in experimental procedure, …  [but] these were not great enough to change the interpretation of the relative hazards of the test chemical involved. However, because I was concerned with a controversial poison [1080] and its toxicity to a variety of wild animals, I felt it was important to assess the effects that differences in experimental procedure might have on LD50 values of 1080 and, if necessary, design a procedure to minimize such sources of variation.” (McIlroy 1981a)

In his second paper detailing the results of his experimental studies on marsupials and placental mammals, John began on a cautionary note:

“The effect that these [1080] poisoning campaigns are having on non-target or native animal populations is not known, despite occasional reports of individuals of these species being found dead or ‘vanishing’ from areas in which 1080 has been used.” (McIlroy 1981b).

Targeting dingoes

McIlroy was very considered in any reliance of these experimentally derived LD50 values:

“In reality many factors are involved in determining whether an individual or what proportion of a population may be killed by a [1080] poisoning campaign. The preceding theoretical analysis involved mean body weights of only small samples of animals, LD50s obtained under specific experimental conditions, and a particular concentration of 1080 in each bait plus the assumptions about bait intake by free-living species. All are likely to vary in different field situations, altering the risk each individual carnivore faces.”

Based on 1080 baiting campaigns targeting dingoes (& wild dogs), John McIlroy made some thoughtful recommendations when deciding on the most effective bait size and quantity of 1080 per bait for maximal kill of target species and minimal impact to non-target (native) species.

“The data on [1080] sensitivities do provide fundamental information for the planning of dingo-poisoning operations. For example, if the aim is to obtain maximal control with minimum dose it would be best to plan the baiting on the basis of a LD100 based on twice the upper confidence limit of the LD50 and the weight of the heaviest specimen reported. In contrast, to assess the hazard to a non-target species, calculations might be best based on the lower confidence limit of the LD50, or some other lower figure, and either the mean weight or much lower body weights of, for instance, immature animals.”

McIlroy went on to do a theoretical calculation to show this point for dingoes (the target carnivore) and spotted-tail quolls (a non-target carnivore).

“The heaviest individual [dingo] caught in the Eastern Highlands was 25 kg. Thus if the LD100 is assumed to be approximately twice the upper confidence limit of the LD50 (i.e. 0.3mg/kg BW), it would be necessary to get 7.5 mg of 1080 into a dog of this size to kill it. Similar calculations for tiger cats [spotted-tail quolls], using twice the lower confidence limit of the LD50 (i.e. 2.56 mg/kg BW) and taking the mean body weight of 2.8 kg, indicate that 7.17 mg of 1080 is a lethal dose for [this species].

Applying McIlroy’s precautionary recommendation to the mean body weight for immature spotted-tail quolls of 1.1 kg, only 2.8 mg of 1080 is a lethal dose.

Obtain a lethal dose

The same theoretical calculation and logic can be applied can be applied to 1080 poisoning campaigns targeting foxes.

For an extreme body weight fox of 6 kg and applying an LD100 that is approximately twice the upper confidence limit of the LD50 (i.e. 0.26mg/kg BW), it would be necessary to get a fox to consume 1.56 mg of 1080 to kill it (not 3 mg of 1080 per bait). If each dried kangaroo meat (DKM) baits contained this amount of 1080, one bait would kill all foxes less than 6 kg. When applying McIlroy’s precautionary calculation to a mean body weight for immature quolls, such animals would need to ingest at least two baits to obtain a lethal dose.

“From the viewpoint of trying to safeguard tiger cats [spotted-tail quolls]; therefore, it is obviously necessary to keep 1080 concentration in baits as low as possible.” (McIlroy 1981b)

One variable that McIlroy particularly commented on was the effect of ambient temperature on the sensitivity of 1080 poison. He was concerned that his experimental trials to set the LD50 for many native marsupials were carried out at about 22°C (in controlled environment rooms). He noted that in relation toxicity studies on the spotted-tail quolls, trials were conducted at 13°C where the LD50 was calculated at 1.85 mg/kg BW.

“… different ambient temperatures cause two to five fold differences in the susceptibility of mice and guinea pigs to 1080. Both species are susceptible at both low and high ambient temperatures than they are at medium temperatures. If similar responses occur amongst other, larger homeotherms, this might explain the relatively low LD50 for the tiger cat [spotted-tail quoll] compared to those for the other native cats [quolls]. The possibility exists, therefore, that if these trials had been carried out at 22°C [instead of 13°C], the LD50 would have been slightly higher than 1.85 mg/kg BW.

Ambient temperatures obviously vary considerably between field poisoning situations, both geographically and diurnally, so a LD50 obtained at 22°C, or a dose that will kill 50% of a population experiencing this ambient temperature, must be regarded as only a general value. Greater population mortality may be expected at much lower or higher environmental temperatures.” (McIlroy 1981b)

In relation to the most susceptible non-target marsupial carnivore, the spotted-tail quoll, 1080 baiting programs targeting foxes and wild dogs are still reliant on McIlroy’s highly qualified toxicology studies and LD50 calculations.

In obtaining his LD50 levels for each species, McIlroy orally dosed between 3 and 5 individuals at dose intervals of 1.26 in 4 distinct dose groupings. For spotted-tailed quoll he used 12 animals. The LD50 was calculated at 1.85 mg/kgm with 95% confidence intervals of 1.28 to 2.68 mg/kgm BW.

Other animals begin to vomit

Clinical observations were made on the experimentally poisoned animals.

“Most commonly, affected animals suddenly became hyper-excited, with rapid breathing, bouts of trembling and sometimes periodic circling within their cages. Again, some animals may then recover while other begin to vomit, convulse, or both. With some animals, particularly the eastern native and tiger cats [quolls] and Tasmanian devils, the first symptom is the sudden onset of vomiting.

Convulsions were triggered by disturbance, such as the opening of a door, sudden movement by an observer, or convulsion by a neighbouring animal. In rough order, these symptoms include: restlessness; increased hyperexcitability or response to stimuli; bouts of trembling; rapid, shallow breathing; incontinence[involuntary passing of urine and/or faeces] or diarrhoea; excessive salivation; twitching of the facial muscles; nystagmus (involuntary eyeball movement exposing the whites of the eyes)or bulging eyes with large (dilated) pupils and rapid blinking plus, in domestic cats, discharge of mucus from the eyes); slight lack of coordination or balance; abrupt bouts of vocalisation; and finally, sudden burst of violent activity such as racing around the cage, or biting the cage mesh or other objects. All affected animals then fall to the ground in a tetanic seizure, with hind limbs or all four limbs and sometimes the tail extended rigidly from their arched bodies. At other times the front feet are clasped together, clenched or used to scratch frantically at the cage walls. This tonic phase is then followed by a clonic phase in which the animals lie and kick and ‘paddle’ with the front legs and sometimes squeal, crawl around or bite at objects. During this phase the tongue and penis may be extruded, the eyes rolled back so that only the whites show and the teeth are ground together. Breathing is rapid but laboured, with some animals partly choking on their saliva. Finally such animals begin to relax, breathing more slowly and shallowly and lying quietly with the hind legs still extended but apparently semiparalysed (paresis).

From then on individual animals either: (1) gradually recover; (2) die shortly afterwards; (3) after a short or long delay (e.g. 5 min or 3-4 h) experience another one or two series of convulsions and then die shortly afterwards or eventually recover; (4) remain lying quietly, scarcely breathing or moving, until death up to 6 days later.

It is noteworthy that in McIlroy’s observations on carnivorous marsupials exposed to sub-lethal doses of 1080, he noted that animals that did not die but ‘remained weak for 2 or more days’. From this we can infer that the sub-lethal consequences of 1080 poisoning may therefore affect an animal’s ability to evade predation by other animals and affect their ability to find safe refuge.

McIlroy also makes the following observations:

“The pouch young of tammar wallabies are significantly more susceptible to 1080 than adults (P>0.01. The pouch young of brush-tailed possums and northern native cats, Dasyurus hallicatus, similarly appear to be more sensitive than adults. More pouch young pouch young possums than adults died at each dose level, although only their mothers were dosed with 1080; presumably the young ingested lethal amounts of 1080 in the milk. The eight pouch young of one northern native cat also died within 24 h after their mother received a non-lethal dose (84% of a LD50 )but the five pouch young of a tiger cat, Dasyurus maculatus, survived in similar circumstances (74% of a LD50 ). [There are] similar reports of young rats killed by milk from their poisoned mothers.” (McIlroy 1981).

Fox entry into Tasmania

Fox entry into Tasmania has ALWAYS been a biosecurity/biodiversity risk for Tasmania, yet it is remains unclear whether foxes have established breeding populations in Tasmania.

Despite the unsubstantiated stories of intentional introductions of foxes the most likely source of single-fox introductions into Tasmania has been slack and inadequate quarantine measures. In the decades of inadequate quarantine measures at our ports, any foxes that have arrived and escaped into Tasmania, the questions remains which locations have the highest frequency of receiving fox-risk materials?  Might these be the places where foxes might just get lucky and breed?

Over fifty years of 1080 use in Tasmania to control native herbivores like Bennett’s wallaby, Tasmanian pademelon and brush-tail possum coupled with the high sensitivity of red foxes to secondary 1080 poisoning (i.e. through eating a poisoned carcass) is rarely acknowledged.

Where will they ‘get lucky’ in the landscape? Closest to the farms & feedlots that have historically received container-loads of stock feed grain; agri-businesses that transport or deal with used farm equipment; freight forwarding depots. The highly reliable sighting reports of foxes in remote areas (where 1080 poisons have not been used) like the western Central Plateau or our National Parks must be the basis for intensive investigation. Maybe the remote camera used by the DFT team can be now deployed for fox studies.

It ALWAYS comes down to validating the risk assessment.

References:

1. McIlroy, JC (1981) The Sensitivity of Australian Animals to 1080 Poison I. Intraspecific variation and Factors affecting Acute Toxicity. Australian Wildlife Research 8, 369-383.
2. McIlroy, JC (1981) The Sensitivity of Australian Animals to 1080 Poison II. Marsupial and Eutherian Carnivores. Australian Wildlife Research 8, 385-399.

David Obendorf

With DPIW poised to embark on a decade-long $56 million dollar fox eradication campaign using 1080 meat baits as the principle eradication tool, I believe there are several very good reasons why 1080 testing of non-target Tasmanian species exposed to these baits must now be repeated. For Tasmanian wildlife authorities to rely solely on this unrepeated toxicological data would be reckless.

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