This article relates to the ongoing debate on Australian Rural & Regional News: Open for Debate: Koalas

Dear Editor,

Thank you for the opportunity to answer your questions.

ARR.News: Koala monitoring.  What is your assessment of the different methods for monitoring koala numbers, acoustic monitoring and counting faecal pellets (and any others)? In your opinion, what are the strengths and weaknesses of each? Upon what do you base this?

Vic Jurskis: Gathering numbers should not be an end. Deliberations of the Threatened Species Scientific Committee (TSSC) assume that more is better. The koala’s ecological history of irruptions and crashes in numbers after European arrival clearly shows this not to be the case. Effective monitoring requires an understanding of the reasons for any real changes in numbers.

Koalas occurred naturally at very low densities because they rely on tender, juicy young shoots for nutrition. These are rare in healthy mature forests where koala numbers remain fairly stable because healthy trees are resilient to both drought and flood. So solitary koalas occupy large home ranges and travel around them seeking soft young growth. They are cryptic.

In spring, males bellow to attract females. The spring-summer growth flush boosts females’ nutrition, helping them to carry their young through to independence. Newly independent young females don’t compete with their mothers for food because their smaller arm-span allows them to use younger saplings. But saplings are a very limited resource in healthy mature forests. Most young koalas in healthy forests die because they can’t get enough to eat.

Natural habitats are mostly occupied at their full carrying capacity.

Radiotracking is currently the only effective technique for ecological monitoring of inherently stable low-density koala populations. It provides data on forest and tree use by koalas of known sex, age, and condition as well as data on fecundity, survival and mortality over time.

NSW Forestry Commission’s radiotracking at Eden was the first detailed ecological study of a naturally sparse population. It was shut down at the insistence of National Parks and Wildlife Service (NPWS) after finding that some koalas in a mosaic of unlogged and regrowing coupes preferred heavily logged regrowth stands.

In 1991, Forestry Commission used spotlight and listening surveys to assess the distribution of koalas and other animals on the north coast according to environment and history. These surveys can provide reliable information on relative numbers and trends but not on absolute numbers. They showed three times as many koalas in dense logging regrowth as in unlogged forests.

In 1997, NPWS used data from repeated mail out surveys at Eden to argue that koalas were declining in the region and were virtually restricted to State Forest in two areas near Tantawangalo and Bermagui which they wished to ‘protect’ from logging. Mail out surveys are heavily biased according to the activities of respondents and availability of access in forests.

Forestry Commission, timber workers and community volunteers conducted systematic call-playback and listening surveys to assess the regional distribution of koalas. This was the most effective and efficient survey method available at the time. These surveys and additional sightings confirmed that koalas were present in all six localities where NPWS had reported local extinctions.

The highest detection rates were at Mumbulla State Forest in the northeast of the region. But koalas at Tantawangalo and Bermagui were ‘protected’ from logging under the Regional Forest Agreement (RFA). NPWS organised faecal pellet surveys using Phillips’ method.  There were some surveys at Tantawangalo, but the most intensive surveys were in the northeast.

After some drawn-out, labour-intensive surveys, NPWS, in 2010, reported koala faecal pellets at two sites in Tantawangalo and many sites in the northeast. They listed the percentage of sites and trees with faecal pellets in the northeast by area and tenure. Also, percentages with faecal pellets by tree species. They estimated a population of 23-47 koalas occupying 21,000 hectares in the northeast. Since faecal pellet surveys indicate only that an unknown koala has probably been in a tree at some time within an unknown period, they cannot provide credible population estimates.

In 2013, NPWS used data from four successive mail out surveys to report that koalas had become extinct by 1997 at Tantawangalo and generally in the Eden region, except for a ‘small remnant subpopulation’ in the northeast. However, mail out surveys cannot provide unbiased information about relative densities of animals, let alone presence/absence or absolute numbers. Sightings at Tantawangalo and in other parts of the region, before and after this report, proved it incorrect. Nevertheless, it was used to ‘protect’ additional areas in the northeast from logging, in an apparent contravention of the RFA.

In 2017, acoustic recordings in the new koala park at Mumbulla, supposedly occupied by a “low density population” in ‘low quality habitat’, produced a higher detection rate than in ‘prime koala habitat’ on the north coast. Acoustic recordings are a very effective and efficient survey method which provides reliable information on relative densities, but they effectively sample only male koalas.

Used systematically, in conjunction with some limited, targeted radio tracking studies, acoustic recordings could quickly and relatively cheaply provide a goldmine of reliable information on koala ecology, numbers, trends and causes. For example, radio-tracking studies near Campbelltown confirmed that a subpopulation, which became visible within a decade of a 1977 megafire in Sydney’s water catchments, is irrupting. Female young were establishing home ranges adjacent to their mothers, showing that carrying capacity was increasing.

A radio-collared koala was translocated 100 km from Campbelltown to habitat supposedly unoccupied for the previous 30 years. It quickly bred with a local animal, demonstrating that mail-out surveys are ineffective. Two translocated females set up large ~ 100 ha home ranges before their radio-signals were lost. Repeated field surveys failed to find them or any faecal pellets.

Even the sub-population irrupting in declining fire and logging regrowth at Mumbulla is virtually invisible. After a friend was lucky enough to spot a female koala in a regrowth coppice tree there, a diligent search revealed only two tiny faecal pellets from its joey under the tree. Acoustic recordings in the area detected (male) koalas at four times the rate of occupancy compared to faecal pellet surveys – effectively eight times the rate of faecal pellet surveys.

Sound recorders have recently detected koalas at 14 sites in the Byadbo Wilderness. Over the previous 80 years there were only 16 reported sightings in the whole of Kosciuszko National Park. The changed perspective is due to increasing numbers as well as an effective survey technique. Byadbo was incinerated by megafires in 1988 and 2003. Koalas there, as elsewhere, are increasing with high intensity fire regimes. Science for Wildlife described the same process, in the Blue Mountains, to NSW Koala Inquiry. They said that they use sniffer dogs to detect koalas and faecal pellets.

Irrupting sub-populations of koalas in the Blue Mountains, at Campbelltown, in the Eden region and in Kosciuszko are linked by continuous habitat to irrupting populations in Victoria. The authors of a 2015 paper reporting the radio-tracking results from Campbelltown considered that there was sufficient evidence that “functional populations of very low densities” comprising “a large number” of koalas occur throughout the continuous habitat, even though this was not apparent from NPWS mail-out surveys.

TSSC accepted ‘expert’ guesses, some loosely based on data from ineffective survey techniques, in recommending the Endangered listing of the NSW part of this continuous and largely unknown koala population. The experts advised that there were no koalas in Kosciuszko National Park. It disturbs me that governments have announced massive spending on additional ongoing ineffective koala surveys and ‘consultations’ dressed up as citizen science.    

ARR.News: How many koala feed trees are needed per hectare to support a sustainable koala population? (and on what do you base this?) Does this number need to be adjusted depending on the nature of the forest, and to allow a margin for drought conditions?

Vic Jurskis: The concept of fixed koala food trees is not ecologically sound and dense koala populations are not sustainable in the long term. This is evident from historical irruptions and crashes, especially during the Federation Drought and the Millennium Drought. Modern ‘experts’ incorrectly attribute the first of those crashes to clearing and hunting and the second to clearing and climate change.

Koalas at medium densities near Eden, Campbelltown and Coffs Harbour continued to irrupt through the Millennium Drought and the Black Summer Drought. Low density sub-populations remained stable in Central Queensland during the Millennium Drought while nearby dense populations in supposed high quality habitat crashed, as did others in the Pilliga and on the Koala Coast.

Solitary koalas in healthy mature forests forage amongst many thousands of trees in their large home ranges. They select an individual tree with a flush of tender young growth and make the most of it before moving to another suitable tree. The availability of soft shoots depends not only on seasonal conditions, but also on the competitive position and health of each tree’s crown as well as the history of previous folivory in the tree.

That’s why increasing folivory of declining trees continually resprouting soft shoots is often described as ‘koala overbrowsing’. However a range of insects is usually involved as well.

Intensive logging coupes are small areas compared to natural home ranges of koalas in native forests. Logging increases the short to medium term abundance of koala feed because all trees retained within coupes are released from competition and gain increased access to sunlight, water and nutrients. So do all the edge trees on the perimeter of coupes or of retained filter strips and other logging exclusions within coupes.

Growth flushes in retained trees explain observed preferences of koalas for intensively- logged coupes in the 1990s at Eden. Abundance of soft shoots in regrowth trees was responsible for higher densities of koalas observed in heavily logged forests compared to unlogged forests on the north coast at the same time.

ARR.News: Do you consider leaving 10 feed trees per hectare of state forest harvested enough to a support a sustainable koala population?

Vic Jurskis: Koala numbers increased as a result of intensive harvesting operations with no requirements to retain any ‘feed trees’. More recently, research has shown unequivocally that koala numbers are unaffected by the intensity of, extent of, or time since harvesting. Leaving additional trees specifically for koala feed is unnecessary.

ARR.News: In your opinion, what more might the forestry industry in NSW do to protect koalas in areas that are harvested?

Vic Jurskis: The forestry industry might reinstate sustainable fire management in all areas available for harvesting, were it not illegal under current environmental regulations in NSW.

ARR.News: Are you aware of any current evidence that koalas are surviving in the Ellis State Forest and Clouds Creek State Forest on the Western Dorrigo Plateau?

Vic Jurskis: I’m not aware of data on koala numbers or trends specific to that area. However I’m sure that the following statement by anti-logging MP, the Hon. Sue Higginson, which you’ve published, must be incorrect:

“In places such as Clouds Creek State Forest on the Western Dorrigo Plateau, field research commissioned by the NSW EPA found that the sequential industrial logging of tall wet Eucalypt forests since the late 1990s has resulted in the collapse of what were formerly large intact breeding colonies of Koalas. Koalas are sadly now effectively functionally extinct across these industrially logged landscapes with no signs of population recovery evident.”

Data from effective surveys and monitoring on the north coast hinterland show that koalas are ‘functionally’ extant. They increased in response to intensive logging before the 1990s and since then have been unaffected by logging operations of any description. EPA’s record of regulations and prosecutions indicates that action surely would have been taken to stop logging if there had been any evidence of it causing “collapse” of sub-populations. Koalas have been officially listed as vulnerable to extinction in NSW since 1992.   

ARR.News: Do you believe that “all is well for our koalas”?*

Vic Jurskis: No. I’ve tried my best to publicise irrefutable evidence that the koala is an irruptive species in unnaturally high numbers across a wider area than its natural range. Koalas are consequently suffering overcrowding, disease, dog attacks and injuries by vehicles. Unsustainably dense subpopulations and the megafires which inevitably affect them are both results of lack of sustainable fire management.

A hugely successful multi-media advertising campaign is misrepresenting the consequences of koala irruptions as causes of species decline. The koala is in absolutely no danger of extinction. But huge numbers of koalas are suffering from Lock It Up and Let It Burn conservation policies. On the other hand, the increasingly rare species that rely on open, grassy and diverse forests are truly endangered by these policies.

ARR.News: Do you believe that “destroying their habitat is OK”?*

Vic Jurskis: Bill Gammage stated categorically in his award winning historical work that koala habitats were “distinct, lightly populated and few” in 1788. I’ve assembled additional historical information and combined it with scientific explanation in my peer-reviewed Ecological History of the Koala. It has been attacked in the media but remains unchallenged in the scientific journal Wildlife Research after five years.

The literature is full of stories about loss of habitat through clearing for agricultural development. Red gum woodlands are a good example and red gums are considered ‘primary food trees’. NPWS has repeatedly publicized the story of the Bega Valley, where there were high densities in the 1880s and koalas were gone by 1909. However, Europeans arrived in 1830, followed by koalas in the 1860s.

An extreme example is blue gum plantations in western Victoria, now reportedly supporting 50,000 koalas where there were naturally none. The koala lobby wants to stop ‘destruction’, i.e. harvesting, of this habitat. It would be more sensible to sustain a timber industry and an ethical koala industry by exporting young koalas from plantations to zoos and wildlife parks around the world.

* Quotations from the response of Sue Higginson MP: “The only voices suggesting that all is well for our Koalas, or that destroying their habitat is ok, are coming from the extractive logging industry and supporters”.

Related stories: Koala update: Brad Law; More on koala monitoring: Brad Law; NSW koalas and industrial logging of the public forest estate: Sue Higginson.

Vic Jurskis has written two books published by Connor Court, Firestick Ecology and The Great Koala Scam.