Too Many Koalas, Too Little Science

koalaDespite three separate rounds of deliberation by the Federal Government’s Threatened Species Scientific Committee, a Senate Inquiry, a ‘workshop’ involving 17 of Australia’s “most experienced koala ecologists”, the subsequent publication of a Review in Biological Conservation1, and a partial listing under Commonwealth environmental legislation, Australians remain in the dark about the basic ecology of koalas.

Koalas live in humid to semi-arid forests and woodlands in eastern Australia between about Innisfail in North Queensland and the Eyre Peninsula in South Australia. Those north of Victoria are supposedly declining whilst in the south they are seen either as secure or as requiring population control measures. Ecologists are finding this difficult to explain.

Being “one of the world’s most iconic mammals”1, the koala continues to be used as a battle standard to rally forces for nature conservation by NGOs such as Australian Koala Foundation and bodies such as New South Wales’ National Parks and Wildlife Service (NPWS). This strategy relies upon profound ignorance of Australia’s ecological history. To employ it effectively in their crusades for expanded reserves and increasing restrictions on use of natural resources, green ecologists must obfuscate or deny the well-known but poorly documented natural history of koalas.

They have a problem because this icon can be a pest and contribute to chronic decline and death of another icon, the eucalyptus tree.  Koalas are naturally rare animals, living solitary lives in large home ranges containing thousands of trees. They are virtually invisible in their natural condition.  Unfortunately for the crusaders, invisible animals aren’t useful icons. Koalas became icons only after they became pests. A fundamental ecological principle: “Plenty alright, too much no good”2 refers just as well to icons as to acknowledged pests in natural ecosystems. But ecologists who use icons to crusade for “conservation” prefer to push a contrary line that “more is better”. So it suits their cause if koalas are seen to be in danger and requiring salvation.

The koala was first sighted by a European in 1798, fully ten years after settlement at Sydney. Another four years elapsed before the architect and explorer Francis Barrallier obtained two koala feet from Aboriginal hunters. Despite considerable interest and much searching, a further year elapsed before a live specimen was procured. Koalas occurred at such low densities in forests on the southwestern fringe of the Cumberland Plain that they were rarely seen. Aborigines climbed trees to capture them, but they caught far more possums than koalas3. However, by 1836 koalas had become common at the fringes of European settlement, and Aborigines had devised a technique (recently adapted by koala ecologists) whereby they twisted a bark noose on the end of a long stick around koalas’ necks to get them more efficiently4. In the late 19th century, koalas became pestilent and Europeans used rifles to kill them for their pelts. The population on Sydney’s outskirts crashed early in the 20th Century, and koalas were no longer seen in these rural areas after the Federation Drought. By the 1980s they were once again irrupting in forests on the new urban fringe3.

Explorers and early settlers didn’t see koalas anywhere. A pattern of initial invisibility followed by irruptions and declines has recurred through much of the koala’s range in eastern Australia. The timing of their ups and downs has varied regionally according to the timing of initial European settlement and, in many cases, later urbanization. Speculation that koalas were originally kept in check by Aborigines and dingoes soon became the conventional wisdom. This is nonsense, because predators are actually kept in check by their limited capacity to catch prey. That’s why we think of trophic pyramids. But even highly efficient hunting with rifles didn’t control irruptions of koalas after European settlement5.

The most recent scientific review has koalas declining in most regions north of Victoria1. But these are declines from unnaturally high benchmarks such as the one set by the recent secondary irruption of koalas on Sydney’s urban fringe. In southern Australia, “managed declines” (culling or sterilization) are being implemented in some regions, whilst increasing populations in other regions are clearly heading for decline, whether managed or un-managed, as their food trees spiral into chronic decline. Supposedly stable populations scattered through the koala’s range1 are in fact irrupting. If they are visible, they must be unnaturally dense2.

A natural, low-density population of koalas persists in the forests around Eden on the south coast of New South Wales, where I have worked for 30 years. The average home range of these animals is more than 100 hectares and contains tens of thousands of trees, most of which have poor, tough leaves that cannot sustain koalas. In the breeding season, female koalas travel long distances away from their home ranges to mate with males whose bellows carry far and wide on still, summer nights 2.  Experts have repeatedly claimed that koalas are extinct here because people rarely see them or report them in mail-out surveys. But sometimes it suits the green cause to find the ‘last remaining colony’ of these solitary animals so that their presence can be used to influence land management. The ecological and political history of koalas at Eden is illuminating.

Settlement of the Bega Valley commenced in 1830, but koalas weren’t seen until they irrupted in the 1860s after agricultural development had initiated chronic decline in red gum woodlands. Sick eucalypts provide very palatable and nutritious food for any animal that eats any part of a tree. A koala pelt industry flourished until the Federation Drought, when the population crashed along with the red gums. Koalas haven’t been reported from The Valley since 1909. Five government sponsored mail-out surveys between 1949 and 2011 all produced very few, very scattered records of koalas in the forests6. Over 90 years, across this region of 700,000 hectares, the reporting rate was about one koala per decade per 30,000 hectares.

Following the second mail-out in 1987, NPWS reported that koalas were extinct in six localities. One of these was the area around Tantawangalo State Forest. Tantawangalo Catchment Protection Association (TCPA) was at that time lobbying to protect the domestic water supply catchment against predicted adverse impacts of logging. After logging trials were conducted without adverse effects on water supplies, TCPA’s focus shifted to ‘protection’ of koalas. A third mail-out survey in 1991, perhaps surprisingly, identified Tantawangalo State Forest as one of two ‘regional strongholds’ for koalas. However, radiotracking studies showed that healthy koalas actually lived at very low densities in Tantawangalo, as they did elsewhere in the region2.

After three radio-collared koalas in the region died of natural causes, lobbying by TCPA and others encouraged NPWS to prohibit radiotracking. TCPA then carried out faecal pellet surveys at Tantawangalo and made wildly exaggerated estimates of koala densities. Consequently, Tantawangalo State Forest was reserved as a National Park to ‘protect’ koalas. A prominent member of TCPA, who lacked any scientific credentials, championed this process. He was subsequently employed by NPWS to carry out further koala ‘research’.

Attention shifted to the other alleged stronghold of koalas in the region, which still retained its status as multiple-use State Forest. NPWS organized intensive faecal pellet surveys in this area between Bermagui and Bega. Extraordinarily high detection rates were achieved in long unburnt, chronically declining regrowth stands from logging and/or wildfire around 1980. Ironically, NPWS had stated in 1989 that koalas had never been seen in this area. Meanwhile, less intensive surveys in the mostly unlogged, newly declared National Park at Tantawangalo achieved very low detection rates. These surveys were abandoned after they covered less than 2% of potential home range areas of koalas. NPWS reported that koalas were probably extinct at Tantawangalo.

Two further ‘mail-out surveys’ were conducted in 2006 and 2009-11. They attracted only four ‘confirmed’ reports of koalas in the region after 2000, all from the Bega-Bermagui area. NPWS or Department of Environment, Climate Change and Water, or Office of Environment and Heritage (one GO with changing names and structure) brushed aside all other evidence and used these results to construct a model ‘showing’ that koalas were extinct in the region except for the ‘colony’ between Bermagui and Bega. This model supposedly demonstrated that koalas had progressively disappeared from the vast majority of the region after 1970, as a consequence of climate change and ‘woodchipping’. It somehow proved that koalas had disappeared from Tantawangalo by 1996, so the newly established National Park had come too late to save the koalas6. In October, 2013, a logging contractor saw a healthy koala crossing a road within the National Park at Tantawangalo and advised the exact location to an officer of NPWS, but this record does not appear on the NPWS ‘Wildlife Atlas’ database.

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