An animal that was rare once but isn't now

The Koala (Phascolarctos cinereus) is a thick-set, tail-less arboreal marsupial that feeds almost entirely on the leaves of a few species of Eucalyptus.  The Koala deals with such a low-nutrient diet by a specialised digestive system and a very low metabolic rate - it sleeps a lot.  The current distribution of the Koala includes most forest areas of the state outside of the alps and north-east of the Dividing Range.  The species is not listed as rare or threatened in Victoria or Australia but it is listed as near threatened in the IUCN Red Book.  It is listed as rare in South Australia, vulnerable in parts of NSW and least concern in Queensland.

When James Cook and Joseph Banks landed in eastern Australia in 1770 they saw kangaroos, quolls, flying foxes and possums but no Koalas.  After the First Fleet, in 1788, new species of arboreal marsupials were quickly noticed and collected, and by 1792 the Common Ringtail Possum, Yellow-bellied Glider, Common Brushtail Possum, Squirrel Glider and Greater Glider had all been formally described.  Even the tiny Feathertail Glider had been described by 1794.   But it wasn't until 1798 that the first specimen of a Koala was collected by a European and a formal description of the species was not completed until 1817.  This gives a strong indication that Koalas were not very common in the Sydney region at the time of European settlement.  Victorian records tell a similar story with very few accounts of Koalas outside of the forests to the east of the state in the first few decades after settlement.

The relative rarity of Koalas in Victoria changed quite rapidly and it has been suggested that the increase in numbers corresponded to the decline of Koori populations across the state.  Koalas at one time formed significant part of the Koori diet - they are slow-moving and relatively easy to catch - and their numbers were probably kept low where Kooris hunted regularly.  The widespread eradication of dingoes, which began in the mid 1800s, would also have released pressure on the Koala population.  By the late 1880s Koalas were in large numbers throughout the forests and woodlands of Victoria wherever suitable eucalypts were found. 

Koalas are fairly particular about their diet and when they have a choice they will only eat the leaves of a few species of eucalypt.  In Victoria, the Koala's favourite eucalypt is the Manna Gum (Eucalyptus viminalis) which is also the most widespread of all Victorian tree species.  In fact the four most commonly utilised eucalypts (Swamp Gum - E. ovata : River Red Gum - E. camaldulensis : Blue Gum - E. globulus) are all in the top eight most widespread tree species and their combined distribution covers all of Victoria except for the Mallee and the Alps.  Consequently, the apparent restrictive nature of the Koala's diet does not present any significant barriers to its establishment almost anywhere in the state, something that is reflected by the current distribution.

The huge populations of Koalas inspired the fur trade into action and the late 19^th and early 20^th century was a time of almost nation-wide hunting of the species.  The export of hundreds of thousands of Koala pelts to England and the USA coincided with a decline in chinchilla numbers and as Koala fur became more popular (some of it sold as chinchilla) the wild populations declined dramatically.  By 1924 the Koala was extinct in South Australia and Victorian numbers were down to about 500, scattered across the state, often in isolated areas, and there were genuine fears for the species survival.  Shortly afterwards Koalas were designated as protected species by the Victorian government and plans were put in place to halt the decline in its numbers.

In the late 1870s some Koalas had been taken by private individuals to French and Phillip Island, south-east of Melbourne, places where they were not native.  By the 1920s they had reached unsustainable numbers and in some places the koalas were starving while the trees they fed on were being killed by defoliation.  Some animals were translocated to nearby Quail and Chinaman Islands to alleviate the problem but the overpopulation was simply repeated some years later.  Relocation from all four islands was continued to other parts of Victoria (and South Australia) and over the next few decades these animals formed the core of most of the state's Koala population.  Koalas were re-established in areas from which they had vanished and new populations were created in places that they had never been recorded from before.  In many places the colonisation was very successful and numbers began to increase.

Currently the Koala is considered to be secure in Victoria but a serious problem remains that a large proportion of the animals come from a very limited breeding stock.  Other matters such a bacterial disease that causes infertility on females, fragmentation of suitable habitat and overpopulation in isolated locations have all created significant management problems for biologists.  Koala numbers are almost certainly not back to what they were in the early 1900s but it is doubtful that there is enough suitable habitat to sustain populations at those levels.