Stress-related disease

James Warren & Associates Ecological Assessment 2011 (JWA 2011) noted that all koalas observed during the survey appeared to be fit and healthy.  However, since the JWA 2011 assessment, the resident koalas have been subjected to ongoing disturbance from increased human-related activities.   The above known incidences of disease provide evidence that there is a link between this disease and the cumulative effects of ongoing disturbance and threats since the JWA 2011 ecological assessment.

Possible causes of disease

The Dreamworld Wildlife Foundation Koalaland Report (Coomera) has gathered information relating to koala disease from researchers, scientists, vets, wildlife carers, wildlife rescuers and zoo keepers. They state that in the wild a large proportion of koalas live with Chlamydia. However, the symptoms of the disease only manifest when koalas are stressed, thereby causing their immune system to become compromised.  When this occurs they are unable to fight the Chlamydia bacterium, which then becomes dangerous and fatal. Koalas become stressed due to habitat loss, habitat fragmentation, dogs, road trauma, bush fires and disturbance generally. Koalas are especially prone to Chlamydia when their home ranges are isolated due to fragmentation of habitat – families stop breeding and reproducing, and koalas die off.

A paper by koala expert and leading ecologist, Dr Steve Phillips (set to be published in late 2016) establishes a link between human disturbance and stress-related disease.  His evidence reveals that the manifestation and incidence of stress-related disease in koalas residing adjacent to the human interface is much higher than in their counterparts residing in large habitat blocks which buffer koalas from human disturbance.

There are 1.5km of edge effects (perimeter of the sports field and access road) where koalas are exposed to stress-related disturbance caused by human-related impacts.  Other possible causes are the Pottsville Wetlands’ Christmas day 2014 bush fire and the habitat fragmentation created by the location of the sports field and access road within the koala corridor.

In his email dated 26/1/2015 leading Ecologist and Koala expert Dr Steve Phillips states:

It may already be that the levels of disturbance at Black Rocks are already contributing to elevated levels of disease in the small population that is now left following the recent fire event.”

Black Rocks Independent Koala Plan of Management 2004, 3.4 page 11 states:  

Disease may be a major threat to the Pottsville koala population.  Animals most at risk are those which occupy disturbed or isolated habitats which are subject to human related disturbance.... koalas occurring in more fragmented habitats are likely to be highly stressed.’

The following are extracts from a report by ecologist Dr Steve Phillips to the Environmental Defenders Office dated 24/2/2016 regarding the development application relating to the construction of a Men's Shed at the Black Rocks sports field (click here ) :-

6.(i) Increases in noise levels associated with construction of the shed.  Koalas have recently been confirmed as responding adversely to loud noise, in some instances departing from their known home range areas.  The implications of this behavior can result in elevated stress response manifesting in disease, joey mortality and death by misadventure.....The implications of this knowledge are that episodic disturbance events brought about by loud noise can potentially result in elevated stress responses and/or disease levels resulting in reduced reproductive output and even mortalities (page 4).  (See impacts here )

7.  .....Photographic and veterinary evidence compiled by the local community indicates that koalas in the vicinity of the Black Rocks sports fields already have higher levels of clinical expression of disease than do their counterparts in other population cells comprising the population of the koala in the Tweed Local Government Area east of the Pacific Highway.  Whether this is a consequence of the extent of existing levels of disturbance or not remains to be determined, but in my opinion again warrants that a precautionary approach to considerations of potential impact be undertaken (page 4).

9.  Population Viability Analyses has confirmed that the annual loss of just 2% - 3% of a local koala population due to incidental mortalities such as vehicle strike and/or domestic dog attack and/or stress related disease is sufficient to drive ongoing population decline (Phillips et al. 2007).  In the case of the Pottsville Wetlands - Black Rocks local koala population and because of the 2014 fire event, it is likely that the population size is currently less than the 35 individuals estimated in 2010 (page 5).   [NOTE:  The rate of koala death at Black Rocks is twice the 2% - 3% that Dr Phillips says will drive ongoing population decline.] See more here .

10.  It is clear that even the loss of 1 or more individuals each year from this population should be avoided if ongoing population decline is not to be accelerated (page 5).


How many more koalas must suffer and die before Tweed Shire Council understands the gravity of the situation and does something constructive about it? Clearly the signage isn’t working to stop stressful, impactive behaviours of people. It’s because of the isolated location of the sports field that these events are happening. Clearly it’s the wrong place for a sports field.

What is chlamydia?

Chlamydia is an organism that lives in the body tissues of most healthy koalas. In normal populations it may act as an inbuilt mechanism to limit the population so trees are not overbrowsed so that only the strongest and fittest koalas survive. Chlamydia can sometimes make koalas sick but usually only when they are stressed due to habitat loss, fire, cars, dogs, hunger and so on.

What are the symptoms?

Chlamydia causes blindness and infertility in koalas and can be fatal. Visible symptoms include conjunctivitis and ‘dirty tail’ caused by urinary tract infections and incontinence. About 50% of females become infertile as a result.

Cumulative effects of stress-related disturbance

Koalas in the Black Rocks sports field vicinity have a considerable number of stressors.  8 known Black Rocks koalas have been affected by symptoms of the stress-related disease chlamydia and/or death between January 2014 and January 2016:-

     • “DAVE” euthanased on 24/2/2014 (captured in tree on edge of access road) 


"MAX" euthanased on 27/5/2014 (captured in Kellehers Road)

• Koala sighted in tree on edge of Black Rocks sports field access road 6/1/2015, uncaptured, presumed dead


• "POTTSY" euthanased on 9/9/2015 (captured west of Border Crescent)

• "CANARY" found dead on ground near red gum koala breeding 250m north-east of sports field on 22/11/2015, cause of death known


• "LUCIA" (juvenile) captured on 13/12/2015 in tree on edge of access road (received treatment in Currumbin Wildlife Hospital and released on 7 February 2016


• The mother of "LUCIA" (sighted on 5 occasions during 2015 koala breeding season adjacent to sports field and access road [PHOTO]) has advanced symptoms of chlamydia.  If uncaptured and untreated, she will suffer a slow miserable death in the bush.


     •     "SANDY" euthanased on 9/1/2016 (captured in red gum breeding area east of sports field) 

•     Photos of at least 8 other koala sightings reveal chlamydia-like symptoms.

The entire sports field and access road were closed down to vehicular access for a day (7/1/2015) to minimise stress to diseased koala sighted on 6 January 2015.