Stressed, Hungry, and Disappearing, The Life of a Koala
Author: Cameron Hersey, Edited By: Autumn Berlied
Koala populations are declining due to the effects of climate change. What does this mean for the future of Koalas?
When you first think of a koala, you probably think of a small cute fuzzy bear that lives in Australia, spending its time lazing around and eating leaves. While this is true, it is important to know that current populations of koalas are declining due to the rapidly changing climate that they live in. Koalas are known as specialized folivores, feeding primarily on leaves of specific plants such as the eucalyptus plant. This specialized feeding makes koalas very dependent on an environment that specifically suits their needs, meaning they must live in an environment with eucalyptus leaves. Being confined to a specific environment makes koalas extremely vulnerable to weather extremes that occur there, such as intense heat waves and droughts (3) which are becoming increasingly common where they reside in their home range.
When taking a closer look at koala populations, data clearly shows that the previously mentioned weather extremes of heatwaves and droughts (3), as well as the environmental factors consisting of diminishing quality of their leaves (2), and stress in the form of environmental changes (1) is affecting koalas in a handful of ways that are concerning to the survival of natural populations
Stressful environments for Koalas
The current heatwaves and droughts due to climate change, is causing koalas to have increased levels of physiological stress, which affects the overall stability of their populations (1). These sources of stress include predation from large birds and wild dingoes, competition for food and space, and increased temperatures in the form of global warming. In particular, increased global temperatures from global warming are having the most significant impact to koalas. With the increasing occurrences of droughts, storms, and heatwaves, koalas are facing much more stress than they are naturally used to. In a study conducted in 2013, researchers observed the stress levels of populations of koalas that reside on the outer edges of their home range to determine if they were experiencing stress, and if so, be able to predict that the rest of the population would become stressed. The koalas that live on the outer edges of their habitats are the ones who are going to be affected by outside sources of stress before the ones who live more centrally within their habitat will. By examining these koalas and finding out if they are experiencing increased levels of stress, then it can be predicted that these stressors will make its way centrally until the whole population has become increasingly stressed from these same factors. When an animal is exposed to continual amounts of stress, this starts to make them more vulnerable to diseases and lowers their reproductive and survival rate (1). It is of the upmost importance to understand why and what is causing an animal stress to determine the ways in which we can help them before the populations begin to decline drastically enough to the point of extinction. One of the results of this study found that koalas are experiencing higher levels of stress during periods of decreased rainfall (droughts), which is a cause of our warming climate. This is because there is a lack of water availability for the populations, causing dehydration. One should see these results as concerning to health of koala populations (1).
Impacts of Droughts on Leaf Quality
A decrease in water availability increases the stress levels of our koalas in the form of dehydration. Their food supplies are also decreasing and the quality of the plants they eat are decreasing as well, which reduces the amount of nutrients they are receiving. Both water availability (1) and the rising levels of CO2 in the environment are affecting the leaf quality, therefore the nutritional content, of eucalyptus leaves in Australia (2). Without a sufficient amount of rainfall, eucalyptus trees are not able to produce enough leaves or will lose most of their leaves as they fall off (2). The increasing drought levels will only further damage the koala’s food source which will in turn only be able to support a smaller number of koalas. Furthermore, plants growing in conditions of higher CO2 levels will exhibit a 30% reduction in proteins within eucalyptus leaves that help with digestion in koalas (3). Both factors of increased droughts and CO2 levels are bad for the future of eucalyptus leaf coverage in koala habitats.
Impacts of Such Stressful Environment
So, what are the short and long-term impacts that koalas will come to face? In the short term, we have seen a decrease of 59,000 to 11,600 (an 80% decrease) in koala populations located in Queensland Australia (3) due to the effects of these stressors in just a short 14 years (1995-2009). In the long-run, researchers expect to see an influx on koalas searching for new habitats that have trees that offer them more shade and leaves with better moisture content for their nutritional value. Koalas are not well adapted to travel far distances, which makes them more susceptible to predators, passing vehicles, and additional stress that could bring about more disease and sickness among koala populations (2). Additionally, within the next 50 years it has been predicted that even further rates of decline will occur in koala populations (figure 2).
Koalas are in dire need of our help as soon as they can get it. These peaceful creatures are being harmed by us through deforestation, increasingly warmer climate, increasingly rising CO2 levels, and overall habitat loss (3). If you are interested in providing any support you can to these small and adorable animals then here are some charities you can donate to that go directly to helping koala’s by protecting their habitats, offering aid to hurt koalas, as well as finding new, safer, habitats to live in: Australia Koala Foundation, Koala Hospital, and Give2Asia which aids the ongoing crisis of the Australian bushfires.
Figure 2: Illustrations of the predictions for diminishing koala habitats over the next 50 years. (source: insideclimatenews.org)
Citations
1. Davies, Nicole Ashley, et al. “Physiological Stress in Koala Populations near the Arid Edge of Their Distribution.” PLoS ONE, vol. 8, no. 11, Dec. 2013, doi:10.1371/journal.pone.0079136.
2. Seabrook, Leonie, et al. “Drought-Driven Change in Wildlife Distribution and Numbers: a Case Study of Koalas in South West Queensland.” Wildlife Research, vol. 38, no. 6, 2011, p. 509., doi:10.1071/wr11064.
3. Lunney, Daniel, et al. “Koalas and Climate Change: a Case Study on the Liverpool Plains, North-West New South Wales.” Wildlife and Climate Change, 2012, pp. 150–168., doi:10.7882/fs.2012.022.