Endangered Koalas Emphasize Consequences of Climate Change

The koala (Phascolarctos cinereus), is a herbivorous marsupial that is native to Australia. Distributed from the broad coastal swathe to the eastern seaboard of Australia, the koala is an animal very representative to the country. Due to threats of vegetation loss, climate factors and man-made actions mostly in coastal regions of Australia, the Commonwealth government listed koalas as “vulnerable” in 2012 under the Environment Protection and Biodiversity Act 1999. Koalas living in Queensland, New South Wales and Australian Capital Territory are under the protection of national environmental laws due to its population pressure, while koalas living in Victoria and Southern Australia are not considered threatened and are found to be common and even over populous.

Many of koala’s homes have been lost and are more susceptible to climate change following up to droughts and wildfires. Climate change has directly impacted a koala’s habitat, diet, behavior, and reproduction, seizing them to decline in their population throughout the years.

The koala and its effects on climate change

The koala (Phascolarctos cinereus) is an Australian marsupial distributed throughout Australia, with a concentration in the country’s coastal regions. [Toons, Toons, 2004]. The scientific classification of a koala goes as follows: Phylum: Chordata, Class: Mammalia, Order: Diprotodontia, Family: Phascolarctidae, Genus: Phascolarctos, Species: P. cinereus [Toons, Toons, 2004]. The koala is believed to be descended from their closest marsupial relative the wombats, almost 25 million years ago, and 6 distinct members of the family have evolved. [Toons, Toons, 2004]. Although koalas have “bear-like” features and are often mistaken with the nickname “koala bears”, they are not bears but herbivorous marsupials. Their physical appearance consists of a small compact body, a broad head, large nose, and small eyes [Toons, Toons, 2004]. They are a medium sized animal that usually weighs 11 to 26 pounds and measures at about 28 to 31 inches. Sizes vary depending on their sex (males are 50% larger than females), and distribution (koalas from Queensland are relatively smaller than koalas from Victoria) [Toons, Toons, 2004]. They have large and rounded ears with white edges on them and a vestigial tail [Toons, Toons, 2004].

Koalas have the benefit of having strong limbs with large paws and sharps claws, useful for climbing trees where they live and gripping onto smooth eucalypt bark. Their fur is highly important for insulation and the texture and color of their fur depends on their distribution. Koalas located up in northern Australia have lighter and shorter coats, compared to koalas living down in southern Australia where their fur is more dense and darker in color [Toons, Toons, 2004]. Males have scent glands to mark their trees for territory claiming and females have pouches for their babies and two teats [Toons, Toons, 2004]. Koalas are herbivores and their diet consists of 30 different species of eucalypt trees and non-eucalypt leaves, but they can be very picky eaters because out of the 650 species of eucalypt found in Australia, they choose to feed on about 30 species of them [Toons, Toons, 2004]. They eat up to 1.3 to 1.8 pounds of leaves a day and they grab their food by climbing up smooth eucalypt trunks and can even leap up to 6 ft. to another trunk [Toons, Toons, 2004].

Eucalypt leaves are not very nutritious and are indigestible due to large continents of cellulose, lignin and toxic chemicals, but koalas have the capacity to detoxify and excrete toxic compounds through their liver. [Toons, Toons, 2004]. Their water intake is through their consumption of eucalypt leaves and drinking from streams at times. A koala's habitat consists of eucalypt forests and woodlands. Adult koalas occupy fixed ranges where they live in only a dozen favored trees. Up in northern Australia, the temperature is high year round and have strong seasonal rainfall while down in southern Australia, rainfall is very high and winters are cold [Toons, Toons, 2004]. Koalas have the cool ability to use evaporative cooling in their airways to regulate temperatures, and when they are exposed to cold temperatures, they conserve heat by reducing blood flow to extremities and shiver to produce heat by rapid muscle contractions [Toons, Toons, 2004]. A koala’s behavior is usually solitary with no or little interaction, with exception to when they are in breeding season. They are nocturnal animals, where they use that time of day to feed or to move, but they rarely leave the security of their tree. Koalas can sleep up to 20 hours and when they are awake, they usually rest and feed for about 10% of their day [Toons, Toons, 2004]. Individual koalas will own their own food trees and trees within their habitat fixed range, leaving scent marks to warn other animals and may aggressively attack trespassers [Toons, Toons, 2004]. Adult male koalas will use 2.5 aces of fixed range, while a female will use only half of that. For their reproductive biology, male koalas will reach full maturity when they are 4 years old, and females when to reach to be 5 [Toons, Toons, 2004]. Koalas maintain polygamous relationships.

A dominant male will attempt to mate with a female within his fixed range. They do this by defending their territory for breeding rights with females, using chest glands to scent mark tree trunks, and bellowing to warn fellow rivals and to attract females [Toons, Toons, 2004]. Females breed once every year, usually between the months of November all the to the month of March, and gestation for a female will usually last about 35 days before a single young koala is born (they very rarely have twins) [Toons, Toons, 2004]. A young koala will usually weigh about 0.5 grams and will measure to at about 2 cm long. Newborns will then crawl into its mother’s pouch and it attaches itself to one of its mother’s teats and will spend inside their mother’s pouch for about 5 to 7 months, and then move on to wean for another 6 to 12 months [Toons, Toons, 2004]. When the juveniles reach the age of 2, they will set out to find their own home range [Toons, Toons, 2004]. The legal status of koalas is “vulnerable” under the Environment Protection and Biodiversity Conservation Act 1999, set in 2012 by the Commonwealth government for koalas habiting in Queensland, New South Wales and Australian Capital Territory [Koala Facts, 2017]. The legal status of koalas is quite complex because some populations are under serious pressure due to habitat loss in certain parts of Australia and in other parts they are even quite over populous. [Department of Environment and Energy, 2012]. Koalas that are living in Victoria or in South Australia not considered to be “vulnerable” and are not protected under any national environmental law [Department of Environment and Energy, 2012].

The effects of climate change have become a threat to koalas. Reason to why environmental regulations were being done to give the koala a better chance of survival. It is significantly important to understand how a koala is impacted by climate change, and by any means, what can be done in their favor. Climate change has influenced a koala’s overall state in relation to its diet and habitat. In warmer regions, using mesowear methods, a koala’s mandibular teeth will decrease with increased temperatures [Desantis, Alexander, Biedron, Johnson, Frank, Martin, Williams, 2018]. Plants with high water contents are preferred because they will regulate body temperature and will restore water loss, so in warmer regions, koalas increase their panting to ease evaporative cooling and this can lead to water loss. [Desantis, Alexander, Biedron, Johnson, Frank, Martin, Williams, 2018]. Basically, koalas thrive better in cooler environments than in hotter ones. Climate changes can affect their nutrients and moisture that is available to their diet, for example, low rainfall results in low leaf moisture. [Davies, Gramotnev, Mcalpine, Seabrook, Baxter, Lunney, Bradley, 2013]. Since eucalypt leaves are from wear koalas mostly get their water intake, a low leaf moisture would mean less water for the koalas. Droughts and heatwaves have caused a low to a koala’s health like anemia and having high loads of ticks, causing their mortality rate to go higher. [Davies, Gramotnev, Mcalpine, Seabrook, Baxter, Lunney, Bradley, 2013].

From 1995 to 2009 in Queensland, a decline up to 80% resulted in the lasting numbers of koalas with drought being the main reason [Davies, Gramotnev, Mcalpine, Seabrook, Baxter, Lunney, Bradley, 2013]. That being said, it can be assumed the climate change predictions in relations to drought and heat waves will lower moisture levels in a koala’s home and food, making them cope badly with climate change. Wildfires have also played a huge role in the destruction of a koala’s habitat and resources. Some have resulted seriously burned (especially their paws because of their contact with their tree or trying to escape its ground) and most likely killed due to the fires [Feltman, 2015]. During the summer season in Australia, hot and dry weather makes it easy for wildfires to start, and they move very fast, making koalas who sleep at an average of 18 hours in their trees and an easy target for destruction. [Feltman, 2015]. A picture of a firefighter sympathetically offering a water bottle to a koala after another fire outbreak broke a media cry [Moyal, 2014]. Climate change also has an effect on their behavior and reproduction. Droughts and winters trigger their stress levels due to the decline of water and nutrient moisture [Activity Patterns of Free-Ranging Koalas, 2013] And efforts in breeding are reduced due to intolerable hot conditions [Activity Patterns of Free-Ranging Koalas, 2013].

The koala is an animal that relies heavily and significantly upon around its environment, and climate change effect on it has caused koalas number to go down. Even though they are listed as “vulnerable”, hopefully, koalas will not get to a point where their breeding will be made in captivity just to secure their survivorship. Keeping these creatures safe rely on national and state governments in Australia, and securing their survival depends on human action. 

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