Table of Contents
The Koala’s Plight
The Natural History of the Koala
In conclusion
The Koala’s Plight
The koala is an unusual and unique animal. The koala, although commonly mistaken for a bear is actually a marsupial. It is closely related to bandicoots and American opossums than any other species of bear. Most people know the koala as a cute, furry creature that lives on the Australian continent. The koala, although it is known as a cute and furry animal in Australia, is actually a more interesting creature. The koala’s turbulent history, its unique mating rituals, and reproductive habits will be explored.
Before we discuss the natural history of the Koala, it is important to describe the physical characteristics of the animal. Koalas have pouches in which the young are developed. The pouch has a drawstring-like muscle and faces backwards. Koalas live alone and only meet to mate. Koalas have been the sole members of their species due to evolution and extinction. (Phillips,1994) Koalas average between 680 to 820 millimeters from head-to-tail, with males being longer. The average koala weighs between 4.9 to 14.9 kilograms. Males are heavier than females. Due to climate differences, northern koalas are shorter and lighter than southern koalas (Smith and Harman 1997). Koalas, which are arboreal animals, live in the trees. Their fur is thick and wooly, and they are usually grey with white spots on their rump.
Koalas have a unique biological makeup. Koalas are very selective eaters and only eat leaves of certain species of eucalyptus trees that can only be found in the rich soils along the east coast. The leaves of these trees are half-water, so the koalas can drink without ever leaving the safety and security of their trees. The eucalyptus leaves are also very high in fibre and low in proteins. The koala’s digestive system is unique, with a small stomach and an extremely large caecum. This caecum could be considered the equivalent to a human’s appendix. Here, the leaves that are chewed are stored. A flora micro-organisms in the koala carry out symbiotic metabolism. A very low metabolic rate is another adaptation that koalas make to a low-protein diet. It results in lower body temperatures than most mammals (Phillips, 1994). It is believed that koalas sleep for 18 hours per day on average due to their lower metabolism. Koalas use a number of strategies to maintain a higher body temperature. For example, they have thick dark fur that covers their backs in order to hold and absorb energy from the sunlight. Their large, black, moist nose is also used as a sort of thermostat.
The marsupial group has existed for millions of ages in forms very similar to the modern koala. Evidence suggests that pre-historic marsupials dominated the landscape before Pangaea divided into our seven continents. These evidences suggest that marsupials once inhabited the region that is now Australia, South America, Antarctica, and that koalas were first evolved 45 million year ago. The marsupial group may have reached its evolutionary peak due to the diversity and vastness of their habitats. Today, marsupials are in decline and their habitats have shrunk. The koala population has decreased by more than 90% according to some estimates.
Australia was peaceful before Europeans arrived. There were very few interspecies attacks. Soon after their arrival, Europeans learned just how easy it was to capture and kill koalas (Phillips, 1994). Though koalas are preyed on by the European Fox, dingos and pet dogs as well as some owls or goanna treelizards, they are very rare. Only humans are the koalas’ only true natural predators. The Europeans were raping and pillaging the species soon after they arrived. Millions of Koalas were killed and hunted to get their fur. By the end of 1890s, when first records were made, 30,000 skins or more were sent each year to London. The furs used were not high-fashion but rather a durable and cheap fur. Koala populations had been decimated on the East Coast by the turn of this century. By the 1930s, South Australia was a koala-free state and the Mideast and North were home to very few koalas. The laws prohibiting the killing were passed in 1898. But economic hardships led to the hunting being necessary. Between 1915-1920, open hunting of koalas allowed around 1,000,000 koalas to be exported each year. In 1927 an additional half million koalas could be slaughtered in a single month and sent primarily to America. In 1927, Herbert Hoover signed legislation permanently banning koala-skin imports. But the damage was already done. By 1940, South Australia’s koalas had become extinct, and there were very few left in the north. Inadvertently, the extinction of the koalas was prevented by a Victoria resident who gave three koalas as a gift to a Phillip Island resident. The koalas thrived on the island, which was mostly empty. When a healthy number of koalas accumulated, they were then translocated to Victoria, in Southern Australia. The koalas population is now below 100,000, and they are scattered franmentally along the east coast. The eucalyptus tree population has been impacted by development and deforestation, affecting the location of koalas (Wright, 2001).
The anatomy and physiology involved in reproduction is what separates marsupials. In contrast to most mammals, marsupials do not have a placenta that is complete. This allows nutrients to be transferred from the mother into the embryo. In marsupials an egg-like placenta forms through which a memberane encircling the embryo is developed. The amion is what we call it. Koalas and other female marsupials have an aduplicate reproduction system. In order to facilitate the passage of urine between their two vaginas, they are sufficiently separated. When the birthing process is in progress, the offspring usually exits via a birth canal that runs between the two uteri and the urogenital area (Phillips, 1996). Koalas also have a very unique way of reproducing. The breeding begins in summer and this is signaled by meales bellowing. These low-pitched exhalations and halations of the meales can be clearly heard up 600 meters. They serve to advertise to females that are receptive to males’ presence. Koalas differ from other mammals when it comes to sex in that they initiate and carry out the courting by the female, not the male. The male does advertise himself though. The female will usually initiate the foreplay, which can be rough and elaborate. She holds her tree while jerking her arms and flapping her ears. In the next sequence, the female bites the neck of her male partner. This takes about 15 to 20 minutes. It culminates with a short period of copulation and intercourse. The male penetrates while the female lifts her rump. After the male has gone, she appears to go into an orgasmic cycle of contractions. Her head is thrown back wildly. It is important that the mating ritual be performed quickly because female koalas reproduce only once a year.
The gestation for a koala lasts about 34-36days. Once the baby has left the urogenital opening, it moves into the marsupial sack where the development of the animal will continue for another six months. Koalas have an average lifespan ranging from 10 to 18, with males having a shorter life span than females. With the increasing deforestation in Australias eucalyptus forest (Phillips 95), there is a trend towards shorter lifespans.
The debate in Australia and around the world is about whether koalas should be classified as endangered or not. The eucalyptus trees, the only source of food for the koalas, are being cut down at an alarming rate. As a result, the habitat that they need to survive is shrinking. Deforestation can also lead to small, isolated forests that are not able to move, which could be dangerous if a deadly disease like chlamydia were introduced. This rate of reproduction will overwhelm the vegetation as the koalas outpace new tree growth. Koalas are starving as forests disappear (2001). This is exactly the view taken by most non-environmentalists, where the problem lies in the exploding population rather than the rapid decrease in forests habitable by koalas caused by deforestation and development of highway systems. Other solutions proposed by these people include the illegal shooting of koalas as well as relocation and sterilization. These solutions are useless if habitat is not preserved. Relocation isn’t feasible as there aren’t enough forested areas to accommodate the koala and sterilization can be expensive and difficult. The Australian Koala Foundation is one of many Australian groups dedicated to preserving the koala. The AKF is one of many groups in Australia that are dedicated to the preservation of the koala.
ConclusionKoalas can be described as a very unique species. It has been peaceful for a very long time. The koalas are not being blamed for the current heated debate on endangered species. Instead, the focus is still placed on how to reduce the number of animals. The public, with the help of organizations such as AFK will come to realize that the best way to control the koalas is by halting deforestation.