Despite its teddy bear appearance, the koala is not at all related to bears. It is a marsupial mammal native to Australia that has a bag in which its young develop. It spends about four hours a day feeding primarily on eucalyptus leaves and spends the rest of the time sleeping. We invite you to continue reading this article so that you can have all the information about the Koalas.
Koala Information
The koala is a variety of marsupial that lives in Oceania and is the only member of the Phascolarctidae family, exclusive to Australia. It is closely related to another extant marsupial, the wombat. It populates the coastal areas of the eastern and southern regions of Australia, in the states of Queensland, New South Wales, Victoria and South Australia.
It is easily recognized by its stocky build without a tail, huge head with rounded, furry ears, and large spoon-shaped nose. Its size varies from 60 to 85 centimeters and its weight is between 4 and 15 kilograms. Their fur color ranges from silver gray to chocolate brown. The specimens from the northern regions are usually smaller and of a less dark color than those from the south, so it is estimated that they may constitute a separate subspecies, although this thesis is still under discussion.
They reside in cleared areas of eucalyptus groves, whose leaves are the element with the greatest presence in their diet. Since this diet provides insufficient nutrients and calories, koalas live a sedentary existence, usually sleeping up to twenty hours each day. They are creatures with little social interaction and hardly show an elementary link between mothers and their dependent offspring. Communication between adult males consists of powerful roars that instill fear in rivals and serve to attract females.
The males demarcate their territory through the secretions of the scent glands located on their chest. Like other marsupials, their young are not fully developed at birth and immediately climb into their mothers' marsupium or abdominal bag, where they stay for their first six or seven months of existence.
The young are fully weaned at one year of age. They have few parasites and natural predators, despite the fact that they are threatened by various pathogens and are exposed to chlamydial infections and the koala retrovirus. Forest fires and droughts are other threats facing the koala.
There is evidence that Australian Aborigines were already hunting these creatures and they have been depicted in their legends and rock art for thousands of years. The initial encounter between a European and a known koala took place in 1798 and the naturalist George Perry published an image of this animal in 1810.
Botanist Robert Brown wrote the first detailed review of the koala in 1814, despite the fact that his work remained unpublished for 180 years. The ornithologist and artist John Gould drew and detailed these creatures, making the species known to the general British population, and throughout the XNUMXth century other English scholars expounded more on its biology.
Due to its characteristic appearance, it is recognized worldwide as one of the representative images of Australia, and is also the symbol of the fauna of the state of Queensland. The koala is listed as vulnerable on the International Union for Conservation of Nature Red List. The Australian government has also listed particular populations in Queensland, New South Wales and the Capital Territory as vulnerable in their national statutes on the environment.
At the beginning of the XNUMXth century it was hunted in huge numbers by European settlers, particularly for its fur. Its greatest current threat is the devastation of its habitat caused by agriculture and urbanization. As is the case with most Australian wildlife, it is illegal to keep koalas as pets, both in Australia and elsewhere in the world.
Etymology
Phascolarctos cinereus is the scientific name for this animal, whose genus, Phascolarctos, comes from the ancient Greek language pháskōlos, which means 'bag', and árktos, which means 'bear', while the particular name, cinereus, derives from the Latin and translates as 'ash-colored'.
The word koala originates from the term 'gula', which in the Dharug language (Australian Aboriginal language), means "not water". Since these animals were rarely seen descending from the trees, it was thought that they could survive without drinking water. Eucalyptus leaves have a high water content, so the koala does not need to drink it often, but the idea that they did not need to drink water was shown to be a myth. Although the vowel 'u' was written in English spelling as 'oo' (as well as coola or koolah) it later became 'oa', perhaps by mistake.
The various Australian aboriginal groups use names such as cullawin, koolawong, colah, karbor, colo, coolbun, boorabee, burroor, bangaroo, pucawan, banjorah or burrenbong to refer to this animal. Due to its similar appearance to that of a bear , on occasions it was even named "koala bear", particularly among the first settlers who arrived in that region.
Taxonomy and Evolution
French-born zoologist Henri Marie Ducrotay de Blainville first cataloged the koala under the generic name Phascolarctos in 1816, although he decided not to give it a specific name until further review. In 1819, the German Georg August Goldfuss designated it with the binary name Lipurus cinereus but, since Phascolarctos was the first to be disclosed, according to the International Code of Zoological Nomenclature, it has higher priority as the scientific name of the genus.
The French naturalist Anselme Gaëtan Desmarest raised Phascolartos fuscus in 1820, stating that the specimens with brown fur were of a different variety than the gray ones. Other names proposed by European authors include Marodactylus cinereus by Goldfuss in 1820, P. flindersii by René Primevère Lesson in 1827, and P. koala by John Edward Gray in 1827.
The koala is classified together with the wombats (family Vombatidae) and other now extinct families (such as Palorchestes, Thylacoleonidae and Diprotodontidae) in the suborder Vombatiformes of the order Diprotodontia. The Vombatiforms are a sister grouping to a clade that incorporates the Macropodiformes (kangaroos and wallabies) and Possums. The ancestors of the Vombatiforms were possibly arboreal, and the koala evolutionary lineage was probably the first to branch off about 40 million years ago back, throughout the Eocene.
Today's koala is the only living member of the Phascolarctidae, a family that at one time incorporated various genera and species. Throughout the Oligocene and Miocene, koalas dwelt in jungles and had less specialized diets. Certain species, such as Nimiokoala greystanesi and some varieties of Perikoala, were similar in size to the modern koala, while others, such as those of the genus Litokoala, were one-half to two-thirds the size of today.
Like modern varieties, prehistoric koalas had highly evolved ear structures, suggesting long-distance vocalizations and sedentary behavior at an early stage. Throughout the Miocene, the Australian continent began to dry out, causing the decline of the forests and the spread of cleared eucalyptus forests.
The genus Phascolarctos separated from Litokoala at the end of that era and underwent various adaptations that enabled it to subsist on a diet that specialized in eucalyptus leaves, such as a modification of the palate towards the front of the skull, an increase in the size of the molars and premolars, a decrease in the size of the pterygoid canal and a wider gap between the molars and the incisors.
Throughout the Pliocene and Pleistocene, Australia underwent alterations in its climate and vegetation, and the varieties of koalas became larger and larger. Phascolarctos cinereus may have emerged as a smaller form of the giant koala (Phascolarctos stirtoni). The decrease in the size of large mammals is considered to be a frequent event throughout the planet throughout the Upper Pleistocene and some Australian mammals, such as Macropus agilis, are traditionally considered to be a consequence of this phenomenon.
However, a 2008 investigation objected to this thesis, pointing out that Phascolarctos cinereus and Phascolarctos stirtoni had the same distribution area from the Middle to the Late Pleistocene or even from the Pliocene. Fossil finds of the current koala extend at least until the Pleistocene Medium.
Genetics and Variations
There are three different traditionally recognized subspecies: the Queensland koala (P. c. adustus, Thomas 1923), the New South Wales koala (P. c. cinereus, Goldfuss 1817), and the Victoria koala (P. c. victor, Troughton 1935). They are recognized by the coloration and thickness of their fur, the size of their body, and by the shape of their skull. The Queensland is the smallest of the three, with shorter silver-colored fur and a smaller skull; Victoria's is the largest, with a larger skull and longer brown fur.
The limits of such variations are established in the same borders of these states and their status as a subspecies is still under discussion. Genetic research conducted in 1999 indicates that such variations are evidence of distinct populations that retain restricted gene flow between them and that the three subspecies make up a single Evolutionarily Significant Unit (ESU). Other research determined that koala populations showed high levels of inbreeding and little genetic diversity.
It was observed that in the northern areas there was greater genetic variability, while in the southern areas there was less variability and a higher level of inbreeding, which was consistent with certain abnormalities recorded, among others, in the testicles, in the southern individuals. At the continental level, obvious biogeographic obstacles could be observed, such as the Brisbane Valley, the Hunter Valley and the Clarence River, which make gene flow between populations impossible.
This little genetic variability may have been a particularity of koala populations from the late Pleistocene. It has been shown that rivers and roads restrict gene flow and contribute to the genetic differentiation of individuals from south-east Queensland. By 2013, researchers from the Australian Museum and the Queensland University of Technology declared that they had succeeded in sequencing the koala's genome.
The koala genome is made up of 16 chromosomes. Centromeres are smaller in marsupials than in eutherians (such as mice or humans). 47,5% of the koala genome is made up of repeated sequences, 44% of these are transplantable components. Regarding the coding regions, 6124 protein-coding genes have been identified.
Physical characteristics
It is a stocky animal, with a huge head and a poorly developed or non-existent tail. Its body length is 60-85 centimeters and it can weigh between 4 and 15 kilograms, which makes it one of the largest arboreal marsupials. Koalas in Victoria weigh twice as much as those in Queensland. The species does not show clear sexual dimorphism, despite males being 50% larger than females; those also differ from these by their more curved nose and by having pectoral glands (which produce odorous excretions), which can be seen as spots without hair.
Anatomy and Physiology
Like most marsupials, the male has a bifurcated penis and the female has two lateral vaginas and two independent uteri. The skin with which the male penis is lined has natural bacteria that play an important role in fertilization. The mouth of the female's pouch can be constricted by a sphincter to prevent the young from falling out.
Its fur is longer and thicker on the back and shorter on the belly. The ears are densely furred both inside and out. The fur on its back changes from light gray to chocolate brown, while the fur on its belly and hindquarters is whitish. The fur on its back It serves to be more effectively protected from the elements than other marsupials and has a lot of resistance to wind and rain, while the skin of the belly allows it to reflect the sun's radiation.
Its claws, curved and sharp, are well adapted to climbing trees. Its huge front legs have five fingers, the first and second being in the opposite direction to the other three, which enables them to grab small branches. On their hind limbs, the second and third fingers are glued together (something typical among diprotodonts) and the claws of these fingers (which are still separated) are used for grooming. As well as humans and other apes, koalas have with dermal papillae on their feet.
It has a solid skeleton and a short, highly muscular trunk, where its much longer forelimbs are of great help when climbing and clinging. Vigorous thigh muscles that fuse to the tibia in a lower area than in other animals give them extra strength when climbing. They have a cartilaginous pad at the end of the spine that is useful for feel more comfortable perching on tree branches.
Among all mammals, the koala brain, weighing just 19,2 grams, is one of the smallest in proportion to its body weight, up to 60% smaller than that of a typical diprotodont. The surface of its brain is extremely flat, a characteristic feature of the most "primitive" creatures (plesiomorphy). It reaches barely 61% of the cranial cavity and is pressed against the internal surface by cerebrospinal fluid.
The purpose of this fairly large amount of fluid is unknown, although it is possible that it acts as a shock absorber, absorbing shock and protecting the brain when it falls from a tree. The small size of its brain may be a adaptation to the energy limitations imposed by its diet, which is insufficient to support a larger brain.
Because of their tiny brain, koalas' ability to conduct complex or unfamiliar behaviors is restricted. For example, when offered leaves taken from a tree on a flat surface, the animal cannot adjust to the alteration of its regular feeding routine and does not eat them. Its ability to smell is normal and there is evidence that it smells oils from individual branches to determine their likely edibility. Its nose is extremely large and covered with leathery skin.
Their ears are rounded in shape and give them good hearing and they have a fairly evolved middle ear. In contrast, their vision is not very efficient and their eyes are not like those of other marsupials, since they are extremely modest and their pupils they have the shape of a vertical slit. To generate serious sounds they use a peculiar vocal organ; that, in contrast to the characteristic mammalian vocal cords, which fold into the larynx, this organ is located on the soft palate and is called the velar vocal cords.
Koalas have undergone various adaptations to adjust to their diet based on eucalyptus leaves, which are of low nutritional value, high toxicity and high in dietary fiber. The teeth of this animal are made up of incisors and postcanines (a single premolar and four molars for each jaw), which are separated by a large diastema (typical of herbivorous mammals).
The incisors are used to catch the leaves, which are then cut by the petiole with the premolars before passing them to the molars, with prominent cusps, in which they are crushed into small pieces. They can accumulate food in their pouches (bags on the cheeks) before chewing. The slightly worn molars of middle-aged koalas are perfect for breaking leaves into small pieces, facilitating more efficient digestion and assimilation of nutrients by the small intestine, where they are digested the eucalyptus leaves that provide most of the animal's energy.
Sometimes they regurgitate the food to the mouth to repeat their chewing. In contrast to kangaroos and possums, which also eat eucalyptus, koalas have a caudal fermentation digestive system (a process that takes place in the large intestine) and their digestive containment lasts up to 100 hours in the wild, and up to 200 hours in captivity. This occurs thanks to the exceptional extension of its cecum (200 centimeters in length and 10 in diameter), which is considered, proportionally, as the largest of all animals.
This anatomy allows them to choose which food particles to keep for longer fermentation and which to let circulate: large particles usually pass through faster, as they require a longer digestion time. Although their lower gastrointestinal tract is , proportionally, much larger than in other herbivores, the koala only obtains 10% of its energy through fermentation.
Since they obtain a meager amount of energy from their diet, the minimum amount of energy they need is half that of a typical mammal, although this is variable, depending on the season and the sexes. They have the ability to conserve water in the body by evacuating fecal balls that are almost dry but abundant in undigested fiber and accumulating water in the cecum.
Food and Activity
Koalas are herbivorous and, although the largest proportion of their diet is made up of eucalyptus leaves, they can be found in trees of other classes, such as Acacia, Allocasuarina, Callitris, Leptospermum and Melaleuca. Eucalyptus leaves include raised levels of secondary metabolites (phenolic complexes and terpenes) that are usually fatal to most mammals.
However, these marsupials can metabolize these xenobiotics. This is explained by the two particular monophyletic expansions of the cytochrome P2 450C family (CYP2Cs) achieved in koalas. Cytochrome P450 function plays an essential role in the detoxification throughout phase I of oxidative metabolism of a variety of compounds including xenobiotics.
Although they have foliage of more than six hundred varieties of eucalyptus in their range, they show a clear preference for only about thirty of them. They usually choose species that contain a high protein content and small amounts of fiber and lignin. Additionally, they choose those leaves with a lower amount of toxic secondary metabolites, thanks to the fact that they have a greater number of receptors in the vomeronasal organ and taste receptors such as TAS2R, which enable them to recognize elements such as terpenes, phenols and glycosides, some of which they are poisonous.
The foliage they prefer are those of Eucalyptus microcorys, E. tereticornis and E. camaldulensis, of which they make up on average more than 20% of their diet. Despite its reputation as a finicky eater, the koala is more generalist than other varieties marsupials, such as the giant glider. Since eucalyptus leaves have a high water content, they do not require frequent drinking; their daily water replenishment rate varies from 71 to 91 milliliters per kilogram of body weight.
They also choose the foliage with the highest water content, thanks to a duplication of the aquaporin gene. Although females can meet their water requirements only by feeding on leaves, the larger males need additional water supplies that they locate in the ground or in the cavities of tree trunks. To feed, they support themselves on a branch, securing themselves with the hind legs and one front leg while with the other front leg they detach the foliage.
Smaller koalas can reach the tip of a branch, but larger koalas stay close to the base of thicker ones. They gobble up to 400 grams of leaves each day, spread over four to six feedings. Despite their adaptations to a low-energy lifestyle, they have low fat reserves and require frequent feeding. Because they get so little energy from their diet, they must restrict their energy expenditure, so they only perform active movements per day. four hours a day and sleep the remaining twenty hours.
They are predominantly active at night and spend most of their waking hours eating. Generally, they feed and sleep in the same tree, where they usually stay for a day. On very hot days they tend to descend to the coolest part of the tree, much cooler than the surrounding air where they hug the tree. tree to dissipate body heat without having to pant. On hot days they often rest with their backs against a branch or lie on their stomachs or backs with their legs dangling.
In cold and wet seasons, they roll up into a ball to conserve energy. On windy days, koalas seek out thick, low branches on which to perch. Although they spend most of their time in trees, they come down to the ground to move from tree to tree, walking on all fours. They usually groom themselves using their hind legs, although they occasionally use their front legs or their mouths.
Reproduction and Development
They reproduce according to the season and births take place from mid-spring to summer and early fall, from October to May. Females in heat tend to have their heads further back than usual and often have tremors and spasms. However, the males do not seem to recognize these signals and cases have been contemplated in which they mount females that are not in heat.
Being much larger, males can force females to mate, copulating with them from behind and, in extreme cases, throwing the female out of the tree. The female may scream and fight vigorously against her suitors, but she will submit to an authoritative or acquaintance male.
The roars and cries they produce during mating can draw the attention of other nearby males, forcing the male to postpone mating and fight off intruders. Such contests make it easier for the female to decide which is dominant. It is normal to see cuts, scars, and markings on older males, particularly on the exposed areas of the nose and eyelids.
Ovulation is provoked, this means that, after intercourse, the male's ejaculated semen causes the luteinizing hormone (LH) to be produced, inducing ovulation in the female. The gestation period can last from 33 to 35 days and females regularly have a single young.
Like all marsupials, the young come into the world while still in their embryonic stage, weighing just 0,5 to 2 grams, despite the fact that they already have more or less well-developed lips, shoulders and limbs, as well as respiratory systems. , digestive and urinary operative. The newborn crawls to its mother's pouch to continue its development. In contrast to most marsupials, the koala does not clean its pouch.
The female has two nipples and the calf clings to one of them to nurse for as long as it will live in the pouch. Among all mammals, the koala has one of the lowest rates of milk energy production in the world. relation to their body size; to remedy such a limitation, the lactation period is extended for a full year.
Upon reaching seven weeks of existence, the head of the calf begins to grow proportionally to the body, the development of pigmentation begins and its sex can be defined, since in males the scrotum can already be seen and in females the marsupium begins to evolve. By the thirteenth week, the calf weighs 50 grams and its head has doubled in size, its eyes begin to open, and thin skin develops on its forehead, nape, shoulders, and arms.
At 26 weeks the calf already begins to resemble an adult, is fully covered with hair and already pokes its head out of the bag. As the young approach six months of existence, the mother begins to prepare it for its birth. eucalyptus regimen predigesting the foliage and generating a fecal paste that the young ingest from its cloaca. The composition of this paste is nothing like regular stool, more like the contents of the cecum, and includes a high concentration of bacteria.
The young begin to feed in this way for almost a month, obtaining through this paste a complementary source of protein, meanwhile the passage from a diet based on milk to one based on leaves takes place. It leaves the marsupial bag for the first time at six or seven months of existence, when it weighs between 300 and 500 grams, and then begins to explore its new environment cautiously, clinging to its mother for support. When they reach nine months, they exceed one kilogram in weight and begin to show the coloration of adult skin.
After having definitively left the pouch, it climbs on its mother's back to move around and learns to climb trees holding on to the branches. Gradually it becomes independent of its mother, completely weaning at 12 months, already weighing about 2,5 .XNUMX kilograms. When the mother becomes pregnant again, the link with her previous offspring is completely broken and she acts violently with the newly weaned so that they move away and separate from her. Females reach sexual maturity around three years of age , time in which they can already be pregnant.
In contrast, males reach sexual maturity when they reach four years of existence, despite the fact that they can already generate sperm at two years. Although their pectoral glands are already operative at 18 months of age, males do not they undertake their scent marking behavior until they reach sexual maturity. Since the young have a long dependency period, females usually reproduce in alternate years, although they may be favored by certain environmental factors, such as a contribution abundant with high-quality food-producing trees, may reproduce annually.
Health and Mortality
Their existence can last up to 13 or 18 years in the wild, although males usually live less than females due to their more dangerous behaviors. They usually survive falls from trees and immediately climb again, but cases are known in which they can suffer injuries or even perish, particularly among inexperienced juveniles or when fights occur between males.
Around the age of six, their molars begin to wear down which reduces their chewing efficiency. Over time, the crests of these teeth disappear completely, causing the death of the animal due to weakening due to lack of food.
The predators of the koala are few. They are known to be hunted by dingoes and huge pythons, while birds of prey such as the robust nymphus or the bold eagle can take the young. They do not regularly suffer from external parasites, with the exception of ticks in coastal areas. They can suffer from scabies caused by the mite Sarcoptes scabiei and skin ulcers caused by the bacterium Mycobacterium ulcerans, although the two ailments are rare.
Likewise, internal parasites are not frequent and if they do exist, they are normally harmless. Among them are the cestode Bertiella obesa, usually found in the intestine, and the nematodes Marsupostrongylus longilarvatus and Durikainema phascolarcti, which are rarely found in the lungs. In an investigation that lasted about three years and was carried out with some 600 koalas housed at the Australian Zoo Wildlife Hospital in Queensland, 73,8% of them were infected with at least one variety of protozoan parasites of the Trypanosoma type, the most frequent of which was T. Irwini.
They can be affected by pathogens such as Chlamydiaceae bacteria, which can cause keratoconjunctivitis, urine infection, and reproductive tract infection. These infections are common in mainland populations, but do not occur in certain island populations. Koala retrovirus (KoRV), which belongs to the Gammaretrovirus genus, can cause Koala Immune Deficiency Syndrome (KIDS), a syndrome similar to HIV/AIDS in humans.
The proportion of KoRV-carrying individuals in koala populations shows a trend of spreading from north to south Australia, with northern populations fully infected, while some in the south (including Kangaroo Island) are free of this virus.
Social structure
Koalas are often thought of as extremely lazy creatures. Since their metabolism is very slow, they usually do nothing for 18 hours a day. Most of that time is spent sleeping. They like to be kept alone, which is not the case when a female tends to her young. Most people consider the koala to be a simple and calm animal.
However, they are recognized for being very violent with each other, as they get very upset if others try to invade their territory. As a result, it can be very difficult for young koalas to get their own space. They frequently bite and fight with each other. The young females stay by their mother's side until they reach a year of existence. By that time they are newly weaned and have an arduous road ahead of them depending on themselves if they have not been taught how to subsist. The males, in general, remain close to the parent until they approach three years of age.
It is interesting that it is the koalas themselves who choose to reside near each other. With only one of them in a tree, except for mothers with their young, they are usually close neighbors. However, they find satisfaction in being alone as long as possible. As there are few koalas in an area and a great abundance of trees, they will stay very close to each other, as it is considered that this is how they get comfort.
Most of the social interactions between these animals take place while they are searching for food. Since there is more than enough, they seem to show no interest in feeding in the same place as the others. Indeed, they prefer to enjoy short encounters and then go their separate ways.
Throughout the daytime hours, the koala chooses to hide in the trees, and there are several reasons for this. Firstly, that way they avoid predators, secondly, their body could dehydrate very quickly if exposed to the scorching Australian sun. They need to stay moist, so they explore shady places where they can take maximum shelter.
There are different kinds of calls that the koala can make for the purpose of communication. They force sounds to travel long distances in order to attract a mate. They use bellows to attract attention while growling to show aggression and warn when they want to be left alone. Mothers often use soft clicks to communicate with their young, this is a sweet way to bond with their child as well as teach them how to survive.
By screaming loudly, the koala seeks to alert everyone in the area that there is danger. They may display frantic behavior from the added stress and even begin to shake violently. This is a behavior by which koalas seek comfort from other individuals around them. For this reason, they usually make several sounds to each other to provide calm until the fear has vanished.
The non-verbal communication style they use serves to mark the trees with their particular scent. The males have huge, large scent glands that enable them to release greater amounts of their scent. The explanation for this is based on the fact that, in this way, they are more aggressive. From a general perspective, the social structure of the koala, in addition to being complex, is worthy of interest.
Sociability
They are creatures with little social interaction and spend just 15 minutes each day on social behaviors. In Victoria their range is small and very overlapping, while in central Queensland it is larger and less overlapping. The community of these animals appears to be made up of "residents" and "transiters", composed mainly for the first case of adult females and by males for the second. Resident males appear to be territorial and subdue other males with their larger body build.
Alpha males usually establish their territories in the vicinity of breeding females, while younger males act in a subordinate manner until they reach maturity and full body development. Adult males tend to occasionally venture outside their territory or area. of influence, maintaining its condition. When a male moves to a new tree, he marks it as his own by rubbing his pectoral gland against the trunk or a branch; they have also been seen on occasions urinating on the trunk.
This territorial defining behavior possibly serves to communicate a message and there is evidence that individuals smell the base of a tree before climbing it. Scent signaling is common in violent encounters. The excretions of the pectoral glands are complex substances chemical (in an examination about 40 compounds have been recognized) that are variable in density and composition since they depend on the season and the age of the animal.
Adult males communicate through powerful roars, deep sounds that are based on inhalations similar to snoring, and noisy exhalations that resonate as growls. Such sounds are believed to be generated by vocal organs unique to this species. low frequency, these roars can carry enormous distances through the air and vegetation. They are produced during any season of the year, but particularly at mating time, when they are used to attract females and probably to intimidate other males. .
They also warn their neighbors of their presence when moving to a new tree. With these roars they signal their body size and can exaggerate it, since females are more attracted to the roars of larger males. Females also produce roars. , although more subtle, to which growls, moans and screams are added. These calls are generated when in danger and to make defensive threats. Young koalas tend to screech when in danger.
As they grow, the shriek becomes a kind of cry generated both when they feel anguish and to show aggressiveness. When another individual climbs on it, it produces a low growl with its mouth closed. Koalas show numerous expressions with their faces. When grunting, moaning, or screeching, the upper lip puckers and the ears droop forward. As they scream they shrink their lips and ears. Females protrude their lips and prick their ears when they are restless.
The behavior at the time of the fight usually consists of contests between individuals that climb or pass each other, which sometimes leads them to nibble. Unfamiliar males may fight, harass, and bite each other. In extreme conditions, a male may attempt to drive a smaller competitor out of a tree. This requires the larger aggressor to climb up and try to encircle the victim, who will seek to quickly escape by evading it and descending from the tree or moving to the end of a branch.
The aggressor charges, catching the victim by his shoulders and biting him repeatedly. Whenever the most fragile individual is knocked down, the winner produces a roar and signals the tree. Pregnant or lactating females are especially aggressive and charge individuals that come too close. However, in general, koalas they are inclined to avoid aggressive behaviors that consume their energy.
Ecology and Behavior
The geographical areas in which the koala is distributed comprise about 1.000.000 square kilometers in 30 different ecoregions. They extend from the east and south-east of Australia, which includes the north-east, center and south-east of Queensland, the from New South Wales, Victoria and southeastern South Australia. The koala was introduced in the vicinity of Adelaide and on some nearby islands, such as Kangaroo Island and French Island.
Those individuals residing on Magnetic Island represent the northern limit of their range. Fossil finds indicate that their geographic range extends west to southwestern Western Australia throughout the Late Pleistocene. Their disappearance in this area was possibly caused by environmental disturbances and the hunting activities of Aboriginal Australians.
In Queensland, koala populations are unevenly distributed and rare except in the south-east, where they are large. In New South Wales they are only abundant in the Pilliga forests, while they are frequent throughout the state of Victoria. In the south they were totally exterminated in the 1920s and later reintroduced.
Koalas can be found in habitats ranging from more or less open forests to forests and in climatic environments ranging from tropical to temperate. In the case of semi-arid climates, they prefer riparian habitats, in which rivers and Nearby streams provide shelter in times of drought and extreme heat.
State of conservation
In 2016, the International Union for Conservation of Nature (IUCN) included the koala in its Red List, classifying it as a vulnerable species due to "the lack of certainty about the outstanding parameters of its population and the evident variation in trends in the population in its wide area of distribution. The overall rate of population size reduction over the past 18-24 years was estimated at about 28% by the Scientific Committee on Endangered Species (2012), with the rate heavily influenced by severe decline in areas with higher exposure to the recent drought."
In 2009, Australian parliamentarians challenged a proposal to incorporate the koala into the Environment Conservation and Biodiversity Conservation Act 1999. The koala populations of Queensland, New South Wales and the Capital Territory were rated in 2012 by the Australian government as vulnerable in its national environmental statute.
Koalas in Victoria and South Australia appear to be abundant, however the Australian Koala Foundation notes that the exception of Victorian populations from protection provisions is based on the mistaken notion that the entire koala population is 200.000, while they consider it to be probably less than 100.000.
The aborigines of Australia hunted them as a means of subsistence. A common technique used to catch them was to attach a noose made of vegetable fibers to the end of a long, thin stick, thus they could capture an animal high up in a tree, where they could not be reached by climbing the trunk. Once caught with the noose, they annihilated it with a stone ax or a waddy, a kind of wooden mallet. For certain tribes it was taboo to strip them of their skin, while others thought that their head had a special condition and kept it to bury her later.
In the early 1924th century, it was caught in huge numbers by European settlers, particularly for its thick, smooth skin. It is estimated that more than two million skins were removed from Australia in 1915. Its skin was used to make rugs, cover coats, muffs and as decorations on women's clothing. Mass slaughter was carried out in Queensland in 1917, 1919 and XNUMX, when more than a million koalas were killed by means of firearms, poison and traps.
The popular outcry after these killings was possibly the first large-scale environmental issue to spark protests among Australians. Writer and social critic Vance Palmer published a letter in The Courier-Mail newspaper expressing popular sentiment:
The hunting of our innocent and lovable native bear can only be called barbarism… It has never been accused of having ruined the peasant's wheat, of feeding on the occupying settler's grass, or even of spreading prickly pears. There is no bad social custom that can be charged to your account... It does not provide sports to the man with a gun... And it has been almost extinct from certain areas.
Despite the growing social movement to give protection to native species, the poverty caused by the drought of 1926-28 caused the annihilation of another 600.000 koalas during an open hunting season in August 1927. In the year 1934 Frederick Lewis, the then Chief Game Inspector in Victoria, stated that the once prolific animal had been driven to near extinction in that state, implying that only 500 to 1.000 individuals remained.
Initial successful conservation efforts for the species began with the establishment of the Lone Pine Koala Sanctuary in Brisbane and the Koala Park Sanctuary in Sydney in the 1920s and 1930s. The owner of this second park, Noel Burnet, became who first managed to reproduce koalas in captivity, thereby gaining fame as the leading contemporary authority on this animal.
In 1934, David Fleay, in charge of conserving Australian mammals at the Melbourne Zoo, installed the first native fauna room in an Australian zoo, which included the koala, allowing him to carry out a detailed study of its diet in captivity. Fleay later continued his koala conservation efforts at Healesville Sanctuary and David Fleay Wildlife Park.
Starting in 1870, koalas roamed the outskirts of Adelaide and several nearby islands, such as Kangaroo Island and French Island. Their numbers have increased considerably, but as the islands were not spacious enough to support large numbers of individuals, overgrazing became a problem. In the 1920s, Lewis undertook a relocation and rehabilitation program. on a large scale to move koalas, whose environment had become fragmented or reduced, to new areas with the aim of returning them to their previous range.
As an example, in 1930-31, 165 individuals were transferred to Quail Island (Victoria) and, after a period of population growth and subsequent overgrazing of eucalypts on the island, in 1944 almost 1.300 individuals were released back onto the mainland. The koala transfer experience became routine; Peter Menkorst, manager of the state of Victoria, estimated that from 1923 to 2006 some 25.000 individuals were transferred to more than 250 locations in the state.
Since the 1990s various government agencies have sought to restrict their numbers through controlled culling, but both national and international commentary has forced the practice of transfers and sterilization to continue instead. The largest human impacts on the koala's habitat is the fragmentation and devastation of its environment. In coastal areas, the main reason is urban development, while in rural regions it is agriculture and the indiscriminate felling of original forests for the production of wood products.
For the year 2000, Australia was in fifth position worldwide for its deforestation rate, with a pruning of 564.800 hectares, and according to the Independent, Australia in 2015 led the list in deforestation and disappearance of species. The koala's distribution has decreased by more than 50% since the arrival of Europeans, largely due to the fragmentation of its habitat in Queensland.
Its "vulnerable" status in Queensland, New South Wales and the Capital Territory means that developers in these territories must be aware of the likely impact on this species before moving forward with any construction plans. Keep in mind that koalas reside in numerous protected areas.
Although urbanization can pose a threat to koala populations, these creatures can survive in urban areas, provided enough trees are available, despite the fact that they are subject to being hit by vehicles and attacks by domestic dogs, which kill koalas. about 4.000 each year. In such cases, injured koalas are usually taken to wildlife hospitals and recovery centers.
A 30-year retrospective analysis of a koala rehabilitation center in New South Wales confirmed that trauma, often as a result of a motor vehicle mishap or dog aggression, was the most common reason for income, seconded by chlamydial infections. The protectors of these centers have special permits, but they only have to release the animals by leading them back to the natural environment when they are well or, in the case of the offspring, when they reach the age appropriate.
As is the case with most Australian wildlife, it is illegal to keep koalas as pets, both in Australia and elsewhere on the planet. One of the biggest challenges they face is bushfires, primarily due to their slow movements and how flammable eucalyptus trees are. The koala instinctively seeks shelter in the highest branches, where it is vulnerable to intense heat and flames. Forest fires also fragment their habitat, which limits their movement and implies the reduction of the population and the loss of genetic variability.
Dehydration and overheating can also be lethal. Therefore, the koala is also vulnerable to the consequences of climate change. Climate change models for Australia predict hotter and drier climates, suggesting that the koala's range will shrink in the east and south, moving to warmer and more humid environments. Droughts also impact koala welfare. .
For example, due to a severe drought in 1980, numerous eucalyptus trees lost their leaves, which subsequently caused 63% of the population of south-west Queensland to perish, particularly young animals that were repelled from the main feeding sites. by older and more dominant koalas, with further population recovery being extremely slow.
Later, this population declined from an estimated average of 59.000 individuals in 1995 to 11.600 in 2009, a decline largely attributed to hotter and drier conditions as a result of the droughts that occurred from 2002 to 2007. Another forecast The negative effect of climate change is the consequence of the rise in atmospheric CO2 levels in the supply of food for the koala, since the increase in these levels causes a decrease in protein in eucalyptus trees and increases the concentration of tannins in their leaves. , which lowers the quality of the almost only source of food for these creatures
Koala History
The initial written reference to the koala was documented by John Price, an aide to John Hunter, Governor of New South Wales. Price obtained a cullawin on 26 January 1798 on an excursion to the Blue Mountains, although his discovery was not made public until almost a hundred years later in the Historical Records of Australia. In 1802, the expeditionary Frenchman Francis Louis Barrallier got the animal when his two aboriginal guides returned from hunting, bringing two koala legs with the purpose of eating them.
Barrallier preserved these appendices and forwarded them along with his notes to Governor Hunter's deputy, Philip Gidley King, who in turn forwarded them to the English naturalist Joseph Banks. As with Price, Barrallier's notes were not made public until 1897. An article about the first live capture of a koolah was published in The Sydney Gazette in August 1803. A few weeks later, James Inman , astronomer to the explorer and cartographer Matthew Flinders, acquired a couple of samples to send to Joseph Banks in England, which he described as a creature "somewhat larger in size than the waumbut" (wombat).
These findings led King to commission artist John Lewin to draw watercolors of the animal. Lewin painted three plates, one of which was later made into a print that was reproduced in Georges Cuvier's The Animal Kingdom (first published in 1827) and in various European works on natural history. The initial published image of a koala was shown in George Perry's natural history work Arcana in 1810.
Perry called it "New Holland Sloth" (the sloth of New Holland) since he could see similarities with the arboreal mammals of Central and South America of the genus Bradypus. His disparagement of the koala, made quite clear in his review of the animal, was characteristic of the prevailing early nineteenth-century British stance on the primitiveness and strangeness of Australia's fauna:
... the eye is placed like that of the sloth, very close to the mouth and nose, giving it a queer, incapable, and inelegant appearance ... there is little in its temperament or appearance that would be of interest to the naturalist or the philosopher. However, since nature contributes nothing in vain, it can be supposed that even these inept and senseless creatures are scholarly destined to occupy one of the enormous links in the nature chain of life...
Scientist Robert Brown was the first to develop a detailed scientific review of the koala in 1814, based on a female specimen trapped in the vicinity of what is now Mount Kembla in the Illawarra area (New South Wales). Austrian botanical draftsman Ferdinand Bauer outlined the animal's skull, throat, feet, and limbs. However, Brown's work went unnoticed and unpublished, as his field texts and notes remained in his possession until his death, when they were loaned to the Natural History Museum in London.
These notes were not recognized until 1994 (Bauer's drawings were not made public until 1989). The English surgeon Everard Home incorporated certain details of the koala based on testimonies of the explorer William Paterson, who had befriended Brown and Bauer at throughout his stay in New South Wales. Home, who in 1808 published his report in the journal Philosophical Transactions of the Royal Society, gave the animal the scientific name Didelphis coola.
The well-known English artist and naturalist John Gould drew and profiled this species in his three-volume book The Mammals of Australia (1845-1863) and introduced it to other members of the Australian faunal community as well as to the general English public. Comparative anatomist Richard Owen, in a succession of publications on the physiology and anatomy of Australian mammals, exhibited a paper on koala anatomy to the Zoological Society of London.
In this work, mentioned on numerous occasions, he gave the first careful account of its internal anatomy and indicated its general structural resemblance to the wombat. The British naturalist George Robert Waterhouse, curator of the Zoological Society of London, was the one who first classified correctly the koala as a marsupial in the 1840s. Waterhouse recognized similarities between it and its fossil relatives Diprotodon and Nototherium, which had been found some years earlier.
For his part, Gerard Krefft, curator of the Australian Museum in Sydney, managed to identify the evolutionary mechanisms in his work by equating the koala with its remote relatives in the book The Mammals of Australia. The first living koala arrived in Europe in 1881, acquired by the Zoological Society of London. According to what was narrated by the society's solicitor, William Alexander Forbes, the animal perished accidentally when it could not free itself from the heavy lid of a sink that fell on it.
Forbes took advantage of this mishap to analyze the corpse of this female specimen, from which he obtained precise anatomical details of her reproductive system, brain and liver, parts not previously reviewed by Owen, who only had access to preserved samples. The Scottish embryologist William Caldwell, famous in scientific circles for describing the reproductive mechanism of the platypus, reviewed the uterine development of the koala in 1884, using the new information to convincingly pinpoint the evolutionary span of the koala and the monotremes.
Henry of Gloucester, whose father was Sovereign George V of the United Kingdom, visited Sydney's Koala Park Sanctuary in 1934 and was "very interested in 'bears'"; his joint photo with Noel Burnet, creator of the park, and a koala, was featured in The Sydney Morning Herald. After the Second World War, when tourism began to increase in Australia and its animal species began to be exported to zoos in other nations, the popularity of the koala increased throughout the planet.
Such popularity led several political leaders and members of royal families to take pictures with these creatures, such as Queen Elizabeth II of the United Kingdom, Prince Henry of Wales, Prince Naruhito and Princess Masako Owada, Pope John Paul II , the presidents of the United States Bill Clinton and Barack Obama, the president of the Soviet Union Mikhail Gorbachev, the president of South Africa Nelson Mandela, the prime minister of Australia Tony Abbott or the president of Russia Vladimir Putin.
Cultural Significance
It is a popular animal around the globe and a major attraction for Australia's wildlife parks and zoos. It has made its appearance in advertisements, games, animated cartoons and stuffed animals. It is a boon to Australia's tourism industry. An investigation carried out in 1997 showed that only in 1996 it meant income of more than a billion dollars and about nine thousand direct jobs with an income calculation of 2,5 billion for the year 2000, numbers that have grown since then.
By 1997, 50% of tourists visiting Australia, particularly those from South Korea, Japan and Taiwan, went to zoos and wildlife parks, and close to 75% of tourists from Europe and Japan placed koalas at the top of their preferences for animals they longed to see. According to scientist Stephen Jackson: "If I were to conduct a survey as to which animal is most associated with Australia, it's a very safe bet that the koala it would be placed marginally ahead of the kangaroo."
Among the circumstances that maintain this popularity that has been sustained over time are his childlike body and his teddy bear appearance. The koala is part of the Dreamtime stories and Australian Aboriginal mythology. The Tharawal people believed that this creature had helped row the boat that brought them to the mainland. Another legend relates how a tribe killed a koala and used its long intestines to make a bridge for people from other sides of the world. world. Said narration highlights the condition of the koala as a hunting creature for the aboriginal culture by pointing out the extension of its intestines.
Various accounts tell of how they lost their tail; in one of them, a kangaroo cuts it off to reprimand them for being lazy and gluttonous. The tribes of Queensland and Victoria regard him as a wise animal and seek his advice. People who spoke the Bijara language thought that koalas were responsible for transforming arid lands into lush forests. They are often seen depicted in petroglyphs, although not much like other animal varieties.
The European settlers who first arrived in Australia regarded it as a prowling sloth-like animal with a "fierce and defiant gaze". growing popularity and its presence in many well-known children's stories. It is shown in Ethel Pedley's text Dot and the Kangaroo (1899), in which it is depicted as the "graceful native bear".
Artist Norman Lindsay featured a more human-looking koala in The Bulletin strips, beginning in 190. The character also made an appearance as Bunyip Bluegum in Lindsay's 1918 text The Magic Pudding. The most famous fictional character is Blinky Bill, a figure created by Dorothy Wall in 1933 who was shown in several books and has been the protagonist of films, television series, postage stamps, stuffed animals and a 1986 song dedicated to the environment by Australian country musician John Williamson.
The Australian postage stamp that first featured a koala was issued by the Commonwealth in 1930. A television advertising campaign for Australia's national airline, Qantas, which began in 1967 and ran for several decades, incorporated to a living koala (in the voice of actor Howard Morris) who laments that Australia has too many tourists and ends by saying "I hate Qantas". This campaign was cataloged at the time as one of the best television commercials in history .
It appears on the Queensland state wildlife badge. In the song "Ode to a Koala Bear" it is featured on the B-side of Paul McCartney and Michael Jackson's 1983 single Say Say Say. A koala is the figure main character in the 1980s cartoon series The Kwicky Koala Show by Hanna-Barbera and Noozles by Nippon Animation. There are plenty of koala-shaped treats, and Dadswells Bridge in Victoria has a tourist complex in the shape of a huge koala. The Queensland Reds rugby team has a koala as its mascot.
There are numerous coins featuring koalas, such as the Australian "Platinum Koala", which features the creature on the reverse and Queen Elizabeth II on the obverse. As the opposite of this tame herbivore, contemporary Australian folklore created the drop bear, a fictional figure exhibiting a predatory, carnivorous version of the koala. About this imaginary creature it is usually related in the fantastic tales designed to scare tourists in rural towns and which are described as unevenly huge and heinous animals that live in the treetops and attack unsuspecting people or other prey that pass below. , throwing himself on them.
Koalas and Human Relations
The vast majority of humans consider the koala to be a lovable creature, however others believe it to be boring and silly. Since koalas remain motionless or resting for almost 18 hours a day, there is little interest in studying them. Currently, many people live in areas close to the koalas' habitat and this has caused them to be victims of dog attacks.
Some people become concerned that their pets may catch a disease as a result of these fights. If this is the case, then you should vaccinate your dog as a preventive measure. The construction of roads through the forests where koalas live has caused many of them to die or suffer serious injuries. This happens especially at night, when they go out to look for food, and since they cannot cross these roads quickly, they are run over by cars.
Some people love the idea of having an exotic animal as a pet. Possessing them is not legal in most countries, but there are still people who take them in. Those who adopt a koala as a pet put themselves at risk as these creatures can behave aggressively. There are strong penalties for those who openly do not comply with the legislation in this regard and try to keep them as pets.
At the beginning of the years 1900 million of these beings were annihilated with the purpose of transforming their skins into beautiful coats for humans. The fur features of koalas were considered formidable for such purposes since, in addition to offering a pleasant appearance, they provided a certain degree of warmth. As fashion trends changed, the market for this kind of coat began to shrink. If the same had continued, it is estimated that humans would have caused the complete disappearance of the koala species.
The koala is a creature that does not seem to contribute much to the lifestyle of humans or the ecosystem of the animals around it. That is why many people really do not think twice before cutting down the trees in which koalas live. They are inclined to use these lands for agriculture, mining and for urban development.
What is very puzzling is that the Australian government does not take legal action in this regard. They have pointed out the illegality of their hunting, but even so the laws are not rigorously complied with and people continue to exterminate them without receiving any punishment. The koala is not considered a threat to humans and there are no reports of people being attacked by them. They are the ones who do not seem to care if they extinguish this species forever or not.
A significant part of the land on which these animals are found is private property. Instead of acquiring such spaces and protecting them, the government sides with the owner, allowing them to do what they want in them. There are different laws in force for the protection of the koala according to the place in Australia in which they live. All of this leads to confusion and frustration as their numbers continue to dwindle considerably.
It is also true that many people love koalas and are involved in various conservation programs to keep them alive. They do not want to see that they lose their habitat or have inconveniences to procure their food and they do not like the idea that they can only survive in captivity. Koalas not born in captivity can at some point feel very stressed if they are forced into this kind of existence. As a result, they can get sick or refuse food, causing their death by starvation.
The Koala: an Innocent Marsupial in Danger of Extinction
The emblematic creature of the eastern coast of Australia is one of the most affected by the fires in recent weeks. The forest fires that afflict different areas of Australia have burned five million hectares in just over two months, an area comparable to the sum of the total extensions of Galicia, Asturias, Cantabria and the Basque Country. Added to the human losses and the deterioration of housing and infrastructure, the fire is causing an unprecedented environmental calamity.
Among the animal varieties that were affected by the flames is the koala (Phascolarctos cinereus), one of the most representative and threatened Australian marsupials. It is difficult to estimate how much the losses totaled, but in one of the worst affected areas, Kangaroo Island (off the coast of South Australia, southwest of Adelaide) may have perished half of the 50.000 recorded koalas.
Mutual recognition
In New South Wales, it is estimated that some 3.000 specimens have become extinct in just one month, almost a third of the estimated population of 8.000 of these creatures, according to what was reported to La Vanguardia by the spokesman for Greenpeace Australia Pacific (regional agency of this international environmental group). Deborah Tabart, director of the Australian Koala Foundation, has reiterated in testimonies for this newspaper from Brisbane that the flames are affecting areas of great importance for the survival of koalas, particularly in the strip of the eastern coast of the country.
In recent weeks, "numerous koalas have been transferred to animal hospitals, but this number is nothing when compared to those who have died in the fires," says saddened the woman also known as the koala woman, recognized in 2008 with the Medal of the Order of Australia (OAM) in appreciation for his "contribution to the protection and management of koalas and their habitat, and for his services to Australia and the world at large."
A year has passed since Tabart was criticized by some researchers and the media for claiming that koalas were "functionally disappearing." "She was alarmed [by the koalas] then and I follow it even more today," Tabart emphasizes to La Vanguardia. The rating of the risk that afflicts the survival of the koalas, in any case, remains valid.
General Problem
The red list of animal species under threat, managed by the International Union for the Conservation of Nature (IUCN), catalogs the koala as "vulnerable" since 2014, but thanks to the effect of the fires, it can be justified that in a short time this particular species occupies the most worrying category, that is, that of “endangered”.
“Koalas were already at risk prior to the bushfire crisis as their natural environment and food sources have been drastically declining in recent years due to urban development and deforestation. In New South Wales, for example, the koala is considered vulnerable to extinction under the Biodiversity Conservation Act that was passed in 2016," according to a Greenpeace Australia Pacific spokesperson.
The role of the Australian public administrations and their political leaders in the context of the forest fires has been widely criticized in recent weeks, beyond the deplorable resolution of Prime Minister Scott Morrison to go on vacation to Hawaii for a few days, mediating December, meanwhile much of his country was fighting the flames.
In addition to bearing in mind that the Australian government has been one of the most notorious opponents to advance initiatives to implement the Paris agreement, researchers and environmental groups now affirm that neither the koala nor its natural environment are sufficiently protected. at the government level.
Insufficient Figures
“Our government authorities [in Australia as a whole and in the various territories] should feel ashamed of the way they have managed koala habitats,” says Deborah Tabart. Trying to recover the credibility that they no longer have, on January 6, 2020, Prime Minister Scott Morrison reported on an extraordinary investment of 1.243 million euros over the next two years to rebuild homes, infrastructure and natural spaces that were damaged by the fires.
The notified budget may be important, but if one bears in mind that the fire has incinerated five million hectares, the result of such a division is just 2 euros of investment per hectare and per year. While the authorities have not yet provided satisfactory answers, non-governmental organizations and a large part of the scientific community are leading efforts to understand the effects of this calamity and undertake the search for long-term solutions.
Unique Proposal
As part of one of the projects that have emerged in recent weeks, a group from the University of Newcastle (Australia) led by Ryan Witt has pointed out the need to activate a program that involves freezing the genetic material of koalas. The preservation of tissues and germ cells of individuals of this representative species from different areas of Australia would favor research on their diseases, particularly chlamydia, and proposals for assisted reproduction in captivity if this procedure is necessary in the future. .
In an essay published in The Conversation, the six Newcastle researchers point out that if koala population loss continues at the rate sustained in recent fires, "and climate models warn that it will be like this or even worse, we could lose a genetic diversity that we could no longer replace. The problem is not only that the fires cause a significant loss in the number of koalas, but that the surviving populations will be more fragmented and isolated, with the risk of greater inbreeding and an increase in hereditary diseases, Ryan Witt's team points out. .
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