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Taxonomy
Mother and baby koala in the Australia Zoo. The koala is considered a least concern species by the IUCN Red List of Threatened Species.
- Kingdom: Animalia
- Phylum: Chordata
- Class: Mammalia
- Infraclass: Marsupialia
- Order: Diprotodontia
- Suborder: Vombatiformes
- Family: Phascolarctidae
- Genus: Phascolarctos
- Species: Phascolarctos cinereus
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Physical Features
- According to the Department of the Environment of the Australian government there is only one species of Koala with different physical features.
- Their fur ranges from silver gray to chocolate brown. Koalas in the north are of lighter color and smaller than in the south.
- Koalas’ coat is thicker and longer in the back and shorter on the belly. It protects them from cold and heat, it is also water repellent.
- Their coat has patches of white inside their ears, chin, chest, neck and rump.
- Koalas have stocky bodies, large rounded ears, large nose covered with a leathery dark skin and sharp claws.
- Males are 50% larger than females.
- Males are distinguished from females by their more curved noses and visible chest glands.
- Their head is large in proportion to its body but its brain is small in relation to its skull. Koalas have smaller brains than other marsupials.
- Koalas have large noses covered in leathery dark skin. They have a strong sense of smell.
- Koalas do not have a tail.
- Koalas are well adapted to live in trees. Their sharp curved claws help them climb trees. On their front paws, two digits are opposed to each other, like the human thumb which allows koalas to grab small branches. On the hind paws the first digit lacks a claw and the second and third digits are fused together creating one digit with a stronger claw.
Distribution and Habitat
- Koalas are native to Australia. They are found in the coast of eastern and southern regions of the country.
- There are three subpopulations distinguished by geographic distribution: The Queensland koala, New South Wales koala and the Victorian koala.
- Koalas live where eucalyptus trees are abundant.
Koala distribution map. Source: IUCN Red List of Threatened Species
Diet
- Koalas are herbivores. Eucalyptus leaves make up most of their diet, they eat from one to two pounds of leaves each day depending on their sex and size. The leaves provide low nutritional value, high toxicity and high dietary fiber.
- Because their diet provides low nutritional value they are sedentary and sleep for up to 20 hours a day.
- According to the Department Department of the Environment of the Australian Government there are 700 species of eucalyptus trees available to koalas but they prefer 40 of them based on protein, fiber and toxicity.
- Eucalyptus leaves are high in water so koalas do not need to drink often.
- Feeding occurs 4 to 6 times a day when they are not sleeping.
Size and Weight
- Their body length ranges from 60 to 85cm or 24 to 33 in and their weight from 4 to 15 k or 9 to 33 lbs.
- Koalas in the north are smaller than their counterparts in the south.
Life Expectancy
- Koalas live from 12 to 15 years in the wild. Those living near urban areas live less because of high incidents of car crashes and attacks by dogs.
- The condition of their teeth will affect how long they live. Some koalas are unable to feed so they will die of starvation.
Threats
- Their biggest threat is habitat destruction cause d by agriculture and construction. The construction of roads and urban areas near koalas’ habitat has led to car accidents and dog attacks. According to the Australian Koala Foundation an estimated 4,000 koalas die in such accidents every year.
- Koalas are protected by Australian law.
- Bushfires and droughts.
- A high level of inbreeding is causing koalas to have a low genetic pool.
Social Behavior
- Koalas are solitary animals unless is a female rearing her offspring. They need a lot of space, according to National Geographic, about 100 trees per animal.
- Koalas live in home ranges which can overlap and they are highly territorial creating a socially stable group.
- Male koalas mark their territory by rubbing a secretion from their scent gland located on their chests. Females and males also use their urine on trees and ground to mark their territory.
- These animals are more active between dusk and dawn.
- Koalas communicate by bellows, snarls and screams. Adult males are louder than females, they would make loud bellows to assert their dominance by intimidating other males and attract females.
- Females do not bellow as often but they do to express aggression and to attract males.
Breeding
- Koalas are seasonal breeders. They breed from September to February with joeys being born from October to April.
- During breeding season male koalas move from tree to tree trying to find females. They fight and exclude other males from accessing females.
- Females start to breed at 3 to 4 years old producing one offspring each year, some will produce only every 2 to 3 years depending on diet, age and habitat.
- Males start breeding at 4 to 5 years.
- Gestation period is around 35 days. Koalas give birth to a single young known as “Joey”. Twins happen occasionally.
- As with marsupials, koalas give birth to an embryo weighting 0.02 oz or 0.5 kg. The Joey crawls into their mother’s pouch where they stay to continue its development.
The Young
- The Joey leaves the pouch at 6 or 7 months weighting up to 11 to 18 oz or 500 g. They lactate for up to 12 months.
- At 6 months the mother feeds the Joey pre digested eucalyptus leaves called “pap” which is a special form of feces. This prepares the Joey’s digestive system for a leave diet.
- Joeys will permanently leave their mother’s pouch by 9 months when they weight approximately 2.2 lb or 1 kg. They ride on their mother’s back.
- When the mother becomes pregnant again Joeys are encouraged to leave. Mothers show aggressive behavior towards their young.
Conservation Status
- The IUCN lists the koala as “Least Concern”.
Additional Facts
- When Europeans settled in Australia they mistook koalas as a type of bear and the name “koala bear” stuck.
- The koala is actually a marsupial, a type of mammal that protects and nurtures its newborns in a pouch, just like kangaroos.
- The word “marsupial” comes from the Latin marsupium which means “pouch”
- A male koala is called “buck’; a female koala, “doe”; and a young koala, “joey”.
- The koala closest relative is the wombat.
- In April 2013, scientists from Queensland University of Technology fully sequenced the koala genome for the first time.