Koala (Phascolarctos cinereus) Fact Sheet

Fact Summary
Taxonomy and Nomenclature
Distribution and Habitat
Physical Characteristics
Behavior and Ecology
Diet and Feeding
Reproduction and Development
Diseases and Pathology
Managed Care
Population and Conservation Status
Web Resources
Bibliography

TAXONOMY & NOMENCLATURE
(Houlden, et al., 1999)(Lee & Martin, 1988)(Takami, et al., 1998)

Describer (Date): (Goldfuss, 1817) Lipurus cinereus

Kingdom: Animalia
    Phylum: Chordata
        Class: Mammalia
             Order: Diprotodontia
                    Family: Phascolarctidae
                           Genus: Phascolarctos
                                  Species: Phascolarctos cinereus
                                        Subspecies: P. c adustus - Queensland
                                                                 P. c. cinereus - New South Wales
                                                                 P.c. victor -Victoria

Taxonomy

Family: only member of Phascolarctidae
Subspecies

Three subspecies have been described, but may just represent gradual variation from northern Queensland to South Australia.
The boundaries of the subspecies are state boundaries, rather than geographic.
DNA studies show do not show enough differentiation to support the use of subspecies.

Nomenclature

"Koala" may come from Aboriginal word, meaning "no drink"
Phascolarctos: phaskolos ("pouch"), arktos ("bear"); Greek
cinereus: "ash-colored"; Latin

Phylogeny

Family Phascolarctidae has been around for 15 million years, yielding several different types of koalas.
Widespread in the Pleistocene, extending into southwestern Western Australia.
Closest living relative: the wombat

DISTRIBUTION & HABITAT
(Martin, 2001)(Sharp, 1995)

Distribution

Eastern and southeastern Australia: From Cooktown (Queensland) to South Australia.
Disjunct distribution (isolated pockets) across range.
Have been introduced into the islands off of the southern coast and Western Australia (outside of natural distribution).

Habitat:

Confined to eucalyptus forests, but habitat varies regionally; wet montane forests, dry woodlands, vine thickets.
Greatest preference for trees growing in highly fertile soils.
Prefer larger trees.

PHYSICAL CHARACTERISTICS
(Nowak, 1999)
Body Weight: 4 - 15 kg (9 - 33 lbs), averaging 11 kg (24 lbs) for males and 8 kg (17.6 lbs) for females;
animals significantly smaller in northern part of range.
Head/Body Length: 600 - 850 mm (23.6 - 33.5 in)
Tail Length: vestigial, hidden by fur.

General

Teddy bear like in shape, with small compact body, short limbs, and large rounded ears.
Short, dense, woolly fur. Overall light gray, white under parts, rump dappled with white. Ears fringed with white hair. Black, leathery nose.
Marsupial pouch, which opens towards the rear.
Forefoot: First two toes opposable to other three. Hind foot: First toe opposable to other four. Second and third toes conjoined by skin. All toes with long, sharp claws except first digit of hind foot.

Sexual Dimorphism

Males: 50% heavier, wider face, smaller ears, large sternal gland on chest (females do not have this gland).
Females: rear-opening pouch on underside, two teats.

Other Physical Characteristics

Teeth specialized for chewing fibrous leaves -broad, high-cusped cheek teeth
Cheek pouches.
Small brain: 0.2% body weight; one of smallest in marsupials.

BEHAVIOR & ECOLOGY
(Lee & Martin, 1988)(Martin, 2001) (Mitchell, 1990a)(Mitchell, 1990b)
Activity Cycle

Primarily nocturnal, although some activities may occur during the day.
Sleep up to 20 hours/day. Less than 4 hours/day is spent foraging and resting. The remainder (<1%) is spend moving, grooming, or interacting socially.
Low energy output is necessary for animal that specializes on such a low energy diet.
Foraging is done in 4 - 6 sessions per day, each lasting about 20 minutes to 2 hours.

Home Range/Territory

Home Range

Average home range size on French Island: males 1.70 ha (4 acres), females 1.18 ha (3 acres) (Mitchell, 1990b). Home range sizes reported in the literature vary greatly due to different methods used.
Home range size, and population density vary with habitat: Male's home range up to 100 ha (247 acres) in semi-arid, less productive forest; population density much lower as well (Martin, 2001).
Tend to stay in the same home range for many years, often using the same trees.

Home range of a dominant male may overlap with that of several females, and subadult or subordinate males.

Territorial Behavior

Level of territoriality is unclear. Some authors report no evidence of territoriality; others call them highly territorial (AKF, 2003; Mitchell, 1990b).
Aggression:
- Most often occurs when one animal enters an occupied tree. Depending on level of dominance, either invader or resident can be the aggressor.
- Male-male: One usually ends up leaving, but will not be chased beyond the base of the tree. Usually seen in males at least 4 years old.
- Male-female: Male is the aggressor, and attacks or tries to copulate with female. Female does not flee, but responds defensively.
Tree sharing occurs occasionally by male-male, male-female, and female-female pairs.

Social Groups

Dominance hierarchy among males: Subordinates recognize dominants and may retreat even before any overt aggression is shown.
Solitary; tend to avoid one another. 86-89% (breeding season) to 93-96% (non-breeding) time spent alone.
Tend to occur in clusters of overlapping home ranges = stable breeding groups. Consists of one dominant male and several females and subordinate males.

Communication

Vocalization

Bellowing

"Consists of a series of harsh inhalations each followed by a resonant growling expiration." (Martin, 2001)
Both sexes, but most often by adult males.
More common during mating season.
More frequent at night.
To attract mates, and to warn off other males. May assist in maintenance of spacing between individuals.
The call is often answered by other males in the area.

Encounter calls: Mitchell (1990a) described four types, in addition to bellowing. Response to aggressive encounters.

Squawks: short, harsh
Snarls: longer (up to 2 seconds), atonal to moderately tonal
Screams: high pitched, sound travels farther
Wails: Longer than screams, similar to wail of domestic cat

By females or young in distress.

Olfaction/Scent Marking

Sternal gland used to mark trees, possibly to mark territorial boundary; most frequent during breeding season; by males at least 4 years old.
Occasional marking with drops of urine has been observed by both sexes; on or at the base of trees. The exact meaning of this is unclear.

Play

By young animals
Solitary or with another
Climbing and jumping or chasing one another

Locomotion

Arboreal, but must travel on the ground to move to another tree. Travel on all fours.
Sedentary, but can move relatively quickly on the ground or up a tree if necessary.
Males tend to move to new trees more often than females.
Climb (a) by bounding up rapidly, using hind legs to push them up or (b) slowly, using arm, then opposite hind limb. Recurved claws and opposable digits help them grasp trunks and branches.
Climb down a tree with head facing up.

DIET & FEEDING
(Cork & Sanson, 1990)(Martin & Handasyde, 1999)(Moore & Foley, 2000)

Feed and move around about 4 hours/day

Most between 1700 and 2400 (5pm-12am)
Feed intermittently for approximately 20-minutes at a time
Main food source : eucalypt foliage (poor-quality food - little protein)

Browsers. Eat about 600-800g of leaves per day. May also include soft stems, flowers, and occasionally bark

Lactating females increase intake 20-25%

Usually concentrate on a limited number of eucaluptus species from their geographic range, but will also consume non-eucalypt species
Prefer leaves of only a few species of Eucalyptus tree, which vary population to population. . (There are 500+ species of Eucalyptus in Australia. Martin and Handasyde list 42 species eaten by Koalas).

Southern preference: E. viminalis, E. ovata, and E. globulus
Northern preference: E camaldulensis, E. tereticornis, E. microcorys, and E. punctata

Seasonal changes in species preference -may be due to water content or increased concentration of toxic chemicals
Occasionally forage in non-Eucalyptus species: Leptospermum, Melaleuca, Tristania, Bombax, Pinus. But these are only a small percentage of total diet
Foraging behavior
- Pulls a branch to its nose with forepaw before eating; smell may play a role in identifying preferred species
- Usually select a single leaf at a time
- Sharply ridged molars slice up leaf into small pieces. When molars wear down with age, animal suffers from malnutrition
Digestion
- Eucalyptus leaves high in indigestible fiber, high in toxins (terpenes and phenolics) and low in nutrients
- Some toxins are processed and eliminated by the liver.
- Stomach is small in relation to the digestive tract and has a cardiogastric gland, which increases acid and enzyme production. Wombats are the only other marsupial that has this gland.
- Large food particles pass through the colon and are excreted rapidly. Small particles undergo microbial fermentation in the caecum, which is largest of any mammal in proportion to body size.
Produce dry faecal pellets. (Water conservation for an animal that rarely drinks in the wild)

REPRODUCTION & DEVELOPMENT
(Gordon et al., 1990)(Lee & Martin, 1988)(Martin, 2001)
(Martin & Handasyde, 1990)(Mitchell, 1990a)(White & Kunst 1990)
Courtship

Males polygynous (mate with more than one female).
Males may not be able to detect when a female is in estrus and will copulate any time during the breeding season.
Copulation usually forced by male; female tries to back away and makes defensive vocalizations ("snarls, weak bellows, squawking, screaming").
Dominant male often chases off subordinate male who tries to mate with a nearby female.

Reproduction

Breeding: October - November (spring)
Inter-birth interval: once every 1 - 2 years.
Females are seasonally polyestrus (repeated estrus cycles during the breeding season).

Gestation: Approximately 35 days

Life Stages

Birth

Birthing season: most births occur December - February (summer).
Litter size: one, rarely two
Birth weight: less than 0.5 g]
Size: about 2 cm long
As with all marsupials, newborn is blind, very underdeveloped, and fetal-like. Forelimbs and claws more developed, which assist in crawling. Senses of touch and smell well developed.
Newborn crawls into pouch unassisted by mother, and attaches itself to one of the teats.

Infant (< 1 year old)

Young also called "joey".
Develops in pouch for 6 months, and then starts making short excursions outside of pouch.
Once outside of pouch, young rides on mother's back.
Starts feeding on paste of partially digested leaves that is excreted by mother ("pap"). This may give the young microorganisms it needs to digest eucalyptus leaves. Continues drinking milk for up to a year.
Starts eating leaves in addition to pap and milk.

Juvenile/Subadult

Independent of mother: 12-24 months of age, when next joey is born; remains close by for several more months.
Males tend to disburse from natal home range, but females tend to set up home range nearby.
Females will occasionally accept an unrelated joey to care for.

Adult

Sexual maturity: Females sexually mature at approximately 6 kg ( 13 lbs), 2 - 3 years of age. Males sexually mature at 2 years, but mating success is low until 4th or 5th year.
Sternal gland begins to develop in males at about 1.5 - 3 years of age.

Longevity

Captivity: Up to 18 years
Wild: 14+ years under ideal conditions. Much shorter near human habitation.

Mortality

Main causes of mortality: being hit by cars, or preyed on by dogs/dingoes. Most vulnerable when on ground.
Drought: reduces availability of forage, causing death due to starvation or poor nutrition.
See Threats to Survival for more information

DISEASES AND PATHOLOGY
(Gordon et al., 1990)(Martin, 1989)(White & Kunst, 1990)

Bacterial infection of Chlamydia
- Sexually transmitted. Spreads easily.
- Widespread in Victoria, probably due to translocations of infected koalas from Phillip Island.
- Infection of the female reproductive tract, and reduced fertility.
- Prevalence of infection and level of resulting infertility vary widely among populations.
- Can also cause infections of the eye.
Cystitis
- Cysts on the female reproductive tract.
- Prevalence low, but when present, mortality is high
Other
- Pneumonia
- Stress, leading to lowered immunity to disease and malnutrition
- Digestive tract problems (more common in captive animals)

MANAGED CARE
(Doyle, et al., 2002)(Lee & Martin, 1988)

Captive Breeding
- In the past, koalas did not survive long in captivity. This was mostly due to a misunderstanding of diet preference.
San Diego Zoological Society

1925: First pair of koalas at the zoo - Snugglepot and Cuddlepie.
1960: Fist koala born at the zoo. More than 100 have been born between 1976 and 2002.
Most successful koala breeding and rearing program outside of Australia.
Browse: The zoo grows 35 species of Eucalyptus. At least 4 species are offered to koalas every day.
Conservation and Education Loan program: koalas are loaned to zoos all over the world to use in educational and conservation programs.
Partnered with the Australian Koala Foundation to produce Koala Habitat Atlas.

POPULATION AND CONSERVATION STATUS
(AKF, 2003)(NCC, 2003)(Martin, 1989)(Martin, 2001)
Population Status

Beginning of European settlement: An estimated 10 million koalas existed.
Early 20th century: Extinct in South Australia due to uncontrolled hunting (2-3 million skins exported).
Present status (from AKF website; date of estimates unknown): Total of 100,000.

Queensland - up to 50,000
New South Wales - 10,000-15,000
South Australia + Victoria - 20,000
Tasmania - None
Western Australia - not present for 10,000 years
Northern Territory - None
An estimated 80% of koala habitat has been destroyed due to development, drought, and fires.

ISIS captive population

Conservation

IUCN Status: LR (Lower Risk)
CITES Status: not listed
Intensive conservation efforts
- 1870-1890: Introduced onto Phillip and French Islands (Victoria); French Island population (Chlamydia-free) prospered, and became overpopulated by the 1920's.
- 1920's: Official translocation program began; moved individuals from French Island to Victorian islands.
- 1940's: Populations translocated to mainland Victoria and South Australia.
- Present: Despite high infection rate of Chlamydia, many populations are doing well, but useable habitat is decreasing rapidly, resulting in overpopulation in some areas. This may lead to decimation of food sources due to over browsing.
- Culling is not supported by the community, so translocation may be only solution to avoid starvation.
Conservation genetics

DNA studies show low variability in the Victoria and South Australia populations.
Most of these probably originate from French Island translocations. The French Island population was started with only a few individuals from the mainland.
Could lead to inbreeding problems.
South Gippsland populations may be only endemics left in Victoria.

Threats to survival

Over hunting: Heavily hunted for their pelts in the 19th and 20th centuries. More than two million skins were exported in 1924.
Habitat destruction and fragmentation: Due to development, wild fires. Habitat is not currently protected.
Extended drought
Hit by cars, mostly during breeding season when males are moving about more frequently.
Drowning in swimming pools.
Predation by dogs, dingoes, feral cats, feral foxes, owls, and wedge-tail eagles. Young most vulnerable.
Disease: Most common - Chlamydia, which may cause infertility and sometimes death.

Important Web Resources:

Australian Koala Foundation -Lots of information about biology and conservation.
Australian Wildlife Conservancy - Conservation projects and general facts.
Australian Biodiversity Information Facility - Taxonomic, bibliographic, geographic and biological information on plants and animals of Australia.
Atlas of New South Wales wildlife - Shows recorded sightings of plants, mammals, birds, reptiles, amphibians and endangered invertebrates in New South Wales. Generates a map of user defined parameters.

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