Kangaroos

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Aliases
Taxonomic classification
Superfamily	Macropodoidea	big footed 62 species in Australia & Papua New Guinea size 1 kg – 90 kg
Family	Macroprodinae	kangaroos and wallabies
Genus	Macropus	kangaroos six largest species of the family

Relationships among Kangaroos

Genus	MacropusKangaroos share:large sizegrazers – specialised teeth for cropping grass – complex forestomachs for the breakdown of plant fibre by fermentation
Species	rufus	fuliginosus	giganteus	antilopinus	robustus	bernadus
Common Names	Red Kangaroo, Marloo. Blue-flier (female)	Western Grey, black-faced kangaroo, sooty kangaroo, mallee kangaroo, stinker	Eastern Grey, forester, scrubber, Great Grey	Antilopine Kangaroo	Common Wallaroo, Euro, briggada	Black Wallaroo
Grouping	Red Kangaroo	Grey Kangaroos	Antilopine Kangaroo	Wallaroo / Euro

Appearance

Red Kangaroo

Black and white patch at side of muzzle; the tip of the nose is naked and sharply outlinedMale: 1.8 m 90 kg
Female: 1.25 m 35 kg

Grey Kangaroos

Muzzle covered by fine hair; only the margins of the nostrils are bare black skinMale: 1.6 m 70 kg
Female: 1.2 m 35 kg

Antilopine KangarooMale: 1.5 m 49 kg
Female: 1.0 m 20 kg

Euro

Nose is completely nakedMale: 1.6 m 58 kg
Female: 1.2 m 25 kg

Black Wallaroo

Nose is completely nakedMale: 1.0 m 22 kg
Female: 0.8 m 13 kg

*Height is measured when sitting up on their haunches.

Behaviours

These are actions that promote the unity of a group; don’t include either displays of aggression or reproductive behaviour

Between group members:

• mutual nose touching and sniffing, touching the lips of another, other touching and sniffing, grooming others, nuzzling a female’s pouch
• submissive behaviour – one animal, often smaller, holds its body close to the ground and its head may quiver
• play-fighting among young, subadults, or mother and young – two animals involved grasp each other around the neck, touching forepaws and kicking

Mother and offspring:

• mother grooms a young at foot while it is suckling or just after
• young nuzzles its mother’s pouch either to get in or to suckle or for reassurance the young may put its head into the pouch for a few seconds
• young licks its mother’s lips for several minutes, apparently collecting saliva; it is thought that this may result in the passage from mother to young of the digestive micro-organisms required for the fermentation of vegetation for nutrition
• play-fighting

Aggression

• fights (‘boxing’) between large males are rare
• most fights are one-sided and end quickly; the challenged individual usually moves away
• a submissive ‘cough’/cluck is heard in eastern greys, wallaroos, euros but not in reds
• threat displays indicate an intention to act aggressively; these include upright posture, stiff-legged walking, pulling on grass or bushes

Distribution

• Between them, the kangaroos range over most of Australia.
• In some areas there may be only one species while in other places several species occur.

Habitat preference

Red Kangaroo

• arid and semi-arid regions;
• most of the vegetated habitats – grasslands, shrublands, mulga

Western Grey Kangaroo

• dry regions of the inland (lower half of the continent) and Western Australia

Eastern Grey Kangaroo

• eastern third of the continent;
• wide variety of habitats – high mountain forests, semi-arid ranglands;
• only kangaroo found in Tasmania

Antilopine Kangaroo

• monsoonal region of north Australia;
• grassy, eucalypt woodlands

Euro group (4 subspp)

• most widespread of the kangaroos;
• most of the continent except the southern edge;
• rough, hilly country

Black Wallaroo

• central and western Arnhem Land in the Northern Territory;
• woodlands, shrub cover, monsoonal forest

Feeding

• reds and greys may feed in large mobs – size depends on the quality of food
• most active at dawn and dusk; relatively inactive in middle of both day and night
• time spent grazing varies seasonally between 7 and 14 hours
• rest during the day in the shade of woodland; move onto grasslands to feed
• eat a variety of plants but mainly grasses

Hopping

• kangaroos are unique in being the only large animals that use hopping for locomotion
• they walk at slow speeds and start hopping as speed increases

Energetics of hopping

• when hopping starts its costs are high
• as speed increases, the energy costs change little which means that a kangaroo hopping at a moderate speed (>15 km/hr) uses less energy than a similarly-sized animal that is running
• for red kangaroos, the most comfortable speed is 20-25 km/hr
• as speed increases up to about 40 km/hr, the hopping rate remains constant but the length of the hop increases
• although red kangaroos can hop at speed of 65-70 km/hr for short distances, at these speeds the hopping rate increases as well as the hop length
• while hopping has benefits in energy expenditure at high speed, at low speeds (below 6 km/hr) they have an awkward walk using their hind legs with the tail providing additional support for the front legs, and this is both clumsy and energetically expensive

Causes of mortality

Lack of Nutrition

• particularly in young animals that don’t have body reserves

Predation

• dingoes, eagles, foxes, humans

Disease

• filarioid nematode worm, Pelecitus roemeri found in the connective tissue; lumpy jaw caused by bacterium Fusobacterium necrophorum *

Environmental stress

• drought, flooding, severe wet and cold weather

The incidence of mortality by disease vectors usually involves the interrelationship of some of the other factors listed

General

• reds, euros, wallaroos – breed continuously under good conditions; greys are usually seasonal breeders
• marsupial reproduction depends on lactation to nourish the poorly developed young; consequently, female marsupials have a greater investment in the care of their young
• females coming into oestrus extend their area of activity to attract the largest male in that area; so, a large male will be able to mate with more females
• there are indications that a female (of some species) may invest less in male offspring in years when conditions are poor and that this explains the increased male mortality of young males; the reasoning behind this is that to be a successful breeder a male needs to be large and males raised in poor seasons will never become the dominant male, whereas a female produced during a poor season will still breed and pass on her mother’s genes

Gestation and birth

• kangaroos have a relatively long gestation period compared to other marsupials ranging from about 31-36 days
• exhibit embryonic diapause – a viable embryo is carried in the uterus with its development arrested at an early stage (except the Western Grey); development is recommenced after final pouch exit by the previous young
• mother assists the newly-born into the pouch through pouch cleaning and birth posture (characteristic for each species); in reds, the female brings her tail forward between her hind legs and leans back against a tree while antilopines don’t require back support and greys don’t bring the tail forward; the newborn are visible for about three minutes before disappearing into the pouch

Lactation

• in the euro, wallaroos, and red the young is continuously attached to the nipple until 120-130 days
• composition of the milk is tailored to the requirements of the developing young e.g. around the time of hair formation, there is an increase in sulphur-containing amino acids (hair has a high content of sulphur-containing proteins)
• facilitates the transfer of immunity to the newborn that is now in an unsterile pouch; around birth the mammary glands secrete a clear fluid that has free-floating cells and maternal immunoglobulins (similar to the colostrum of placental mammals)
• mother can simultaneously produce milk of two different compositions for the joey that has emerged from the pouch but is not weaned and for the newborn

Emergence from the pouch

• young first emerges from the pouch usually by falling out; this occurs after 185 days in reds, up to 298 days for western greys
• mother’s muscles control pouch size and opening; when she is alarmed, the pouch is pulled tight against her body so that the joey cannot emerge; she can relax the pouch and let the joey fall out; she can also contract the pouch and tip the joey out
• joeys entering the pouch complete a somersault and end up facing the pouch opening
• even after permanent emergency, the joey will continue to suckle on its usual teat for some months

TIMING OF SEXUAL MATURITY (months)

Species	Male	Female
Red	24	15-20
Western Grey	31	14
Eastern Grey	48	18
Euro	24	21

Social system

• generally sedentary, home range (the area covered by an individual in the normal activities of feeding, mating, and caring for young) of a few kilometres across; home ranges are not defended
• show fidelity to the home range, often returning after being forced away to find food in other places during drought

Aggregation

• grouping of individuals at a resource (food, water, shade); individuals are not necessarily interacting

Mob

• a set of individuals whose home ranges overlap; commonly interact with each other; young animals and a lesser number of adults may disperse to different mobs; sufficient interaction to establish dominance hierarchies in relation to feed and shade for resting

Group

• social neighbourhood of an individual; members of a group communicate and interact as a unit; consist of less than 6 individuals; mainly females and their offspring, particularly daughters

Species	Typical group size*	Aggregation size	Home range size**
Red	3 – 4	20	150 ha
Western Grey	2 – 16		100 ha
Eastern Grey	3 – 23	80	20 ha
Eastern Grey  (Tasmania)	5
Antilopine	3 – 12	50	female14 ha male 76 ha
Euro	2 – 3		10-37 ha
* (from Dawson TJ, 1995, p29) ** depends on sex, season, habitat, time span

Status

• None of the kangaroos are endangered, although locally populations may be limited.

References – books

• Kangaroos – Biology of the Largest Marsupials, TJ Dawson, 1995. University of New South Wales Press Ltd, Sydney.
• Encyclopedia of Australian Wildlife, Reader’s Digest Australia Pty Ltd, 1997. Reader’s Digest (Australia) Pty Ltd, Surrey Hills.
• Complete Book Of Australian Mammals, R Strahan (ed), 1983. Angus & Robertson Publishers, London.