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Macropus rufusred kangaroo

By Tanya Dewey and Minerva Yue

Geographic Range

Macropus rufus occurs over most of the dry, inland, central part of Australia. This expansive area includes scrubland, shrubland, grassland, and desert habitats. (Department of the Environment and Heritage, 2005; Nowak, 1991)

Habitat

Red kangaroos live over most of the central part of Australia in areas where rainfall averages less than 500 millimeters. They prefer to forage in open plains habitats with neither trees nor bushes, but are seldom found in regions without shade and shelter from scattered trees. (Kangaroo Conservation Center, September 14, 2000; Nowak, 1991)

Physical Description

Macropus rufus is the largest living marsupial. Males range in total body length from 1,300 to 1,600 mm and females from 850 to 1,050 mm. Tail length is from 1,000 to 1,200 mm for males and 650 to 850 mm for females. They may weigh as much as 90 kg and may reach 1.8 meters in height when standing. Coat color is usually reddish brown in males and bluish gray in females, although these colors are reversed in some areas, with females being reddish and males blue-gray. Red kangaroos are robustly built, with large, well-muscled tails and powerful hindquarters. The tail is strong enough to support the kangaroo's body weight, acts as a balance when jumping, and is used, with the two legs, to form a tripod for resting. The second and third toes of red kangaroos are fused and shaped into a grooming claw. Their foreshortened upper limbs terminate in clawed paws used with great dexterity in eating, grooming, and self-defense. Females have a forward facing pouch and 4 mammae. (Nowak, 1991; Snelling, Sept-Nov 1988)

  • Sexual Dimorphism
  • male larger
  • Range mass
    90 (high) kg
    198.24 (high) lb
  • Range length
    650 to 1200 mm
    25.59 to 47.24 in
  • Average basal metabolic rate
    31.353 W
    AnAge

Reproduction

Male red kangaroos compete for mating opportunities with several females. Males will try to monopolize access to several females and will actively drive away other males. This competition sometimes leads to "boxing" matches, where males hit at each other with their forepaws and kick with their feet. There is no permanent association of males and females. (Nowak, 1991)

Macropus rufus has a short gestation period. The young are born 33 days after mating, and mating can occur again a day or two after parturition. The fertilized egg resulting from this post-partum mating develops only to the blastocyst stage and then undergoes a period of embryonic diapause. Development is resumed if the previous young, which is still suckling in the pouch, reaches 204 days old or if it dies or is removed. Young kangaroos are known as joeys. Red kangaroo joeys are tiny when born, averaging only 2.5 centimeters long and 0.75 grams. After the joey is born, it crawls up the mother's fur, into her pouch and immediately attaches itself to a nipple. During this period, the sucking stimulus prevents the re-occurence of fertility cycles. Given favorable conditions, a mother red kangaroo produces and raises an average of three young every two years. Individual females often have, simultaneously, a joey outside of the pouch, a joey in the pouch, and a blastocyst awaiting implantation. Compared to the gestation period, the period of lactation is long, about one year in red kangaroos.

A mature female red kangaroo which is appropriately nourished, and which is not suckling a young in its pouch already, becomes fertile at approximately 35 day intervals and is, like the male, potentially fertile throughout the year. Unlike the suckling period, pregnancy does not interrupt recurrence of fertility.

Sexual maturity is reached at 15 to 20 months in females and 20 to 24 months in males, but maturity may be delayed in unfavorable conditions. (Nowak, 1991; Snelling, Sept-Nov 1988)

  • Breeding interval
    Given favorable conditions, a mother red kangaroo produces and raises an average of three young every two years.
  • Breeding season
    Red kangaroos can breed throughout the year.
  • Range number of offspring
    2 (high)
  • Average number of offspring
    1
  • Average number of offspring
    1
    AnAge
  • Average gestation period
    33 days
  • Average gestation period
    33 days
    AnAge
  • Average weaning age
    12 months
  • Range age at sexual or reproductive maturity (female)
    15 to 20 months
  • Range age at sexual or reproductive maturity (male)
    20 to 24 months

Red kangaroo young are tiny when born and make their own way from the birth canal to the pouch and a nipple to which they permanently attach themselves for about 70 days. They are born with well-developed tongues, jaw muscles, nostrils, forelimbs, and digits. Otherwise their external features are embryonic. Females lactate their young for about a year and carry them in their pouch for about 235 days. (Nowak, 1991)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

Lifespans are potentially long in red kangaroos, although most individuals probably do not survive their first year of life. Red kangaroos have been recorded living up to 22 years in the wild. (Nowak, 1991)

Behavior

Red kangaroos occur in small groups, averaging 10, called "mobs." These groups are made up mainly of females and their offspring, with one or several males. Females stay within their natal mob. Occasionally, large numbers of red kangaroos congregate in areas of excellent forage, sometimes numbering as much as 1,500 individuals. Red kangaroos are mostly crepuscular and nocturnal, resting in the shade during the day - but have been known to move about during the day. Most of their active period is spent in grazing. Most kangaroo species are relatively sedentary, staying within a relatively well-defined home range. This is also often characteristic of Macropus rufus populations, but they may travel widely in response to adverse environmental conditions. A red kangaroo was recorded traveling 216 km. Population densities have been estimated by two, separate studies at 4.18 individuals per square kilometer and 1 individual per 89 hectares.

Red kangaroo hind legs are powerful and the tail acts to balance the body in a bipedal hop as their legs propel them forwards. Large kangaroos can reach a running speed of 64kph, with leaps as long as 8 meters and as high as 3 meters, although 1.2 to 1.9 meters is more typical of an average pace. Red kangaroos also use their tail an a kind of 5-"legged" gait, where the forelimbs and tail balance the animal as the two rear legs are moved forward simultaneously. (Kangaroo Conservation Center, September 14, 2000; Nowak, 1991; Snelling, Sept-Nov 1988)

Communication and Perception

Little information on communication among red kangaroos is available. Like most mammals, red kangaroos are likely to make extensive use of chemical modes of perception and communication. They also have excellent vision and hearing, suggesting these are important sensory modes.

Food Habits

Red kangaroos are exclusively plant-eaters, with a preferred diet of green herbage including grasses and dicotyledonous flowering plants. These herbivores can go without water for long periods of time by consuming moisture-filled succulent plants. (Nowak, 1991)

  • Plant Foods
  • leaves
  • wood, bark, or stems

Predation

Their large size reduces the predation risks faced by red kangaroos. Very young joeys are protected in their mother's pouch and red kangaroos can use their robust legs and clawed feet to defend themselves from attackers with kicks and blows. They may be preyed on by dingos and very young joeys, just out of the pouch, may be taken by large raptors. Humans have historically hunted kangaroos for their meat and hides and human hunting continues to be the primary source of predation for red kangaroos. (Nowak, 1991)

Ecosystem Roles

Macropus rufus is important in shaping vegetation communities in the ecosystems in which they live through their action as grazers.

Economic Importance for Humans: Positive

A fairly large Australian industry exists around the use of kangaroos for their skins and meat. Red kangaroos are also integral parts of the healthy ecosystems in which they live. (Nowak, 1991)

  • Positive Impacts
  • food
  • body parts are source of valuable material

Economic Importance for Humans: Negative

Kangaroos are sometimes considered pests by livestock owners because they compete for forage with livestock. In areas where vegetation is limited, kangaroos may cause reduce forage significantly.

  • Negative Impacts
  • crop pest

Conservation Status

Macropus rufus is not considered endangered. Nearly 3 million square miles of Australian territory now lies within the boundaries of excellent national parks. All Australian states regulate the hunting of kangaroos. (Department of the Environment and Heritage, 2005)

Contributors

Tanya Dewey (author), Animal Diversity Web.

Minerva Yue (author), West Windsor-Plainsboro High School, Joan Rasmussen (editor), West Windsor-Plainsboro High School.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

crepuscular

active at dawn and dusk

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

embryonic diapause

At about the time a female gives birth (e.g. in most kangaroo species), she also becomes receptive and mates. Embryos produced at this mating develop only as far as a hollow ball of cells (the blastocyst) and then become quiescent, entering a state of suspended animation or embryonic diapause. The hormonal signal (prolactin) which blocks further development of the blastocyst is produced in response to the sucking stimulus from the young in the pouch. When sucking decreases as the young begins to eat other food and to leave the pouch, or if the young is lost from the pouch, the quiescent blastocyst resumes development, the embryo is born, and the cycle begins again. (Macdonald 1984)

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

nomadic

generally wanders from place to place, usually within a well-defined range.

polygynous

having more than one female as a mate at one time

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

scrub forest

scrub forests develop in areas that experience dry seasons.

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

References

Department of the Environment and Heritage, A. 2005. "Kangaroos-Wild harvest of native species" (On-line). Australian Government, Department of the Environment and Heritage. Accessed June 26, 2005 at http://www.deh.gov.au/biodiversity/trade-use/wild-harvest/kangaroo/index.html.

Kangaroo Conservation Center, September 14, 2000. "Red Kangaroos" (On-line). Accessed September 20, 2000 at http://www.kangaroocenter.com/redroo.html.

Nowak, R. 1991. Walker's Mammals of the World. Baltimore: The Johns Hopkins University Press.

Snelling, A. Sept-Nov 1988. "The Amazing Austrailian Kangaroos" (On-line). Accessed August 11, 2000 at http://www.answersingenesis.org/docs/1151.asp.

The World Book Encyclopedia, 1989. World Book Encyclopedia of Science: The Animal World Vol. 6. Chicago, IL: World Book Inc.

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