Isoodon macrourusnorthern brown bandicoot

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Geographic Range

The large short-nosed bandicoot, a marsupial, is found only on the northern and eastern coasts of Australia and nearby islands, mainly Papua New Guinea. It is not, however, found far inland in Australia where the environment is extremely hot and unsuitable for most organisms.

Habitat

The populations of I. macrourus live in two different habitats: one during the dry season and the other during the wet season. During the dry season, this species lives in thick vegetation consisting of tall weeds, small trees, and dense shrubs. This probably occurs because of the sparse food supply that can be found. During the wet season though, I. macrourus "come out" and roams open grasslands where a more abundant food source exists (Friend and Taylor, 1985).

Large short-nosed bandicoots make individual nests or homes on the ground consisting of simple mounds of hay and twigs that are well camouflaged and waterproof. The inside is hollow and large enough for just the single bandicoot. Some bandicoots use hollowed out tree trunks or abandoned rabbit dens for shelter. In general however, I. macrourus show a strong preference for homes in areas of low ground cover (Seebeck et al. 1990).

Physical Description

These bandicoots can be set apart from other marsupials by two traits. They are both polyprotodont and syndactylous (Seebeck et al. 1990). I. macrourus have typical body and tail lengths of 40cm and 15cm, respectively. On average they weigh 1200g. This rodent-like marsupial has a thick harsh coat but is not spiny. The dorsal pelage is light brown in appearance with speckled black patterns throughout. On the ventral surface it is solid white (Grzimek 1990). This bandicoot also has short, rounded ears and a short nose. One can easily mistake large short-nosed bandicoots for Isoodon obesulus, or small short-nosed bandicoots. The two species differ in both size, with I. macrourus larger, and regional locality, in that I. obesulus are found only on the southern coastline of Australia (Seebeck et al. 1990).

The male is typically 5-7cm longer and half a kilogram heavier than the female (Seebeck et al. 1990).

  • Range mass
    260 to 1500 g
    9.16 to 52.86 oz
  • Average mass
    1200 g
    42.29 oz
  • Average basal metabolic rate
    3.202 W
    AnAge

Reproduction

The large short-nosed bandicoot breeds throughout the year. An average litter consists of 2-4 young. Being marsupials, the newborns are naked and immature and thus undergo extensive development within the mother's pouch (Gemmell and Johnson, 1985). The gestation period (12.5 days) is the shortest recorded for any mammal (Seebeck et al., 1990). Bandicoots are also the only metatherian marsupials that have placentas similar to eutherian mammals. Juveniles are weaned at 60 days post partum. By this time, the marsupial young are capable of sustaining endothermy on their own (Gemmell and Johnson, 1985). I. macrourus have a lifespan of approximately two years.

Female bandicoots produce between 8-11 litters in their lifetime (Gemmell and Hendricks, 1993). Male bandicoots don't play a signifacant role in the care of juvenile I. macrourus.

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual
  • Average number of offspring
    4
    AnAge
  • Average gestation period
    12 days
    AnAge
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    122 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    200 days
    AnAge

Lifespan/Longevity

Behavior

Large short-nosed bandicoots diligently mark and retain their territories. They have scent glands on the ears, mouth, pouch, and cloaca (Grzimek, 1990). These solitary marsupials are aggressive only towards each other. If a bandicoot is startled in its nesting site, it will flee. Hardly ever will I. macrourus defend themselves unless two males confront one another over territorial rights. Then, either a male is killed or one male becomes subordinate to the other and avoids confrontation. The subordinate male also forfeits to the dominant male all sexual relations with local females (Stonehouse and Gilmore, 1977). Bandicoots are not social animals and do not live in groups, with the exception of mother and her young.

Communication and Perception

Food Habits

I. macrourus is omnivorous. They eat insects, earthworms, berries, and grass seeds. Sometimes when food is scarce, the female bandicoot will eat her young. These marsupials forage alone during the night and have a keen sense of smell. This allows bandicoots to find food either laying in the open or burried underground. Hunting at night, however, also has its consequences. The bandicoot is prime prey for many nocturnal cats, foxes, and owls found in Australia (Grzimek 1990).

Economic Importance for Humans: Positive

Large short-nosed bandicoots are a delicacy to the aboriginal populations of Australia. Also, this species can be bred with relative ease in captivity. This could allow it to serve as a "model animal" for future experimental studies (Seebeck et al. 1990).

Conservation Status

Over the past century, populations of I. macrourus have decreased after the European introduction of rabbits and livestock into Australia. This dramatically heightened the direct competition for food and habitat. Bandicoot populations further suffered after the introduction of the fox and cat, both predators of small animals (Grzimek 1990).

Other Comments

It has been suggested that Isoodon macrourus reached New Guinea via Late Pleistocene flooding of a former land bridge called the Torres Strait (Stonehouse 1977).

Contributors

Benjamin Fishman (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Australian

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

World Map

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

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.

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.

scrub forest

scrub forests develop in areas that experience dry seasons.

sexual

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

tactile

uses touch to communicate

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.

References

Friend, G., J. Taylor. 1985. Habitat preferences of small mammals in tropical open-forest of the Northern Territory. Australian Journal of Ecology, 10: 173-185.

Gemmell, R., J. Hendrikz. 1993. Growth rates of the bandicoot Isoodon macrourus and the brushtail possum Trichosurus vulpecula. Australian Journal of Zoology, 41: 141-149.

Gemmell, R., G. Johnston. 1985. The development of thermoregulation and the emergence from the pouch of the marsupial bandicoot Isoodon Macrourus. Physiological Zoology, 58(3): 299-302.

Grzimek, B. 1990. Encyclopedia of Mammals Volume 1. New York, NY: McGraw Hill.

Seebeck, J., P. Brown, R. Wallis, C. Kemper. 1990. Bandicoots and Bilbies. Chipping Norton, New South Wales, Australia: Surrey Beatty & Sons Pty Limited.

Stonehouse, B., D. Gilmore. 1977. The Biology of Marsupials. Baltimore, Maryland: University Park Press.