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Bettongia gaimardiTasmanian bettong

By Melissa Gallego

Geographic Range

Predation and habitat destruction in the early 1900s have restricted Tasmanian bettongs, Bettongia gaimardi cuniculus, to their current range, which includes most of the eastern half of Tasmania. Bettongia gaimardi inhabits arid regions, semi-arid regions, and sclerophyll forests of Tasmania and formerly parts of southern Australia. Eastern bettongs, B. g. gaimardi, were once found on mainland Australia in southern New South Wales and Victoria along the coast but are now extinct. ("Parks and Wildlife Services Tasmania", 2003; "Parks and Wildlife Services Tasmania", 2004; "Tasmanian Bettong", 2003; Rose and Rose, 1997; Rose, 1986; Rose, 1997; Rose, et al., 1998; Wakefield, 1967)

Habitat

Bettongia gaimardi is found in terrestrial, temperate habitats including grasslands, grassy woodlands, dry eucalyptus forests, and sclerophyll forests (i.e., forests containing plants with hard, short and usually spiky leaves). This species is found from sea level to elevations around 1,000 m. ("Parks and Wildlife Services Tasmania", 2003; "Tasmanian Bettong", 2003; Wakefield, 1967)

  • Range elevation
    0 to 1000 m
    0.00 to 3280.84 ft

Physical Description

Bettongia gaimardi has a small, compact body. Average total length is 65 cm. Males are slightly longer and thinner than females, although sexual dimorphism is not pronounced. These animals weigh between 1.2 and 2.3 kg.

Pelage is light brown with white flecks. This species has the longest fur and the lightest coloration in Bettongia. The long tail gradually gets darker from base to tip. The hair is slightly longer on the tail and has white tips, a distinguishing characteristic of B. gaimardi. The tail of B. gaimardi tends to be slightly longer than its head-body measurement, although both range between 32 and 33 cm in adults. The belly is very light in color. Digits II and III are, as in other macropods, syndactylous.

An adult female has four teats and a forward opening pouch. A resting, non-lactating female has a basal metabolic rate of approximately 229 kJ/day or 0.51 g of oxygen per hour.

Body temperatures vary with time of day and with estrous cycle, but typically fall between 36.2°C (midday) and 37.5°C (midnight). Bettongia gaimardi sweats to cool off, using sweat glands on its hind limbs, at the base of the tail, and inside the female’s pouch. ("Parks and Wildlife Services Tasmania", 2003; "Parks and Wildlife Services Tasmania", 2004; Fisher, et al., 2001; Rose and Rose, 1997; Rose, 1986; Rose, 1997; Rose, et al., 1998; Wakefield, 1967)

  • Sexual Dimorphism
  • male larger
  • Range mass
    1.2 to 2.3 kg
    2.64 to 5.07 lb
  • Average mass
    1.6-1.8 kg
    lb
  • Range length
    31 to 33 cm
    12.20 to 12.99 in
  • Average basal metabolic rate
    389 cm3.O2/g/hr
  • Average basal metabolic rate
    3.578 W
    AnAge

Reproduction

Female B. gaimardi will not allow males near them except while in heat or while the males check the female for estrus by sniffing. If the male takes too long to check, the female will sometimes kick and hiss until the male leaves. Estrus lasts one night, though mating may occur several times during that single night so occasionally a male and female may be seen together. The estrous cycle lasts 22 to 23 days. Bettongia gaimardi is believed to be polygynous and to breed continuously, however, harsh environment conditions may limit breeding in the wild. ("Parks and Wildlife Services Tasmania", 2003; "Parks and Wildlife Services Tasmania", 2004; "Tasmanian Bettong", 2003; Fisher, et al., 2001; Rose, 1986; Rose, 1997)

As in other macropods, B. gaimardi embryos experience a pause in development between fertilization and implantation. A single female may have one young leaving and re-entering the pouch, another suckling, and a third offspring in utero waiting to implant. This allows for continuous reproduction with offspring at all stages of development, and allows for fast replacement of young should one be lost. The estrous cycle is 1.5 days shorter in a pregnant female so that she gives birth just before releasing another egg. Before birth, the pouch muscles tighten so that older offspring cannot re-enter it. The female’s reproductive tract also lacks a birth canal, which forms just before birth and degenerates after birth. It is re-formed for every offspring. Males are atypical for macropods because they do not have a forked penis.

Females can produce 1 offspring per gestation but because a female can produce up to 3 young per year, she can have as many as 10 to 15 young in her lifetime. The young are born ectothermic, blind, and poorly developed. They gradually attain the ability to produce metabolic heat, open their eyes, and continue development in the pouch. The gestation period is 21 days with a 105 day pouch life, and there are 106 days between consecutive births. ("Tasmanian Bettong", 2003; Fisher, et al., 2001; Rose, 1986; Rose, 1997; Rose, et al., 1998; Wakefield, 1967)

  • Breeding interval
    Breeding occurs immediately after a females gives birth. There is a minimum of 106 days between births, assuming that neither the joey nor the embryo is lost.
  • Breeding season
    Breeding occurs year round in captivity and in the wild, though environmental conditions may affect reproduction in the wild.
  • Average number of offspring
    1
  • Average number of offspring
    1
    AnAge
  • Average gestation period
    21 days
  • Average gestation period
    20 days
    AnAge
  • Average weaning age
    154-155 days
  • Average time to independence
    156 days
  • Range age at sexual or reproductive maturity (female)
    8 to 12 years
  • Range age at sexual or reproductive maturity (male)
    12 (high) months

Male B. gaimardi do not take part in parenting; females are solely responsible for the young. Females carry each offspring first in utero and then in the pouch, protecting it and nursing it until the offspring can become independent. The offspring then leaves its mother's nest and disperses. (Fisher, et al., 2001; Wakefield, 1967)

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

Lifespan/Longevity

Little is known about the lifespan of Tasmanian bettongs in capitivity and there is debate about its lifespan in the wild. In captivity, B. gaimardi can live between 7 and 12 years, and its wild lifespan is much shorter, ranging from 3 to 6 years on average. ("Parks and Wildlife Services Tasmania", 2004; Fisher, et al., 2001; Rose, 1986)

  • Range lifespan
    Status: wild
    7 (high) years
  • Range lifespan
    Status: captivity
    Unknown (high) years
  • Typical lifespan
    Status: wild
    3 to 6 years
  • Average lifespan
    Status: wild
    3-6 years
  • Average lifespan
    Status: captivity
    11.8 years
    Max Planck Institute for Demographic Research

Behavior

Bettongia gaimardi is nocturnal. It builds several nests on its territory and has been known to use 5 or 6 nests at a time. Its semi-prehensile tail allows it to pick up and carry grasses or brush while collecting more nesting material or while foraging. The tail is held off the ground and is used as a counterbalance weight. Bettongia gaimardi often uses its forelimbs to dig for fungi, forage for other food sources, or when moving slowly, but it relies mostly on its larger hind limbs for fast movements like escaping from predators. Both sexes are territorial. It is generally a solitary creature except during the mating season or when a female is with her young before weaning. Males in captivity will establish dominance hierarchies if housed together. ("Tasmanian Bettong", 2003; Wakefield, 1967)

  • Range territory size
    0.35 to 0.55 km^2

Home Range

A female’s average territory is 35 to 55 hectares (86 to 136 acres). Males typically have slightly larger territories. ("Tasmanian Bettong", 2003; Fisher, et al., 2001; Rose, et al., 1998; Wakefield, 1967)

Communication and Perception

Adult female B. gaimardi are known to make “tsk-tsk” sounds to call their young back to the pouch. Other species in Bettongia are reported to use their hind limbs to thump the ground and B. gaimardi is known to use scent glands near the anus to mark territories. Because of the interaction with the mother while living in her pouch, it is likely that tactile communication plays an important role between a mother and her young. Tactile communication is also likely to be important during mating.

Food Habits

Bettongia gaimardi is mycophagous. Fungi may comprise as much as 80% of the diet. Other foods may be eaten, but fungi are preferred and unless it is scare. Bettongia gaimardi forages by hopping slowly using all four limbs and often uses the forelimbs to dig for food. ("Parks and Wildlife Services Tasmania", 2003; "Parks and Wildlife Services Tasmania", 2004; Rose, 1997; Wakefield, 1967)

  • Animal Foods
  • insects
  • Plant Foods
  • leaves
  • roots and tubers
  • wood, bark, or stems
  • fruit
  • sap or other plant fluids
  • Other Foods
  • fungus

Predation

Foxes contributed to the extinction of bettongs on the Australian mainland. Thylacines, Thylacinus cynocephalus, were a likely predator before they became extinct in Tasmania. Birds of prey, such as wedge-tailed eagles and owls, prey upon Tasmanian bettongs, as do feral cats and dogs. There have been reports of Eastern quolls preying upon B. gaimardi, but they have been met with skepticism. ("Parks and Wildlife Services Tasmania", 2003; "Parks and Wildlife Services Tasmania", 2004; Rose and Rose, 1997)

Ecosystem Roles

Bettongia gaimardi builds a grass nest and enthusiastically digs for fungi. It therefore helps to aerate the soil, and has some impact on plant communities. To the extent that these animals serve as prey, they may also impact predator populations. (Rose and Rose, 1997)

Species Used as Host
  • None known
Mutualist Species
  • None known
Commensal/Parasitic Species

Economic Importance for Humans: Positive

There are no known positive effects of B. gaimardi on humans, though they probably attract a few tourists to Tasmania. ("Parks and Wildlife Services Tasmania", 2003; "Parks and Wildlife Services Tasmania", 2004)

Economic Importance for Humans: Negative

There are no known negative effects of B. gaimardi on humans. However, other species belonging to the genus Bettongia, especially the burrowing bettong, are viewed as agricultural pests because they are known to dig up roots. ("Parks and Wildlife Services Tasmania", 2003; Rose and Rose, 1997; Rose, 1986)

  • Negative Impacts
  • crop pest

Conservation Status

Bettongia gaimardi is a protected species in Tasmania and is considered to be vulnerable because only 5% of its habitat lies within the bounds of national parks or other protected land. The rest of its habitat belongs to private owners who can alter the land at will. Competition with rabbits introduced to Tasmania also poses a threat. Because there was once a reward for its hide on the Australian mainland, hunting, combined with loss of habitat and introduced species, probably drove bettongs to extinction on the mainland.

Bettongia gaimardi cuniculus has been listed on the IUCN as a lower risk, nearthreatened species since 1996. Bettongia gaimardi gaimardi is listed as extinct and has not been recorded since 1910. ("CITES", 2005; "Parks and Wildlife Services Tasmania", 2004; "U.S. Fisheries and Wildlife Services Species Profile", 2005; "2004 IUCN Red List of Threatened Species", 1996; Rose, 1986)

Other Comments

The classification of B. gaimardi has changed considerably over the years. Bettongia gaimardi was first described in 1822 by the French scientist Desmarest and originally classified as two species in the genus Kangurus (Kangurus cuniculus and Kangurus gairmadi). Bettongs received the genus name Hypsiprymnus from Ogilby’s early work in 1837 (cited in Wakefield, 1967); however, the genus name was later changed to Bettongia, a word derived from its aboriginal name "small wallaby". Wakefield’s work in 1967 consolidated the two former species (B. cuniculus and B. gaimardi) into a single species and created two recognized subspecies instead: Bettongia gaimardi cuniculus (Tasmanian Bettong) and Bettongia gaimardi gaimardi (the mainland and now extinct form). For more information on the classification and discovery of B. gaimardi, please see Wakefield, 1967 or "Parks and Wildlife Services Tasmania" 2003.

For pictures of skulls, whole mounts, and drawings of Tasmanian bettongs (and other creatures native to the Australia area) please visit Museum Victoria ("Parks and Wildlife Services Tasmania", 2003; Wakefield, 1967)

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Barbara Lundrigan (editor, instructor), Michigan State University, Melissa Gallego (author), Michigan State University.

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

delayed implantation

in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.

ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

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.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

island endemic

animals that live only on an island or set of islands.

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.

mycophage

an animal that mainly eats fungus

native range

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

nocturnal

active during the night

polygynous

having more than one female as a mate at one time

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

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

soil aeration

digs and breaks up soil so air and water can get in

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

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

Australasian Marsupial & Monotreme Specialist Group. 1996. "2004 IUCN Red List of Threatened Species" (On-line). Bettongia gaimardi ssp. cuniculus. Accessed April 14, 2005 at http://www.iucnredlist.org/search/details.php?species=2792.

2005. "CITES" (On-line). Appendices I, II and III. Accessed April 15, 2005 at http://www.cites.org/eng/app/appendices.shtml.

2003. "Parks and Wildlife Services Tasmania" (On-line). Mammals of the Freycinet Peninsula. Accessed March 15, 2005 at http://www.parks.tas.gov.au/notesheets/wildlife/MammalsofFreycinet.pdf.

2004. "Parks and Wildlife Services Tasmania" (On-line). Tasmanian Bettong, Bettongia gaimardi . Accessed March 15, 2005 at http://www.parks.tas.gov.au/wildlife/mammals/bettong.html.

2003. Tasmanian Bettong. Pp. 78 in M Hutchins, D Kleinman, V Geist, M McDade, eds. Grzimek’s Animal Life Encyclopedia, Vol. 13, Second Edition. Farmington Hills, MI: Gale Group.

2005. "U.S. Fisheries and Wildlife Services Species Profile" (On-line). Rat-kangaroo, Gaimard's. Accessed April 15, 2005 at http://ecos.fws.gov/species_profile/servlet/gov.doi.species_profile.servlets.SpeciesProfile?spcode=A04D.

Fisher, D., I. Owens, C. Johnson. 2001. The ecological basis of life history variation in marsupials. Ecology, 82: 3531-3540. Accessed March 09, 2005 at http://www.esapubs.org/archive/ecol/E082/042/appendix-A.htm.

Rose, R. 1997. . Metabolic rate and thermal conductance in a mycophagous marsupial, Bettongia gaimardi. World Wide Web Journal of Biology, 2: 7. Accessed March 11, 2005 at http://epress.com/w3jbio/vol2/rose/rose.htm.

Rose, R. 1986. The habitat, distribution and conservation status of the Tasmanian bettong, Bettongia gaimardi (Desmarest). Australian Wildlife Reservation, 13: 1-6.

Rose, R., N. Kuswanti, E. Colquhoun. 1998. Development of endothermy in a tasmanian marsupial, Bettongia gaimardi, and its response to cold and noradrenaline. Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology, 168/5: 359–363.

Rose, R., R. Rose. 1997. Bettongia gaimardi. Mammalian Species, 584: 1-6. Accessed April 12, 2005 at http://www.science.smith.edu/departments/Biology/VHAYSSEN/msi/pdf/i0076-3519-584-01-0001.pdf.

Wakefield, N. 1967. Some taxonomic revision in the Australian marsupial genus Bettongia (Macropodidae), with a description of a new species. The Victorian Naturalist, 84: 8-22.

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