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Potorous gilbertiiGilbert's potoroo

By Jennifer Gumas

Geographic Range

There is only one extant population of Gilbert's potoroos. This population lives in the Two People's Bay park area of Western Australia. (Sinclair, et al., 2000)

Habitat

Gilbert's potoroos are entirely terrestrial. In the Two People's Bay park area, the potoroos hide from predators in the brushy undergrowth. Other members of the genus Potorous also prefer living in thick scrub, forest, low bushes, or long grass. (Lydekker, 1896; Lyne, 1967; Sinclair, et al., 2002)

Physical Description

Gilbert's potoroos measure approximately 558 mm in length, with the tail taking up 158 mm of this total. The short, silky coat of Gilbert's potoroos are grayish-brown, fading to a reddish-brown color on the back. The under parts are whitish-gray, and the tail consists of hairs which are gray at the base turning into black at the tips. The face is long and narrow with a black line running from the nose to the forehead. (Harper, 1945; Lydekker, 1896)

  • Average length
    558 mm
    21.97 in

Reproduction

The reproductive behavior of Gilbert's potoroos has not yet been studied in detail by scientists. In Potorous tridactylus, the mating system is polygamous. Gilbert's potoroos may share a similar mating system. (Nowak, 1991)

The reproductive behavior of Gilbert's potoroos has not yet been studied in detail by scientists. However, reproduction in Potorous tridactylus has been well documented, and it is likely that Potorous gilbertii is similar in many respects. The following information pertains to P. tridactylus.

Females typically breed two times a year at any time during the year. Litters always containt a single pup, which is born after a gestation period of approximately 38 days. Females may breed again immediately after giving birth, but the newly conceived embryo remains dormant and implantation is delayed for at least four and a half months, or until the first pup dies. Females can breed starting at one year of age. Newborn pups measure 3/4 inches long at the time of birth. It takes 10 minutes for the pup to crawl to the mother's pouch. In the pouch, the pup attaches to a teat, where it remains for two months. Pups continue to suckle until four months of age. (Lyne, 1967; Nowak, 1991)

  • Breeding interval
    The breeding interval of P. gilbertii has not been documented, but if these animals are like other members of the genus, they probably breed twice per year.
  • Breeding season
    The breeding season for this species has not been documented.

Parental care in Potorous gilberti has not been described. However, as marsupial mammals, some generalizations about these potoroos can be made. It is likely that most parental care is provided by the mother, first when the offspring is in her pouch, and later when it becomes more mobile. Females typically provide their young with protection, grooming, and food while they are still dependent. (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

The lifespan of Potorous gilbertii is unknown, but its close relative, Potorous tridactylus, is known to live up to 7 years in the wild and up to 12 years in captivity. (Nowak, 1991)

Behavior

Little is known about the behavior of Gilbert's potoroos. However, Potorous tridactylus, a closely related species, is primarily nocturnal. Males are considered territorial, but they defend home ranges only when nearby females are in estrus. Potorous tridactylus typically lives a in simple nest, with females spending a particularly large amount of time nesting while they are breeding. (Nowak, 1991)

Home Range

Information on the home ranges of P. gilbertii is not available.

Communication and Perception

The communication patterns of of Gilbert's potoroos are unknown. However, as with other marsupial mammals, these creatures can perceive visual stimuli, noises, and smells. It is not known what role scent, visual signals, or vocalizations play in their communication. (Nowak, 1991)

Food Habits

The food habits of Gilbert's Potoroos have not been studied, but one can infer that it is primarily herbivorous by studying the habits of its relative, Potorous tridactylus. Fungi are the major food of Potorous tridactylus, although these potoroos will also consume roots, grass, other vegetables, and an occasionally insect in the summertime. The roots and tubers are dug up with the potoroo's foreclaws. Potorous gilbertii reportedly digs holes in the ground while feeding, so it is likely that it is feeding on roots or fungi, also. (Marlow, 1968; Nowak, 1991)

Predation

Predation by introduced European foxes and feral cats is thought to have played a major role in the disappearance of Gilbert's potoroos. Researchers believe that the tiny population of Gilbert's potoroos in Two People's Bay managed to survive because the park did not employ the usual method of burning vegetation in the park. This extra brush gave the potoroos a place to hide from predators and allowed them to survive to the present. In addition, some field researchers report that Natives in Australia would occasionally kill the potoroos in large numbers. (Harper, 1945; Sinclair, et al., 2000)

Ecosystem Roles

The role that Gilbert's potoroos play in their local ecosystem is unknown. However, it can be inferred from their food habits that they modify the vegetation in communities in which they live, and may disturb the soil, influencing plant regeneration.

Economic Importance for Humans: Positive

It is not known whether Gilbert's potoroos have any positive effects on human populations. Although there are reports that P. gilbertii was formerly hunted, because of the species' current restricted distribution, it is not likely that it is a significant resource to indigenous peoples.

Economic Importance for Humans: Negative

It is not known whether Gilbert's potoroos have any negative effects on human populations. Although the closely related species, Potorous tridactylus, is considered a pest by many farmers because it causes damage to potato crops by scratching for food in the ground, it is not likely that Gilbert's potoroos are a significant pest because of their restricted distribution. (Lydekker, 1896)

Conservation Status

Gilbert's potoroos are considered one of Australia's most endangered mammals. Gilbert's potoroos were presumed extinct until the species was rediscovered in Two People's Bay in 1994. Many different factors have contributed to the near extinction of this species. These include predation by introduced foxes and feral cats, disease, poisoned baits, and loss of land due to grazing cattle. Recent scientific studies indicate that the single known small population of Gilbert's potoroos has experienced a dramatic, recent genetic bottleneck. The animals are likely vulnerable to disease due to lack of genetic variation. To prevent the extinction of Gilbert's potoroos, scientists estimate that the population must be increased to at least 500 individuals in order to provide sufficient genetic variation (the current population size is unknown). To do this, the Two People's Bay area must be conserved, local predators must be controlled, captive breeding programs must be created, and searches for other possible remaining populations of Gilbert's potoroos should be conducted. (Gilbert's Potoroo Action Group, 2004; Harper, 1945; Sinclair, et al., 2000; Sinclair, et al., 2002)

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Jennifer Gumas (author), Michigan State University, Barbara Lundrigan (editor, instructor), 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

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.

fertilization

union of egg and spermatozoan

internal fertilization

fertilization takes place within the female's body

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.

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

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.

References

IUCN. 1997. "The IUCN Red List of Threatened Species" (On-line ). Accessed 03/09/03 at http://www.redlist.org.

Gilbert's Potoroo Action Group, 2004. "Gilbert's Potoroo - Australia's Most Endangered Mammal" (On-line). Accessed June 05, 2007 at http://www.potoroo.org/.

Harper, F. 1945. Extinct and Vanishing Mammals of the Old World. Baltimore: The Lord Baltimore Press.

Lydekker, R. 1896. A Handbook to the Marsupialia and Monotremata. Edward Lloyd.

Lyne, G. 1967. Marsupials and Monotremes of Australia. Sydney: Halsted Press.

Marlow, B. 1968. Marsupials of Australia. Hong Kong: Jacaranda.

Nowak, R. 1991. Potoroos. Pp. 87-88 in Walker's Mammals of the World, Vol. 1, 5th Edition. Baltimore and London: The Johns Hopkins University Press.

Sinclair, E., B. Costello, J. Courtenay, K. Crandall. 2002. Detecting a genetic bottleneck in Gilbert's Potoroo (Potorous gilbertii) (Marsupialia: Potoroidae), inferred form microsatellite and mitochondrial DNA sequence data. Conservations Genetics, 3: 191-196.

Sinclair, E., A. Murch, M. Di Renzo, M. Palermo. 2000. Chromosome morphology in Gilbert's potoroo, Potorous gilbertii (Marsupialia: Potoroidae). Australian Journal of Zoology, 48: 281-287.

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