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Cercartetus concinnuswestern pygmy possum

By Ryan Pollen

Geographic Range

Western pygmy possums are found only on the Australian continent, more specifically in the southwestern, southern, and southeastern portions of Australia. Cercartetus concinnus has been found in only 50 locations within the New South Wales, South Australia, Victoria, and Western Australia areas of the continent. ("Australian Faunal Directory", 2006; "Western Pygmy-possum", 2001)

Habitat

Western pygmy possums are terrestrial mammals that reside in temperate forests in Australia. These pygmy possums are arboreal and tend to nest during the day in a tree hollow filled with leaves, but can also nest on the ground in clumps of twigs. They prefer habitats with a dense shrubby understory that provides shelter and food. They are most abundant in the woodlands of southwest Western Australia, and can also be found in some bushlands. While small remnants of bushland can provide suitable habitat, they may not be large enough to support viable populations of western pygmy possums in the long term. Structurally diverse habitats are necessary for nesting and traveling. Western pygmy possums prefer to travel using clumps of twigs or leaf litter as cover, indicating that diverse ground cover should be a focus of conservation efforts. ("New South Wales Department of Conservation", 2005; Pestell, 2006)

Physical Description

Western pygmy possums are small, nocturnal marsupials. Adults average 80 mm in body length, with an 86 mm long tail to aid them when moving through foliage. The average weight of an adult is only 13 grams. They are fawn or reddish-brown on the dorsal side, and are white ventrally with a finely-scaled naked tail. These pygmy possums have a noticeably whiskered and short, pointed snout, very large eyes which are well adapted for seeing at night, and thin rounded ears. For comparison, western pygmy possums are no larger than a typical kiwi fruit. ("Western Pygmy-possum", 2001; Foster, 2006; Pestell, 2006)

  • Sexual Dimorphism
  • sexes alike
  • Average mass
    13 g
    0.46 oz
  • Average length
    80 mm
    3.15 in

Reproduction

Little information on mating systems in western pygmy possums is available in the literature. (Menon, 1996; Pestell, 2006)

Western pygmy possums can breed year-round when conditions are favorable. However, females can employ delayed implantation if it is necessary to delay reproduction until environmental conditions are more suitable for reproduction (Pestell 2005). Females typically enter torpor to escape poor environmental conditions, such as low temperatures or decreased food resources, and implantation of the embryo occurs when conditions are again favorable. (Pestell, 2006)

Female western pygmy possums differ from other members of the Burramyidae family in that they have six teats in their forward-facing pouch, rather than four (Pestell 2005). Breeding can occur anytime throughout the year. A typical female may give birth to 2 or 3 litters of up to 6 young in a year. The young typically remain in the pouch for their first 25 days, after which they are transferred to a nest. (Pestell, 2006)

  • Breeding interval
    Females can breed 2 to 3 times a year.
  • Breeding season
    Western pygmy possums can breed throughout the year if conditions are favorable.
  • Range number of offspring
    1 to 6
  • Average time to independence
    25 days

Female western pygmy possums care for and protect their young until they reach independence, but little is known about the details of parental investment and development in these possums.

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

Lifespan/Longevity

No information was found on longevity in western pygmy possums.

Behavior

Western pygmy possums are nocturnal and mainly arboreal. During the day they reside in a leaf-lined nest in tree cavities or in the leaves of trees. Some western pygmy possums have been found sleeping in unused bird nests and on the ground, sheltered by leaves or under stumps and branches. ("Western Pygmy-possum", 2001; Smith, 1999)

Home Range

Home ranges of western pygmy possums are not known. ("Australian Faunal Directory", 2006; Smith, 1999)

Communication and Perception

Like other pygmy possums, western pygmy possums have keen senses of vision, hearing, taste, and touch. They probably use chemical cues to communicate reproductive state.

Food Habits

Based on their general biology and morphology it was initially thought that western pygmy possums were primarily insectivorous. A study done by Horner in 1994 found an abundance of Banksia pollen in the feces of western pygmy possums, with no invertebrate remains present. However, soft-bodied invertebrates, like pupae and larvae, are usually assumed to be totally digestible and would not be found in any scat samples. These possums are currently considered nectarivorous, but may also be insectivorous. They have also been found to prey on small lizards (Smith 1995). ("Western Pygmy-possum", 2001; "New South Wales Department of Conservation", 2005; Pestell, 2006; Smith, 1999)

  • Animal Foods
  • reptiles
  • insects
  • Plant Foods
  • nectar

Predation

Western pygmy possums are small and are likely to fall prey to a number of small to medium sized nocturnal predators, such as introduced, domestic cats and snakes. Their nocturnality and arboreality is likely to protect them from some predation. (Pestell, 2006)

Ecosystem Roles

Western pygmy possums serve as prey for small to medium-sized nocturnal predators in Australia. They may also serve a role in pollinating plants through their nectarivory.

  • Ecosystem Impact
  • pollinates

Economic Importance for Humans: Positive

Western pygmy possums are important members of the native ecosystems in which they live.

Economic Importance for Humans: Negative

There are no known adverse effects of western pygmy possums on humans.

Conservation Status

Western pygmy possums are listed as endangered under Schedule 1 of the New South Wales Threatened Species Conservation Act 1995. However, they are listed as common but limited throughout the rest of their range in southern Australia. (Pestell, 2006)

Other Comments

There is little ecological literature on western pygmy possums since their nocturnal and arboreal lifestyle makes data acquisition difficult. Lack of detailed knowledge may be one of the most important factors threatening the conservation efforts of this species.

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Ryan Pollen (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor, instructor), University of Wisconsin-Stevens Point.

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.

arboreal

Referring to an animal that lives in trees; tree-climbing.

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.

carnivore

an animal that mainly eats meat

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.

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.

herbivore

An animal that eats mainly plants or parts of plants.

insectivore

An animal that eats mainly insects or spiders.

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.

nectarivore

an animal that mainly eats nectar from flowers

nocturnal

active during the night

sedentary

remains in the same area

sexual

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

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.

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

2006. "Australian Faunal Directory" (On-line). Australian Government: Department of the Environment and Heritage. Accessed October 25, 2006 at www.deh.gov.au/cgi-bin/abrs/fauna/details.

Department of Environment and Conservation (NSW). 2005. "New South Wales Department of Conservation" (On-line). Western Pygmy-possum - profile. Accessed October 25, 2006 at http://threatenedspecies.environment.nsw.gov.au/tsprofile/profile.

2001. "Western Pygmy-possum" (On-line). Western Wildlife Consulting Ecologists. Accessed October 25, 2006 at www.westernwildlife.com.au/western/mammals/pygmy.htm.

Foster, A. 2006. "Rare bonus in search for Western Pygmy-possum" (On-line). Foundation for National Parks and Wildlife. Accessed October 25, 2006 at www.fnpw.com.au/enews2/PygmyPossum.htm.

Menon, S. 1996. Slumber down under. Discover magazine, 17: 48.

Pestell, A. 2006. "Patterns of capture, genetic structure, and diet of western pygmy possums, Cercartetus concinnus Gould (Marsupialia: Burramyidae) in Innes National Park, South Australia" (On-line pdf). Sustainable Environments Research Group: Honours theses. Accessed October 25, 2006 at www.unisa.edu.au/serg/documents/Pestell%20Thesis.pdf.

Smith, M. 1999. "Threatened Species Information: Western Pygmy Possum" (On-line pdf). New South Wales National Parks and Wildlife Service. Accessed October 25, 2006 at www.nationalparks.nsw.gov.au/PDFs/tsprofile_western_pygmy_possum.pdf.

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