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Wyulda squamicaudatascaly-tailed possum

By Hudson Berkhouse

Geographic Range

Wyulda squamicaudata (scaly-tailed possum) is found only in the Kimberley region of Northwestern Australia. Scaly-tailed possums are taxonomically placed in the family Phalangeridae and are the only member of their genus. Little is known about this species due to their overall secretive behavior combined with the rugged nature of their habitat. Scaly-tailed possums are considered the least well understood of all phalangerids, with only 54 confirmed scientific captures. (Potter, et al., 2014)

Habitat

Trapping densities suggest that scaly-tailed possums prefer low, open woodlands and vine thickets. They are nocturnal and rely heavily on rock piles for shelter during the day. (Potter, et al., 2014; Runcie, 1999)

  • Range elevation
    0 to 300 m
    0.00 to 984.25 ft

Physical Description

Scaly-tailed possums are small-to-medium sized marsupials weighing an average of 1500 grams. They have relatively small ears and a total body length averaging 415 mm for males and 375 mm for females. All individuals have gray dorsal surfaces and white ventral surfaces with naked paws and noses. Many individuals also have a black stripe running down the center of their back. As their name implies, scaly-tailed possums have rough tails which are covered in scales. These tails, averaging 290 mm in length, are hairless and prehensile which enables these possums to maintain firm grips on tree branches when they forage. This type of tail is unique to W. squamicaudata compared to all other phalangerids. (Runcie, 1999)

  • Sexual Dimorphism
  • male larger
  • Average mass
    1500 g
    52.86 oz
  • Average mass
    1700 g
    59.91 oz
    AnAge
  • Range length
    375 to 415 mm
    14.76 to 16.34 in

Reproduction

Little is known about the mating system of this species. However, substantial research has been done on other phalangerid species. One such highly researched species is the brush-tailed possum (Trichosurus vulpecula). This species is generally regarded as the second most closely related species to W. squamicaudata, although there is some debate over phalangerid relationships. Brush-tailed possums establish dominance hierarchies in which dominant males and females are most likely to breed with one another. In brush-tailed possums, these hierarchies are often matriarchal in structure, with females dominant to males. Breeding pairs might spend up to 40 days courting before they mate. Scent marking and vocalizations are used to avoid direct aggression between co-dominant individuals. It is possible that these or similar behaviors take place in W. squamicaudata mating systems. (Taylor, et al., 2000)

Wyulda squamicaudata females produce only one offspring per year, between March and August. Young are weaned within eight months and females and males become sexually mature at two years and 18 months, respectively. (Humphreys, et al., 1984)

  • Breeding interval
    Scaly-tailed possums breed once yearly.
  • Breeding season
    Scaly-tailed possums breed from March to August.
  • Average number of offspring
    1
  • Average number of offspring
    1
    AnAge
  • Average weaning age
    18 months
  • Average age at sexual or reproductive maturity (female)
    24 months
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    730 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    18 months
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    540 days
    AnAge

Little to nothing is known about parental investment in scaly-tailed possums. However, equal participation of both parents in parental investment has been observed in other phalangerid species like rock-haunting possums (Petropseudes dahlia). As in all mammals, females invest heavily in offspring through gestation and lactation. (Runcie, 2000)

  • Parental Investment
  • male parental care
  • female parental care
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female

Lifespan/Longevity

Because so few scaly-tailed possums have ever been captured, vlittle is known about their longevity or population age-structures. However, studies done on other phalangerid species have produced life expectancy statistics of 17 years for females and 12 years for males. (Barnett, et al., 1982)

Behavior

In general, there is little information about scaly-tailed possum behavior. They are herbivorous, feeding primarily on the leaves of various trees and shrub species. When these phalangerids feed, individuals climb out to the outermost branches of trees and use their forelimbs to pluck leaves. Scaly-tailed possums achieve stability by gripping sturdy branches with their prehensile tails. They are also proficient at moving around in tree canopies and have been recorded making branch-to-branch leaps of up to one meter. (Runcie, 1999)

Home Range

Scaly-tailed possums tend to live solitarily on home ranges of approximately one hectare. Individual home ranges often overlap. (Runcie, 1999)

Communication and Perception

Few intra-specific interactions have ever been witnessed. Phalangerids as a group, however, are known to signal one another both chemically and with physical behaviors such as tail slapping to warn of nearby predators. Like other mammals, they likely have a keen sense of smell. (Kreigenhofer, 2011)

Food Habits

Scaly-tailed possums feed on foliage from at least four different tree species including the myrtle species Xanthostemon eucalyptoides and Xanthostemon pradoxus, gum trees (Eucalyptus species), and cocky apple trees (Planchonia careya). It has also been suggested that they forage on certain shrub species, including wild parsnip (Trachymene didiscoidess). (Runcie, 1999)

  • Plant Foods
  • leaves

Predation

Little to no data is available on which animals act as primary predators of scaly-tailed possums. It is likely, however, that feral cats, large birds of prey, and large snakes may be important predators. (Heinsohn, 2000; McKnight, 2008)

Ecosystem Roles

Little is known about the effects that scaly-tailed possums have on the ecosystems they inhabit. Because they have different foraging and habitat related behaviors than other closely related phalangerids, it is difficult to assess how similar their effects on the ecosystem are to those of other possums.

Economic Importance for Humans: Positive

Scaly-tailed possums have no easily definable, direct, or large-scale impact on humans. Their remote habitat and rarity make this a difficult topic to research.

Economic Importance for Humans: Negative

Scaly-tailed possums have no easily definable, direct, or large-scale impact on humans. Their remote habitat and rarity make this a difficult topic to research.

Conservation Status

The IUCN lists W. squamicaudata as “data deficient” with a declining population trend. According to the Department of Environment and Conservation Western Australia, more data must be gathered concerning the conservation status of scaly-tailed possums before they can be declared a threatened species.

Contributors

Hudson Berkhouse (author), Texas A&M University, Jessica Light (editor), Texas A&M University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Australian

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

World Map

acoustic

uses sound to communicate

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.

female parental care

parental care is carried out by females

folivore

an animal that mainly eats leaves.

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.

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).

male parental care

parental care is carried out by males

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

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

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

solitary

lives alone

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.

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

Barnett, J., R. How, W. Humphreys. 1982. Habitat effects on organ weights, longevity and reproduction in the Mountain Brushtail Possum, Trichosurus caninus (Ogilby). Australian Journal of Zoology, 30: 23-32.

Heinsohn, T. 2000. Short Communication: Predation by the White-breasted Sea Eagle Haliaeetus leucogaster on phalangerid possums in New Ireland, Papua New Guinea. Emu, 100.3: 245-246.

Humphreys, W., R. How, A. Bradley, C. Kemper, D. Kitchener. 1984. The biology of Wyulda squamicaudata, Alexander 1919. Possums and Gliders, Book: 162-169.

Kreigenhofer, B. 2011. Exploring social interactions and olfactory communication in the common brushtail possum: implications for management: a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in “Conservation Biology”. Dissertation for Massey University, Albany, New Zealand, Dissertation: 1.

McKnight, M. 2008. "Wyulda squamicaudata" (On-line). IUCN Redlist. Accessed October 01, 2015 at http://www.iucnredlist.org/details/23091/0.

Potter, S., D. Rosauer, J. Doody, M. Webb, M. Eldridge. 2014. Persistence of a potentially rare mammalian genus (Wyulda) provides evidence for areas of evolutionary refugia within the Kimberley, Australia.. Conservation Genetics, 15: 1085-1094.

Runcie, M. 2000. Biparental care and obligate monogamy in the rock-haunting possum, Petropseudes dahli, from tropical Australia. Animal Behavior, 59: 1001-1008.

Runcie, M. 1999. Movements, dens and feeding behavior of the tropical scaly-tailed possum (Wyulda squamicaudata). Wildlife Research, 26: 367-373.

Taylor, A., P. Cowan, B. Fricke, D. Cooper. 2000. Genetic analysis of the mating system of the common brushtail possum (Trichosaurus vulpecula) in the New Zealand farmland. Molecular Ecology, 9: 869-879.

Wemmer, C., L. Collins. 1978. Communication patterns in two phalangerid marsupials, the gray cuscus (Phalanger gymnotis) and the brush possum (Trichosurus vulpecula). Säugetierkunde Mitteilungen, 26: 161-172.

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