Geographic Range
Red-necked pademelons (
Thylogale thetis
) are only found in parts of eastern Australia. They range from eastern Queensland
to just below mid-coast of New South Wales.
- Biogeographic Regions
- australian
Habitat
The habitat of red-necked pademelons consists of rainforests, thick scrub or grassland
areas, and eucalyptus forests.
- Habitat Regions
- temperate
- terrestrial
- Terrestrial Biomes
- savanna or grassland
- rainforest
Physical Description
Red-necked pademelons have a head and body length of 290 to 630 mm, with a tail length
of 270 to 510 mm. They exibit sexual dimorphism in size, with the males weighing approximately
7 kg compared to the average female weight of 3.8 kg.
Red-necked pademelons are grizzled gray in color above with a light hip stripe often
present. The short tail of these animals is only lightly furred. It is also thick
and rounded.
- Other Physical Features
- endothermic
- bilateral symmetry
- Sexual Dimorphism
- male larger
Reproduction
Little is known about mating systems in pademelons. Males in captivity tend to be
somewhat aggressive toward one another. Taken with the pronounced sexual dimorphism
in this species, this is suggestive of polygyny. Polygyny is common in macropods.
It has been recorded that female red-necked pademelons when in oestrus will be found
around larger males, suggesting active mate choice by females.
- Mating System
- polygynous
Red-necked pademelons reach sexual maturity at about 18 months of age. Reproduction
occurs in the autumn and spring in the north, and during the summer in the south.
These pademelons usually give birth to a single young, although twins have been recorded
in the genus.
Embryonic diapause is known to occur in red-necked pademelons. Embryonic diapause
is when the division of the cells in the embryo stops when there are about 100 cells.
This "started" but unfinished embryo is held in the uterus until conditions are right
for development to continue. This allows for an embryo to be in the uterus while a
mother is weaning another joey in the pouch. Once the nursing joey is weaned, development
of the embryo can continue. The embryo experiences a short "actual" gestation period
of approximately 30 days, but can stay in the pouch for up to 6 1/2 months.
In all marsupials, the young are altricial, and must make their way from the birth
canal into a pouch, where they receive milk from the mother and complete their development.
In another member of the genus,
T. billardierii
, a joey stays in the pouch for 202 days, and weaning occurs about 4 months after
the young permanently leave the pouch. Sexual maturity is slightly earlier in
T. billardierii
than in
T. thetis
, and it is possible that these other developmental events occur slightly later in
the latter species as well.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- fertilization
- viviparous
- embryonic diapause
Parental care in this species has not been detailed in the literature. However, like
other macropods, it is likely that the bulk of parental care is performed by the mother.
Mothers nurse their joeys in a pouch, providing them with protection and grooming,
until the young have developed enough to leave the pouch. Leaving the pouch permanently
is a slow process, and during that time, the mother continues to nurse, groom, and
protect her offspring. It is likey that
T. thetis
is like other macropods in this respect.
- Parental Investment
- no parental involvement
- altricial
-
pre-fertilization
-
protecting
- female
-
protecting
-
pre-hatching/birth
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-independence
-
provisioning
- female
-
provisioning
Lifespan/Longevity
I found no documented information on this topic.
Behavior
Red-necked pademelons are solitary animals, sometimes forming small groups. They will
sleep during most of the day in leaf litter and may bask in the sun when cold.
Red-necked pademelons rely on saltatorial locomotion for movement. They have an increased
muscle fiber to tendon area ratio in their ankles. The tendons may be size or function
dependent, and the strength of these tendons may limit locomotion.
Thylogale thetis
may also travel on all four legs and drag its tail behind, but, as in other macropods,
this type of locomotion is reserved for slower travel.
- Key Behaviors
- terricolous
- saltatorial
- nocturnal
- motile
- sedentary
- solitary
Home Range
Thylogale thetis
has a home range of about 5 to 30 ha.
Communication and Perception
Red-necked pademelons communicate with one another using different clicks and by thumping
their hind feet. As mammals, they also have visual capability, and probably use some
visual signals, such as body postures, to communicate. Although not specifically
reported for this species, it is likely that there are some scent cues, especially
related to reproduction. Tactile communication occurs between mothers and their young,
as well as between mates.
Food Habits
Food consists of grass, leaves, roots and bark. Foraging behaviors of red-necked pademelons
consist of feeding on forest edge at night. This apparently reduces their risk of
falling prey to diurnal predators. A larger group size increases the range of feeding
from forest cover.
- Plant Foods
- leaves
- roots and tubers
- wood, bark, or stems
Predation
Predators of red-necked pademelons are the introduced fox and the dingo, and possibly
even large birds of prey. They decrease predation risk by foraging at night.
Ecosystem Roles
The major ecosystem role that red-necked pademelons play is that they are food for
their predators. Through their foraging habits, they are likely to impact the growth
of vegetation.
Economic Importance for Humans: Positive
Red-necked pademelons have been important for ecotourism in the areas in which they
occur.
- Positive Impacts
- ecotourism
Economic Importance for Humans: Negative
There is no documented information about red-necked pademelons having a negative effect.
Conservation Status
The distribution of red-necked pademelons has decreased in Australia due to clearance
of native vegetation for agriculture, dairying, and forestry. Even with this, the
species is common in some areas.
The red-necked pademelon is not currently protected under CITES or IUCN.
Other Comments
Red-necked pademelon mothers may throw the joey out of their pouch during hard times
to ensure that their own survival. This is a type of infanticide, but probably has
a low cost to the mother because she is probably already pregnant with another offspring
in embryonic diapause, just waiting for conditions to improve before proceding in
its development.
Additional Links
Contributors
Nancy Shefferly (editor), Animal Diversity Web.
Toni Lynn Wainio (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor, instructor), University of Wisconsin-Stevens Point.
- Australian
-
Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- 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.
- 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.
- rainforest
-
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
- polygynous
-
having more than one female as a mate at one time
- 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).
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- fertilization
-
union of egg and spermatozoan
- viviparous
-
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- 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)
- 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.
- saltatorial
-
specialized for leaping or bounding locomotion; jumps or hops.
- nocturnal
-
active during the night
- motile
-
having the capacity to move from one place to another.
- sedentary
-
remains in the same area
- solitary
-
lives alone
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- 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.
- herbivore
-
An animal that eats mainly plants or parts of plants.
- folivore
-
an animal that mainly eats leaves.
- 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.
- 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.
References
Bennett, M. 2000. Unifying principles in terrestrial locomotion: Do hopping Australian marsupials fit in?. Physiological-and-Biochemical-Zoology , 73: 726-735.
Nowak, R. 1995. "Pademelons" (On-line). Walker's Mammals of the World Online, V. 5.1. Accessed October 14, 2002 at http://www.press.jhu.edu/books/walkers_mammals_of_the_world/marsupialia/marsupialia.macropodidae.thylogale.html .
Ord, T., C. Evans, D. Cooper. 1999. Nocturnal behaviour of the parma wallaby, Macropus parma (Marsupialia:Macropodoidea). Australian Journal of Zoology , 47: 155-167.
Wahungu, G., C. Catterall, M. Olsen. 2001. Predator avoidance, feeding and habitat use in the red-necked pademelon, *Thylogale thetis*, at rainforest edges. Australian Journal of Zoology , 49: 45-58.
University of Queensland. 2000. "Red-necked Pademelon- Thylogale thetis " (On-line). Mammals of Lamington National Park. Accessed June 23, 2004 at http://lamington.nrsm.uq.edu.au/MainMenu.html .
Hobart & William Smith Colleges and Union College. 2002. " Thylogale thetis (Red-necked pademelon)" (On-line). 2001 QUEENSLAND TERM WILDLIFE FIELD GUIDE. Accessed June 23, 2004 at http://people.hws.edu/mitchell/fguide/show.asp?ID=87 .