Geographic Range
The range of endangered bridled nail-tailed wallabies has been reduced to 11,470 hectares
in the Taunton Scientific Reserve in northeastern Austalia. This reserve is located
near the city of Dingo in Central Queensland.
- Biogeographic Regions
- australian
Habitat
At one time,
Onychogalea fraenata
inhabited the semi-arid region of eastern Australia. This region is made up mainly
of Acacia shrub land and grassy woodlands. Now it is only found in Taunton National
Park although a population has recently been released into Idalia National Park.
- Habitat Regions
- tropical
- terrestrial
- Terrestrial Biomes
- savanna or grassland
- scrub forest
Physical Description
Onychogalea fraenata
is named for the white "bridle" line that starts on the center of the neck and goes
around the shoulders and ends at the forearms on each side. A black stripe runs dorsally
across the whole body.
Males weigh between 5 and 8 kg, whereas females weigh from 4 to 5 kg. The head and
body length of this species is 430 to 700 mm, with the tail contributing an additional
360 to 730 mm to the total length.
The genus
Onychogalea
gets its common name, nail tailed wallabies, from a small, horny spur (3 to 6 mm)
at the end of the tail. This "nail" is partially concealed by hair.
- Other Physical Features
- endothermic
- bilateral symmetry
- Sexual Dimorphism
- male larger
Reproduction
Onychogalea fraenata
mates polygynously. Males roam widely, checking nonestrus females briefly by smell.
They may accompany estrus females that they encounter for up to a week. Groups of
males sometimes accumulate around receptive females. These males follow females roughly
in order of body weight, and the largest male appears to defend access to the female.
The main difference between
O. fraenata
and most other terrestrial macropods is that there is no dominance hierarchy prior
to encounter. Because
O. fraenata
is solitary, males cannot establish dominance relationships until they have encountered
one another. However, these animals can recognize dominance from prior encounters,
so rather than waste energy on another combat sequence they behave toward one another
based upon the hierarchy determined in previousl encounters.
Copulation times may exceed more than ninety minutes, which is longer than most macropods.
During estrus cycles, females increase their home range. They also increase their
activity, and are more attractive to males prior to mating. Such features are not
unique to this species, but are common in most solitary mammals.
Male that are the largest in size and have the largest home ranges have higher copulatory
success. Males and females participate in mate chasing. Because females do not appear
to be attempting to evade the males, based on their slow speed and repetitive movements,
this appears to be some sort of courtship behavior.
- Mating System
- polygynous
Onychogalea fraenata
has been studied both in captivity and wild. In captivity, these animals breed continuously.
Females have an average estrous cycle of 32.6 days and gestation lasts an average
23.6 days. Newborns spend 119 to 126 days in the pouch. Males reach sexual maturity
in about 270 days, whereas females reach it in 136 days.
If conditions are suitable in the wild, bridled nailtail wallabies can raise up to
three young per year and mate continuously throughout the year.
- Key Reproductive Features
- iteroparous
- year-round breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- fertilization
- viviparous
Like other macropods,
O. fraenata
, have extremely altricial young. Young are born excessively underdeveloped, and must
complete their delopment inside the mother's pouch, attached to her nipple. Based
on the mating system, it is unlikely that there is paretal care provided by males.
- 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
-
protecting
- female
-
protecting
Lifespan/Longevity
Not much information is available regarding the lifespan/longevity of this species.
However, individuals in captivity have lived 5.5 years.
Behavior
Onychogalea fraenata
is a solitary animal and is nocturnal, emerging at night to feed on forbes and grasses.
During the day it spends most of its time underneath grass or a bush in a small shallow
nest.
- Key Behaviors
- terricolous
- saltatorial
- nocturnal
- motile
- sedentary
- solitary
- dominance hierarchies
Home Range
Male home ranges are about 60 ha while females home ranges are about 25 ha. Movement
is very restricted during the day, but at night movement increases to between 10 and
200 meters per hour.
Communication and Perception
Very little information was available on communication in O. fraenata . However, some generalizations can be made, based on what we know of mammals in general, and other macropods in particular.
These animals are known to transmit information through scent cues, especially when
females are in estrous. Males determine the readiness of females to mate based upon
their smell. In addition, there is some visual and tactile communication during mating,
based upon chasing behavior and the mating process itself.
Other macropods are known to vocalize, and it is likely that
O. fraenata
is similar.
Food Habits
Onychogalea fraenata
feeds on a diverse selection of forbes, grasses, and woody browse. During observation
in Taunton National Park, these foods were selected by the animals: The herbaceous
forb
Portulaca oleraceae
, pigweeds such as
Helipterum spp.
, daisies such as
Trianthema triquetra
and
Zalea galericulata
, and grasses such as
Sporobolus carolii
,
Chloris divaricata
,
Dactyloctenium radulans
, and
Bothriochloa bladhi
.
- Plant Foods
- leaves
Predation
No information on anti-predator adaptations was available for
O. fraenata
. Native dingoes may be predators of these animals. Exotic carnivores such as red
foxes may prey on these animals.
Ecosystem Roles
Onychogalea fraenata
feed on a variety of plants and may affect plant communities in then region.
Economic Importance for Humans: Positive
Because nail-tailed wallabies are only found in national parks, they may be important
for ecotourism.
- Positive Impacts
- ecotourism
Economic Importance for Humans: Negative
This species has little effect on humans.
Conservation Status
Onychogalea fraenata
is part of a large recovery plan. The number of these wallabies has declined due
to competition with domestic animals, habitat destruction, and the introduction of
carnivores (mainly foxes and dingos).
Onychogalea fraenata
has already been successfully reintroduced into the Idalia National Park and there
are plans for other reintroductions from animals in captive breeding programs. The
species is listed as Endangered by IUCN and is on Appendix I of CITES.
Additional Links
Contributors
Nancy Shefferly (editor), Animal Diversity Web.
Peter Hundt (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.
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- 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.
- scrub forest
-
scrub forests develop in areas that experience dry seasons.
- 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).
- year-round breeding
-
breeding takes place throughout the year
- 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.
- 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
- dominance hierarchies
-
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals 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
Hendrikz, J., P. Johnson. 1999. Development of the bridled nailtail wallaby, Onychogalea fraenata , and age estimation of the pouch young. Wildlife-research , 26(2): 239-249.
Lara, M., D. Fisher. 1999. Effects of body size and home range on access to mates and paternity in male bridled nailtail wallabies. Animal Behaviour , 58: 121-130.
Lundie-Jenkins, G. 2001. "Recovery plan for the bridled nailtail wallaby ( Onychogalea fraenata ) 1997-2001" (On-line). Environment Australia. Accessed June 01, 2004 at http://www.deh.gov.au/biodiversity/threatened/recovery/bridled-nailtail/index.html .
Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition . Baltimore and London: The Johns Hopkins University Press.