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Onychogalea fraenatabridled nail-tailed wallaby

By Peter Hundt

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. (Hendrikz and Johnson, 1999)

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. (Lundie-Jenkins, 2001)

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. (Lundie-Jenkins, 2001)

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. (Lundie-Jenkins, 2001; Nowak, 1999)

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. (Lundie-Jenkins, 2001; Nowak, 1999)

  • Sexual Dimorphism
  • male larger
  • Range mass
    4 to 8 kg
    8.81 to 17.62 lb
  • Range length
    790 to 1,430 mm
    31.10 to in

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. (Lara and Fisher, 1999)

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. (Lara and Fisher, 1999)

Copulation times may exceed more than ninety minutes, which is longer than most macropods. (Lara and Fisher, 1999)

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. (Lara and Fisher, 1999)

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. (Lara and Fisher, 1999)

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. (Lara and Fisher, 1999; Lundie-Jenkins, 2001)

If conditions are suitable in the wild, bridled nailtail wallabies can raise up to three young per year and mate continuously throughout the year. (Lara and Fisher, 1999; Lundie-Jenkins, 2001)

  • Breeding interval
    Females of this species are capable of producing three offspring per year.
  • Breeding season
    Breeding is not seasonal when conditions are favorable.
  • Average number of offspring
    1
  • Average number of offspring
    1
    AnAge
  • Average gestation period
    23.6 days
  • Average gestation period
    23 days
    AnAge
  • Range weaning age
    119 to 126 days
  • Average age at sexual or reproductive maturity (female)
    136 days
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    185 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    270 days

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. (Lara and Fisher, 1999)

  • Parental Investment
  • no parental involvement
  • altricial
  • pre-fertilization
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • protecting
      • female

Lifespan/Longevity

Not much information is available regarding the lifespan/longevity of this species. However, individuals in captivity have lived 5.5 years. (Lundie-Jenkins, 2001)

  • Range lifespan
    Status: captivity
    5.5 (high) years
  • Average lifespan
    Status: captivity
    7.4 years
    AnAge

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. (Lundie-Jenkins, 2001)

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. (Lundie-Jenkins, 2001)

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. (Lara and Fisher, 1999; Lundie-Jenkins, 2001)

Other macropods are known to vocalize, and it is likely that O. fraenata is similar. (Nowak, 1999)

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. (Lundie-Jenkins, 2001)

  • 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. (Lundie-Jenkins, 2001)

Ecosystem Roles

Onychogalea fraenata feed on a variety of plants and may affect plant communities in then region. (Lundie-Jenkins, 2001)

Economic Importance for Humans: Positive

Because nail-tailed wallabies are only found in national parks, they may be important for ecotourism. (Lundie-Jenkins, 2001)

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. (Lundie-Jenkins, 2001)

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Peter Hundt (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.

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

dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

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.

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

folivore

an animal that mainly eats leaves.

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).

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

polygynous

having more than one female as a mate at one time

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

scrub forest

scrub forests develop in areas that experience dry seasons.

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.

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.

year-round breeding

breeding takes place throughout the year

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.

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