Red-necked Wallaby (Macropus rufogriseus) Fact Sheet: Reproduction & Development

• Dominant males do not prevent subordinate males from mating (after they themselves have done so) (Tyndale-Biscoe & Renfree 1987) (Tyndale-Biscoe & Hinds 1990)
• Mating may occur only 2 hours after a birth
• Courting male checks sexual status of female by sniffing her rump and her pouch (Coulson 1989)
• Males give a soft clucking vocalization during sexual interactions; females hiss (Coulson 1989) (Ord et al. 1999)
• Male may flick tail and paws; female may hit male with paws (Ord et al. 1999)
  • An exchange of blows sometimes ends the courtship
• Male paws at female's rump; she adopts a standing crouch while male mounts (Bourke 1989)

• Estrus cycle in managed care: 33 days (Jarman & Calaby 2008)
• Two subspecies have different breeding patterns (Merchant & Calaby 1981)
  • Mainland Australia wallabies, M. r. banksianus, females give birth in all months
  • Tasmanian Bennett's wallabies, M. r. rufogriseus, give birth late January to July, 2 to 4 months after summer solstice
    • If female has no pouch young, and mates near the end of a breeding season, she doesn't give birth until 8 months later in the next breeding season
    • Bennett's wallabies birthing season may have evolved in the last 11,000 years after global sea level rise separated more southerly (and colder) Tasmania from mainland Australia (Tyndale-Biscoe & Hinds 1990)
    • If these wallabies are transferred to northern latitudes, they keep their seasonality and adjust the timing to give birth after the northern summer solstice
    • Reproduce efficiently due to (Merchant & Calaby 1981):
      • Delayed implantation of the embryo (embryonic diapause) which is controlled both by whether the female is lactating and also by the light available in a particular season of the year
      • Only the tammar wallabies (Macropus eugenii) which also are a colder climate, southern species have the same dual control of embryonic diapause; other macropods delay implantation depending only on whether the female is nursing or not
      • Tammar and Bennett's wallabies thus can delay their births until a warmer time of year
      • In New Zealand, M. r. rufogriseus is "pre-adapted" for surviving well in a new environment after introductions from a similar habitat in Tasmania (LePage et al. 2000)

• In both subspecies of red-necked wallabies a new birth is 16-29 days after a joey leaves the pouch (Merchant & Calaby 1981)
  • All other macropods give birth to a new young or come into estrus within a day or two after an older joey permanently leaves the pouch
• Gestation period about 30 days (Merchant & Calaby 1981)
• Pouch life about 280 days (Merchant & Calaby 1981)
• Pouch life varies depending upon (Stuart-Dick & Higginbottom 1989):
  • Sex of offspring
  • Season of permanent emergence
  • Age of the mother
  • Mother's previous reproductive history
• Young continue to be suckled until 12-17 months (Merchant & Calaby 1981) (Renfree et al 2011)
  • More than placental mammals, marsupials' undeveloped young depend on mother's milk for a very long lactation period
  • Throughout lactation, the composition and amount of milk produced is synchronized with joey's development
  • Milk of a tammar wallaby has been discovered to contain powerful anti microbial properties, more effective even than penicillin (Williams 2007)

Birth

• Weighs less than 1 g (0.04 oz) at birth (Ganslosser 1990)
• Normally only one joey born, but twins have been observed (Jackson 2003)

Infant (< 1 year old) (Jarman & Calaby 2008)

• Infants first look out of pouch around 6 months
• Begin to emerge from pouch for first time around 7 months

Juvenile (Jarman & Calaby 2008)

• Juveniles continue to return to pouch for nourishment and comfort until about 9 months in age
• Juveniles permanently out of the pouch are called "young-at-foot"
• Young-at-foot stay continue suckling for another 4 or 5 months
• Juveniles are most likely to die in the interval between permanent emergence from pouch and the end of suckling

Adult

• First mating for females about 13-14 months; males produce mature sperm about 19 months (Merchant & Calaby 1981)
• Oldest, worn molar teeth move forward and are shed (Tyndale-Biscoe 2005)
  • Very old adults may be left with only the last two worn down molars (M3 and M4) in each jaw, upper and lower (Marshall & Corruccini 1978)

Managed care

• Median life expectancy
  • 5.2 years (AZA 2023)

• Dingos and wedge-tailed eagles are chief predators on red-necked wallabies
• Human hunters kill wallabies for meat, pest control, and skins (Jarman & Calaby 2008)

This joey has not yet turned around in its mother's pouch.

Young typically become independent of the pouch around 9 months of age.

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.

Bourke (1989)
Coulson (1989)
Ganslosser (1990)
Jackson (2003)
Jarman & Calaby (2008)
Marshall & Corruccini (1978)
Merchant & Calaby (1981)
Ord et al. (1999)
Stuart-Dick & Higginbottom (1989)
Tyndale-Biscoe (2005)
Tyndale-Biscoe & Hinds (1990)
Tyndale-Biscoe & Renfree (1987)
Williams (2007)