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Endangered Brush-tailed Rock-wallaby “pauses” pregnancy and shocks all our wildlife rangers!    

Aussie Ark, have been shocked at the arrival of a new miracle Brush-tailed Rock-wallaby. The joey was conceived in October 2021, however in a process called Embryonic Diapause, the mother wallaby ‘paused’ her pregnancy for some months before resuming development. 

Embryonic diapause, a condition of temporary suspension of development of the mammalian embryo, occurs due to suppression of cell proliferation at the blastocyst stage. It is an evolutionary strategy to ensure the survival of neonates. The tiny wallaby is thought to be at the development stage of 4 months. Rangers at Aussie Ark believe that the mother underwent the unique process, in order to finish rearing a joey she already had in pouch. 

“It was quite a shock noticing the distinguishable bulge of a joey on this particular female. We knew that the only time she had for breeding was back in 2021” Said Kelly Davis, Curator at Aussie Ark. 

She continued “It is the first time I have witnessed first-hand this incredible process; I had only ever previously read about it. It really shows the incredible tenacity and survival instincts of wild animals” 

Aussie Ark has worked with the endangered Brush-tailed Rock-wallaby since 2018, when they established the first breeding program for the species. Following the devastating impacts of the 2019/2020 bushfire season, which annihilated much of the wallaby’s habitat, the organisation doubled its holding capacity for the species, with the help of the Australian Governments bushfire recovery program and FAME (Foundation for Australia’s Most Endangered). Now the organisation boasts 12 state of the art breeding yards, which all incorporate incredible rock mounds to make the wallabies feel right at home. 

The team at Aussie Ark will continue to monitor the mother wallaby on her new journey, through camera traps, but will remain largely out of the way during the process. Once the joey is out on foot, a health check will be given. The joey will remain with mum until it is old enough to be placed into a new breeding yard to continue the vital conservation work being undertaken onsite. 

The Brush-tailed rock-wallaby is found from South-Eastern Queensland to Western Victoria, roughly following the line of the Great Dividing Range. Their range has significantly declined, leaving remaining populations fragmented and vulnerable to further catastrophe. They inhabit rocky escarpments, outcrops and cliffs with a preference for complex structures with fissures, caves and ledges, often facing north.

Threats to the Brush-tailed rock-wallaby are varied but include predation by foxes, cats and wild dogs, competition with feral goats as well as pigs, degradation and fragmentation of habitat, fire regimes that reduce the abundance and diversity of ground forage and infestation by invasive weeds causing loss.

The population of wild Brush-tailed rock-wallabies is in decline – with less than 20,000 expected to be left in the wild and as little as under 10 in some fragmented populations.

You can support Aussie Ark’s work with the endangered species by donating today!