Rare eastern bettongs return to Australian mainland.
Credit: Adrian Manning
A predator proof fence at the Mulligans Flat Woodland Sanctuary.
Credit: Adrian Manning
SYDNEY: A rare native Australian mammal has returned to the mainland, after an absence of over 80 years, researchers have reported.
The eastern bettong (Bettongia gaimardi) is a nocturnal, rabbit-sized species of kangaroo that lives in a grass nest by day and digs for food such as fungi by night. Due to the introduction of predators such as foxes and cats, the bettongs were quickly wiped out from the mainland, and haven't been seen since the early 20th century. But the species have thrived on the Tasmanian island because until very recently, there were very few foxes.
Now, scientists have translocated 19 bettongs from Tasmania to specialist breeding facilities at the Tidbinbilla Nature Reserve, in preparation for reintroduction to Mulligans Flat Woodland Sanctuary, which is located in the north of the Australian Capital Territory (ACT), in hopes of boosting the overall population and improving the biodiversity and health of the site.
"We have prioritised [the eastern bettong] because it is what ecologists call an 'ecosystem engineer', because it digs the soil looking for truffles, and in doing so moves fungal spores, improves soil conditions and encourages excellent water infiltration, which are all essential to good ecosystem health," said Adrian Manning from the Australian National University (ANU) in Canberra, leader of a larger restoration project for endangered Australian woodlands.
Ensuring extinction isn't total
The eastern bettong once occupied a vast area of grassy woodlands in southeastern Australia, but went extinct by the 1920s, primarily because of the northern migration of European foxes from New South Wales.
According to Manning, other factors that contributed to the species extinction on the mainland include land clearing and vegetation modification for agriculture, competition from rabbits and direct persecution. "For example, in New South Wales, three million 'rat-kangaroos' were harvested between 1883 and 1920," he said.
While the bettongs have persisted in Tasmania because of the lack of introduced foxes, foxes have recently been introduced illegally, which could see a similar pattern of extinction in what was their final remaining habitat. "The Tasmanian authorities are working very hard to make sure this doesn't happen," said Manning. "However, the value of re-establishing a secure mainland population, should the worst happen, is clear."
Ecosystem engineers
The move is part of a larger grassy woodlands restoration project called the Mulligans Flat and Goorooyarroo Woodland Experiment, which is a collaboration between ANU researchers, the ACT Government and the national science agency, CSIRO.
The aim of the project is to reintroduce as many locally extinct species as possible to the woodland to restore lost ecosystems and biodiversity to Australia's critically endangered box gum grassy woodlands. If all goes well in the initial breeding program of the reintroduced 19, some will be released into the Mulligans Flat Woodland Sanctuary next year, which is protected by a 11.5 km feral-animals proof fence.
"As part of the planning for the Sanctuary, we undertook a systematic review of all the species that may have occurred in woodland such as these before European settlement," said Manning. "This involved small mammal expert Fred Ford (from CSIRO), who examined evidence from cave deposits containing owl pellets, examination of museum specimens and modelling of habitat."
Because of the bettongs' role as 'ecosystem engineers', the species was put on the project's priority shortlist for reintroduction. "In doing this, we hope to find out whether bettongs could have a future role as a 'restoration tool' - helping bring highly modified woodlands back to the condition they were before European settlement," said Manning.
Coming back home
Fortunately for the researchers, eastern bettongs breed very well in the absence of feral predators, according to Manning, which makes him optimistic about the potential for recolonisation, so long as foxes are actively controlled.
"All projects will need to establish an effective regime of feral predator control before bettongs could be released, either by fencing or baiting," said Manning. "However, the long-term vision is that the eastern bettong will ultimately re-populate large areas of its former range, and bring with it its critically important ecological effects."
rare bettongs returns.
the best way to get a species to thrive is to introduce it to a habitat where it is not a native, they will ultimately increase their numbers due to non competition.