The end of the line? Sandalwood surveying on Bon Bon Reserve
For National Tree Day, Richard McLellan takes us into the South Australian outback for a sandalwood survey, exploring the significance of the species and its unfortunate plight.
When Dutch explorer Dirk Hartog first arrived at a large island off the coast of what is now West Australia in 1616, he encountered a pristine landscape known as Wirruwana by the Malgana traditional custodians. Bandicoots, Dibblers and desert mice scurried through shrubland, while pairs of brown grasswrens called to each other in high-pitch squeaks and twinkles.
Since Dirk Hartog’s arrival the island, which was subsequently named after him, has suffered greatly from European invasion. The sheep and goats that were introduced to the area saw vast swathes of vegetation across the 633km2 island destroyed. Feral cats contributed to the extinction of 10 out of the 13 mammal species that called the island home.
Dirk Hartog Island went from one of the most untouched ecosystems in the country, to a landscape marred by habitat destruction and species extinction.
But now an ambitious conservation project is breathing new life back into the island.
The Return to 1616 ecological restoration project run by the Department of Biodiversity, Conservation and Attractions (DBCA) and funded by the Gorgon-Barrow Island net Conservation Benefits Fund aims to return the vegetation, habitats and species of Dirk Hartog Island to the condition it was found in in 1616.
The project has already seen the translocation of
- the Banded Hare-wallaby
- the Rufous Hare-wallaby
- the Shark Bay Bandicoot
- the Greater Stick-nest rat
- the Shark Bay mouse
- the Dibbler
And a few weeks ago, 85 Western Grasswrens were successfully translocated to the island from and Francois Peron National Park and Bush Heritage’s Hamelin Station Reserve on Malgana and Nanda Country, bordering the Shark Bay World Heritage Area.
Image Information
Aline Gibson Vega and a Western Grasswren at Hamelin Station Reserve Photo Richard Winterton
The translocation was informed by researcher Aline Gibson Vega’s PhD project and is part of a collaboration between DBCA, Bush Heritage Australia and the University of Western Australia.
As an undergrad searching for an exciting PhD project, Aline was immediately drawn to the Return to 1616 project and eager to get involved.
“I went to the Australian Mammological Society Conference and heard Keith Morris [principal research scientist at the WA Department of Parks and Wildlife] talk about Dirk Hartog Island. I just thought, this is amazing. It’s at the forefront for translocation. I was so keen to get involved in some way, shape or form.”
After approaching the research team, Aline was introduced to the Western Grasswren, the only bird species to be translocated as part of the project.
“Through this PhD project, my love for the birds has grown a lot. They’re great and strangely mouse-like. They love being on the ground to forage on the base of shrubs and sometimes they’ll literally just scuttle into the shrub like a mouse.”
After studying the birds extensively, Aline determined from their genetics and behaviour that the best translocation approach would be to mix birds from the subpopulations at Hamelin Station and Francois Peron National Park.
Conservationists from Bush Heritage and DBCA captured family groups of grasswrens in specifically designed mist-nets and transported them to Dirk Hartog Island in a helicopter. When the birds were released on to the island, the first brave bird would venture out before calling to the others to follow.
“They form these little trains so the male will run across first and the female will come along, and then usually a third individual as well. They’re like little carriages,” says Aline.
Western Grasswrens are territorial birds who assert their territory through song, calling to their neighbours and defending their patch if they hear a bird inside their territory. Though territorial dispute are uncommon, it was crucial for the research team to release the birds in areas with sufficient space for the family groups to establish a new territory, as well as areas with suitable habitat so that later generations could thrive.
“I’ve seen some territory disputes before and it’s really quite fierce,” says Aline. “I’ve even seen one pin another to the ground and really tell it off before just running away as if nothing had happened!”
A subset of the 85 birds were fitted with small transmitters that will record their movements for the first month post-translocation.
The research team will then install compact audio recorders to monitor the grasswrens calls remotely, minimising on-ground disturbance as they settle into their new home.
According to Dr Michelle Hall, Bush Heritage ecologist and one of Aline’s PhD supervisors, “It was very exciting to see the first grasswrens taking off to their new island home after all the research, planning, and hard work leading up to the moment. It will hopefully expand the extent of the Western Grasswren in Western Australia.”
The success of the Return to 1616 project will be measured by the response of the native wildlife species and vegetation recovery, but it is hoped that the translocated species will become self-sufficient and that the island will provide a safe haven for them to thrive.
“Island populations are becoming much more valuable in conservation because we don’t need to contend with feral animal predation,” says Aline. “Dirk Hartog Island, as West Australia’s largest island, is an awesome bit of land that we can put animals on that will eventually be the largest population of that species. It’s just great to see that we’re going to have this little insurance population essentially.”
Aline’s project was supported by the Paul Hackett Memorial Scholarship, Wettenhall Environmental Trust, Holsworth Wildlife Endowment and The University of Western Australia. The Return to 1616 project is supported by the Gorgon Barrow Island Net Conservation Fund.
