“Making transparent and rational decisions to manage threatened species in situations of high uncertainty is difficult. Managers must balance the optimism of successful intervention with the risk that intervention could make matters worse”
Together with Stefano Canessa (IOZ), Dean Ingwersen (BirdLife Australia) and John Ewen (IOZ), ResearchEcology lab members Gemma Taylor, Rohan Clarke, and James Vandersteen (former 3rd year research student), have published a case study that presents management alternatives for the Endangered Regent Honeyeater in the journal Conservation Science and Practice.
“Risk aversion and uncertainty [in management] create a conundrum for planning recovery of a critically endangered species”, said lead author Dr Stefano Canessa.
“There are very few Regent Honeyeaters left in the wild, but organisations such as Taronga Zoo manage captive breeding populations to support reintroduction programs. Unfortunately, these reintroduction programs have resulted in little breeding success post-release. This is mostly because of high rates of nest failure”, says Rohan.
Whilst further management intervention was clearly required, each potential action had both advantages and disadvantages in a setting where decisions were hampered by uncertainty. There were a few immediate options: Tree collars, or (in a first ever attempt) arboreal nest cages. However, the team was averse to testing these methods on active nests given the potential for disturbance.
“Instead, we opted to use surrogates – artificial eggs in artificial nests”, says Gemma. In a series of paired field experiments the team found that The results of the experiment suggested neither action was likely to significantly reduce predation risks (<3% mean differences in survival between treatment and control). Yet, interestingly, when shown these results, expert stakeholders made only minor revisions to their estimates; in part, this reflected low confidence by managers that artificial nests could reflect real predation risks.
The team faced what might be a common conundrum for conservation of critically endangered species. High uncertainty affects management decisions; however, perilous species status also leads to strong risk aversion, which limits both the willingness to act on limited information and the ability to learn effectively. Structured methods can increase transparency, facilitate evaluation, and assist decision making, but objective limitations and subjective attitudes cannot be circumvented entirely.
Photo by Rohan Clarke
Dr Rohan Clarke, and Dr Rowan Mott from the ResearchEcology lab were recently deployed to Howe Flat (east of Mallacoota) to lead the capture of 15 of the ~160 Endangered Eastern Bristlebirds that remain in Victoria. This unprecedented action was undertaken to ensure an insurance population was safely held away from the fires that have devastated much of eastern Victoria and NSW. Along with their project partners (from Zoos Victoria, DELWP, Parks Victoria, University of Wollongong, Currumbin Wildlife Sanctuary), and supported by first class logistics teams (Fisheries Victoria, The Australian Defence Force in Partnership with Singapore Defence Force, and the Orbost Incident Control Centre), Rohan and Rowan were flown in via Chinook Helicopter and got to work.
"There were literally aircraft water-bombing the fire only a couple of kilometres away while we were working," Dr Clarke said. "It [the fire] was incredibly close; it burnt into the northern edge of the heath where the bristlebirds live."
“We were able to catch 15 birds and move them to Melbourne Zoo – an insurance population should the remaining birds at Howe Flat be wiped out by fire”, said Dr Mott.
"The fire is still really active. We can't put them back until the fire is completely out," Dr Clarke said. "Hopefully this insurance population wasn't needed, if we haven't lost the site. If the fire burns and get worse, fortunately we have this insurance population."
Photo by Tony Mitchell
Five lab members recently presented at the Victorian Biodiversity Conference at Monash University in Melbourne. PhD students Flossy Sperring (pictured), William Mitchell, and Alexandra Nance presented their latest findings concerning some of Australia’s rarest birds. Flossy walked the audience through her first field season on Norfolk Island, and the first insights into the Endangered Norfolk Island Morepork territory size; Will spoke of the Endangered Mallee Emu-wren, and the outcomes of the first-ever conservation translocations; and Allie shared her insights on the Norfolk Island songbird community and the conservation objectives for a suite of threatened species. Morgan Humphrey presented the combined outcomes from two third-year research projects (Morgan’s and current Honours student Claire MacKay’s) where thermal scanning technology was employed to monitor the Critically Endangered Plains Wanderer - their findings in the thermal sensing space will underpin research directions for Finella Dawlings, who has recently joined our research group. Finally, Nick Bradsworth who has been working as a research officer alongside Flossy on Norfolk Island (and current PhD student at Deakin Uni) presented his latest findings on urban land use by Victorian Powerful Owls.
Will Mitchell and Allie Nance also ‘cut their teeth’ as conference organisers given their active roles on the organising committee for this important event.
“The VicBioCon was a great success. It provides opportunities for emerging and established scientists alike to present their findings to a wide audience. It fosters collaboration, and it’s a really nice atmosphere!” Remarked PhD student, Flossy Sperring.
03/09/2020 in News“Making transparent and rational decisions to manage threatened species in situations of high...
02/29/2020 in NewsDr Rohan Clarke, and Dr Rowan Mott from the ResearchEcology lab were recently deployed to Howe...
Baker, D.J., Garnett, S.T., O’Connor, J., Ehmke, G., Clarke, R.H., Woinarski, J.C.Z. & McGeoch, M.A. (2019) Conserving the abundance of nonthreatened species. Conservation Biology 33, 319-328
Baker, D.J., Clarke, R.H. & McGeoch. M.A. (2019) The power to detect regional declines in common bird populations using continental monitoring data. Ecological Applications doi:10.1002/eap.1918
Sorrell, K.J. Clarke, R.H., Holmberg, R. and McIntosh, R.R. Remotely piloted aircraft improve precision of capture-mark-resight population estimates. Ecosphere (accepted 5 June 2019)