Analysis highlights sharp decline of koalas in Queensland and NSW

Koala populations in Queensland and New South Wales have declined by more than one third in the last 18 years, or in three generations of the koala, according to new analysis of koala research.

The project, ‘Conserving koalas in the 21st century’, was conducted by a working group brought together with the support of TERN’s Australian Centre for Ecosystem Analysis and Synthesis.

The project leader, Associate Professor Clive McAlpine, who has studied koalas for 10 years, said the project confirmed the suspicions of many researchers who worked with koalas.

‘We wanted to investigate what was happening to koala populations, on the back of a recent Senate inquiry that found that we really don’t know how to conserve and manage koalas nationally because we lack a comprehensive and integrated understanding of how koala populations have changed across their range. The Senate committee investigated the status, health and sustainability of Australia’s koala population,’ Clive says.

‘The decline in New South Wales populations is similar to that in Queensland, although it is more striking in NSW because some populations have become locally extinct in coastal areas. In contrast, the introduced populations of Victoria and South Australia are mostly stable, increasing, or being actively managed to reduce overpopulation.’

By providing more accurate information about the dynamics of koala populations, the group’s results will assist governments, land managers and others to conserve koala populations across their natural range, particularly in Queensland and New South Wales, where the koala is now listed nationally as vulnerable under the Environment Protection and Biodiversity Conservation Act.

The group came up with its findings after holding two workshops to integrate and analyse available data and expert opinion on koala population numbers and trends, and using this to synthesise new understanding about the status of koalas in the 38 bioregions where they occur. At the first workshop, held in February, they identified areas with available data where koala populations are in decline, where they are stable, and where populations are natural or introduced.

They built on this work at the second workshop, held in June, when they estimated the sizes of the koala populations and estimated changes in population size in the regions where they occur. The group conducted a four-step Delphi expert elicitation procedure, which was facilitated by Professor Mark Burgman, the Director of the Australian Centre of Excellence for Risk Analysis (ACERA) at the University of Melbourne. This approach allowed the group to address the gaps in knowledge regarding national koala populations with the robustness of collective judgement. The four steps of the Delphi method ask for an upper estimate, a lower estimate, a best guess, and a level of confidence. As part of the process, the 15 participants had completed a questionnaire before the workshop, and the results of this were re-evaluated during the workshop and a second round of elicitation conducted during it.

This process allowed the team to assemble new understanding from existing data, and confirmed, with scientific confidence, what many believe to be a deteriorating situation among koala populations in Queensland and New South Wales.

A visualisation of the findings together with a final report will be made available on the ACEAS website.

Published in TERN e-Newsletter September 2012

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