In March 2025, 13 koalas from Upper Nepean State Conservation Area were translocated to the Tantawangalo area of South East Forest National Park. The translocation resulted in a number of mortalities and the program was suspended while an investigation was conducted.

Project review

The National Parks and Wildlife Service (NPWS) undertook a comprehensive review of the koala reintroduction to South East Forest National Park to identify which factors may have impacted project success and koala survival. 

The project review incorporated analysis from independent specialists in koala ecology and wildlife veterinary science, and researchers at Western Sydney University, the University of Sydney and the University of Queensland. 

In addition, 3 highly regarded independent koala translocation experts evaluated the review and provided comment on its findings.

Key findings

The review found that the objectives, design and methodology of the South East Forest National Park koala reintroduction project were sound and aligned with current best practice standards.

The review concluded:

  • The project was appropriately licensed and authorised under the Biodiversity Conservation Act 2016 and the Animal Research Act 1985.
  • Project planning was comprehensive and key stakeholders were engaged and consulted throughout the project.
  • Habitat assessments were thorough but could be expanded in future to include soil nutrient levels and leaf chemistry.
  • The project followed best practice animal welfare guidelines, but opportunities were identified to reduce cumulative effects associated with capture, handling, quarantine and transport.
  • Post-release monitoring and incident response at South East Forest National Park was timely and followed approved methods.

The review identified several factors which may have contributed to negative project outcomes, but the relative influence of these factors is not well understood. They are:

  • An unexpectedly severe rainfall event occurred soon after translocation. This may have suppressed koala feeding behaviour, caused hypothermia and hypoglycaemia and increased exposure to pathogens, leading to septicaemia in some animals.
  • High toxin concentrations and low available nitrogen in foliage at the recipient site may have led to reduced food intake and nutritional stress in the translocated animals.
  • Cumulative stress associated with the capture, holding and release of animals likely compounded the risks.

Independent reviewers differed in their assessment of the relative importance of the key causes of the project outcomes.

Further analysis is underway to assess koala gut microbiome and diet composition (tree species eaten) at the source and recipient sites, which may offer clearer insight into the mechanisms involved.

NPWS has been advised the RSPCA has also finalised their investigation into this matter and found no evidence of animal cruelty.

Key recommendations

The review makes 15 recommendations, with the aim of improving koala translocation outcomes in the future.

Recommendations address expanding habitat suitability assessments, researching rainfall as a threat to koala health, reducing holding time for animals and further researching the physiological response of koalas to translocation.

The Department of Climate Change, Energy, the Environment and Water has accepted all recommendations of the review.

The full report, including all recommendations, attachments and appendices, is available at Project review: koala reintroduction to South East Forest National Park.