Effectiveness, risk, and impacts of orangutan conservation interventions

Sherman, J (2025) Effectiveness, risk, and impacts of orangutan conservation interventions. Doctoral thesis, Liverpool John Moores University.

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Abstract

Conservation interventions conducted without evaluating empirical evidence o their impacts on target species and habitats can lead to conservation funding being directed to ineffective or counterproductive measures. My research filled an important gap by assessing the conservation effectiveness of interventions to protect Critically Endangered Bornean orangutans (Pongo pygmaeus), Sumatran orangutans (Pongo abelii), and Tapanuli orangutans (Pongo tapanuliensis) in Indonesia. All three species are critically endangered at risk due to habitat conversion and fragmentation, killing, and trade, but few of the interventions that aim to conserve them have been evaluated. I built novel datasets from primarily public data sources to examine the relative prevalence and costs of orangutan conservation interventions, whether they were monitored, and their impacts on individual orangutans and orangutan populations. I first assessed orangutan conservation action plans implemented in 2007 – 2017. Although orangutans and forests in Indonesia declined during this period, the study provided valuable information on what interventions were attempted. I then evaluated the outcome of one of the most widely applied interventions, orangutan “rescue”—seizure or surrender of illegally held orangutans and capture of wild orangutans perceived to be at risk—and the orangutans’ subsequent release (translocation) into natural habitats. Although rescues are thought to aid law enforcement efforts, rescue of 1517 orangutans between 2007 and 2017 suggested high poaching rates and a flourishing local pet trade in spite of rescue efforts. I also assessed disease and conservation risks of orangutan translocations and identified pathogen transmission pathways to wild orangutan populations and for zoonotic diseases. Risks were highest for wild orangutans captured and removed from insecure situations and released elsewhere (wild-to-wild translocation), which had few biosafety controls and high risks for negative conservation outcomes. I analysed killing, capture, and trade affecting Indonesian orangutans from 2007 - 2019 and found records of 2229 reported crimes, only 22 (0.9%) of which ended in court cases. Most orangutan trade crimes (an average of 98% of the crimes for all species) involved local, not international, trade. At expected detection rates, killing rates exceeded the 1-2 % orangutan hunting mortality threshold expected to drive populations to extinction, showing that killing remains a serious threat to orangutans. Finally, we conducted a counterfactual analysis of the orangutan protection and cost effectiveness of conservation interventions from 2000 - 2019. We found habitat protection and anti-poaching patrols were the most effective activities overall, while rescue and translocation had little effect on species populations. My research elucidated the relative effectiveness of key orangutan conservation interventions, enabling informed decision making and prioritisation of conservation activities. My studies provide replicable approaches for evaluating species conservation impacts in situations with limited or no systematically collected monitoring data.

Item Type:	Thesis (Doctoral)
Uncontrolled Keywords:	Orangutan; Conservation; Evidence; Effectiveness; Risk; Biodiversity
Subjects:	G Geography. Anthropology. Recreation > GE Environmental Sciences Q Science > QH Natural history > QH301 Biology
Divisions:	Biological and Environmental Sciences (from Sep 19)
Date of acceptance:	23 October 2025
Date of first compliant Open Access:	28 November 2025
Date Deposited:	28 Nov 2025 14:20
Last Modified:	28 Nov 2025 14:21
DOI or ID number:	10.24377/LJMU.t.00027576
Supervisors:	Wich, S and Meijaard, E
URI:	https://researchonline.ljmu.ac.uk/id/eprint/27576

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