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Providing evidence to improve practice

Action: Implement continuous health monitoring with permanent vet on site Primate Conservation

Key messages

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  • One controlled, before-and-after study in Rwanda, Uganda and the Democratic Republic of Congo found that the population size of mountain gorillas that were continuously monitored by vets, alongside other interventions, increased by 168% over 41 years.

Supporting evidence from individual studies


A controlled, before-and-after study in 1967-2008 in tropical montane forest in Volcanoes-, Mgahinga-, and Virunga National Parks in Rwanda, Uganda, and the Democratic Republic of Congo found that a mountain gorilla Gorilla beringei beringei population that was continuously monitored by vets alongside ten other interventions, increased in size over time. Annual population growth was 4.1%, resulting in an overall population increase of 168% over 41 years. No statistical tests were carried out to determine whether this increase was significant. Veterinary treatment for snares, respiratory disease, and other life-threatening conditions explained up to 40% of the difference in growth rates between this population and another population in the same area, which did not receive veterinary care. The remaining 60% were likely due to increased protection against poachers. As part of an ecotourism- and research project, gorillas in the treatment population were habituated to human presence where visitors/researchers had to follow strict health procedures; these included keeping a safety distance to the gorillas, wearing face-masks, spending only limited amounts of time with gorillas, ensuring that visitors/researchers were healthy and disinfecting visitor’s/researcher’s clothes, boots etc. Dead gorillas were clinically examined. The study does not distinguish between the effects of the other interventions mentioned above

Referenced papers

Please cite as:

Junker, J., Kühl, H.S., Orth, L., Smith, R.K., Petrovan, S.O. & Sutherland, W.J. (2019) Primate conservation. Pages 439-491 in: W.J. Sutherland, L.V. Dicks, N. Ockendon, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2019. Open Book Publishers, Cambridge, UK.