Impact - SOS – Sumatran Orangutan Society

Andrew Walmsley

Our Impact

It's really important to measure the impact of the projects that we support to ensure that they are making a real difference to the fate of orangutans and their forests.

We try to measure the impact of all of the work we fund and support. We work in partnership with a variety of organisations, government agencies and academic experts to measure and evaluate the effectiveness of various approaches to conservation in Sumatra.

It’s easy to count how many orangutans have been rescued and easy to count how many trees have been planted. We are working hard to find more scientific ways of measuring prevented deforestation. We plan to use the latest in satellite monitoring technology to enable more accurate recording of deforestation. This will then be overlaid with areas where we have funded boots on the ground to develop an impact measure for that investment.



An evidence-based approach to conservation enables us to ensure that we are using resources wisely. Tracking projects over time helps determine why some strategies are successful and others are not, enabling us to focus on scaling up those that have the greatest potential outcomes for Sumatra’s wildlife, forests and people.

These are some of the questions our evaluation project aims to answer:

  • What is the impact of reforestation on orangutan populations?
  • What is the economic impact of protecting rainforest on the human population living in that area?
  • What is the impact of community education and agroforestry projects on deforestation rates?


In terms of measuring our outcomes, here are some of our key achievements to date:

2,292,253 trees planted


277 orangutans rescued




local people have participated in training to support conservation-friendly livelihoods

Value for money

Not only are we proud of what you have helped us to achieve, we are also proud of the fact that our projects represent extraordinary value for money:
Rainforest in Sumatra at sunset

For every £1 we raise to help orangutans, just over 3p is spent on fundraising.


For every £1 we spend on fundraising, we turn this into £21 for projects and campaigns to protect orangutans and their habitat.

An adult sumatran orangutan

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