Monkey business: Building a global database of primate conservation studies (commentary)

Primates are our family. From tiny, delicate golden lion tamarins to impressively muscular gorillas, we are part of the same evolutionary lineage; a tree of life stretching back about 65 million years. But while one primate — Homo sapiens — has flourished and spread across the planet, about 60 percent of non-human primate species are threatened with extinction.

Conservation of these intelligent, complex creatures can be challenging on many levels. We must work wisely towards finding the best solutions to the multi-faceted problems threatening their survival.

Researchers at the Max Planck Institute for Evolutionary Anthropology, together with researchers at the University of Cambridge (where I work), have just published the results of a three-year project gathering the data on how well primate conservation initiatives have worked to conserve species from lemurs to chimpanzees. The ‘Primate Synopsis’ collects scientific papers and, where possible, NGO reports, testing conservation ‘interventions’ — actions that conservationists might undertake in order to have a favorable impact on these species.

A panel of 23 primate experts from around the world identified 162 interventions that could be implemented for primates, and the research team at Max Planck searched nearly 170 conservation journals and newsletters for studies testing them. They summarized all the papers in plain English, so that even conservationists without access to scientific journals can read the findings.

The idea is simple: to present the current evidence for every intervention people might do to conserve primates, so that primate conservationists can learn from the best available data at the click of a mouse. This global database on primate conservation interventions is available to view for free, and a PDF of all the studies can be downloaded for use in areas without reliable internet access.

So what works to conserve primates?

The answer is understandably complicated, given the diversity of the group and the nature of conservation work. Non-human primates and humans conflict in many places on multiple levels. Non-human primates raid crops, chew cables, scatter garbage, steal food, and can become aggressive when they get used to being fed by people. Humans destroy primate habitats, kill primates with motor vehicles, and hunt them for food and pets. Furthermore, non-human primates are socially and psychologically complex creatures, whose responses to conservation efforts can be difficult to predict.

However, some patterns can be observed. Infrastructure such as roads, for example, can have devastating effects on primates. Primates crossing roads may be killed by vehicles, and food waste thrown from cars can lure primates towards areas where they are at risk of collision. Large roads can represent impenetrable barriers, preventing gene flow between primates living on each side of the road.

Fortunately, there are some tantalizing hints at solutions: black lion tamarins and capuchins in Brazil have been seen using custom-built pole bridges to cross roads, and six species of lemurs in Madagascar used canopy bridges to cross roads and mining areas rather than walk on the roads below. Even better, a thirteen-year study in Belize found that black howler monkey numbers increased after the construction of pole bridges over man-made gaps, as one part of a wider conservation plan.

Involving local human communities was also very successful in some studies, but exactly how best to involve them – or under which circumstances involving communities works best – needs more research. Of three studies testing how well it worked to involve local communities in primate research and conservation management, two saw successes – with black howler monkeys in Belize, and gorillas in Cameroon – while another, on mountain gorillas in several central African countries, saw gorillas decline despite a local environmental education program.

Figuring out what makes the difference between success and failure is critical

Were external factors such as conflict part of the reason that mountain gorillas continued to decline in the central African study? Or was the environmental education program inherently less likely to work than the ‘Gorilla Guardian’ program in Cameroon, where local communities selected representatives to collect data on the gorillas? The current data do not allow us to do more than speculate, but hopefully they will encourage more primate conservationists to evaluate their work in order to answer these questions.

Despite the failure of the gorilla environmental education program, multimedia campaigns to change behavior and promote positive attitudes towards primates have worked well in many places. Three studies found increased knowledge about primates in areas where multimedia campaigns, among other interventions, had been carried out; two studies found improved attitudes towards primates; one found a reduction in poaching; and three studies found increased numbers of primates. Clearly multimedia campaigns can be powerful — the next stages are to look at the messages, and messengers, that maximize the chances of success.

Other interventions had more variable results. Despite being one of the most commonly tested interventions, reintroducing groups of primates had unpredictable success rates. Some projects saw primate numbers boom, with high survival rates among the released animals, and rapid breeding; others saw the majority of released animals die. The reasons are not always obvious, as many projects seemed to be undertaking similar interventions, such as veterinary screenings of animals before release, acclimatizing the animals to the new area before releasing them, and providing supplementary food after release. Some species may simply be more suited to translocation or release from captivity than others — but there is a clear need to carefully test variations on how best to release animals, to give each project the best chance of success.

For example, most gorillas (up to 85 percent) seemed to survive even over several years post-release, and to reproduce successfully. However, for vervet monkeys, survival ranged from 60 percent for six months post-release in one study, to 17 percent over 10 months post-release in another study. Are gorillas inherently more likely to survive translocation than vervet monkeys? Are the differences in survival between studies for vervet monkeys due to the landscape that they were released into, the rehabilitation and release process itself, or where the monkeys were sourced from? How could you develop the optimal method for reintroducing vervet monkeys to the wild? These questions and more will only be answerable with further studies, but gaining an overview of all the existing work will help guide the direction of key research.

Which interventions urgently need more studies?

For 59 percent of interventions, the authors of the Primate synopsis were unable to find any studies that examined how well they worked. These are the areas where good experiments would add the most to primate conservation, and the full list can be seen on the online database. The authors note that more studies testing interventions are urgently needed for small, nocturnal species, and for primates in South America and Asia, as these species were under-represented in the global database of studies.

As mining activities are increasing globally in primate habitats, the authors stress the need for innovation in ways to mitigate the effect of mining and energy production on primates and their habitats. These might include minimizing ground vibrations caused by open cast mining activities, establishing no-mining zones in/near watersheds so as to preserve water equilibrium, and using ‘set-asides’ for wildlife (primate) protection within mining areas.

Research into ways to optimally engage with local communities in areas of primate habitat would also hugely benefit primate conservation. More studies on the effects of interventions to promote education and awareness-raising, and interventions that provide monetary or non-monetary benefits to local communities for sustainably managing their wildlife, would help to gauge the relative merits of each approach. Given the high level of conservation spending on community engagement of various kinds, it seems worthwhile dedicating five or 10 percent of primate conservation budgets to testing their efficacy.

One of the main problems when trying to test the effectiveness of interventions is that, typically, many interventions are conducted at once, making it hard to tell which ones were beneficial and which were not. While this reflects the reality of trying to undertake complex and urgent conservation projects, there are ways of isolating and testing interventions within bigger projects, such as staggering the times at which interventions are rolled out. The ‘PRISM’ toolkit can help practitioners on the ground to test interventions and it is available for free online. Tests of interventions can be published without publication fees in the Conservation Evidence journal, among other places.

Many fascinating pieces of research have gone into creating this global database on primate conservation; with the continued hard work of primate conservationists, the next update of the database in a few years time should be even better, helping to make primate conservation more effective.

CITATION

• Estrada, A., Garber, P. A., Rylands, A. B., Roos, C., Fernandez-Duque, E., Di Fiore, A., … & Rovero, F. (2017). Impending extinction crisis of the world’s primates: Why primates matter. Science advances, 3(1), e1600946. doi:10.1126/sciadv.1600946

Dr. Claire Wordley is a researcher with the Conservation Evidence group at the University of Cambridge. Her background includes working on the responses of tropical bats to forest fragmentation and agricultural activity. This led to an interest in researching how to make conservation change happen, and she now works at Conservation Evidence working with NGOs and government agencies to see how they can best use and produce scientific evidence.

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