Losing forest boundaries

Unlike previous studies that examined the issue from primarily an ecological standpoint, the new study is the first to integrate landscape-level ecological factors with individual-level behavioral factors and weigh risks to human health.

The researchers began by collecting land use survey data from small-scale farmers living near forest fragments. They combined this information with high-resolution satellite imagery from the same time period to model how landscape patterns and individual behaviors together make certain people more likely to have contact with wild animals.

They found the strongest predictors of human-wild primate contact were the length of the forest boundary around people’s homes and the frequency with which people ventured into these forested areas to collect small trees for construction material. Searching for these pole-like trees entails spending more time deep in primate habitats than other forest-based activities.

The researchers were surprised to find some of their assumptions turned upside down. For example, small fragments of residual forest—not larger expanses of habitat—were most likely to be the site of human-wild primate contacts due to their shared borders with agricultural landscapes.

Similarly, the researchers speculate that increasing intrusion of agriculture into forests and resulting human activities in these areas could lead to more spillover of infections from wild primates to humans worldwide.


Preventing human-primate interaction

The researchers suggest that relatively small buffer zones, such as tree farms or reforestation projects, around biodiversity-rich forests could dramatically lessen the likelihood of human-wild primate interaction.

Using external resources, such as national or international aid, to provide fuel and construction material or monetary supplements could also reduce pressure on people to seek out wood in forested areas.

“At the end of the day, land conservation and the reduction of forest fragmentation is our best bet to reduce human-wild animal interactions,” says coauthor Tyler McIntosh, a former graduate student in the Stanford Earth Systems Program now working at the Center for Western Priorities.