Wild chimpanzees look both ways before crossing roads

In a 29-month survey, researchers observed and recorded 20 instances of wild chimpanzees crossing a busy road in Sebitoli, in the northern part of Uganda's Kibale National Park. They watched 122 chimps cross the highway used by 90 vehicles an hour, many speeding at 70 to 100 kilometres an hour.

It's the first report on how chimpanzees behave crossing a very busy asphalt road, says Marie Cibot of the National Museum of Natural History in Paris. Chimps are exceptionally cautious when they cross the road. Ninety-two per cent of them looked right, left, or both ways before or during crossing, and 57 per cent ran across, showing that they knew the value of reaching the other side as quickly as possible.


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Alpha males led and organised 83 per cent of the road-crossing groups. This implies that they recognised the importance of extra vigilance during road crossings. There was also evidence that healthy and dominant chimps often made sure that stragglers or more vulnerable members of the group crossed safely. Some 86 per cent of the healthy chimps looked back or stopped when at least one vulnerable individual, such as an infant or injured chimp, trailed behind.

Cibot now hopes to work with the Ugandan authorities to test new safety measures. "We aim to test mitigation measures such as bridges, underpasses, reduced speed limits, speed-bumps and police patrols in the area," she says. "Road infrastructure is spreading throughout Africa to support regional development, industry and tourism, and studying chimpanzee adaptation facing roads represents a way to reduce the risk of collisions."