The Zanzibar red colobus is an endangered monkey species native only to the Zanzibar archipelago with precious few numbers to lose. About half of the primate’s population lives in the Jozani-Chwaka Bay National Park, where cars traversing a busy road endanger wildlife in the park.

Since the road was built in 1996, a study found that of the estimated 150 colobuses exposed to the road, as many as 12 to 17 percent were lost to vehicle accidents. This, of course, poses a serious problem to the colobus, which is one of Africa’s rarest primates and has been listed as an endangered species by the International Union for the Conservation of Nature (IUCN) Red List.

“Cars are not selective in the animals they kill,” says primatologist and study senior author Alexander Georgiev, who is also the director of the Zanzibar Red Colobus Project. “This means that while natural predators may target the very young and old more often, cars are equally likely to kill reproductively active young adults, who would contribute the most to population growth.”

Sleeping policemen put a bump in survival rates

To help reduce the number of wildlife fatalities associated with road crossings a team of conservationists has installed four speed bumps along the road. A 2021 report shows that after three years of evaluating their effects, the team has found that the speed bumps reduced colobus road fatalities to about one every six weeks. That’s compared to one fatality every two to three weeks prior to the project.

The promising findings of this recent study may help other conservation projects to better protect wildlife threatened by traffic. This solution demonstrates how simple changes can make a big impact. Animal crossing bridges, about which we have written before, are another great way to achieve this.