Monkeys in Costa Rica have a clear preference when crossing a busy road: they would rather use a rope bridge than a ladder bridge. A new study from the Osa Peninsula shows that canopy bridges become more effective the longer they are in place, and that design matters more than previously thought.
Rope bridges win over ladder bridges
Researchers monitored 14 canopy bridges along a road in the Osa Peninsula over several years. They recorded more than 1,200 crossings by six mammal species. The most frequent users were white-faced capuchin monkeys and howler monkeys. The study found that rope bridges were used far more often than ladder bridges. Monkeys crossed rope bridges at a rate of 0.6 crossings per day, compared to just 0.1 crossings per day on ladder bridges. Squirrels and other small mammals also used the bridges, but less frequently.
Time makes bridges better
The study also found that the bridges became more effective over time. In the first year after installation, crossings were relatively rare. But by the third year, usage had increased significantly. The researchers believe that animals need time to learn about the bridges and become comfortable using them. This suggests that conservation projects should not judge the success of a canopy bridge too quickly. Patience may be key.
Why locals care about canopy bridges
The Osa Peninsula is one of the most biodiverse places in Costa Rica. Roads cut through forests that are home to monkeys, sloths, and other arboreal animals. When animals try to cross roads on the ground, they risk being hit by cars. Canopy bridges are meant to give them a safe route above the traffic. Local conservation groups and residents have invested in these bridges to reduce roadkill and keep forest habitats connected. The new findings help them understand which designs work best and how long it takes for animals to adopt them.
Closing
The study provides some of the first long-term data on how animals actually use canopy bridges in Costa Rica. It shows that rope bridges are more popular than ladder bridges, and that usage grows over several years. For conservationists working to protect wildlife in fragmented forests, these results offer a clearer picture of what works and what does not.
