Volunteers build bamboo bridges, close roads to protect mangrove crabs

For egg-carrying crabs navigating the coastal mangrove forests of Tainan in southern Taiwan, the journey to the sea is perilous — but they don't make it alone. 

A growing band of volunteers is helping to protect local mangrove land crabs by monitoring population numbers, collecting research data and closing roads during peak migration periods.

The mangrove land crab is Taiwan's largest terrestrial crab species. Taijiang National Park is home to the species' largest known population, according to park officials.

Volunteers aim to reduce roadkill and help egg-carrying females reach the sea safely, while also coming up with creative ideas like building bridges for the crabs.

Like many who grew up near this coastal mangrove forest in a rural area near Tainan, 61-year-old volunteer Chen Kuo-chung remembers playing with the crabs as a child due to lack of other entertainment options.

Now, through a common interest with his cousin, he uses his passion and handicraft skills to help ease the hardships female crabs encounter when migrating to the sea to lay their eggs.

"Diving is not okay for a female, no one with a big belly wades through the water, absolutely no one," Chen said, adding that he felt it was worth the effort of building a bamboo bridge over a creek for the crabs to use.

Researchers found that mangrove land crabs in Taijiang National Park must cross first a road and then a concrete coastal dyke to reach the sea, where females release their eggs.

As large numbers of crabs migrate along one major route, the park began seasonal road closures and traffic controls during peak migration periods.

Wang Ming-chieh, a six-year-old elementary school student living nearby, was visibly excited when watching the crabs succeed.

"It just feels like they're having a hard time, so I came over to watch them," he said. "It just makes me feel very moved," he added when asked about his mood when seeing the crabs make their journey.

According to Taijiang National Park Director Chen Jun-shan, the measures have helped reduce roadkill and contributed to a rise in observed crab numbers from more than 5,000 annually in earlier years to more than 10,000 last year.

Chen said the crabs play an important ecological role by breaking down leaf litter and returning nutrients to the soil, helping support coastal forests.

Through volunteer programs, community outreach and environmental education, the park hopes to encourage broader protection of the wetland ecosystem and its biodiversity.

Camera: Fabian Hamacher. Production: Fabian Hamacher, Ann Wang. Writing: Fabian Hamacher/Reuters