Taiwan study shows new system slashes crab roadkill

Taipei, May 15 (CNA) Roadkill rates among land crabs on Green Island during the breeding season dropped significantly in areas with "guidance facilities" that help crabs safely crawl to the sea, the Taiwan Biodiversity Research Institute (TBRI) said Thursday.

Research by the institute showed that in 2022, roadkill rates in areas with the system were 8.5 percent, compared with 26.8 percent in areas without it. In 2023, the rates were 12.1 percent and 32.1 percent, respectively.

Summer is peak season for both tourism and land crab breeding on Green Island, and roadkill often occurs as female crabs cross from the mountain side to the sea to release their offspring, the TBRI said in a news release.

To help lower roadkill rates, researchers installed guidance facilities to lead crabs through exisiting culvert channels instead of across open roads.

One part of the system included roadside pipes with vertical slits and plastic barriers at the ends to guide crabs toward the pipes, researchers said.

Halved pipes were also installed along vertical retaining walls to guide crabs toward the lower entrance of the culvert.

Based on the results, the institute recommended installing guidance facilities in high-risk road areas.

Researchers also called for efforts to raise tourists' awareness of the crabs' ecological importance and to teach them how to protect juvenile crabs during their migration to the sea.

The research was commissioned by the East Coast National Scenic Area Headquarters under the Tourism Administration.

The research results were published in the June 2025 issue of the journal Global Ecology and Conservation in an article titled "Using innovative guidance facilities to reduce roadkill rates during land crab breeding season in Green Island, Taiwan."