Projects and Research

Diamondback Terrapin Crossing Prevention Project

Fisherman island NWR is home to the iconic northern diamondback terrapin (Malaclemys terrapin), a species often seen on roadways in warmer months as the females venture over land in search of suitable nesting sites. Meanwhile, the Chesapeake Bay Bridge-Tunnel, carries Highway 13 directly through Fisherman Island which places terrapins directly in the path of traffic.

This concrete barrier prevents diamondback terrapins from entering the busy highway.

After collecting information about diamondback terrapin road mortality in 2016, refuge staff started an effort to reduce vehicle strikes by trying to keep the animals off the highway. Beginning in 2007, we installed several types of temporary barriers along a portion of the bridge-tunnel that crosses Fisherman Island. Unfortunately, these were mostly ineffective so, in 2020, a longer, permanent concrete barrier was installed. The replacement should reduce barrier maintenance, while further reducing terrapin mortality.

Fifteen remote cameras were placed along 1.5 miles of the new barrier in 2020 to monitor nesting diamondback terrapin activity. Additional monitoring efforts include road surveys to document diamondback terrapin vehicle mortalities and foot surveys to provide real time observations. Thus far, the concrete barrier appears to be an improvement over the previous barriers with fewer mortalities being documented.