Population’s Dwindling Again

AVALON – The diamondback terrapin is uniquely adapted to the brackish coastal marshes of the East Coast and plays an essential role in the marsh ecosystem.
The resilient turtle has come close to extinction in the past, especially in the early years of the 20th century when they were commercially harvested for food at levels the population could not support. Terrapin numbers are shrinking and the culprit is habitat destruction and coastal development.
An ongoing project at the Wetlands Institute seeks to enhance nesting habitats while educating humans on ways to reduce the dangers to the terrapins, especially during their nesting period.
From May to July, female terrapins come out of the marsh to look for high ground to lay their eggs. The impact of human development on their natural habitat means fewer safe nesting locations, along with greater dangers traveling to them. Road mortality remains one of the biggest threats during the nesting season.
Dr. Lisa Ferguson attended the Avalon Borough Council meeting Sept. 11 to update borough officials on the progress of the Habitat Enhancement Project. Avalon is one of the project partners with the institute.
Ferguson focused on several areas of concern, as she outlined the problem and described the project’s activities to combat the population decline.
Coastal development is an ongoing problem for the terrapin’s habitat. Realizing that development will continue, the project is seeking ways to create safe, accessible and attractive locations for nesting. Avalon’s Bay Park Marina presents a testing area for restoration and nesting habitat improvement.
A barrier was erected at the marina, with a sand nesting habitat created behind the barrier. Existing lawn was removed, and sand added to provide natural nesting locations above the high tide mark. Digital wildlife cameras monitor the area, providing ongoing information to the project team.
A graphic showed that almost half of the terrapins monitored chose to nest on one of the mounds.
The Bay Marina enhancement efforts also allow the project to further a second goal, that of education about the dangers of human disturbance. Unintentional human disturbance can reduce nesting activity. 
Natural predators also present an increasing problem. Ferguson argued that “human activities work to increase populations of predators to terrapin nests, eggs, and hatchlings.” She spoke of “subsidized predators” that have increased their numbers in the marshes.
In an attempt to deal with the predation challenge, the project team is investigating the use of nesting boxes that allow the turtles to enter and leave eggs, but reduce the ability of predators to reach the nests. One study Ferguson cited claimed that protected nest mounds had a predation rate of less than 4%.
A common problem during the nesting season is road mortality of female terrapins. Barrier fences, the tubing seen along Avalon Boulevard, are effective in reducing road deaths.
The project is testing a potential alternative to the corrugated tubing: animex wildlife barriers. The solid plastic fence promises longer life, less maintenance headaches and a lower profile from roadways.
Two outdoor areas at the Wetlands Institute are test sites for the fencing. Based on results, Ferguson said that there may be planned testing on Avalon Boulevard next nesting season.
Testing fencing, monitoring the success of nesting mounds, and investigating the effectiveness of nesting boxes to reduce predation; all these activities have the goal of helping the terrapin population adapt to habitat changes.
To contact Vince Conti, email vconti@cmcherald.com.