Abstracts of Papers
A Mark-Recapture Study of the Northern Diamondback Terrapin (Malaclemys terrapin terrapin)
A.B. Bragin1 and R.C. Wood2
Despite its unsavory popular image of a degraded marsh cut-up by a complex transportation network dominated by oozing landfills, toxic waste, rail yards, and reeds (Phragmites australis), fisheries research in the late 1980s and early 2000s revealed a seemingly large population of northern diamondback terrapins (Malaclemys terrapin terrapin) in northern New Jerseys Hackensack Meadowlands. In an area that was once a freshwater Atlantic white cedar (Chamaecyparis thyoides) swamp, then drained for agricultural production, and more recently (until 1950) a relatively dry reed field, scientists began a mark-recapture study of the northern diamondback terrapin within the Sawmill Creek Wildlife Management Area in 2009. Terrapins were captured using baited Maryland-style crab traps, and were weighed, measured, sexed, photographed and internally tagged with 12.5 mm Biomark RFID Passive Integrated Transponder (PIT) tags. Each terrapins shell anomalies were also documented. All terrapins were released at their capture location. By the conclusion of our third field season in 2011, we had tagged 676 terrapins, and recovered 114 (17%) as recaptures. Several aspects of this terrapin population are being investigated, including estimates of population size, food habits, range of movement within the marsh, frequency and types of shell anomalies, sex ratios and growth rates. This research will continue in 2012.
Barrier Fences Reduce Diamondback Terrapin (Malaclemys terrapin) Road Mortality
D.J. McLaughlin, D.J., R.C. Wood, J. Cuthbert, and P.J. Baker
Every year during their nesting season (typically late Maymid July), hundreds of adult female northern diamondback terrapins (Malaclemys terrapin terrapin) are killed on roads crossing or adjacent to salt marshes along the coast of southern New Jersey. To mitigate this problem, we conducted experiments to determine whether roadside barrier fencing is an effective conservation tool. Over the past eight years, we experimented with several different terrapin barrier fence designs including silt fencing, plastic mesh fencing, concrete blocks made from dredge disposal material, chicken wire attached to roadside guardrails, and corrugated plastic tubing. Through these trials we discovered several practical concerns, which should be considered to minimize costs and maximize barrier function. Since 2004, collaboration between governmental agencies, volunteers, local businesses, and the Wetlands Institute has resulted in over ten miles of terrapin barrier fence being installed along salt marsh roads in southern New Jersey. Data so far indicate that terrapin barrier fences reduce the total number of terrapin road kills. Experiments conducted in 2011 demonstrate that the majority of nesting activity occurs on the marsh side of a terrapin
Site Fidelity to Tidal Creeks and Nesting Sites
P. Baker1, D. McLaughlin2, R. Boerner2, and R. Wood2
Northern diamondback terrapins (Malaclemys terrapin terrapin) inhabit tidal creeks, bays, and pannes of salt marsh ecosystems along the mid-Atlantic coast of the US. While these habitat types are continuous or semi-continuous (connected at high tide), the extent to which terrapins move within a salt marsh is poorly understood. We conducted a 15-year mark-release-recapture study to understand site fidelity in M. t. terrapin. Ten salt marsh creeks in southern New Jersey were trapped for at least two years, and in some cases up to nine years. Terrapins were individually marked and released at the creek of original capture (COC). We concurrently monitored nesting activity at The Wetlands Institute. High rates of recapture (80.5-95.3%) of individuals in the COC and low rates of recapture (4.719.5%) in nearby tidal creeks suggest high fidelity to specific tidal creeks. Multiple recaptures of adult females over several years at the same nesting site suggest that terrapins also exhibit a high degree of nest site fidelity. After nesting, female terrapins return to the COC, even when the distance to the COC is relatively far and they bypass other available habitat en route to their COC. Because site fidelity is high, conservation efforts should focus on preserving habitat.
Variation in Scute Anomalies among Three Diamondback Terrapin (Malaclemys terrapin) Populations
S. Wolfe1, R. Wood2, and D. McLaughlin2
Diamondback terrapin scute anomalies (irregularities of the scales that cover a turtles shell) were analyzed for 2,703 individuals from three different populations (the Hackensack Meadowlands and Cape May Peninsula of NJ, and Key West National Wildlife Refuge, FL). The pattern and frequency of seven types of anomalies for all of these terrapins were recorded. In all three of the populations sampled, females tend to have more anomalies than males. Carapace anomalies are more common than plastral anomalies. The Key West and Hackensack Meadowlands populations have roughly the same frequency of anomalies (60 and 62% respectively) while only 31% of the Cape May Peninsula population exhibited one or more kinds of anomalies. The Key West population has a distinctive pattern of anomalies different from that found in either of the NJ populations. These results suggest that one or several different biological, environmental, or anthropogenic factors may account for differences in anomalies between sexes and among populations.