The effects of mesocarnivores on the nesting success of the diamondback terrapin are highly variable across the distribution of the species. In some regions, nest predation can be as high as 90%. At Chincoteague Bay, our past research has shown that 30-40% of terrapin nests are predated each year, primarily by raccoons and the red fox. The goal of our study was to determine the spatial distribution of terrapin nest predators along the causeway that leads to Wallops Island, Va. This causeway connects the more rural mainland Virginia to the barrier island which has been substantially altered by human activity. Between June 6th to the 30th, 2018 (during the majority of the terrapin nesting season), we deployed seven motion-activated trail cameras in equally spaced increments along the causeway. Four of the cameras were located on the more vegetated west side of the causeway bridge, while three were on the more developed east side of the bridge. Visual sightings of predators were also recorded while driving back and forth across the causeway.
Results/Conclusions
Based on trail camera photographs we identified raccoons and red foxes as the dominant nest predators along the causeway. We found there was an uneven distribution of mesocarnivores along the causeway, with most observations occurring on the west side (chi-square = 30.08, critical = 12.6, df = 6). Species differences were also observed. Raccoons showed a significant preference for the east side (chi-square = 22.3, critical = 12.6, df = 6). Conversely, foxes were seen more often on the west side of the causeway (chi-square = 31.88, critical = 12.6, df = 6). For the most part, our visual observations of nest predator distribution supported data collected from trail camera photographs. We suggest that the uneven distribution of nest predators along the causeway is a function of resource partition and may also be due to differences in these species adaptability to human-altered habitat. These findings provide some insight on how to effectively develop predator management and terrapin conservation strategies at Chincoteague Bay, in efforts to increase terrapin population sizes.