Population and Nesting Site Evidence for Diamondback Terrapins, Malaclemys terrapin, in Northeast Florida

Joseph A Butler,J David Lambert,Michelle Dedeo,Daniel P Murphy

doi:10.3389/fevo.2022.833199

Joseph A Butler, J David Lambert + Show 2 more

Open Access

https://doi.org/10.3389/fevo.2022.833199

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Abstract

Diamondback terrapins (Malaclemys terrapin)are listed as Vulnerable by the IUCN Red List Index of Threatened Species. Among the challenges terrapins encounter are habitat loss due to coastal development and sea level rise, mortality at all life stages by mammalian and avian predators, road mortality, boat strikes, harvest for the pet trade, and drowning in crab traps. The primary objective of this study was to locate populations and nesting areas of diamondback terrapins in the four northeastern-most counties of Florida (Nassau, Duval, St. Johns, and Flagler). We conducted head counts and performed land surveys of shorelines and high spots for evidence of terrapin presence. During the land surveys we searched for crawls, intact and depredated nests, dead terrapins, and terrapin bones. To evaluate whether woody plant presence affected nest site choices, we recorded the occurrence of 10 common woody plant species during each land survey and compared areas where nesting did and did not occur. We collected 404 records of terrapin activity in 2013 and 2014. Most were from Nassau County (277) and only one was from Flagler County. Most data were in the form of depredated nests (205) and terrapin remains (147). The woody plant data suggest that terrapins were significantly more likely to nest when Christmas berry (Lycium carolinianum) was present, and nesting was less likely when either wax myrtle (Myrica cerifera) or oak (Quercusspp.) were present.

Highlights

Diamondback terrapins (Malaclemys terrapin) are listed as Vulnerable by the IUCN Red List Index of Threatened Species (Roosenburg et al, 2019)
We discovered most of the terrapin remains in Nassau County (Table 1), and it is notable that 87 of these were collected on 1 day from a site near the mouth of Jackson Creek (Figure 3B, where we recorded the most heads)
There is a high level of confidence (95 to 99%) that the only collection of non-random terrapin evidence data points occurs at the “Jackson Creek Concentration” in Nassau County (Figures 3A,B)

Summary

Introduction

Diamondback terrapins (Malaclemys terrapin) are listed as Vulnerable by the IUCN Red List Index of Threatened Species (Roosenburg et al, 2019). Used references concerning reptile natural history (e.g., Ernst and Lovich, 2009; Powell et al, 2016) describe the distribution of diamondback terrapins to be from Cape Cod, Massachusetts to Corpus Christi, Texas They provide range maps with a continuous line drawn. Terrapins in Northeast Florida along the Atlantic and Gulf coastlines between those two places While these maps are useful for general information, terrapin distribution along those lines is not truly continuous due to natural or anthropogenic habitat interruptions. Accurate local distribution information can inform governmental decisions concerning allocation of conservation resources and protection of essential habitats To this end, one of the major objectives of the Diamondback Terrapin Working Group has been to create a “living” map of historical and current terrapin populations throughout the range (Butler et al, 2006). Historical populations can be identified from existing literature or museum collections, while the distribution and abundance of contemporary populations is determined by surveys

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