The diamondback terrapin (Malaclemys terrapin) is an estuarine endemic that lives in the mangrove forests and salt marshes of the United States and Bermuda. As major predators of marsh periwinkles, this species likely plays a role in maintaining ecosystem health by preventing over-grazing of foundational salt marsh grasses. Diamondback terrapins are considered of conservation concern throughout much of their range (including Georgia) due to historical overharvest, habitat loss, road mortality, and crab trap bycatch. Mark-recapture studies have suggested strong fidelity to natal sites and tidal creek foraging sites, but previous genetic studies have typically failed to detect fine scale structure (within estuaries) that would be expected with limited dispersal. It’s not clear if this lack of fine-scale structure reflects cryptic juvenile dispersal or male-mediated gene flow. We are employing novel genetic markers and collaborating with several partners to characterize the scale of natal homing, dispersal, seasonal movements, and population structure locally (within estuaries) and regionally from North Carolina through Florida.