Identifying brumating Northern Diamondback Terrapins (Malaclemys terrapin terrapin) by incorporating environmental sensor and drone technology

During extended cold water temperatures, the Northern Diamondback Terrapin (Malaclemys terrapin terrapin), a brackish water turtle species, undergoes a period of dormancy called brumation. Little is known about brumation, its environmental conditions, or habitats. To establish a range of conditions that a terrapin experiences during brumation, we affixed an environmental sensor to a carapace for one year to record water depth and temperature. Our sensor reading determined that during the brumation period, the terrapin rested in water temperatures < 13.90°C and in a water depth of < 1.0 m. Under similar environmental conditions, we also remotely navigated a drone from a land-based position and found brumating terrapins in a cove within the Barnegat Bay-Little Egg Harbor estuary. The best visibility for terrapin identification occurred when the drone was flown 1.5 – 4.6 m above the water, during a low tide with low tidal heights of less than 0.063 m and low wind speeds of < 12.9 km/h. These findings indicate that drone site surveys can assist researchers in finding locations with brumating terrapins during specific water temperatures and depths.