Evaluating efforts to decrease Northern Diamondback Terrapin (Malaclemys terrapin terrapin) mortality rates along a coastal causeway

Amanda Lillie ¹Coastal Conservation Research Program, The Wetlands Institute ²Tufts University

Conclusions

Results and Discussion

References

¹ Baldwin JD, Latino LA, Mealey BK, Parks GM, Forstner MRJ. (2005). The Diamondback Terrapin in Florida Bay and the Florida Keys: Insights into Turtle Conservation and Ecology. Krieger Publishing Company: Amphibians and Reptiles.

³ Crawford BA, Maerz JC, Nibbelink NP, Buhlmann KA, Norton TM, Albeke SE. (22 November 2013). Hot spots and hot moments of diamondback terrapin road-crossing activity. Journal of Applied Ecology. Volume 51, Issue 2.

⁶  Northern Diamondback Terrapin: State Species of Special Concern. (15 September 2015). State of Connecticut Department of Energy and Environmental Protection. Retrieved from: http://www.ct.gov/deep/cwp/view.asp?Q=326000.

⁹ Schlussel A. (2017). Temporal and spatial patterns of diamondback terrapin (Malaclemys terrapin) activity and road mortality along a coastal causeway. The Wetlands Institute.

Acknowledgements

A huge thanks to Brian Williamson, Lisa Ferguson, Brittany Morey, Steve Luell, Amanda Lyons, Kirstine Grab, Jaime Infanti, Danny Stoner, and Sarah Kerr for their help with experimental design and data collection and analysis.

• Adult female terrapins seek nesting sites at higher nesting grounds near roadways, leading to increased road mortalities ^{1, 3}

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• Spatial and temporal patterns relating to diurnal high tide have been identified for this nest-seeking behavior ⁹

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• Data suggests that the new terrapin nesting and activity has been effective at lowering turtle mortality rates in front of The Wetlands Institute (based on public survey results and ArcMap Hot Spot analysis).
• Terrapins were active at dawn, dusk, and night, but their presence was not affected by whether the tide was rising or falling.
• For both of the above statements, a larger sampling effort and size are necessary to determine how the sign and environmental factors have influenced turtle activity and mortality rates.

Original Photo : Terrapin ready to cross Stone Harbor Boulevard in front of The Wetlands Institute; terrapin crossing sign visible across the street

Road Patrols

Camera Trapping

Public Survey

• Road patrols looked for crossing terrapins along Stone Harbor Boulevard in Cape May County, NJ
• Collected data using EpiCollect5 software
• Logged date/time, GPS location, in/out transect, locality/detail, passive integrated responder check on turtle, vitality w/details

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Survey Times

June 27^th – July 13^th

• 6am (crepuscular)
• 8am (diurnal)
• 9am (diurnal)
• 11am (diurnal)
• 2pm (diurnal)
• 4pm (diurnal)
• 10pm (nocturnal)

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Road Patrols

Camera Trapping

• Camera trapping at three sites on The Wetlands Institute property from 4:00pm – 10:00am every night to capture activity that researcher was unable to observe in person

Sites

June 19^th – July 19^th

• The Wetlands Institute entrance driveway alongside Stone Harbor Boulevard, monitored terrapin crepuscular and nocturnal activity near roadway
• Two trail sites on The Wetlands Institute’s property alongside salt marsh pathway

Original Photo: Research intern Sarah Kerr with vehicle ready for road patrolling

Public Survey

• Asked questions regarding the frequency and time of day people travelled on Stone Harbor Boulevard, whether or not they saw the new sign, if it affected their driving, and their zip codes

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• Optimized hot spot analysis run in ArcMap 10.6 using road mortality data only

• Terrapins were active during both crepuscular and nocturnal hours (see Figure A).
• Presence of terrapins at a given time was not impacted by whether or not the tide was rising or falling. See Figure A (X2 = 4.1, p = 0.25)

Original Photo: Trail Camera 2 placed alongside The Wetlands Institute’s salt marsh pathway.

Original Photo: Three Wetlands Institute interns testing possible sign locations on the property.

Road mortality data analyzed only during the time period in summer 2018 where the new terrapin nesting and activity level sign was in place, allowing for a comparison with the same time period in 2017 when the sign was not present

2017: Significant road mortality hot spots observed around The Wetlands Institute ⁹

2018: Significant road mortality hot spots no longer observed around The Wetlands Institute

Figure A

• 484 total responses collected
• 64% of respondents had seen a wildlife sign along SH Blvd and correctly identified it as a terrapin nesting and activity level sign
• 67% of respondents consider either bright colors or flashing lights to be most eye-catching for roadway signs, an important consideration for future signage