Individual-level behavioral responses of immature green turtles to snorkeler disturbance


Despite many positive benefits of ecotourism, increased human encounters with wildlife may have detrimental effects on wild animals. As charismatic megafauna, nesting and foraging sea turtles are increasingly the focus of ecotourism activities. The purpose of our study was to quantify the behavioral responses of immature green turtles (Chelonia mydas) to disturbance by snorkelers, and to investigate whether turtles have individual-level responses to snorkeler disturbance. Using a standardized disturbance stimulus in the field, we recorded turtle behaviors pre- and post-disturbance by snorkelers. Ninety percent of turtles disturbed by snorkeler (n = 192) initiated their flights at distances of ≤3 m. Using principal component analysis, we identified two distinct turtle personality types, ‘bold’ and ‘timid’, based upon 145 encounters of 19 individually identified turtles and five disturbance response variables. There was significant intra-individual repeatability in behavioral responses to disturbance, but bolder turtles had more behavioral plasticity and less consistent responses than more timid individuals. Bolder individuals with reduced evasion responses might be at a higher risk of shark predation, while more timid turtles might have greater energetic consequences due to non-lethal predator effects and repeated snorkeler disturbance. Over the longer term, a turtle population with a mix of bold and timid individuals may promote more resilient populations. We recommend that snorkelers maintain >3 m distance from immature green turtles when snorkeling, and that ecotourism activities be temporally and spatially stratified. Further, turtle watching guidelines need to be communicated to both tour operators and independent snorkelers to reduce the disturbance of turtles.

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We like to thank Dr. Craig Lilyestrom and Carlos Diez (Department of Natural and Environmental Resources, Commonwealth of Puerto Rico), Ricardo Colón-Merced and Ana Roman (Culebra National Wildlife Refuge, US Fish and Wildlife Service), and Todd Plaia (Culebra Divers) for logistical support. We thank Diego Morell Parea (Culebra Adventures) for his support and additional data collection. Further, we would like to thank Chris Haak and Sarah Becker for field assistance. We would also like to thank Dr. Curtice Griffin for writing assistance and Dr. Kevin McGarigal, Blake Massey, and Dr. Chi-Yun Kuo for assistance with statistical analyses. Finally, we would like to thank the Associate Editor, Dr. Aaron Wirsing, and all of the anonymous reviewers for their time and insightful comments on the manuscript.

Author contribution statement

LPG and AJD conceived the study. LPG, JWB, TOG, SJC, ADMW, and AJD designed the methodology. LPG, JWB, and TOG conducted the fieldwork. LPG analyzed the data and wrote the manuscript. All authors provided editorial advice and assisted with revisions.

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Correspondence to Lucas P. Griffin.

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The authors declare that no conflict of interest exists. Funding source had no involvement in study design collection, and analysis and interpretation of data; in the writing of the report; and in the decision to submit the article for publication. LG was partially supported by the University of Massachusetts Intercampus Marine Science Graduate Program and the Allen Family Foundation. JB is supported by the Natural Sciences and Engineering Research Council of Canada and the Berkeley Marine Conservation Fellowship from the American Fisheries Society. TG was partially supported by the University of Massachusetts Environmental Conservation Department. AD was partially supported by UPR Sea Grant.

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Communicated by Aaron J. Wirsing.

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Griffin, L.P., Brownscombe, J.W., Gagné, T.O. et al. Individual-level behavioral responses of immature green turtles to snorkeler disturbance. Oecologia 183, 909–917 (2017).

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  • Ecotourism
  • Flight initiation distance
  • Principal component analysis
  • Personality
  • Repeatability