Orientation of Leatherback (Dermochelys coriacea) Sea Turtle Hatchlings to Aerial Accoustic Cues

We investigated the response of sea turtle hatchlings to natural (crashing beach waves) and anthropogenic (human conversation and vehicle traffic) noises present on their nesting beaches during sea-finding. ). In the presence of three stimuli, a) beach wave sounds (72.0 dB re: 20 μPa), b) human conversation (72.4 dB re: 20 μPa), and c) vehicle traffic noise (71.1 dB re: 20 μPa), hatchlings exhibited no phonotaxic response. The responses of hatchling leatherback sea turtles, Dermochelys coriacea, collected from the Sandy Point National Wildlife Refuge, St. Croix, were measured in a circular arena. We examined hatchling response to trial auditory signals in a circular arena raised 14.0 cm off the floor. The arena’s circular platform was surrounded by 36 converging cushioned pitfall bins constructed to correspond to 10 degree intervals. Each bin had a degree range of 10 degrees and the midpoint of this range was used for statistical analysis. For example, if a hatchling crawled into bin 1 they were deemed to be orienting between 0-10 degrees and 5 degrees was the value used for analysis. We encased the entire arena in a light-proof tent to eliminate light cues. A speaker producing the recorded beach wave and anthropogenic sounds was placed outside the tent and moved to alternating locations (in relation to compass bearings: North, South, East, and West) to ensure turtles were orienting toward the speaker and not in relation to any given compass bearing. We suspended the speaker producing the trial sounds from a PVC frame above the table and off the floor to prevent vibrations. We leveled the platform to eliminate potential slope cues. Nest ID/Location indicates the nest identification number from the Sandy Point National Wildlife Refuge, St. Croix. Bin indicates the bin the hatchling oriented into relative to the speaker location. Bun corrected indicates the bin number when all 4 speaker locations were standardized after location was determined not to have an effect.