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Hydrophone / Nest Videos

 
For the past five years nest parents and other N.E.S.T. volunteers have used stethoscopes and then later on sophisticated hydrophones to listen to nests and the noise made by embryos/hatchlings as they hatch and then make their way to the surface of the sand. By identifying and classifying these sounds volunteers can better determine when hatchlings are ready to emerge.
During hatching and emergence, it’s thought hatchlings are getting organized, likely communicating with each other through subtle vocalizations and body contact to improve synchronization for emergence. There is also time for the closing and straightening of the plastron (bottom shell) and absorbing remnants of the yolk sac. Pipping (making a break in the egg shell) to hatching takes 0 to 2 days or so.  From hatching to emergence takes approximately 4 to 7 days.

Embryos and hatchlings vocalize making burping, chirping and/or mewing sounds for up to ten days before emerging from the nest. Pipping sounds like someone tapping or scrapping as embryos struggle to open the egg shell. Once out of the shell, hatchlings move around beneath the sand. It sounds like gentle sand movement or “furniture moving.” The falling sand of a hatchling making its way to the surface sounds like a “waterfall” or even a “roaring waterfall” when emergence is imminent.

Hydrophone
The Dolphinear (hydrophone) microphone is the black disc in the lower left hand corner.  The receiver is in the lower right hand corner and speaker in upper left hand corner.

Hydrophone Recordings:

The types of sounds we hear can give us clues about the nest’s stage of development.  Vocalizations, for example, can be heard at any stage but are heard most frequently as made by embryos (i.e. in the shell). Tapping sounds come from embryos trying to first pip their way out of the shell. Falling sand or “gentle waterfalls or rustling” sounds are made by hatchlings as they leave the confines of the egg shell or make their way up the column of sand to the surface. As more and more hatchlings are involved the waterfalls become louder or even roaring and are much later in the process.

Not all sounds heard at the nest are made by turtles.  Sounds coming from the ocean, human activities or other creatures on the beach can easily be confused for turtle sounds.  Careful listening and observation of beach activities can usually determine the source.  Examples of the noises heard are below.

Sounds made by movement of hatchlings or embryos:

This is a recording of rustling and vocalizations 2 days before emergence
This clip is “furniture moving” noises with hatchlings getting organized 3 days before emergence
This is a recording of furniture moving sounds and early water fall.

Sounds made by vocalizations:

This recording is of a nest shortly before emergence.  The intense waterfalls sounds come in waves as the hatchlings are making it to the surface.
Many mewing vocalizations intermingled between furniture moving  several days before emergence
This clip contains a variety of vocalizations within a 30 minute period 2 days before emergence