Green turtle hatchlings are swimming, not climbing, their way to the surface as they emerge from their nests, new research found.
And in a UNSW statement, scientists say they used tiny ‘backpacks’ to learn more about this largely unknown stage of a hatchling’s life.
In a study published in the Royal Society’s online biological research journal Proceedings B, scientists say they used a small device, known as an accelerometer, to study hatchlings emerging from their nests.
Sea turtle eggs are buried in nests 30-80cm deep in sand. Once hatched, the hatchlings make their way to the surface over three to seven days.
The results from using the ‘backpacks’ revealed that buried hatchlings maintain a head-up orientation and, unexpectedly, move vertically through the sand by rocking forwards and backwards rather than tipping side-to-side as expected with digging, the statement says.
“When I visualise a hatchling that has just come out of its egg, it is completely in the dark in its surroundings. There’s no sign to point which way is up toward the surface yet they will orientate themselves and move upwards, regardless,” says Davey Dor, who led the study.
“Our initial findings and ‘proof’ of this new methodology opens the door for so many new questions in sea turtle ecology.”
Dor, Associate Professor Lisa Schwanz and Dr David Booth, from the University of Queensland, set out to find a new way to observe the hatchlings. They settled on accelerometers, which measure changes in speed or direction, have previously been used to study animal movement, behaviour and physiology.
The research took place on Heron Island, a long-term monitoring nesting site for green turtles in the southern Great Barrier Reef, where the nesting season typically runs from December to March.
A tiny accelerometer was carefully attached to each one of 10 hatchlings who were carefully reburied and monitored.
The accelerometer provided new data on the direction, speed and time it took for 10 hatchlings to emerge.
“We found that their movement and resting periods are generally quite short, that they move as if they were swimming rather than digging, and that as they approach the surface of the sand, they restrict their movement to nighttime,” Dor says.
These findings also provided new insights and changed previous assumptions about hatchlings’ earliest days in the sand.
“There are lots of factors that we don’t really understand because we haven’t been able to observe this stage of their lives but we hope this will change as a result of this new method, particularly in answering questions about best conservation practices,” says Dor.
