‘Homing turtles’ go back to familiar grounds
A James Cook University study has found turtles released back into the wild almost always return home — even if they have to swim more than 100km or have spent more than a year away.
Lead author, Dr Takahiro Shimada said the JCU team tracked 59 turtles released outside of the areas where they had been found along the Queensland coast.
"We lost communication with the tracking devices on two of them, but all except one of the rest returned home," he said.
While most of the turtles travelled to their old homes after a short time in captivity, one of the returning turtles had been held for more than 500 days while it recovered from injury. Another was released more than 117 km from where it was originally found and successfully made the journey back.
"It was surprising, we weren't quite sure if they would make it back over that distance or after that amount of time," said Dr Shimada.
He said researchers were also surprised with the precision of the turtles' navigation – with most eventually ending up within a few hundred metres of their home.
Researchers think the animals navigate using a combination of geomagnetic cues and other processes not yet fully understood.
The researchers returned another 54 turtles directly to their original home areas and found they didn't leave.
Dr Shimada said it's difficult to definitively prove why the turtles have such an attachment to a certain place. "Common sense suggests it's because they are familiar with the sources of food and shelter and where predators may be," he said.
The scientists say the finding has important implications for turtle conservation, with long-term resettlement of turtles away from dangerous or damaged environments not a realistic option.