Olive ridley turtle nest found on Australia's east coast for first time
Olive Ridley sea turtles are usually found in Queensland's Gulf, not on the east coast. (Supplied: Mackay and District Turtle Watch)
An endangered olive ridley turtle may have travelled close to 2,000 kilometres to nest on Queensland's east coast in a find described by renowned researcher Col Limpus as "quite a phenomenon".
While conducting a dawn patrol along Campwin Beach, south of Mackay, about two months ago, volunteer conservation group member Janet Boxall spotted an unusual looking turtle entering the water.
It was smaller than what she usually observed, and she believed it was a loggerhead turtle.
With the help of her fellow volunteers, she said an egg chamber was located, and they moved about 90 eggs up onto a cliff and out of danger.
"It didn't look like any nest that we'd ever seen before, it was like chopped up sand," Ms Boxall said.
Historic hatchlings
Ms Boxall said hatchlings started emerging from other nests along the beach about 40 days later, with tiny turtles making their way along the sand to the ocean.
But volunteers including Ms Boxall's sister, Shirley Sidey, noticed that there was no sign of movement in what was thought to be the loggerhead nest.
"It was at about 60 days we were just sitting on the beach and they all just came out in one bunch," Ms Sidey said.
"Unlike the flatbacks where you'd see all their little heads and then they'd start streaming out, they all massed around the nest and then they took off in one wave and there were about three waves that we saw."
She said 47 tiny, dark-brown hatchlings emerged from the 90 eggs in the nest.
After the excitement of the event died down, Ms Sidey began closely examining pictures of the hatchlings.
She noticed that they didn't have the characteristics of a loggerhead at all.
So she sent the images to Queensland chief scientist with the aquatic threatened species program, Col Limpus.
"He came back to us and said, 'There's no ambiguity, that's an olive ridley,'" Ms Sidey said.
"We were very excited, we celebrated with champagne," Ms Boxall said.
Rare discovery
The species, known for its olive-grey shell and large head, was first detected in Australia in the 1960s, in the Northern Territory.
The olive ridley nests all year round, but their major breeding events happen in Mexico, the western coast of Costa Rica and along India's east coast.
In Australia, nesting had only previously been discovered at five isolated sites in the Gulf of Carpentaria.
"We have been organising systematic surveys of marine turtle nesting throughout eastern Australia for more than 50 years and up until now we didn't have a single record of it nesting in eastern Australia," Dr Limpus said.
"It's quite a phenomenon and it raises the question, where has this turtle come from?"
Dr Limpus believed the nest could indicate that the species had expanded its breeding ground.
"It's actually quite abundant in its breeding in Asia, and Australia is sort of on its outer limits."
Breeding expansion
Olive ridleys have been detected foraging in the Great Barrier Reef since 1974.
Dr Limpus believed they travelled to the reef from their nesting site in the Solomon Islands.
He said there was no indication that they had travelled from the Gulf of Carpentaria through the Torres Strait and down along the east coast of Australia.
"We could be dealing with an expansion of breeding by the species into eastern Australia," Dr Limpus said.
"They breed every one to two years so hopefully it comes back to breed again and expands the population."
Dr Limpus said the network of citizen scientists along Queensland's coast that monitored the state's turtle populations was highly valued in the conservation movement.
"Hats off to the Mackay volunteers and top marks for their training to be able to recognise such a unique event," he said.