KOTA KINABALU: The unusual event of green turtles coming ashore to lay their eggs in broad daylight was likely due to environmental disturbances.
Universiti Malaysia Sabah's Borneo Marine Research Institute senior lecturer Dr Pushpa Palaniappan said green turtles usually came ashore to lay their eggs from dusk to dawn.
"For these creatures to land during the day was definitely unusual", said Dr Pushpa, a marine reptile specialist.
She said there were various possible reasons why two green turtles were spotted laying their eggs just before noon at Pulau Libaran off Sandakan for two days from May 24.
Noting that green turtles were sensitive to movement and light while nesting, she said that the creatures would return to the sea immediately if they were disturbed.
"As it needs to release its eggs, a female turtle may be forced to go ashore during the daytime to lay them", Dr Pushpa told The Star.
She said there were occasions when the egg laying process took too long because sand conditions were unsuitable.
"During the extremely dry weather between March and May, the turtles faced difficulty nesting at Pulau Selingan, Gulisan and Bakungan Kecil, which make up the Turtle Islands Park off Sandakan", Dr Pushpa said.
The turtles were found to have dug many egg chambers only to have them collapse, as the sand particles were too dry to stay in place, she said, forcing the turtles to dig body pits and egg chambers repeatedly until they finally manage to lay their eggs safely.
"Turtles tend to go ashore with the high tide to avoid having to make a long crawl to the beach during low tide", Dr Pushpa said.
If the high tide occurs during the early morning, and a turtle is unable to complete nesting by dawn, then she may still be found on the beach during daylight hours.
Also, if the turtle is unable to lay her eggs on the first night, she may return to the beach during the next night to finish nesting.
"If the turtle fails to deposit its eggs in its nest on the beach, she may release them on the surface of the sand or at the water's edge", Dr Pushpa added.
She said an adult female turtle would carry between 500 and 800 unshelled eggs in its body at the start of its breeding cycle.
After the mating process, where the female is able to store sperm from more than one male to fertilise her eggs, about 100 eggs then form shells in about 10 to 14 days.
"The female then goes ashore to deposit its eggs in a clutch and this process is repeated until all the eggs are laid and the turtle returns to her foraging area", Dr Pushpa explained.
Pulau Libaran honorary wildlife warden Harun Willam said he was taken aback at seeing a green turtle laying up to 80 eggs at the island at about 11am on May 24.
"It then came ashore at about 11am the following day and laid 61 more eggs", he said.