Nature’s War Zone
Raine Island is a harsh cradle for new life for thousands of Pacific green turtles who come to nest each year. Waiting for them are one of the ocean’s most ferocious predators—tiger sharks.
Each year during the relentless Australian summer months thousands of green turtles travel up to 2,500km to reach their breeding ground—Raine Island, a tiny speck of land at the top of the Great Barrier Reef, on the edge of the Continental Shelf.
Although Raine Island is just 32 hectares in area, more Pacific green turtles nest here than anywhere else in the world, and it is the most significant sea bird breeding site along the entire Great Barrier Reef.
Guided by their own magnetic compass and driven by the urge to nest, the turtles begin arriving at the island. As the sun goes down each night during the nesting season, several thousand turtles lumber up the sand to excavate deep body pits and egg chambers in which to lay their eggs. For many this will be the first time on land since leaving the island up to 50 years ago and will be the first time they have nested.
By sunrise, most of the turtles have escaped the heat and returned to the cool waters surrounding the island. Here they remain, resting among the coral or drifting in the shallows, until it’s time to lay another clutch of up to 200 eggs—usually 10-14 days later.
But while Raine Island is a cradle for new life for the turtles, it is also one of nature’s warzones, where signs of death are never far away.
The scattering of bleached bones and decayed shells strewn across the sand is all that remains of the dozens of turtles that are trapped and cooked by the searing sun. Some of the rotting carcasses are swept into the sea by the high tides and provide an easy meal for the tiger sharks attracted to the island at this time of year.
And it isn’t just the adults that meet their fate here. Many hatchlings will be crushed by adult turtles, snatched by waiting night herons, or become a tasty snack for any fish large enough to prey on them as they enter the water for the very first time.
While a large number of the turtles will reach the open waters, it’s estimated that out of every thousand eggs laid, only a few hatchlings will reach adulthood 30-50 years later. But as long as just two hatchlings from each female survive to be adults then she has reproduced herself and her mate. This numbers game has so far kept marine turtles on Earth for about 120 million years.
The fate of many of the hatchlings may seem cruel, but it’s all part of the fight for life in nature’s warzone. Each hatchling provides vital nourishment for other animals, fuelling their breeding cycle and maintaining their population. A loss for one species is a gain for another.
Nature’s Warzone is there to witness the annual transformation of this boneyard into a cradle for new life. Beginning with the first glimpse of a turtle at the shoreline, the programme joins the reptiles on their many trips across the pitted sand, until it’s time for the hatchlings to set off on their journey of life. The programme also joins two scientists on their quests to learn more about the movements of both the tiger sharks and turtles who visit Raine Island.