Bilang-bilangan and Mataha Islands: Vital Habitat for the Green Sea Turtle in East Borneo

Bilang-bilangan and Mataha, known as "Islands of the egg of sea turtle", are two uninhabited islands in Derawan, Batuputih regency, Berau, East Borneo, Indonesia. Both islands are used by Green Sea Turtle (Chelonia mydas) as nesting sites, and has become the 8th largest nesting site in the world. 60% of the eggs in Berau come from these islands.

Culturally, the Bajau people who live in Balikukup island (+- 200 families) not far from Bilang-bilangan and Mataha claim that the two islands also belong to their territory.

The circumference of Bilang-bilangan is 2,5 kilometers, stands 3 meters above sea level. While Mataha's circumeference is 2 kilometers, and it stands just 1 meter above sea level.

The low elevation of Mataha makes it necessary to relocate all sea turtle eggs to a semi-natural hatchery to prevent decay when the eggs got submerged by the tide.

Thousands of Nesting Turtles

Each year, 3,000-5,700 Green Sea Turtles come ashore at Bilang-bilangan and Mataha. It is estimated that 800,000-1 million eggs are produced here, with its peak in July-October. This makes the two islands special and very important for sea turtle conservation in Indonesia.

Sea turtles nest all year here, and at its peak season we could find 60-70 sea turtles per night along the shores of Bilang-bilangan, and around 30 would lay there eggs there.


Because Bilang-bilangan and Mataha islands are both uninhabited, poaching used to be rampant. Despite its protected status, sea turtle eggs trade are common. In Tanjung Redeb, Berau regency, sea turtle eggs are sold for IDR 125,000 per package, each containing 10 eggs.

To curb eggs poaching and ensure the safety of the nesting sea turtles, several organizations have assigned local men to become Rangers who work to guard both islands.

Since February 2015, a local organization under the support from Turtle Foundation and PROFAUNA, has been working on managing a sea turtle conservation program on the islands. The rangers of BLB work everyday to guards the islands, including protecting the eggs from poachers and tide. They are also in charge of taking records of the number of eggs and sea turtles nesting on the islands.

The Marine Affairs and Fisheries Agency of Berau also supports our work. PROFAUNA has in advance established a mutual partnership with the agency and the Natural Resource Conservation Agency of the Ministry of Environment and Forestry, in doing campaigns to stop trade of sea turtle and its body parts.


Conseravtion effort taken at Bilang-bilangan and Mataha islands faces many challenges such as egg poaching, sea turtle hunting for its meat, and fish bombing. Eggs poachers and bombers mostly come from Balikukup island, whereas sea turtle hunters mostly come from Tembudan, Batuputih.

Other than the human factors, rats and waste along the shoreline also pose great threat for the program. The rangers are working hard to solve these problems.

For more info about about sea turtle conservation program at Bilang-bilangan and Mataha islands, please contact:


© 2003 - ProFauna Indonesia

ProFauna Indonesia is an Indonesian society for the protection of
wild animals and their habitats