On the Wings of Conservation in the Cagayan Ridge Marine Biodiversity Conservation Corridor
Jürgen Freund

The Tubbataha Reefs Natural Park in the south western part of the Philippines, in the middle of the Sulu Sea, is legendary amongst marine biologists and avid divers for the great diversity of marine life, which many believe may be greater than any such reef of its size in the world. This UNESCO World Heritage site, the only one in Southeast Asia, is teeming with life – from 479 species of fish, including 6 species of sharks, 9 species of marine mammals, manta rays and 2 species of sea turtles. Every dive promises an unforgettable encounter with majestic creatures of the sea.

But the Tubbataha experience isn’t limited to underwater explorations. Nature’s wonders radiate all throughout almost 97,000 hectares, around the islets dotting the Sulu Sea. Seabirds glide through the air, dive into the ocean for food, and congregate around the islands. The islets serve as an important refuge for seabirds in Southeast Asia. Tubbataha’s islets are believed to be one of the last breeding grounds for a host of endangered bird species.

Seabirds as indicators of healthy ecosystems

The presence of large seabird congregations serves as a key indicator of the wider marine ecosystem health. Conservation International, through the Sulu Sulawesi Seascape Program is working on tropical seabird conservation activities through customized marine management programs, which may have significant implications for wider seascape-level conservation.

A Conservation International report conducted by Arne Erik Jansen in 2007 surveys the presence of seabirds and threatened avifauna, and conservation efforts to protect them in the Cagayan Ridge Marine Biodiversity Conservation Corridor (MBCC). The report shows that the seabird populations are largely under threat due to land conversion and land erosion, the introduction of alien plant species, and bird egg collections.

According to the report, the breeding populations of seabirds within the Philippine territorial waters and elsewhere in Southeast Asia have suffered a dramatic decline particularly since World War II. Many species and populations have disappeared from most of their former breeding ranges in Southeast Asia and nearly all species can now be considered threatened at both the regional and national levels. The last known major breeding strongholds are a few isolated atolls without human habitation and predators in the central Banda Sea (i.e. Gunung Api), the South China Sea (Paracels, Spratly Islands, and Truong Sa Marine Protected Area, Vietnam) and in the Malaysian-Philippine territorial waters of the Sulu Sea.

In Asia, the Philippines appears to represent the only known breeding area for the endemic subspecies of the Black Noddy Anous minutus worcestri, one of the four known remaining breeding areas for the Sooty Tern Sterna fuscata nubilosa (Tubbataha Reefs and Lawak Island, the Philippines, Layang-layang, Sabah, Malaysia, and the Paracel Islands, China), and the last known breeding area for the Masked Booby Sula dactylatra personata.

Seabirds distribution and status

Seabirds generally require undisturbed and intact habitats for successful breeding and roosting along with an abundance of their main food sources such as squid and smaller fish species. Such areas are found on some of the islands and islets of the atolls located along the Cagayan Ridge MBCC from north to south of the Sulu Sea. All areas in the Sulu Sea where seabirds are found have been declared by the Palawan Council for Sustainable Development as core zones of a Bird Sanctuary, but the policy remains largely unimplemented because of the conflict in resource access by local people and lack of enforcement.

Nine seabird species are known to breed mainly in six localities of the Sulu Sea. The breeding areas are located on the islands and islets of the atolls located along the Cagayan Ridge from north to south of the Sulu Sea. Recent accounts of seabirds in the Sulu Sea, notably in the Tubbataha Reefs Natural Park and World Heritage Site (TRNP) reported seven species breeding: Masked Booby Sula dactylatra, Brown Booby Sula leucogaster, Red-footed Booby Sula sula, Great Crested Tern Sterna bergii, Sooty Tern Sterna fuscata, Brown Noddy Anous stolidus, and Black Noddy Anous minutus.

In 2004 it was estimated that the overall population decline over a period of just 22 years was over 55% and with the Masked Booby becoming locally extinct. The Christmas Island Frigatebird Fregata andrewsii is one of only seven marine species in the Sulu- Sulawesi Seascape currently listed as Critically Endangered and recently found to occur in Philippine waters, as well as in Indonesian and Malaysian waters. It is also an Alliance for Zero Extinction species, and was profiled by Defying Ocean’s End as one of “10 Marine Species on the Brink”. It is therefore a clear species conservation priority of global importance together with the severely regionally threatened seabird species: Masked Booby, Sooty Tern and Black Noddy.

The CI report says that among the globally threatened and near-threatened avifaunal small island specialists occurring in the MBCC are the Grey Imperial-Pigeon Ducula p. pickeringii, Nicobar Pigeon Caloenas n. Nicobarica and Blue-naped Parrot Tanygnathus lucionensis salvadorii. The report also reviews the status of these three species together with the status of the Tabon Scrubfowl Megapodius cumingii pusillus and the Pied Imperial-Pigeon Ducula bicolor bicolor. Although the latter two species are considered locally common their numbers may now be in rapid decline within the corridor.

Saving the seabirds

Conservation International is working with local groups such as the Tubbataha Management Office and the Philippine Coast Guard to improve the management of globally and regionally threatened seabird species of the Sulu Sea, most of which congregate in the Tubbataha Reefs Natural Park. They aim to enhance the understanding of threats to these species through increased data collection on feeding areas, migration routes and dispersal areas, and breeding success and mortalities. CI emphasizes the need for the local communities to be actively engaged in the monitoring and protection of the islands and wildlife populations of conservation importance. These actions are best carried out through the Local Government Units but with involvement and assistance from national authorities, such as the Philippine Navy.

See the full CI report Conservation of seabirds and threatened avifauna in the Cagayan Ridge Marine Biodiversity Conservation Corridor conducted by Arne Erik Jensen.

Photos by Jürgen Freund for Conservation International.