How the Olango Island Wildlife Sanctuary supports avian life in Asia

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CEBU, Philippines – The Olango Island Wildlife Sanctuary (OIWS) is home to rare and endangered migratory birds that visit the country every year.

Located in Barangay San Vicente in Olango Island, Cebu, the OIWS is one of four wetlands of international importance in the Philippines. It was the first in the country to be included in the Ramsar Convention’s list of Wetlands of International Importance on July 1, 1994.

“Wetlands are vital for human survival. They are among the world’s most productive environments; cradles of biological diversity that provide the water and productivity upon which countless species of plants and animals depend for survival,” the Ramsar Convention on Wetlands official website reads.

Data from the Ramsar Sites Information Service (RSIS) indicate that the reason for the OIWS’ inclusion in the Ramsar list was because of the high count of migratory birds that use the sanctuary as a staging or wintering ground. 

A staging ground is where birds rest before going on a long journey, while a wintering ground is where birds stay to wait for the end of the winter season of their places of origin. 

“Over 10,000 shorebirds have been recorded at one time, with total numbers approaching 50,000. The most important site in the Philippines for the rare waterbird species Asiatic Dowitcher,” the RSIS said of the OIWS.

Vital resting ground

The entire OIWS consists of 5,800 hectares of coralline sandflat, mangrove forests, seagrass beds, and coral reef areas, which provide a stable food source for the birds as well as a reliable nesting ground.

SANCTUARY. The Olango Island Wildlife Sanctuary hosts at least 60 species of migratory birds and 53 kinds of resident birds. Photo by Jacqueline Hernandez

According to the Department of Environment and Natural Resources (DENR), the sanctuary supports around 60 species of migratory shorebirds that travel through the East Asian-Australasian Flyway (EAAF) and 53 species of terrestrial birds.

Shorebirds are a subset of coastal birds that can be found along shorelines and mudflats. “Waterbird” is the general term for bird species that inhabit diverse aquatic environments.

“During winter, shorebirds from the northern hemisphere going to Australia and New Zealand arrive in OIWS to rest and feed from September to March,” DENR’s pamphlet on the OIWS reads.

From 2021 to 2024, international bird watching organizations have kept a close eye on the population of birds passing through the EAAF, especially through the Philippines.

In Southeast Asia, waterbird sightings dropped from 675,852 in 2021 to 619,417 in 2022. The sightings eventually made a strong recovery all the way to 2024 at 742,609 waterbirds spotted in the region.

At the OIWS, the most notable sightings of vulnerable bird species include the Chinese Egret, Far Eastern Curlew, Black-faced Spoonbill, Great Knot, and Bar-tailed Godwit.

The Asiatic Dowitcher is the OIWS’ flagship species. From 2021 to 2022, sightings of the bird increased from 201 to 311. The sightings dropped to 257 in 2023 but rose again to 378 in 2024.

As a vital stopover for vulnerable bird species, the OIWS is important for the repopulation of avian life that are at risk of extinction due to various factors.

SURVIVING. In 2016, the International Union for Conservation of Nature listed the Grey-tailed Tattler (Tringa brevipes) as a near threatened species but as of 2024, it has been classified as a species of least concern owing to its increasing and stable population size. Photo by Jacqueline Hernandez

Birds and biodiversity

Josiah David Quimpo, conservation research head of Haribon Foundation, told Rappler that the birds in the OIWS carry out an important role in maintaining the biodiversity of Olango’s ecosystem.

“The birds also control the [population] of [pests] in the fields…. They have a natural role to keep our ecosystems in balance,” Quimpo said in a mix of English and Filipino.

The conservation expert explained that birds have an innate sense in finding areas that best suit their needs for nesting and roosting, making them reliable indicators of a conservation site’s natural health.

STRONGLY MIGRATORY. The Bar-tailed godwit (Limosa Iapponica) is a near threatened waterbird species that has a lifespan of 5 to 15 years and frequently migrates from its southern non-breeding grounds in Australia and New Zealand to the northern hemisphere like Scandinavia, northern Asia, and Alaska. Photo by Jacqueline Hernandez

A 2025 study funded by the Ministry of Higher Education Malaysia noted that the richness of bird species in a given area can be used to measure the progress of restoration efforts in mangrove forests.

Avian biologists and experts have also suggested for years that guano or accumulated seabird excrement are great fertilizers and nutrient contributors to natural habitats like coral reefs and mangrove forests.

A large portion of the OIWS is covered in mangroves, which serve as buffer zones for coastal communities in times of strong weather conditions and “natural storage” for large amounts of carbon in the atmosphere.

SHARED SPACE. A native of Olango shares the shellfish catch along the mudflats of the wildlife sanctuary with the shorebirds.Photo by Jacqueline Hernandez

But besides being good bio-indicators and source of guano, Quimpo said that data gathered on the population of waterbirds in an area often contributed to the declaration of some Philippine wetlands as recognized conservation sites.

The Haribon Foundation occasionally assists the DENR in the counting of waterbirds in the country.

Quimpo theorized that if the quality of the natural resources at the OIWS begins to degrade either due to the exploitation of natural resources or increased pollution, the presence of the birds would also go down.

“Kung mawawala sila doon, baka mawala din ang tourism aspect doon at may effect na din sa pagkawala ng biodiversity ng area (If they disappear, it is possible that the tourism aspect there would also be lost and there would also be an effect on the loss of biodiversity in the area),” the conservation expert added.

Saving, keeping birds from harm

At present, the DENR has implemented measures to maintain the ideal conditions for the reception of bird visits at the Olango sanctuary.

OIWS Warden Cristino Patigdas told Rappler that they have installed solar panels at the sanctuary to not only reduce operational costs tied to energy, but also remove the need to connect to the mainland power grid which would require transmission lines.

“The transmission lines are not safe for the birds. They risk getting electrocuted,” Patigdas said in Cebuano.

Patigdas shared that the OIWS management consistently monitors the presence of human activity in the sanctuary, ensuring that no poaching or hunting of wildlife ever happens. The OIWS wildlife rangers also conduct seminars, workshops, and coastal cleanups with advocacy groups and state agencies to cultivate environmental stewardship with local stakeholders, especially the youth.

According to the OIWS warden, visitors and birdwatchers are required to watch an informative presentation about the sanctuary, which includes pertinent information on conservation efforts and how regular citizens can contribute.

PROTECTOR. Olango Island Wildlife Sanctuary warden Cristino Patigdas takes a peek in his telescope to record the presence of rare migratory birds that visit the sanctuary. Photo by Jacqueline Hernandez

“Our family lives because of the sanctuary. That is why we will protect it,” Patigdas said in Cebuano. – Rappler.com

Reporting for this story was supported by the Institute for Climate and Sustainable Cities under the Jaime Espina Klima Correspondents Fellowship.