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06/08/2026 | Press release | Distributed by Public on 06/08/2026 09:17

Palau Study Shows First‑Ever Evidence of Seabird‑Driven Land-Sea Recovery

Published Date

June 08, 2026

Article Content

Data from Ulong Island, Koror Republic of Palau shows that seabirds are returning, nutrients are moving from land to sea, and nearby reefs are beginning to rebound just one year after invasive rats were removed, providing evidence that holistic island restoration can deliver benefits to coral reef ecosystems far sooner than previously understood.

This research, conducted as part of the Island-Ocean Connection Challenge (IOCC), is the world's first experimental study demonstrating that seabird recovery following invasive rodent removal drives nutrient transfer from land to reef, confirming prior observational findings that restored islands benefit their surrounding ecosystems.

"Seeing measurable ecological change just one year after restoration is extraordinary," said Coral Wolf, Conservation Impact Program Manager at Island Conservation. "It demonstrates the power of local leadership and science working together to heal island ecosystems from ridge to reef."

Island Conservation and Scripps Institution of Oceanography at UC San Diego monitored Ulong Island before and after the operation on land and in the sea to track seabirds, nutrients, reef fishes, and benthic communities. The IOCC is a volunteer collective founded by Island Conservation, Scripps Institution of Oceanography, and Re:wild to restore and rewild 40 globally significant island-ocean ecosystems by 2030, one of which is Ulong. The IOCC aims to demonstrate the connections between healthy islands and healthy oceans.

Photo credit: Nathaniel Holloway/Scripps Institution of Oceanography

Early indicators point to strong biological rebounds. Detections of the rare, endangered Palau Ground Dove increased, and seabird activity surged-Bridled Tern calls rose by 286%, while Brown Noddy and White Tern calls increased by roughly 50% compared to the control island Ngeruktabel, which is a nearby similar island with invasive rats and no eradication. These shifts suggest that seabirds are beginning to return and resume their role as nutrient "connectors" between land and sea.

At the same time, nutrient and fish data revealed unexpected early responses. Nitrogen signature decline was less swift on Ulong compared to other sites, consistent with seabird guano beginning to influence soils and nearshore waters. Fish biomass also increased significantly at Ulong, indicating that nutrient inputs are already supporting reef productivity.

"These early signals from Ulong show how quickly ecosystems can rebound when stressors are removed," said Nathaniel Hanna Holloway, marine ecologist at Scripps Oceanography. "For the first time in Palau, we're seeing measurable evidence of seabird-driven nutrient flow returning to the land and sea. It's powerful proof that terrestrial action spills over into benefits for surrounding reef communities, which people rely on for their livelihoods."

Photo credit: Island Conservation

One monitoring site showed especially strong cascading effects: increases in multiple seabird species, an ~80% rise in leaf nitrogen, and an increase of 183% in total fish biomass. While localized, these changes occurred far faster than predicted.

For community members and visitors, Ulong is now a pest-free destination and one of the best places to observe the endemic and elusive Palau Ground Dove.

"Managing invasive species is everyone's business," said Princess Blailes, Coordinator of the Protected Areas Network (PAN), Coastal Management - Department of Conservation and Law Enforcement. "Through collaborative efforts with the community, conservation partners, and stakeholders we can better protect our Koror Rock Islands Southern Lagoon unique biodiversity and ensure healthy ecosystems for future generations."

The IOCC monitoring effort engaged more than 100 local team members, students, and community participants in island-ocean connectivity science. Using a Before-After-Control-Impact monitoring model, the study measured the effects of restoration on Ulong by comparing them to data from a nearby island where no conservation action was taken, sampling the land and sea before and after the intervention. The project also generated one of the largest ecological datasets of its kind in Palau-over 30,000 hours of acoustic recordings and more than 11 terabytes of seafloor imagery-now publicly available to support long-term research and global knowledge sharing.

Photo credit: Island Conservation

Regional and Global Significance

The Ulong results contribute to a growing body of evidence that restoring islands can strengthen coral reefs, enhance fisheries, and build climate resilience across the Pacific. As climate impacts affect more island-ocean ecosystems around the world, nutrient-rich seabird islands may help reefs recover more quickly and maintain ecological function.

Next steps include continued monitoring, expanded analysis of seabird and reef-fish trends, and integration of terrestrial and marine datasets to deepen understanding of ridge-to-reef recovery. Additional IOCC sites across the Pacific will help determine how broadly and how quickly these benefits can scale.

This work was led by Koror State Government, Department of Conservation and Law Enforcement, Palau-based field teams, Island Conservation, Scripps Institution of Oceanography, and IOCC partners. Analysis of acoustic recordings was led by Conservation Metrics.

- Release adapted from Island Conservation

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