Plastic ingestion and body condition of Wedge-tailed Shearwaters in Vanuatu

Plastic pollution poses a serious, increasing hazard to many species and habitats. In the tropical marine environment, the Wedge-tailed Shearwater (Ardenna pacifica) has been the focus of numerous studies that have provided valuable insights into geographic and temporal variation in plastics exposure. We document the ingestion of macroplastics (>1 mm) in Wedge-tailed Shearwaters (known as koroliko in Vanuatu) in collaboration with the Traditional Custodians of the colony using a sample of birds taken during a traditional harvest on the remote island of Laika, Vanuatu. The harvest provided a random sample of 70 known-provenance birds and necropsies were conducted using standardised methodology for assessing plastic ingestion in seabirds. We found very low levels of plastic exposure in birds sampled during 2024 (frequency of occurrence: chicks 0%, fledglings 2.6%). Measurements of these birds indicated that they were in excellent condition, with mean fledgling body mass of 487.6 ± 37.0 g. Conclusions. These results indicate that this population of Wedge-tailed Shearwaters is healthy and currently at low risk of plastic-associated impacts. This result highlights the value of seabirds as indicator species and the importance of sampling biomonitors across a broad area and over many years.