Clear-white plastics are most common in global oceans and seabird stomachs, but local species can ingest specific colours

Plastic is a major threat to seabirds and the ingestion of plastic may involve a sensory trap, where the odours and appearance of marine plastics can resemble food, or exploit animals' pre-existing sensory biases. Our global survey of the literature reveals that clear-white plastic is the most common plastic colour found in the ocean and is also most ingested by seabirds. However, our case study in a seabird diversity hotspot (northern Aotearoa New Zealand) indicates that although clear-white plastic is also the most common colour found on beaches, local seabirds have more species-specific colour patterns in plastic ingestion. Our dissections of 13 species of Procellariiformes (eight petrels, four shearwaters and one prion, n = 72 individuals in total) revealed that although they often ate clear-white plastics, other colours were ingested more or less often than expected given their relative availability in the environment. Other seabirds may also preferentially ingest specific plastic colours, but region- or species-specific patterns may be hidden by global scale analyses. Spectral wavelength measurements (radiation) of the ingested plastics reveal wavelengths invisible to humans, e.g. UV (ultraviolet radiation), indicates potential sensory biases in seabirds towards certain plastics. This emphasises the importance of considering species differences in behaviour and visual perception in understanding seabird plastic ingestion.