King penguins and gentoo penguins prefer to behaviourally interact with white plastics over other colours

Seabirds are a speciose and at-risk animal group with specialized sensory ecologies that are highly responsive and vulnerable to sensory-related threats such as plastic ingestion. Seabirds may consume plastic because it functions as a sensory trap, exploiting the birds’ pre-existing biases for specific odours or colours. Previous studies have documented white plastics as a common colour in the ocean and is frequently ingested by seabirds, potentially due to its abundance. Alternatively, seabirds may selectively choose to ingest the colour white regardless of abundance in the marine environment. To evaluate whether seabirds prefer to behaviourally interact with white plastics over others, we used standardized behavioural assays to test seabird attraction to various colours of a commonly ingested plastic item: bottlecaps. Assays were performed with captive gentoo and king penguins ( Pygoscelis papua ; and Aptenodytes patagonicus ; Tokoraki) by simultaneously presenting white, black, red and blue bottlecaps and quantifying responses. Overall, penguins were looking and showing interest with all four colours but strongly preferred the white bottlecap, showing a colour preference behaviour towards white plastics among seabirds. Seabirds may be actively attracted to white as it could be strongly associated with cues from eggs and prey associated with a potential foraging or reproductive benefit. It would be beneficial for future research to explore how plastic maybe exploiting the seabird’s sensory biases, using a sensory ecology approach to mitigate plastic ingestion for a threatened avian group. • Seabirds may consume plastic because it exploits pre-existing sensory biases. • Seabirds may choose to ingest white plastic colours regardless of abundance in the ocean. • Captive penguins were presented with different bottle cap colours to perform behavioural assays. • Penguins showed a colour preference behaviour towards white plastics. • Seabirds may be attracted to white as it could be associated with positive factors e.g. foraging.