Plastic Diet

Oceanic plastic debris is sickening and killing the world’s seabirds

- Sitaraah Joshi

Situated more than 600 kilometres east of the Mid North Coast of New South Wales, Howe Island is home to an oceanic bird species known as the fresh-footed shearwater. The name expresses the elegant way it cuts through the grooves of the waves on tense, stretched wings. These dark grey, slender-billed birds can have a wingspan of more than a metre and weigh as much as 750 grams. They can often be found nesting in the burrows of coastal hills and islands of the Northern Atlantic region, the Mediterranean as well as throughout the majority of the Pacific.

Each day, before dawn, the shearwaters make their way to feed at sea before returning to the island at dusk. They breed in great colonies on the forest floor in the period between September and May, and migrate to different regions. Shearwaters are ocean predators, primarily feeding on seafood, but as our oceans become increasingly contaminated with waste, birds like these are unknowingly adding something else to their diet: plastic.

A study back in 2015 estimated that as much as 90 percent of all seabirds have consumed plastic (Wilcox et al., PNAS, August 31, 2015). Compare that with less than 5 percent in the early 1960s. Parent birds blindly feed small pieces of plastic to their young, often mistaking the floating particles for squid and fish eggs. Little chicks appear from their burrows with meagre levels of nutrition as their stomachs brim with plastic debris. This consistently poor diet has crippled the health of shearwaters, making the journey from home to sea an arduous one.