Plastic diet could be causing seabird chicks to shrink - Natural History Museum
Seabird colonies worldwide have shrunk in recent decades as human pressure on the marine environment continues to increase.
New research shows how the body condition of young shearwaters has rapidly deteriorated in just over a decade, with plastic consumption believed to be the most likely cause.
Oceans are under extreme pressure due to increased human activities such as habitat loss, overfishing and plastic pollution.
Seabirds rely on a healthy marine environment as the resources it provides are essential for surviving prolonged periods in the open oceans. However, as the state of the ocean deteriorates, it's likely that these species will also suffer.
A new study published in the ICES Journal of Marine Sciences looks at how body condition has changed in flesh-footed shearwaters on Lord Howe Island, which are on the front line of the Anthropocene.
Between 2010 and 2022, the mass and length of wings, head and bill of fledglings in the colony has significantly decreased, which will have severe impacts on their survival.
Dr Alex Bond, Curator in Charge of Birds at the Museum and co-author of the study, says, 'When we looked at the data collected over the last 13 years, it was just an idle thought of wondering how chick body condition has changed. We expected it to fluctuate up and down with good and bad years, but we were speechless when we saw the results. That's when we realised we hadn't seen any of the really heavy birds we would often see in the early years. So putting it together and seeing it in the bigger context of the last 13 years was surprising because it was not what we expected.”
Why does a decline in body condition matter?
Lord Howe Island lies 600 kilometres off the east coast of Australia and supports the largest colony of flesh-footed shearwaters in the world. The island's biodiversity faces many pressures, including habitat loss, invasive species, fishing, and plastic pollution.
Shearwater chicks spend around 90 days in their burrow being fed by their parents. After this time, the parents will abandon their young, leaving them to fend for themselves.
Usually, the chicks will stay in the colony for a night or two before flying to Japan. After leaving land, they won't return for another five to eight years until they are old enough to breed. As the chicks have to forage for themselves, they must be well-fed enough to survive on their own.
“Even the healthier birds are getting lighter, which is worrying because body mass is probably one of the biggest predictors of survival in the first couple years,' explains Alex.