Why do seabirds eat plastic? It's not as simple as you think
The article below contains images that some readers may find graphic. Discretion is advised.
Contrary to popular belief, this figure has little to do with plastic looking like food -- it's about plastic smelling like food.
A recent study published in the journal Science Advances explains that marine plastic pollution produces a signature sulfurous scent (dimethyl sulfide) that some seabirds have used to find food for thousands of years.
Researchers from the University of California, Davis, say that this olfactory prompt dupes seabirds into mistaking ocean plastic for food.
The study adds insight into an area of limited research: There's been little probing as to why birds eat ocean plastic to begin with. The findings help clarify why birds like the albatross and petrels (tube-nosed seabirds) are among the birds most significantly impacted by plastic ingestion. Tube-nosed seabirds are driven by an avid sense of smell, which plays a strong role in their hunting habits.
The scent of dimethyl sulfide (DMS) was not detected on "virgin plastic samples," the study's introduction reads. "In contrast, we detected DMS in the headspace of every plastic sample from both sites after marine exposure."
The results indicated that three common types of plastic gain a DMS scent that some seabirds can detect, but only after the plastic has seen less than one month of marine exposure.
The three most common types of plastic debris were high-density polyethylene, low-density polyethylene, and poly-propylene.
Polyethylene is one of the world's most commonly used plastics, with a global production rate of approximately 80 million tonnes, annually. It can be found in plastic bottles, plastic bags, and packaging containers./p>
"Animals usually have a reason for the decisions they make. If we want to truly understand why animals are eating plastic in the ocean, we have to think about how animals find food," Gabrielle Nevitt, the study's co-author, said in a statement. Nevitt is also a professor at the University of California.
"This study shows that species that don’t receive lot of attention, like petrels and some species of shearwaters, are likely to be impacted by plastic ingestion," she adds. "These species nest in underground burrows, which are hard to study, so they are often overlooked. Yet, based on their foraging strategy, this study shows they’re actually consuming a lot of plastic and are particularly vulnerable to marine debris."