We’ve all seen pictures of birds that have died because they ate too much plastic. Some seabirds eat so much plastic, there is little room left in their gut for food. Furthermore, adult birds pick up plastic and feed it to their young, with disastrous consequences. It is estimated that by 2050, nearly 200 species of seabirds – from penguins to petrels – will be eating plastic. But do you know why seabirds eat plastic? What attracts them to this often-deadly debris is more than its resemblance to a tasty morsel of jellyfish or seaweed.
According to Dr. Miranda Dyson of The Open University, and others, it is because so many of the tube-nosed birds (which include petrels, shear-waters and the magnificent albatross) are attracted to plastic by their sense of smell. Dr Dyson says “Tube-nosed birds such as the albatross travel vast distances across the ocean to find food which occurs in patches; so, the search is much like finding a needle in a haystack… To find food, these birds use their keen sense of smell. Their food includes fish, squid and small crustaceans known as krill, which they locate by detecting a chemical (called dimethylsulfide or DMS). DMS is released by the cells of marine algae when krill eat it. DMS therefore serves as an olfactory cue that alerts the birds to the presence of krill.”
When plastic has been in the ocean for a while it becomes coated with algae. A study by biologists from the University of California at Davis found that this results in the plastic having high levels of DMS associated with it. To the birds, the presence of DMS is an indication that food is about …not algae, but krill feeding on algae. This prompts foraging behavior with the result that the birds ingest plastic. So, in addition to looking like food, plastic debris in the ocean may also confuse seabirds that hunt by smell.
But we’re a long way from the ocean, you might say. How does this affect me? Bucks County may not have a coastline, but we have no shortage of freshwater streams and rivers. While research on plastics pollution in freshwater has lagged behind marine research, we do know that microplastics are also found in our streams, rivers and lakes, taking a toll on inland birds, and contributing to coastal problems as the water drains to the ocean.
And, even though we live hundreds of miles from the coast, the plastic we throw away can make its way into the ocean in the following four ways:
- Throwing plastic in the trash when it could be recycled. Plastic you put in the trash ends up in landfill. When rubbish is being transported to landfill, plastic is often blown away because it’s so lightweight. From there, it can eventually clutter around drains and enter rivers.
- Littering. Litter dropped on the street doesn’t stay there. Rainwater and wind carry plastic waste into streams and rivers, and through drains. Drains lead to the ocean!
- Illegal dumping. Careless and improper waste disposal adds greatly to the plastic surge in our seas.
- Products that go down the drain. Many of the products we use daily are flushed down toilets, including wet wipes, cotton buds and sanitary products. Microfibers are even released into waterways when we wash our clothes in the washing machine. They are too small to be filtered out by waste-water plants and end up being consumed by small marine species, eventually even ending up in our food chain.
So, how does plastic get into birds? The bottom line is us. Whether we mean to litter or not, there’s always a chance the plastic we throw away could make it into lakes, rivers and the ocean. And from there who knows? Maybe into the stomach of some far-away seabird.
-Written by guest blogger + Bucks Audubon Advocacy Committee Member + Bucks Audubon Board of Directors Member, Jim Mansfield