OTTAWA - Gulls at landfills are so common that their stomach contents are sometimes used to monitor plastic in the environment.
But plastic, research has found, is just the start.
"It was also aluminum, drywall, wax paper," said Sahar Seif, an undergraduate at Ottawa's Carleton University, who is the lead author of a recently published paper.
"I have photos and you can actually read the cheese wrapper I found in the bird and glass that you could read. Just big chunks, really."
Seif and her co-authors looked at three gull species frequenting a landfill in St. John's, Nfld.
Necropsies of 41 birds found plastic a-plenty in their stomachs. Foam seemed favoured, accounting for more than one-quarter of all the debris found.
More than 20 per cent of the contents were bits of metal and glass. Building materials made up more than five per cent.
"There were a lot of big things," Seif said. "I found rope. I found a piece of plastic knife.
"There's a lot of stuff in there for sure. They're not selective."
Pictures published along with her paper show an entire fast-food plastic snack bag stretching 13 centimetres from top to bottom.
And that's not likely to be the whole picture. Gulls have the ability to regurgitate anything that upsets even their cast-iron constitution, so Seif warns that what she found can only be considered a snapshot.
"It's a small fragment of what the birds were actually eating."
Remarkably, the gulls didn't seem to be suffering from their indiscriminate dining. They seemed in good shape and there were no obvious links between human debris in a bird's stomach and the presence of ulcers or lesions in its stomach lining.
Regurgitation probably helps, suggested Seif.
So does their general constitution.
"They are very tough in that regard."
Gulls evolved as scavengers, said Seif. They are opportunistic by nature and even in the wild regurgitate potentially harmful tidbits such as sharp bone fragments.
But there is a more serious side to her work.
If gulls are scavenging so much debris from landfills, other seabirds such as fulmars are probably eating similar things, said Seif. And they're not as tough as the gulls.
It's highly unusual for an undergraduate to publish original research. But Seif said she feels so strongly about the issue that she looked for three years for a supervisor that would support and assist her work.
Almost everything Seif found in the gulls, from plastic to aluminum to glass, was designed to be used once and tossed away, she said.
"We were trying to get people to implement better waste management and reduce the use of one-use plastic."
— By Bob Weber in Edmonton. Follow him on Twitter at @row1960