Birds of prey ingest large amounts of plastic. But sometimes they eat it on purpose

All over the world, people and animals suffer from the large amounts of plastic that end up in the environment. Vultures also ingest far too much plastic, although they sometimes eat it on purpose to induce vomiting.

American scientists investigated the eating behavior and vomit of the black vulture and the turkey vulture, also known as the red-headed vulture. These are so-called New World vultures, because they originated in America and are common there. They are even the most important scavengers in North America. The study shows that the amount of plastic ingested by these carrion-eating birds of prey is closely related to the number of restaurants and fast food chains in the vicinity of their habitat. Black vultures, in particular, indulge in the local rubbish dump and eat from the open waste containers of eateries. In this way they ingest large amounts of plastic unnoticed.

Plastic in humans and animals
Since the 1950s, humans have produced about 8.3 billion tons of plastic. 380 million tons are added every year. Only 9 percent is recycled, with the result that plastic appears everywhere. Deep in the ocean, on top of Mount Everest, in the roadside, but also in the fabric of humans and animals. It is unclear what the long-term impact of the continuous intake of plastic on public health is. However, research in rodents has shown that ingestion of microplastics has a negative effect on the function of the liver, intestines, pancreas and reproductive organs.

Goblin
Bad news, all that plastic lying around. Perhaps most of all for carrion-eating birds that regularly feast on tasty snacks on the landfill, on the leftovers of food on the street and in waste containers. They not only gobbled up organic material, but also packaging material. In fact, these vultures like to nibble on roofs, rubber layers or, for example, seat covers on boats. “In our study we show that the amount of plastic that black vultures and red-headed vultures ingest depends on their living environment. The more human activity, especially in terms of food production and eating facilities, the greater the amount of plastic found in the stomachs and vomit of the vultures,” says lead researcher Hannah Partridge of the University of North Carolina. “It seems that the birds not only eat the plastic accidentally, but sometimes they do it with premeditation.”

A vomit ball
The researchers followed eight different groups of black vultures and turkey vultures in and around the American metropolis of Charlotte. In total, they collected 1087 vomits from the animals. Sixty percent of these pellets were found to contain plastic. In total, even 2.7 percent of the total mass consisted of plastic compounds. The scientists also found plant remains, dirt, stones, animal remains, metal, textiles, paper, wood and glass in the vomit. An infrared scan showed that three types of polyethylene were most commonly found in the pellets. Silicone rubber also turned up relatively often. The closer the samples were found to human buildings and restaurants, the more plastic they contained on average.

Black vultures, in particular, like a meal from a restaurant’s open dumpsters. “Black vultures often perch on a cell tower near a fast food restaurant at night and fly straight for the garbage can in the morning,” Partridge explains. “Red-headed vultures do this less often. They are more found in rural areas and are more likely to feast on natural food sources.”

Always looking
“Vultures are always looking for new food sources, they are not picky and they try everything. It may happen that they eat plastic while they think they are nutritious bone fragments,” says the researcher. “But it seems that sometimes they also gobble up a large amount of plastic on purpose, just to fill the stomach and induce vomiting. That way they get rid of the indigestible remains, such as hair and other junk.”

Still, it would be better if vultures ingested less plastic. Restaurants and supermarkets should do more about this, says Professor Sara Gagné van de University of North Carolina. “It is important that the waste is properly packed in bags, that the bags consistently end up in the waste containers and that these containers are properly closed. In addition, we must move towards a world without single-use plastics in order to protect the animal world.”