Birds' nests uncover the history of the plastic age

Nest researcher Auke-Florian Hiemstra stumbled upon a bird nest that appeared to go back 30 years in time – filled with historical plastics. His discovery of successive layers of plastic in birds’ nests, from different periods, has now been published in the scientific journal Ecology.‘You flip through these nests, like through pages of a history book, uncovering the past.’ The Eurasian coot is a common bird in the Netherlands and can be found in all the canals of Amsterdam. Traditionally, they don't reuse their nest, as these were built from fast decaying plant material, but in urban environments, these birds appear to be increasingly using plastic trash. Since plastic does not break down, old nesting material is preserved. Layer upon layer, nest season after nest season, a plastic pile was built up. That accumulation of waste now provides a glimpse back in time. Over the past 30 years, the coots of the Rokin-canal must have nested around 10 times in the same spot. ‘The oldest layer is as old as me – all my life a bird was nesting here,' he says.

USA World Cup 1994

But how do you date old plastic nest layers? Simply by looking at the expiry date! For instance, plastics from the early 1990s were found in the deepest layers of the Rokin nest, while coots have only been breeding in the city since 1989. Hiemstra: ‘This nest tells the whole history of these birds in Amsterdam!’ One particular piece is a Mars packaging with an announcement of the 1994 FIFA World Cup in the USA. In stark contrast, the upper layers contained recent face masks, a direct result of the COVID-19 pandemic. One of the other described nests with a plastic stratigraphy, located along the Onbekende Gracht in Amsterdam, also contained a facemask layer. This phenomenon is called a ‘technostratigraphy’: a contemporary deposition of human junk. ‘The Anthropocene, the age of man, documented by a bird, and that entirely in style right in front of Amsterdam's archaeological museum.’

McDonald's archaeology

A significant proportion of the dateable waste materials from the Rokin nest were found to come from fast food packaging, particularly from the McDonald's around the corner. From polystyrene packaging from the McChicken, dating as far back as 1996, to recent fries sauce containers. As one of the biggest polluters worldwide, McDonald's waste is very consistent marker in the layers of plastic we now leave behind. Hiemstra: ‘The “McDonald's archaeology” says something about our “throwaway culture” and it shows that “away” in throwaway, doesn't actually mean anything. Roughly 80% of all the plastic ever produced still exists.’ The study highlights how animals unintentionally document our environmental problems. ‘How we interact with our environment is reflected in the canals and quite literally woven into the nests of the birds that breed there,’ says Auke-Florian. ‘History is not only written by humans; nature is keeping track as well.’ The nesting material is deposited in the collection of the Museon-Omniversum in The Hague, where it will be included in the museum's presentation on the Anthropocene.