Birds’ nests reveal history of the plastic age
by Naturalis Biodiversity Center
Feb. 26, 2025
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 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.
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 (pop-up example). ‘The Anthropocene, the age of man, documented by a bird, and that entirely in style right in front of Amsterdam’s archaeological museum.’
Keep reading: https://www.naturalis.nl/en/follow-our-stories/birds-nests-reveal-history-of-plastic-age
Read the Ecology paper: https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecy.70010