Did you know that it has been estimated that the anthropogenic mass, representing all human-made objects, would exceed the living biomass in 2020 ± 6 years? Each year, humans accumulate 30 Gigatons of anthropogenic mass, based on the averages of the last 5 years. The article that made these estimations even mentions that “this corresponds to each person on the globe producing more than his or her body weight in anthropogenic mass every week” (Elhacham et al., 2020). While this situation is alarming for many different reasons, I would like to focus on its impact on bird nests.
Traditional Bird Nest Materials
Bird nests are collections of materials put together by birds, traditionally made with natural materials such as sticks, lichen, spider silk, bark, and mud. However, with the increased concentration of plastic in the environment, it is not rare for birds to now use plastic for their nests. You might be surprised at some of the objects they use.
The Shift to Plastic in Bird Nests
Common non-natural objects found in bird nests include food packages, face masks, straws, plastic strips, coffee cups, and more. Some of these materials resemble natural ones and can be used as substitutes. For instance, artificial plants have been found in bird nests. While some nests still contain more than half natural materials, others can be made entirely from plastic.
Advantages and Disadvantages of Plastic Nests
At first glance, it might seem that nests containing plastic only have disadvantages. Indeed, plastic can cause entanglement, and ingestion issues, attract unwanted visitors due to their greater visibility or leftover food, or even be removed by cleaners who consider it waste. On the other hand, plastic offers some benefits: it allows birds to continue building nests, requires less maintenance, can be more comfortable to sit on, is lighter, contains fewer parasites, and is more robust. Researchers have also noticed better heat conservation in nests made from plastic, allowing birds to leave the nest for longer periods. Thus, nests made from plastic can be seen as a double-edged sword.
Birds and Anti-Bird Spikes
Another urban factor affecting birds and their nests is the use of anti-bird spikes in places where people don’t want birds to perch (roofs, public spaces, etc.). Interestingly, birds have adapted to these spikes for their own benefit. The spikes can help them build nests in otherwise inaccessible areas, like inclined roofs, and birds even incorporate the spikes into their nests. This behavior mirrors their natural use of spiky branches to deter other birds from approaching their nests and young. Quite ingenious, isn’t it?
Conclusion
In conclusion, the impact of urbanization on bird nests highlights the remarkable adaptability of birds in the face of human-induced changes. While the incorporation of plastic and other non-natural materials into nests presents significant challenges, such as entanglement and ingestion risks, it also offers unexpected benefits, including improved heat retention and reduced parasite loads. Additionally, the creative use of anti-bird spikes by birds showcases their ability to turn urban obstacles into opportunities. As we continue to shape the environment with our anthropogenic activities, it is crucial to remain aware of and address the unintended consequences on wildlife. Understanding and supporting the resilience and adaptability of birds can help foster a more harmonious coexistence between urban development and nature.
Sources :
Bennett, P. (2023, July 10). Birds around the world are building their nests with trash. EcoWatch. https://www.ecowatch.com/birds-building-nests-trash.html
Elhacham, E., Ben-Uri, L., Grozovski, J., Bar-On, Y. M., & Milo, R. (2020). Global human-made mass exceeds all living biomass. Nature, 588(7838), 442–444. https://doi.org/10.1038/s41586-020-3010-5
Hiemstra, Auke-Florian. “Anthropogenic materials and animal nests” Lecture, Leiden University, Leiden, March 22nd, 2024.
Spring is for nesting: How birds build nests. (n.d.). Natural History Museum.
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