Man-made materials in nests can bring both risks and benefit for birds

Newswise — We all dispose of vast quantities of plastic and other synthetic substances into the surroundings, and these are frequently seized by birds. Recent studies indicate that 176 avian species across the globe currently incorporate diverse human-made materials in their nests. Worldwide, avians utilize our unused or thrown-away resources. Australian seabirds include fishing nets, North American ospreys incorporate baler twine, South American urban birds add cigarette butts, and European common blackbirds collect plastic bags to supplement their nests.

Researchers suggest that the material discovered in avian nests can have advantageous effects. For instance, cigarette butts contain nicotine and other substances that repel external parasites, which latch onto the skin of nestling birds and feed on their blood. Additionally, there are indications that more rigid human-made materials might offer structural reinforcement to avian nests, while plastic films could contribute to insulation, keeping the offspring warm. However, it is crucial to acknowledge that while there are potential benefits, anthropogenic materials can also pose harm to birds.

The findings of this study were published in a dedicated edition of the Philosophical Transactions of the Royal Society B, focusing on "The evolutionary ecology of nests: a cross-taxon approach." The special issue was collaboratively organized by Mark Mainwaring, who holds the position of Lecturer in Global Change Biology within the School of Natural Sciences at Bangor University.

According to Mark Mainwaring, "The special issue emphasizes that various taxa, including birds, mammals, fish, and reptiles, utilize their nests to adapt to the challenges posed by human activities. These challenges encompass the incorporation of anthropogenic materials into their nests, as well as providing a refuge for parents and offspring against rising temperatures in a changing climate."

Anthropogenic materials can indeed pose risks to birds. For instance, baler twine can lead to fatal entanglement of both parent birds and their offspring. Additionally, nestlings may mistakenly ingest anthropogenic materials, mistaking them for natural prey items. Furthermore, the inclusion of colorful anthropogenic materials in nests can attract predators, who then prey upon the eggs or nestlings. These observations highlight the need to minimize the disposal of plastic and other anthropogenic materials in order to mitigate these risks and protect avian populations.

The lead author of the study, Zuzanna Jagiełło who is based at the Poznań University of Life Sciences in Poland, added,

Zuzanna Jagiełło expressed concern over the inclusion of anthropogenic materials in the nests of numerous bird species. It is becoming evident that these materials can cause harm to both nestlings and adult birds. Jagiełło also emphasized the necessity for further studies to obtain a comprehensive understanding of the prevalence of such materials among bird species worldwide. This would allow us to fully grasp the extent of the issue at hand.

The second author of the study, Jim Reynolds, a researcher in the Centre for Ornithology at the University of Birmingham in the UK, remarked,

In a world undergoing rapid urbanization, where we coexist with various animal taxa, it is expected that birds would utilize our discarded materials in their nests. While there is still much to learn about the impact of plastics and other materials on birds, it is intriguing to consider that birds, with their ability to move across vast distances and their unique breeding biology, could potentially serve as powerful biomonitors of anthropogenic material pollution in the environment. This highlights the potential for birds to provide valuable insights into the extent and consequences of human-made pollution in our ecosystems.