Urban living influences the nesting success of Darwin’s finches in the Galápagos Islands

Urban living significantly boosts the nesting success of Darwin's finches (Geospiza fuliginosa) during dry years, despite introducing trade-offs. A study on San Cristóbal Island found that urban finches built more nests, laid more eggs, and produced more fledglings than their nonurban counterparts. However, every urban nest contained anthropogenic debris—such as string or plastic—which caused 18% nestling mortality due to entanglement or ingestion. This suggests that while urbanization may buffer the effects of limited natural resources in the Galápagos Islands, it also poses risks from human-made materials. The research quantified nesting behaviors and mortalities in both urban and nonurban areas, revealing a complex balance between the benefits of supplemental food and the costs of anthropogenic contamination.

Harvey, J. A., Chernicky, K., Simons, S. R., Verrett, T. B., Chaves, J. A., & Knutie, S. A. (2021). Urban living influences the nesting success of Darwin’s finches in the Galápagos Islands. Ecology and Evolution, 11(10), 5038–5048. Portico. https://doi.org/10.1002/ece3.7360