Global assessments estimate that up to one million species face extinction within the coming decades. During this same period of loss, cities have expanded to become the primary habitat for more than half of the world's human population. While extinction is often framed as a planetary-scale crisis or a discrete future event, this research examines how it is co-produced locally, within the margins of urban development.

Focusing on Switzerland, where native species are threatened despite strong environmental regulation, the doctoral thesis asks: What role do urban design and architecture play in biodiversity loss or recovery?

The research centers on three locally at-risk species, the alpine swift, the natterjack toad, and the asp vipers, and their respective entanglements with facade renovation, campus construction, and railway expansion. Methodologically, a multispecies ethnographic approach combines fieldwork, oral histories, archival sources, species logs, and conservation reports to trace more-than-human perspectives and agency. The analysis demonstrates how often-invisible cyclical lifeworlds come into friction and partial alignment with the spatial and material logics of urban production, governance, and everyday care practices.

Together, these case studies position design, from the scale of the architectural detail to that of the territory, as a distributed ecological and ethical practice. The thesis contributes to architectural and urban theory by arguing that city-making is not peripheral to the extinction crisis, but actively erodes or sustains habitats and infrastructures for multispecies coexistence. In light of these findings, the thesis argues for more ecologically attuned forms of city-making in support of multispecies urban futures.