The role of vacant lots in promoting avian species diversity and occupancy in a post-industrial city.

In deindustrialized cities, human population decline and building demolitions have created large quantities of vacant land. Land vacancy is a complex social issue but may create habitat that supports wildlife. We explored the relationship between vacant land and other features of the urban landscape and bird diversity and occupancy in Detroit, Michigan. Acoustic recordings were collected annually in June at 110 sites across 11 Detroit neighbourhoods from 2021 to 2024. At each site we manually scanned 28 min of the morning chorus on two days to identify bird species. We compared resulting metrics of species diversity and occupancy with annual spatial data on neighbourhood characteristics including vacancy, vegetation, buildings, and roads measured in 50 m and 100 m buffers around each recording site. Using a mixed-effects modelling approach, we found higher bird species diversity and richness at recording sites surrounded by greater proportions of vacant land (Shannon diversity, βvacantlots100m = 0.08, 95 % CI [0.04, 0.12]; bird species richness, IRRvacantlots100m = 1.08, 95 % CI [1.04, 1.12]). Using a spatial occupancy modelling approach, we found vacant land was associated with higher occurrence of four bird species. However, other urban features, especially roads, were also associated with bird species diversity and occupancy. Our results suggest vacant land can support higher bird diversity and occupancy in Detroit neighbourhoods, while road infrastructure, buildings, and vegetation also play a role. These findings have implications for land management in Detroit and other deindustrialized cities, where there is increasing pressure to determine how vacant land can be used to achieve positive ecological and social outcomes.