• Land covered by spontaneous vegetation provides habitat for local birds. • Vacant lands maintain mainly native and a few exotic bird species. • Bird communities in vacant lands differ from formal greenspaces and residential areas. • Vacant lands support species that are not common in the city. • Vacant lands have the potential to help recover people-nature interactions in cities. Vacant land in growing cities is commonly targeted for development because it is perceived as wasted land that provides no benefit for people or nature. However, vacant sites might contribute to biodiversity conservation. To help inform biodiversity-sensitive urban development, we examined whether vacant land provided suitable habitat for birds in the Latin American city of Santiago, Chile - a growing capital city located in a Mediterranean ecosystem identified as a global biodiversity hotspot. We posed the following questions: How do species richness and abundance of native and exotic birds vary among vacant lands, urban parks and residential areas? And does vacant land support a different bird community compared with urban parks and residential areas? We found that vacant lands helped conserve local birds. Vacant lands exhibited high species richness and abundance of native birds, and maintained significantly fewer exotic species than urban parks and residential areas. In addition, vacant lands supported a different bird community than urban parks and residential areas, including several native birds associated with grasslands and rural areas that are rare in the city. Although vegetation in vacant land was dominated by exotic herbaceous plants, they provided important resources for native birds. Our findings demonstrate that vacant land covered by spontaneous vegetation provides habitat for native birds. Given that vacant lands offer opportunities for biodiversity conservation and to connect urban residents with nature close to home, we discuss strategies to help maintain the benefits provided by vacant lands through urban design, land use planning and urban growth policies. [ABSTRACT FROM AUTHOR]