Tropical bird communities benefit from regular-shaped and naturalised urban green spaces with water bodies

[Display omitted] •Citizen scientists collected avian data across urban green spaces in Singapore.•At broad spatial scale, bird diversity improved in more naturalised green spaces.•At localised scale, water bodies improved the diversity of some functional groups.•Edge effects have an impact even for urban refugia at both spatial scales.•Biodiversity in cities thrive in regular-shaped and more heterogenous green spaces. Urbanisation has been linked to habitat loss and degradation with detrimental impacts on native biodiversity. Urban green spaces can provide refuge habitats for less tolerant bird species which cannot survive elsewhere in a dense network of buildings and impervious surfaces that characterise highly urbanised cities. While there is growing research interest in the importance of urban refugia in sustaining biodiversity in temperate regions, studies in tropical cities, particularly in Southeast Asia, are poorly represented. We investigated how bird diversity across 64 urban green spaces in Singapore are influenced by spatial factors at multiple scales. Data was collected via a structured citizen science program spanning five years with a standardised sampling protocol. At the site scale, where each of the urban green spaces represents a site, bird diversity was positively related to regularly-shaped urban green spaces and seminatural vegetation. At the local scale, indicating surveyed points within each site, the richness of several bird functional groups increased in the presence of freshwater bodies. Our results highlight the importance of considering the spatial effects of environmental factors on bird diversity at multiple scales. Aside from increasing the availability of green spaces in urban areas, land-use planners and landscape designers should also seek to provide green spaces that are regularly shaped to minimise the impacts of edge effects, prioritise the retention of more semi-natural vegetation and include freshwater bodies to enhance and sustain bird diversity in cities.