The expansion and densification of urban environments drive habitat loss and fragmentation, making urbanisation a primary threat to global biodiversity [1,2]. Though some cities may have larger green spaces and protected natural areas on their peripheries, the lack of vegetated habitats in urban centres makes it difficult for species to survive in or disperse across them, resulting in isolated populations and local extinctions [3,4,5]. Despite a large body of evidence documenting the importance of providing green spaces and habitats for species and the resulting environmental and human health benefits such provision brings [6,7,8], green spaces in cities are limited by development pressures and a lack of available ground-level space, which will be exacerbated as city populations grow [9]. However, taking advantage of the abundance of building surfaces in cities for building-integrated vegetation, such as green roofs, could provide a potential solution [10].