What defines an urban butterfly? Life history traits and habitat associations of butterflies in urban environments

Urban areas are encroaching onto semi-natural areas the world over, driving species assemblages into homogenisation. A better understanding of the life history and habitat association traits can help support management efforts to improve urban biodiversity. Urban areas present an ecological filter, limiting the number of species present compared to the wider countryside. What characteristics help define an urban species may also aid in conservation efforts and improve urban biodiversity. Our research aims to identify the subset of butterflies associated with urban areas based on published information about life history traits and broad habitat associations of butterflies in the United Kingdom to define their characteristics. Principal component analysis revealed a group of thirty butterfly species with traits associated with urban areas. This represents 51% of all British species, including 3 habitat specialists. Urban butterflies were closely associated with preference for woodland glades, a habitat that is mirrored in urban areas by the presence of hedgerows and grassland/woodland edges around urban woodlands. Life history traits associated with urban species included negative association with egg laying on short turfs and herbs, perhaps because of the intensive nature of much urban grassland management, and positive correlations with multivoltinism, the latter of which is closely associated with effective dispersal capability and habitat generalism. This research highlights the characteristics of some butterflies which make them suited to urban environments and points towards habitat management that might support these species as well as identifying opportunities for management to broaden the diversity of urban butterflies.