Global urbanization is rapidly increasing, specifically within Africa. However, the effects of these processes on Africa's wildlife are largely unexplored. For many species, the effects are detrimental, whereas others are able to colonize these human-altered environments and can even thrive. Raptors are positioned at the top of the food chain and therefore particularly susceptible to environmental changes, and yet they are increasingly associated with urban areas. Given that adaptations to cope with urban stressors may differ from those occurring in more natural habitats, we might expect that directional selection in urban areas could account for phenotypic divergence between urban and rural individuals. This might include selection for different plumage coloration, which could be facilitated in color polymorphic species because no additional mutations are required to create variation. Color polymorphism is common in raptors, with 22% of the Accipitridae family being polymorphic. In this study, we focus on Black Sparrowhawks (Accipiter melanoleucus) in Cape Town, South Africa. We explore whether the morphs are distributed differently along an urban–rural gradient and thus show a local adaptation. Using a long-term study (16 yr), we also investigate whether morph was related to the timing of breeding and breeding performance along the urban gradient. We found no differences of the morph distribution or of their breeding performance in relation to levels of urbanization. Our study represents the first to examine the breeding distribution of a polymorphic raptor in relation to urbanization and one of the first to explore avian productivity in relation to urbanization in Africa.
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Vol. 52 • No. 1