Nest characteristics of African crowned eagles and black sparrowhawks in urban mosaic landscapes: Potential constraints in finding nesting sites and implications for exotic tree management

The increase in human population and continuous landscape transformations, especially in urban areas, will result in most of the natural habitats being degraded, significantly reduced in size and lost. Consequently, constraints in acquiring resources such as nesting sites and food may occur. In this study, we investigated the nesting site characteristics of two raptor species in the urban mosaic landscape of Durban, KwaZulu Natal, South Africa, to determine the potential constraints affecting acquiring nesting sites. Between October 2020 and July 2021, we visited a total of 52 nests occupied by the African crowned eagle (Stephanoaetus coronatus, hereafter crowned eagle) and the black sparrowhawk (Accipiter melanoleucus) in our study area and compared the nest characteristics of the two raptors. Our results showed that exotic tree plantations were the most commonly used as nest sites by both species, suggesting that exotic trees may be crucial in providing nesting sites for both species in this highly modified landscape. Furthermore, our results showed that there was no significant difference in nest height, tree cover, nest cover and distance to (i) road, (ii) building and (iii) water of nests occupied by the two species. However, there was a significant difference between tree height and nearest neighbour distance. Tall, mature trees, slightly isolated from other trees, influenced nest site use for our study species. Innovative conservation measures and strategies could be vital in protecting raptor nesting sites (i.e., exotic tree plantations) in urban mosaic landscapes with natural and managed green spaces.