Bird community composition across a land use gradient in the eastern Democratic Republic of Congo

Abstract

Cocoa agroforestry expansion is widespread in eastern Democratic Republic of Congo, posing a significant threat to the integrity of protected areas. Despite this threat, the impact of this expansion on forest bird communities remains largely unexamined. This study investigated bird community composition in the Okapi Wildlife Reserve (OWR) and surrounding agroforestry areas using a combination of mist netting and passive acoustic monitoring. Specifically, it examined species richness, diversity, evenness, feeding guild abundance and habitat-specific indicator species across 19 sites. A total of 95 bird species were documented, with acoustic monitoring accounting for 73% and mist netting 43% of the recorded species. Significant differences in species richness, diversity and evenness were observed across habitat types. While cocoa farms exhibited higher species richness than primary forest sites or annual cultures, primary forests had the highest diversity indices, followed by cocoa farms and annual cultures. Bird communities were most even in annual cultures, compared to primary forest sites and cocoa farms. Additionally, 18 bird species showed strong associations with specific habitat types based on combined data from both mist netting and acoustic methods. This study highlights the importance of protected areas such as the OWR for sustaining bird communities, as well as emphasising the potential value of structurally complex agroforestry landscapes for subsets of forest bird communities. Furthermore, it demonstrates the effectiveness of combining mist netting and acoustic monitoring methods in understanding avian community composition amid land use changes.