Larger and older church forests promote bird species richness, diversity and resilience across northwest Ethiopia's deforested landscapes

Birds are vital bioindicators of biodiversity and ecosystem health, but their persistence and ecological roles are under severe threat from human activities in the Lake Tana Basin, Ethiopia. Rapid land and forest degradation driven by agricultural expansion, urbanization, and the rising demand for fuelwood imperil avian community structure and ecosystem functions in this region. However, amidst this ecological challenge, church forests have emerged as crucial sanctuaries. Despite their small size and isolation from each other by mainly agricultural land-use, these church forests provide indispensable ecosystem services and play a pivotal role in preserving biodiversity. Understanding the significance of church forests for avian biodiversity and the factors influencing bird species richness and community composition is paramount. To this end, a comprehensive survey was conducted in 24 church forests between November and December 2018. Data collection involved both point counts utilizing Audiomoth acoustic loggers and transect surveys. The study revealed a total of 131 bird species in the surveyed church forests, including endemic and threatened species. These birds exhibited diverse foraging habits and functional traits. Notably, church forest size and canopy cover were positively associated with species richness, highlighting the importance of preserving and potentially expanding these forested areas. Furthermore, the research identified key factors driving the similarity of bird communities in church forests, notably forest surface area, canopy cover, and altitude. Importantly, resilience metrics demonstrated significant positive relationships with species richness, emphasizing the conservation value of these unique ecosystems. Our study underscores the critical role of church forests in safeguarding avian biodiversity in the Lake Tana Basin, and our findings advocate for conservation efforts aimed at preserving and enhancing the region's church forests, as their continued degradation could jeopardize both ecological and socio-economic potential in this network of remnant forests.