Contrasting Patterns of Species Richness and Functional Diversity in Bird Communities of East African Cloud Forest Fragments

Species diversity, relative abundance, and distribution of avifauna in different habitats within Lewi Mountain, Awi zone, Ethiopia

Almost all habitats on the planet are home to birds, from the lowest deserts to the highest mountains. Birds have proved to be excellent indicators of biodiversity or productivity as they are easily observed and are relatively well known compared to other animals. Although bird species are distributed across the globe, habitat destruction, fragmentation, and loss have adversely affected their survival and distribution. Therefore, this study is an attempt to prepare a baseline data on avifaunal diversity with their relative abundance and species richness in different habitats within Lewi Mountain Awi zone, Ethiopia from December 2018 to October 2020, including both the wet and dry seasons. The sampling sites were stratified based on land cover features, and transect count techniques were employed. The data were summarized per season and habitat type in the excel spreadsheet throughout the study period. In this study, one-way ANOVA was used to determine the effect of habitat type on species diversity and abundance. T-tests are also use to analyze bird populations among seasons. A total of 1591 individuals, 56 bird species belonging to 29 families and 12 orders were identified during the two seasons. The Wetland habitat had the highest species diversity index (H' = 3) with high evenness index (J = 0.88) during the dry season followed by the open shrubs habitat (H' = 2.97) with the highest evenness index (J = 0.95). The settlement had the lowest species diversity (H' = 2.17) and the lowest evenness index (J = 0.8) in the same season. During the wet season, disturbed forests recorded the highest Shannon-Weiner diversity index (H' = 3.2) with the highest evenness (J = 0.92) followed by Wetland habitat (H' = 2.97) with high evenness index (J = 0.87). During dry and wet seasons, the abundance of birds' species in different habitat types did not differ significantly (F = 1.91, p = 0.193, dƒ = 3) and (F = 1.579, p = 0.199, dƒ = 3), respectively. From all studied habitats, the overall mean abundance of bird species between dry and wet seasons was significantly different (F = 3642, P ≤ 0.001, dƒ = 1). In conclusion, settlement had the lowest species diversity and the lowest evenness index in the research area for the entire season. The habitats are important to the conservation of birds, so good habitat management is required, such as minimizing agricultural expansion and overgrazing, demarcating the forest habitats for wild species only, and creating awareness among local communities.

Bird Communities in a Changing World: The Role of Interspecific Competition

Significant changes in the environment have the potential to affect bird species abundance and distribution, both directly, through a modification of the landscape, habitats, and climate, and indirectly, through a modification of biotic interactions such as competitive interactions. Predicting and mitigating the consequences of global change thus requires not only a sound understanding of the role played by biotic interactions in current ecosystems, but also the recognition and study of the complex and intricate effects that result from the perturbation of these ecosystems. In this review, we emphasize the role of interspecific competition in bird communities by focusing on three main predictions derived from theoretical and empirical considerations. We provide numerous examples of population decline and displacement that appeared to be, at least in part, driven by competition, and were amplified by environmental changes associated with human activities. Beyond a shift in relative species abundance, we show that interspecific competition may have a negative impact on species richness, ecosystem services, and endangered species. Despite these findings, we argue that, in general, the role played by interspecific competition in current communities remains poorly understood due to methodological issues and the complexity of natural communities. Predicting the consequences of global change in these communities is further complicated by uncertainty regarding future environmental conditions and the speed and efficacy of plastic and evolutionary responses to fast-changing environments. Possible directions of future research are highlighted.