Trends in Avian Species Diversity And Composition in Green Spaces of Nairobi County in Kenya

Abstract

This study evaluated avian species diversity, community composition, and seasonal trends at the National Museums of Kenya (NMK) and Karen Karara (KK) between 2014 and 2020. Utilizing a retrospective quantitative research design, the study analysed secondary bird ringing records for 3,843 individuals representing 147 species. Data was standardized using rarefaction to reduce the unequal sampling biasness. The methodology employed Shannon-Wiener diversity (H'), Pielou’s evenness (J’), and Jaccard’s similarity indices, with composition differences statistically validated through Permutational Multivariate Analysis of Variance (PERMANOVA). Results revealed that Karen Karara maintained a more evenly distributed community structure (median J'≈0.87) compared to the NMK site (J’≈0.78), where a few species tended to dominate, indicating a greater degree of niche partitioning in the former. However, Karen Karara exhibited a statistically significant decline in Shannon diversity over

the seven-year period (p < 0.005, R2 = 0.68), whereas the decline at NMK was statistically non- significant (p = 0.081). Species similarity between the two sites remained consistently low

(Jaccard index < 0.4), indicating that these proximate green spaces support distinct avian assemblages requiring site-specific management interventions. Furthermore, while seasonal variation significantly influenced the species present (PERMANOVA: p = 0.001), overall diversity levels did not vary significantly across seasons, suggesting a pattern of functional species replacement rather than net diversity loss during different periods of the year. The study concludes that Nairobi’s avian communities within green spaces are undergoing measurable erosion, with peri-urban forests like Karen Karara exhibiting higher vulnerability to species turnover than central urban refuges. The observed decoupling between alpha diversity stability and high beta diversity turnover highlights a system undergoing significant compositional reorganization. To mitigate these trends, the study recommends the enhancement of habitat heterogeneity at NMK and the implementation of urgent restoration efforts and buffer zone creation at Karen Karara. Although sampling efforts differed between the sites, there is an imperative need for increased long-term monitoring to protect declining species and enhance urban biodiversity while reducing pressure on the remaining green corridors in the county. Ultimately, effective urban conservation strategies must move beyond aggregate diversity counts to prioritize seasonal composition shifts and the specific, fine-scale habitat requirements necessary to sustain avian biodiversity in an increasingly fragmented landscape.