Bello Adamu Danmallam ^1* Peggy Ngila ^2* Iniunam Iniunam ^1* Anthony Kuria ³ Talatu Tende ^1* Samuel Ngugi ^4* Peter Njoroge ^5* Colin Jackson ^6* Basil Okoth ^3* Ulf Ottosson ¹ Adams Chaskda ^1* Rosie Trevelyan ^7*

• ¹ A.P. Leventis Ornithological Research Institute, Jos, Nigeria
• ² Centre for Biodiversity Information Development, Strathmore University, Kenya, Nairobi, Kenya
• ³ Tropical Biology Association, Nairobi, Kenya, Nairobi, Kenya
• ⁴ Ornithology Section, National Museums of Kenya,, Nairobi, Kenya
• ⁵ National Museums of Kenya, Nairobi, Kenya
• ⁶ Arocha kenya, Watamu, Kenya
• ⁷ Tropical Biology Association, Cambridge, United Kingdom

Urbanization, characterized by the rapid expansion of human settlements and development, greatly impacts biodiversity, especially where developments and human settlements are not guided by proper environmental consideration. This study evaluates the ecological consequences of urbanization on Afrotropical bird communities using s. We used data collected through citizen science. projects under the African Bird Atlas Project, based on standardized protocols to gather bird occurrence data. Species' ecological traits, related to foraging behaviour, habitat speciality, and body mass, were analyzed to assess functional diversity using Rao's quadratic entropy framework. Geospatial data, including the Global Human Settlement Layer and Human Modification nndex (HMn), along with the probability of urban expansion up to 2030 were integrated to examine the impact of urbanization using Bayesian models. Our findings reveal a marked decline in taxonomic richness, diversity, and functional richness associated with increasing urbanization and human modification, with a similar pattern observed along the gradient from mostly uninhabited areas to cities. However, functional diversity exhibited an opposite trend, increasing with urbanization from uninhabited areas to cities. The relationship between functional diversity and HMn was nonlinear, showing an initial negative trend that became positive as HMn increased. This suggests a transition in bird communities, where generalist species thrive in urban environments, potentially replacing specialized species and leading to functional redundancy. Despite the complex relationships observed, urbanization has a predominantly negative impact on the richness and diversity of Afrotropical bird communities. The decline in avian diversity and functional richness has important implications for ecosystem functions and services, crucial for biodiversity and human well-being. Our research provides valuable insights into the ecological impacts of urban expansion and emphasizes the importance of preserving natural habitats amidst growing urban landscapes.