Abstract. Utama AA, Nurvianto S. 2022. The building size effect on bird community assemblages in tropical urban ecosystem. Biodiversitas 23: 2775-2782. The construction of buildings is one of the factors that cause landscape changes in urban areas. Landscape changes can result in the fragmentation of animal habitats that live in urban areas. Characteristics of urban structures, such as spatial configuration and distribution of building types, are some of the factors that influence the distribution pattern and abundance of bird species in urban areas. This research aimed to describe the effect of building type on the diversity of bird species in Province of Yogyakarta, Indonesia, or Daerah Istimewa Yogyakarta (DIY). Bird data were recorded using the point count method, while building type data and vegetation height were obtained by subtracting Digital Surface Model (DSM) data and Digital Elevation Model (DEM) data in the built-up area. The data was recorded from three levels of urbanization, namely urban, suburban and rural. Canonical Correspondence Analysis (CCA) was used to visualize the response of birds to the type of building. After that, the Generalized Linear Model (GLM) was used to determine the effect of the type of building on the diversity of bird species. The results showed that shrub cover affected species richness and abundance of birds. The building types with a height below 18 meters had a negative effect on the abundance and diversity of birds in suburban areas. The abundance of birds in urban areas was positively affected by the type of building with a height of between 18 and 30 meters. The existence of buildings in urban areas can reduce bird feed sources. Making spatial plans that provide more variety of plant cover and diversity of building heights are expected to increase bird diversity in urban areas.