The association between landscape fragmentation and bird species richness in a neotropical city.

Abstract

Urbanisation is a major driver of changes in the configuration and composition of the landscapes, threatening biodiversity by reducing connectivity and simplifying ecosystems. This study examines the impact of variation in the structure and composition of urban landscapes on bird species richness and functional composition in Chetumal, Mexico. Through passive acoustic monitoring, we assessed bird species richness and, using Sentinel-2 satellite imagery, we calculated vegetation indices, spectral heterogeneity, texture, and landscape metrics to characterise habitat composition and configuration. Our results show that species richness decreased with increasing urbanization, with the forest landscape supporting more species than urban sites, particularly insectivores and shrub-foraging birds. The forest site was more aggregated and contiguous and had a higher effective mesh size, indicating greater structural connectivity. In contrast, urban sites were patchier and had more heterogeneous spectral signatures, reflecting landscape disaggregation. Functional composition of the bird communities also shifted, with urban sites harbouring more generalist species. Our findings highlight the importance of maintaining vegetated corridors and structural complexity to support ecologically diverse bird communities. The integration of acoustic biodiversity monitoring with spatial landscape metrics offers a powerful approach for mitigating biodiversity loss in rapidly expanding tropical cities.