Quantifying the effects of road-building on bird communities before and after activities

Urbanization with a rapid expansion of the road network disrupts ecological processes, fragmenting the landscape, and reducing biodiversity. The frequent machine and human activities involved in road construction led to significant pressure on ecosystems. However, research on the impact of roading building processes in different stages remains lacking information. We performed a bird census for a new highway construction, the SE-40 ring road in Seville, with three-stages: a) active works, b) suspended works stage surrounding, and c) control stage in a natural condition. We analyzed similarities in community composition and bioindicators using the Indicator Value (IndVal) analysis between different stages. Additionally, we calculated several avian biodiversity metrics, including bird species richness, abundance, biodiversity, and diet-specialist species richness (DSR) and abundance (TAB). Road construction significantly impacted species composition (NMDS, ANOSIM p < 0.001, R² = 0.1692); both active (P. adjusted = 0.006) and suspended work (P. adjusted = 0.009) stages display differences compared to the control group. The number of species and bioindicator increases, but diet-specialist species decreased, from active works (bioindicator = 3; mean TAB = 6; mean DSR = 19) to control group (4; 4.89; 12.61) to suspended works (5; 5.67; 14.89), reflecting a higher homogeneity during the active works with lowest biodiversity (mean Shannon = 2.69 and Simpson = 0.92). Our findings highlight the overlooked value of suspended works as provisional habitats for bird assemblages, suggesting that areas with intensive human activity need specific biodiversity monitoring and implications for conservation efforts. Rigorous specific biodiversity monitoring is essential to mitigate long-term impacts and inform adaptive road planning strategies.