Ecology matters: a long-term study on population trend of feral pigeons (Columba livia) in Pisa (Italy)

The feral pigeon (Columba livia) is one of the most abundant animal inhabitants of human settlements, with populations easily reaching tens of thousands of individuals, frequently leading to numerous human-animal conflicts. While several studies have examined populations subjected to active management, long-term dynamics of unmanaged populations remain largely undocumented. In the present study, we report the results of eight Distance Sampling estimates conducted over a 20-year period in the Mediterranean city of Pisa (Italy), when the feral pigeon population was not subjected to specific population control measures. In 2004 Pisa hosted a large number of feral pigeons whereas, in 2024, after their urban habitat underwent relevant changes including a city-wide renewal of waste management and the SARS-CoV-2 pandemic of the early 2020s, pigeon abundance notably and stably decreased. Our results support observations from other systems, indicating a strong dependence of feral population size on trophic resources generated inside the urban environments. A second relevant insight emerging from our findings is that urban populations not subjected to specific control measures can undergo significant changes in both size and spatial distribution over relatively short time as a consequence of modifications to the urban environment. We believe these findings highlight the importance of population monitoring along with a comprehensive understanding of the target environment as essential components of an effective management program.