Phenology of migrating game birds in Italy based on citizen science data

Studying the timing of the seasonal movements of migratory birds, known as migration phenology, is crucial for managing and conserving migratory bird populations. This is particularly important for migratory game bird populations in Europe because, according to the EU, migratory birds should not be hunted during their breeding season or during return movements to breeding grounds (pre-breeding or pre-nuptial migration). To effectively protect these species during these critical periods, it is vital to employ reliable methods for assessing their migration phenology. Citizen science, which involves the participation of skilled volunteers in scientific data gathering, is a valuable resource for migration studies. It allows the collection of large amounts of data across extensive geographic areas, overcoming some limitations of other datasets and analytical methods. In this study we analysed pre- and post-breeding migration phenology of 23 game bird species in Italy, using citizen science data from the www.Ornitho.it portal. We then compared our findings on pre-breeding migration onset with published migration timing data from ringing records and found a close match. Additionally, we compared our results with the pre-breeding migration onset determined for Italy in the ‘Key Concepts Document' (KCD) published by the European Commission that plays a central role in the regulation of hunting activities in EU countries. For 19 species (83%), we estimated an earlier pre-breeding timing compared to that reported in the last KCD for Italy (2021, amended in 2025 for four species), highlighting a potential risk of these species being hunted during their pre-breeding migration. These findings highlight the value of citizen science data in obtaining migration timing and the importance of employing multiple methods to estimate it. This approach is particularly valuable for species subject to hunting, which require well-informed management.