Phenology, morphology, and stopover dynamics of Black Redstarts (Phoenicurus ochruros) at the Monte Pizzoc mountain pass (Veneto Prealps, Italy): insights from a long-term ringing study

Mountain passes are key crossing points for migratory birds traversing mountain ranges such as the Alps. Besides facilitating migration by allowing birds to exploit favourable air currents and reduce energetic costs, these sites may also provide important opportunities for stopover and refuelling. However, their role in supporting migratory birds remains poorly understood. This study investigates the autumn migration and stopover ecology of the Black Redstart (Phoenicurus ochruros) at the Monte Pizzoc Mountain pass (Venetian Prealps, north-eastern Italy) using capture–recapture data collected over 13 consecutive migration seasons (2013–2025). A total of 6,288 captures, corresponding to 5,875 individuals, were analysed to describe migration phenology, estimate stopover duration, and assess changes in body condition through the Scaled Mass Index (SMI) and Fuel Deposition Rate (FDR). Autumn migration occurred mainly between late September and early November, with a peak in the second half of October. Most individuals remained at the site for only a few days, although some birds showed longer stopovers and repeated use of the site across years. Recaptured individuals generally improved their body condition during stopover, indicating successful fuel deposition before resuming migration. These findings demonstrate that Monte Pizzoc functions not only as a migratory corridor but also as an effective refuelling stopover for the Black redstart. Recognizing the dual role of mountain passes as both transit corridors and stopover sites is essential for accurately assessing their ecological importance and developing effective conservation strategies, preventing these habitats from being undervalued despite their crucial role in supporting migratory birds during one of the most energetically demanding phases of their annual cycle.