Investigation of the migration strategies of the Blackbird (Turdus merula) and the European Robin (Erithacus Rubecula) species around Küçükçekmece Lake, İstanbul

Seasonal bird migrations are a fascinating natural phenomenon shaped through evolutionary processes as a survival strategy. Migratory birds navigate to different climatic regions during spring and autumn to adapt to climatic conditions, increase access to food resources, expand breeding areas, and optimize their habitats. Ringing studies, used to understand these processes and examine bird behavior in detail, provide more effective information compared to other methods in identifying migration routes, wintering areas, breeding strategies, and migration dynamics of birds. This study was conducted at Istanbul University-Cerrahpaşa Avcılar Campus (40.996277 °N, 28.728716 °E) between 2020 and 2022. It aimed to investigate the migration strategies, morphometric characteristics, age groups, and population dynamics of the blackbird (Turdus merula) and the European robin (Erithacus rubecula) through bird-ringing studies. The research was carried out over 316 days during four migration seasons using mist nets. Measurements were taken from 305 blackbirds, and 213 individuals were ringed. Of the captured blackbirds, 58.7% were caught in autumn, while 41.3% were caught in spring. The highest recapture rate was recorded in spring, at 69.3%. Daily activity patterns revealed that blackbirds were more active in the morning, showed reduced activity at noon, and increased their activity again in the evening. March and October were the months with the highest activity levels. Measurements were also taken from 2,349 European robins, and 1,589 individuals were ringed. The highest ringing rate, 43.9%, was recorded during the autumn of 2021, while the lowest rate, 5.7%, was observed in the spring of 2022. Monthly analyses showed that 56% of the ringed European robins were captured in October. Hourly analyses indicated that activity was highest in the morning (24.8%) and lowest in the late afternoon (2.4%). Activity patterns of juvenile and adult European robins were generally similar. The recapture of a female blackbird, ringed in April 2022, in Zmiiv, Ukraine, 1,131 km away as the crow flies, in April 2023 highlights the significance of ringing studies and this research. This study contributes significantly to understanding the daily and seasonal activity cycles, ringing rates, migration strategies, population dynamics, and relationships with environmental factors of blackbirds and European robins. It provides valuable insights for the conservation of these species, the improvement of their habitats, understanding migration dynamics, and evaluating their impacts on ecosystems.