Stopovers of Swans (Cygnus cygnus and C. bewickii) (Anatidae, Aves) in the Agricultural Landscape of Southern Karelia during the Spring Migration

Resumo

Abstract—Spring migrations of the Whooper swan and Bewick’s swan were studied on farmland near the town of Olonets during the years 1997–2017. Usually the majority of swans crosses the territory of the agricultural landscape in transit, and only a small portion of the birds stayed in it for feeding for 1–2 days. In 2017, swans formed a mass migration stopover in the fields, 340 to 1328 individuals per day were counted on it for 11 days, the majority of which (about 90%) were Bewick’s swans. It was established that such a high concentration of swans in the fields was a result of an unfavorable ecological situation in the region at the beginning of their mass migration. The places of traditional migration stopovers in shallow waters of Lake Ladoga were closed by floating ice, and unusually cold weather in the second half of April and ice-covered water bodies in the northern part of the migratory route hindered the migration of birds to their breeding grounds. In the current situation, the swans were forced to look for new places of feeding and concentrated in the most favorable (for this purpose) grounds of the agricultural landscape.