Łukasz Krajewski
Ornis Polonica 2018, 59: 197–210
https://doi.org/10.12657/ornis.2018.3.2
Abstract: In 2011–2018 we identified geese observed in 274 flocks of the Bean Goose complex in the Biebrza Basin (NE Poland). Among 47,501 individuals recorded in these flocks, 9,991 were identified to the species level. The autumn migration of Bean Goose complex was truncated, and the number of individuals staying in the area was related to the presence of floodwaters. The largest autumn flock comprised 500 ind. The Tundra Bean Goose Anser serrirostris was the dominant species in autumn, making up 99.7% of individuals identified to the species level. Wintering Bean Geese were recorded only in milder winters (3 out of 6 winter seasons) with the largest flock of 250 inds. The Taiga Bean Goose A. fabalis accounted for 5.4% of wintering birds identified to the species level, and the Tundra Bean Goose for 94.6%. The spring migration was much more intense. The largest flock of the Bean Goose complex during this period consisted of 5,000 ind. The Taiga Bean Goose accounted for 10.9% of all individuals present in February and 2% in March, with the most numerous flock of 190 inds observed in early March. The last spring observation of the Taiga Bean Geese was recorded in late March. The Tundra Bean Goose was much more numerous than the Bean Goose. Tundra Bean Geese constituted 89.1% of all individuals recorded in February, 98% in March, and 100% in April and May.
Keywords: Bean Goose complex, Biebrza Basin, migration, Taiga Bean Goose Anser fabalis, Tundra Bean Goose Anser serrirostris, wintering
