IMPACT OF EXTREME DROUGHT ON THE NUMBER OF ARCTIC GEESE AT A MIGRATION STOP IN THE VALLEY OF THE WEST MANYCH RIVER IN 2020–2021

An extreme drought without precipitation lasted 78 days from August 2, 2020, until the onset of cold weather in the south-west of European Russia in the area of the Veselovsky Reservoir. The amount of precipitation during this period was 0.8 mm. Maximum and average air temperatures were: in September 34.6 and 20.1 °C respectively; in October 25.7 and 14.6 °C respectively. The main foraging habitats for Arctic geese at the Veselovsky Reservoir area are winter wheat fields, which dominate the structure of plant growing in the Rostov Region. Winter wheat did not sprout over large areas due to drought and abnormally high temperatures by the time of arrival of the white-fronted goose Anser albifrons (Scopoli, 1769) and the red-breasted goose Branta ruficollis (Pallas, 1769) in the fall of 2020 to a migratory stop in the valley of the Western Manych River. There were no feeding resources for the geese of these species in the area of the Veselovsky Reservoir, which led to their redistribution for a migratory stop in the area of Manych-Gudilo Lake, where steppe pastures were preserved. The white-fronted goose and the red-breasted goose arrived in the Veselovsky Reservoir in 2020 at the usual dates: in mid-October and early November, respectively. The geese stopped for a short rest and flew south-eastward. There were no large aggregations of the white-fronted goose in the area of the Veselovsky Reservoir in the fall of 2020 (maximum 9000 individuals), whereas in the previous fall, the abundance of this species at the peak of the migratory stop was 17500 individuals. The maximum number of red-breasted goose in the fall of 2020 in the area of the Veselovsky Reservoir was 1700 individuals (5000 individuals in 2019). The length of stay of the two species also decreased in the fall of 2020 compared to the previous year. March 2021 was frosty, and winter wheat sprouted in early April, when geese migration was almost over. White-fronted geese stopped in the area of the Veselovsky Reservoir only for a short rest. Many flocks followed in transit, since there were no food resources, a necessary condition for a migratory stop. The red-breasted goose in the spring migration followed through the reservoir in transit to the migration in the area of Manych-Gudilo Lake. Thus, extreme weather conditions, such as prolonged drought before and during the autumn migration of Arctic geese, can lead to a sharp decrease in the ecological capacity of habitats at the migration stop area. Lack of moisture with a combination of abnormally high temperatures, the early arrival of frost in the fall with precipitation as snow, frosty March are factors that provoked a complete lack of food resources for Arctic geese in the Veselovsky Reservoir area. The situation was aggravated by the lack of natural pastures and the almost monoculture of agricultural crop production in large areas. As a result of drought, as well as accompanying weather and anthropogenic factors, the number of geese at the migration camp is decreasing, the nature of the use of the territory is changing: geese avoid long stops, often following in transit. Part of the migrating group uses a large reservoir only for short-term rest, moving to a long stop east of the Veselovsky Reservoir, to where the steppe pastures have been preserved.

Arctic geese, white-fronted goose, red-breasted goose, migration stop, drought, Western Manych