Spatial distribution dynamics and population trends of Anseriformes in agricultural landscapes of Karelia during the spring migration

The agricultural landscapes of the Olonets District, Republic of Karelia (Northwest Russia), represent a critical component of the White Sea–Baltic flyway used by Anseriformes in Europe. The importance of this stopover site is particularly pronounced during spring migration, as the effectiveness of energy accumulation at these sites is a key determinant of the reproductive success of Anser and Branta geese in northern Russia. Of the approximately 180 km² of open landscapes, the majority comprises cultivated agricultural lands, which are intensively utilized by hunters during the hunting season, excluding a designated 49 km² of the wildlife refuge zone. This study presents an analysis of the seasonal population dynamics and special distribution of Anseriformes in the agrolandscapes of the Olonets region on the basis of data from the last 25 years. We identified the key dates of significant population changes across different species in response to various anthropogenic factors. We also analysed changes in the spatial distributions of bird species during three distinct phases: the prehunting period, the hunting period, and the posthunting period. For the greater white-fronted geese Anser albifrons , we found a significant positive correlation between the relative population size and the area of arable land. The patterns of spatial redistribution of birds in the fields before, during, and after the hunting season followed a consistent trend: before hunting, birds were evenly distributed, whereas during the hunting season and after hunting, they selected open, highly visible fields with minimal surrounding tree and shrub vegetation. The intraseasonal fluctuations in relative bird numbers were mainly due to biological characteristics of species, with notable changes correlated with various aspects of human activity in the field. The tendency of Anseriformes towards certain types of fields may also be due to migratory birds preferring fields with more intensive care, including timely crop renewal, leading to enrichment of the food base.