Abstract

The numbers of waterfowl and shorebirds declining on a global scale is largely due to the reduction in wetland areas in the era of climate warming. Long-term monitoring data obtained in 1995–2020 in two Key Bird Areas of Russia of international importance, i.e. the Sulakskaya and Turalinskaya lagoons, the Republic of Dagestan, are presented, the transboundary populations of Anseriformes (Anatidae) taken as examples, Both model lagoons are located in one of Russia’s largest bottleneck places of the western Caspian flyways, where the fly routes of European and Asian migrants intersect. The Anseriformes model group, which includes 18 predominantly background species, was chosen based on their regular encounters during migration. According to the information on the ring returns obtained from the Research and Information Center for Bird Ringing at the Institute of Ecology and Evolution, Russian Academy of Sciences, a conditional outline of the generalized distribution range of Anseriformes was revealed, the faunogenetic basis of which is composed of widespread representatives of Arctic or Siberian fauna types. Based on all available data, including the information derived from literature sources, the geographic location both of populations and their regular migration areas was determined. The rating of 12 of all 18 study species was found to have significantly decreased, vs 2 that increased, and further 4 that remained stable. The resulting trends were synchronized with data available from literary sources on the same species of Anseriformes in their nesting areas. The coincidence of the corresponding trends with the distribution trends of the same anatid species in their nesting areas ensured the distance of distant populations of Anseriformes obtained along their flyways in the model lagoons to be correctly measured. This was found to correlate with the average monthly air temperatures in the autumn-winter period in the Primorskaya Lowland of Dagestan, 12 model species being associated with temperature fluctuations. The numbers of migratory populations of anatids in cold years are shown to lead to their increased migration in the study area, as a result the migration of migrants along the flight routes slowing down and their wintering places being changed. Correlation analysis showed a significant relation between the increased areas of Anseriformes wintering in the Caspian Sea with sea-level regression, in which the shallowing areas of marine waters limited the access of anatids to food resources (benthos). Three key factors determining the dynamics of a group of Anseriformes populations are discussed: hydroclimatic cycles, anthropogenic influence and foraging. A temporary ban on the hunting removal of 8 vulnerable species of anatids (the Greylag Goose, the Common Teal, the Garganey, the Gadwall, the Eurasian Wigeon, the Northern Pintail, the Northern Shoveler, and the Common Pochard) is proposed to be imposed in Siberia, Kazakhstan, the Urals Federal District, the Cis-Urals, the Volga region, and the Southern and North Caucasus federal districts until their populations become sufficiently restored.