Dynamics of the fauna of warders in the lake Baikal basin and its correlation with current climatological changes (the end of the 18th - the beginning of the 21st centuries)

The article discusses the dynamics of the fauna of waders in the Lake Baikal basin depending on climatological changes (warming) over a very long period of observations (end of the 18th - the beginning of the 21st centuries). Until the middle of the 20th century Eastern Siberia was in a humid and cold period of a centuries-old climate cycle, related to the late Glacial, which lasted about 2000 years. In this regard, the species composition of waders at that time was very poor - 45 species, although some of them reached a very high abundance. From the second half of the 20th century due to the pronounced climate warming, the species composition of warders in Lake Baikal basin significantly increased (from 45 to 57 species), in total in Eastern Siberia there are 63 species. The sharp increase in the species composition and the number of birds of this group are a consequence of the relocation of a number of typically southern species of waders to the north. It has been proven that mass relocation of these birds to the north is initiated by large, often catastrophic droughts in Central Asia, accompanied by long low-water periods. Birds of wet and marshy meadows which area sharply decreases as a result of a very strong drying out are relocated first. So, the beginning of the second half of the 20th century was characterized by mass relocations of meadow-marsh wader species that penetrated to the Central Yakut Plain (northern lapwing, marsh sandpiper, common greenshank, wood sandpiper). At the end of the 20th century due to a very strong drying of wet meadows in the south of Eastern Siberia, there were shifts of the optimums of ranges far to the north - the most common species of waders of this group, such as common snipes, pintail snipes, forest snipes, and ruffs, moved 500 km or more to the north. At that time the abundance of the most numerous species of waders which were typical for wet-cold period of the Late Glacial climate (19th - the first half of the 20th centuries) had been sharply reduced. The southern borders of their ranges remained almost unchanged, but the density of the bird population decreased by 2-3 times or more. Only separate breeding pairs of some species (common greenshank, wood sandpiper) are found in the places, where earlier there was high abundance of them. At the beginning of the 21st century the relocation concerned desert, steppe and alpine species of waders. The green sandpiper - one of the most widespread species of the previous period - leaves even the north of Eastern Siberia. The species composition increases mainly due to vagrant and single-nesting southern species of waders, the northern limits of their ranges were previously located near the borders of Russia. It should be noted that we are talking about a group of birds that naturalize in wetland ecosystems, which are intrazonal habitats of almost all natural zones and mountain belts, and it facilitates extensive movements of such birds.