Avifauna of Basins of the North Caucasus and Peculiarities of Its Formation from the Example of the Botlikh Depression, Inner Dagestan

The analysis of avifauna of the arid Botlikh Depression in the mountains of Dagestan, where 112 species of nesting birds were registered, demonstrated noticeable transformations in its composition over the 19th–21st centuries. An increase in the number and dispersal of nemoral, forest–steppe, and sub-Mediterranean dendrophiles, as well as the emergence of Siberian mountain–taiga species for nesting, has been observed in this arid basin. A decrease in the number and disappearance of xerophilic sclerophiles (that are a part of the desert–mountain faunistic complex of the Nomadic type of fauna) have occurred. This may have been caused both by climate changes that affect birds indirectly (as a result of a change in the species composition and structure of vegetation and reduction in the specific food base for birds) and by the consequences of the anthropogenic effect on the natural environment (forest restoration, degradation of agriculture, and animal breeding), as well as probably by competitive relations between some animal species. Similar changes were noted not only in Dagestan, but also in the Western Caucasus, as well as in the steppe zone in the southern part of Russia, which indicates a large-scale level of zoogeographical processes occurring here. The detected transformations of regional faunas require further intensification of faunistic monitoring, which will allow clarification of the rate of ongoing processes and support zoogeographical predictions for the near future.