Trough bird fauna of the North Caucasus and features of its formation, the Botlikh trough-like depression of Inner Dagestan taken as an example

An analysis of the avifauna of the arid Botlikh depression in the mountains of Dagestan, where 112 breeding bird species have been recorded, shows noticeable transformations in its composition noted during the 19th to 21st centuries. Within the arid depression, an increase in the number and expansion of nemoral, forest-steppe and sub-Mediterranean dendrophiles is observed, as well as the appearance of Siberian mountain-taiga species at nesting sites. At the same time, there is a decrease in the number and the disappearance of xerophilic sclerophylls, which are part of the desert-mountain faunal complex of the Nomadian type of fauna. This may be due to both climate change, which affects birds indirectly through vegetation and a reduction in the specific food supply, and the consequences of anthropogenic impacts on the natural environment (forest restoration, degradation of agriculture and livestock breeding), possibly also through competitive relationships between some animal species. Similar changes are noted not only in the avifauna of Dagestan, but also in the Western Caucasus, as well as in the steppe zone in southern Russia, this indicating large-scale zoogeographic processes occurring there. The identified transformations of regional faunas require further, intensified faunal monitoring, which will make it possible to clarify the speed of ongoing processes and provide zoogeographic forecasts for the near future.