Comparative analysis of the nesting birds fauna found in the settlements of Southern Siberia steppe landscapes

The article presents the results of studies of the nesting bird fauna of the settlements within the steppe landscapes of Tyva and Buryatia, conducted in 2012-2021. We have identified 20 permanently and a number of randomly nesting species. In the settlements of the steppes two or more times fewer nesting spots have been found than in the settlements of Southern Siberia as a whole. This is due to the scarcity of habitat diversity in the steppes and surrounding natural biocoenoses, which are "the suppliers" of certain new species. The core of the settlements' ornithofauna in both republics are the blue-rock Columba livia and white-rock Columba rupestris pigeons, the common swallow Hirundo rustica, the white Motacilla alba (in Buryatia) and the masked Motacilla personata (in Tyva) wagtails, the common wheatear Oenanthe oenanthe, the house Passer domesticus and tree Passer montanus sparrows. In general, there is a tendency of increasing the species wealth from small settlements to large ones. Comparison of the total species composition of the breeding ornithofauna of Tyva and Buryatia has shown that they differ little in the number of species: in Tyva - 17, in Buryatia - 16. However, there are noticeable geographical differences in the taxonomic composition, according to the Jaccard similarity index the average similarity index is 0.5 (from 0.46 to 0.71 for different types of settlements). The results of comparing the taxonomic composition of birds in different types of settlements (small towns, rural settlements of various types and livestock complexes) within the republics have shown greater similarity of fauna in the settlements of similar size. Within the same type of settlements there are small differences determined by the specificity of the environmental conditions of each of them. Currently, the living conditions of animals in the settlements of the region are changing rapidly, which undoubtedly affect the species wealth of the fauna and the structure of their communities.