Analysis of the long-term lark population dynamics (Alaudidae, Aves) in the semi-desert in the Northwestern Caspian lowland

Abstract

The dynamics of the numbers of larks inhabiting several areas differing in physical and geographical (landscape) conditions and the level of anthropogenic impact (pasture) on the natural environment is considered. Four key sites (“Akhmat”, “Zhdanov”, “Baiguzha”, and “Vetelki”) are located on the Priuzenskaya plain in the Aleksandrovo-Gaysky district of the Saratov region. The described territory is characterized by a high mosaicity of the facial structure of landscapes and, consequently, plant communities. This habitat diversity forms the structure of the communities as well as the population density of the individual lark species at the key sites surveyed. Our study of the dynamics of the numbers of species inhabiting the named key areas was carried out using calculations of logarithmic trends in the bird densities by the years of our study. In total, there were five species of larks (Alauda arvensis, Calandrella rufescens, Melanocorypha calandra, M. leucoptera, and M. yeltoniensis). As a result of our statistical processing of the obtained materials, significant differences were found in the dynamics of the numbers of individual lark species nesting in the key areas differing in landscape-ecological conditions and the level of anthropogenic load on ecosystems. In all likelihood, the dynamics of the density of the nesting lark population in the semi-desert of the Trans-Volga region is associated with both changes in the structure of habitats and, apparently, with the dynamics of the abundance of these species in the main part of their habitats, and with a number of other factors.