Fauna of the light harriers of the Samara region: population dynamics due to changes in environmental conditions

The article characterizes the fauna of light harriers ( Circus cyaneus (Linnaeus, 1766), Circus macrourus (S. G. Gmelin, 1771), Circus pygargus (Linnaeus, 1758)) living in open and near-water spaces of the territory of the Samara Region. The dynamics of the number of light harriers and the reasons provoking significant fluctuations in the number of harriers are analyzed in detail. The boundaries of the breeding ranges of light harriers within the European part of Russia, the Middle Volga region and the real nesting zones on the territory of the Samara Region are discussed. The sections to which light harriers especially gravitate during reproduction are given, nevertheless visiting the entire area occupied by the region. Analyzing data from publications and oral reports of ornithologists on avifauna of the Samara region, the authors extrapolate a picture of the dynamics of the ‘squeezing’ of light harriers from the natural environment. The paper provides information on changes in the number of each species of light harriers in recent years. Among the most important factors limiting the number of light harriers, the following are noted: plowing of steppe areas; destruction of the habitat of birds; unauthorized, spontaneous burning of dry grass in the floodplains of small rivers in the spring; scattering of poisoned baits in order to exterminate rodents; poaching; the effect of the ‘anxiety factor’ in the breeding season; instability of the food supply.