Estimation of the number of the toad-headed agama (Phrynocephalus mystaceus) and the stepperunner (Eremias arguta) on the Sarykum dunes and their surroundings (Dagestan Republic, Russian Federation)

Variants of estimating the number of different lizard species in natural populations are proposed. In one sense or another, we are talking about an accounting site of a known area. But depending on the biological features of different lizard species, the accounting indicators may be different: either it is a fixation of the total number of lizards living on the accounting site (which is possible for the toad-headed agama Phrynocephalus mystaceus), or it is a fixation of the number of lizards encounters on accounting routes of a certain length and width, i.e. a certain area (which is possible for the steppe runner Eremias arguta). Correction coefficients should be introduced into the accounting results, which should take into account that: 1) the distribution of lizards across the territory is uneven due to microbiotopic differences (K1), 2) not all lizards that live in the this territory may be active on the surface every day (K2), 3) when using different registration methods, primary accounting data allow registering a different proportions of lizards from their total number inhabiting this site (K3). After such an adjustment of the accounting results, it is possible to calculate the density of lizard settlements and the absolute number of lizards for any separate sections of entire territories. As a result of our work, we have so far determined the composition of these coefficients. Subsequent studies should lead to the development of standardized methods for determining these coefficients. According to our calculations, the density of the population of toad-headed agamas in the area of their most compact habitat on the large Sarykum dune can be up to 125 individuals/ha, and their total number can be estimated at about 7000-7500 individuals. For steppe runners, their population density in places of compact habitat in the vicinity of the small Sarykum dune can be 18.0-23.4 ind./ha, and their total number in the area of about 9 ha, where we carried out our research work, could be 180-220 individuals. By standardizing the methods of evaluating different species of lizards, it is possible to organize correct long-term monitoring of the state of their populations.