Ecological Status of Populations of the Most Common Bird Species in the Dark-Coniferous Taiga of Baikalia

Abstract

Nesting home ranges of individual birds were regularly mapped in 2013 and 2014 from May to July along a permanent census route (3.15 km) in the dark-coniferous taiga on the southern slope of the bed of Lake Baikal. Based on the mapping results, the nesting densities and average sizes of the nesting home range of individual birds are estimated for each bird species and raster maps of spatial allocation (MSAs) at a scale of the raster grid of 50 × 50 m are obtained for each species. The degree of spatial conservatism (DSC) for each local population is inferred from the pairwise comparisons of the specific MSAs obtained on the same area (31.5 ha) in different years with the use of the Gamma rank correlation method. The dependence of the population habitat area on the DSC was demonstrated earlier (Cherenkov, 2017). The larger habitat area is found within the sample plot, an a less dependent individual spatial allocation within a population is observed in different years. Based on the estimated specific habitat areas, average sizes of the individual nesting home range, and estimated nesting density, the maximum possible nesting density and habitat saturation are calculated for each species. The population status is inferred from the degree of habitat saturation. Significant DSC estimates (p < 0.05) are obtained for nine species; their habitat areas and saturation are found. It is shown that habitat saturation in nonmigratory birds is twice as high an in migratory ones. On average, habitat saturation was 54–58% in nonmigratory birds and 26% in migratory ones (F = 9.1; p < 0.01). In the two species, the orange-flanked bush-robin (Tarsiger cyanurus Pallas, 1773) and taiga flycatcher (Ficedula (parva) albicilla Pallas, 1811), the habitat saturation is less than 20%, which indicates the presumably troubled status of their populations.