부산대학교 도서관

The sandhill crane has become a common to abundant breeding species on the tundra of northeastern Yakutia, with the ranges of both sandhill and Siberian cranes presently overlapping widely. Further range expansion of the sandhill crane to the west and a population increase could assist competition to the stenotopic Siberian crane, which is classified as a Critically Endangered species by the International Union for the Conservation of Nature (IUCN). To assess the dynamics of the Siberian and sandhill crane populations, we repeated the historical aerial surveys of 1993–1995 along the Arctic coast of Yakutia and Chukotka in 2020 and 2021. The novel methods of our survey included the use of a photo-camera in addition to a voice recorder and a GPS navigator. The survey data were processed using the QuantumGIS 3.16.5 software. The overlapping area of both crane species expanded significantly in 2020 and 2021 as compared to 1993–1995. The local densities correlate negatively: in those areas where the density of the sandhill crane increased, the density of the Siberian crane decreased or the latter disappeared. The Siberian crane disappeared from the western part of the Kolyma Lowland and the Kolyma Delta, where the peak population density of the sandhill crane has recently been reported. Our data show some concentration of the Siberian crane range in the Yana–Indigirka Lowland. The areas of the maximum density of the two species do not coincide, the distance between their centers amounting to 400 km. The center of the maximum density of the sandhill crane has shifted to the west by 400 km from the Chaun Lowland to the Kolyma Delta over 28 years, while the numbers remain almost stable. They increased 1.22 times between the aerial surveys and can be estimated at 41 930 individuals in the areas under survey. The density of the Siberian crane increased 5.3 times over the same years, the population numbering 2086 individuals in the areas surveyed. [ABSTRACT FROM AUTHOR]