Vol 102, No 2 (2023)

Information concerning the allometric growth of the bivalve mollusk Mya arenaria populations in the intertidal zones of Zelenetskaya and Yarnyshnaya inlets, Barents Sea is presented. The population density in the Zelenetskaya Inlet averages 40 ind./m², biomass 280 g/m², vs 62.6 ind./m² and 142 g/m² in the Yarnyshnaya Inlet, respectively. A detailed analysis of the granulometric composition of the intertidal zone’s bottom sediments and the content of organic matter are determined for the first time. The study areas are found to differ in the composition of bottom sediments. The organic matter in the Zelenetskaya Inlet averages 0.8, vs 2.2% in the Yarnyshnaya Inlet. Shell formation is determined by adaptations to living conditions, also reflecting the different size and age structure of M. arenaria populations. Among the mollusks of older age groups, the shell grows allometrically, following the principle of weak negative allometry, vs. isometrically among young individuals.

The distributions of all eight subgenera and 52 species of the large southern Palearctic genus Allopsontus are analyzed. Species of this genus are found mainly in open foothill and mountain habitats with steppe vegetation and rocky-gravelly substrates. The general distribution range of the genus lies within the Scythian (steppe), Sahara-Gobi (desert), European and Stenopean (broadleaf’s), as well as Mediterranean-Macaronesian and Ortrian (evergreen) regions of the Palearctic. The species of the nominative and most species-rich subgenus occupy most of the range of the genus. Phylogenetically, from the relatively primitive subgenus Kaplinilis to the most specialized subgenus Machilanus, there is a tendency to shift the ranges of the subgenera from north to south, which is accompanied by a shift in their habitats from the lower mountain belts to the upper ones with a rocky substrate. The center of subgeneric diversity of the genus Allopsontus is located in the mountains of the older Ural-Mongolian mountain system, whence its species could have spread to the mountains of the younger Alpine-Himalayan belt.

The Sandhill crane has become a common to abundant breeding species in 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 can assist competition to the stenotopic Siberian crane which is classified as a Critically Endangered species by the 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 to 2021. 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 QantumGIS 3.16.5 software. The overlapping area of both crane species expanded significantly in 2020 to 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 one disappeared. The Siberian crane disappeared from the western part of the Kolyma Lowland and the Kolyma Delta, where a 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. 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 2.086 individuals in the surveyed areas.

An analysis of the video films taken at a Baikal seal rookery in 2011–2021 on the Long Island, Ushkany Islands, northern Lake Baikal, showed that the total number and time of the emergence of animals on the shore were determined by the time of the disappearance of ice in the northern part of the lake. Yet, regardless of the ice regime, a significant part of the animals (up to 80%) leaving land continued molting. At the same time, the nature of molting (its topology) was disturbed in the vast majority of cases, molting being diffuse in character, often with elements of pathological manifestations. The number of molting individuals (in %) decreased by autumn, but still remained large, even though such dynamics were observed not every year. Incomplete molting did not interfere with animals’ fattening, as most seals were well or very well fed (especially by autumn), with individuals leaving the rookery immediately after the disappearance of ice also being well fat. At the same time, animals in coastal haulouts showed pathologies of the skin and hairline annually, the occurrence of which was probably associated, among other things, with abnormal molting. A large number of animals seem to leave for wintering with an incomplete molt, with their further fate being unknown. The data obtained indicate that disturbing the dormancy of molting seals on rookeries is inadmissible, since the excessive factor of disturbance (observed at the rookery at the present time) can play significant negative roles through affecting the physical condition (health) of animals.

Seven new characters were revealed in 722 molars of the Japanese mouse, Apodemus speciosus, from the Kunashir Island, Kuriles. The absence from the Kunashir population of characters previously identified for the Japanese mouse from the island of Honshu, Japan, both Recent and fossil (Holocene, Middle and Late Pleistocene), as well as the stabilization of new traits, indicates either the Kunashir population could have passed through sharp declines in numbers or a small number of founders, or a new type of nutrition. New features of the molars of the mice supplement the list of the morphological and morphometric characteristics of the Japanese mouse and can serve as the basis for clarifying the morphological features of A. s. ainu, as well as to continue the study of the populations from Hokkaido and the small islands adjacent to it.